# Patent

## Title
Immunogenic compositions of Staphylococcus epidermidis polypeptide antigens

## Abstract

The present invention relates to immunogenic compositions, comprising polypeptides isolated from Staphylococcus epidermidis. The invention also relates to polynucleotides encoding Staphylococcus epidermidis polypeptides and their use in immunogenic compostions. In addition, the invention relates to methods of inducing an immune response in mammals against Staphylococcus epidermidis and Staphylococcus aureus using immunogenic compostions of the Staphylococcus epidermidis polypeptides and polynucleotides. The invention also relates to methods for detecting Staphylococcus epidermidis in a biological sample.

## Background
This application is a National Stage application filed under 35U.S.C. §371 from PCT International Application No. PCT/US05/037746, filed on Oct. 19, 2005, which claims the benefit under 35 U.S.C. §119 (e) of U.S. Provisional Application No. 60/620,788, filed on Oct. 21, 2004, the entire disclosures of which are hereby incorporated by reference in their entirety.


FIELD OF THE INVENTION
The present invention relates to immunogenic compositions, comprising polypeptides isolated from Staphylococcus epidermidis. The invention also relates to polynucleotides encoding Staphylococcus epidermidis polypeptides and their use in immunogenic compositions. In addition, the invention relates to methods of inducing an immune response in mammals against Staphylococcus epidermidis and Staphylococcus aureus using immunogenic compositions of the Staphylococcus epidermidis polypeptides and polynucleotides. The invention also relates to methods for detecting Staphylococcus epidermidis in a biological sample.
BACKGROUND OF THE INVENTION
Staphylococcus epidermidis is a major component of the normal human microbial flora on the skin and mucous membranes and was once considered only a contaminant when cultured from an infected patient. See Heilmann, C. and G. Peters, Biology and pathogenicity of Staphylococcus epidermidis, in Gram-positive pathogens, V. A. Fischetti, Editor. 2000, American Society for Microbiology: Washington, D.C. p. 442-449; von Eiff, C., et al., Lancet Infect Dis, 2(11): p. 677-85 (2002). It is now widely accepted to be an opportunistic pathogen of great importance and a leading cause of nosocomial bloodstream infections. See Am J Infect Control, 27: p. 520-32 (1999); Diekema, D. J., et al., Int J Antimicrob Agents, 20(6): p. 412-8 (2002); Edmond, M. B., et al., Clin Infect Dis, 29(2): p. 239-44 (1999). These infections are primarily associated with the presence of an indwelling foreign polymer body such as a venous catheter, prosthetic joint or prosthetic heart valve. See Heilmann, C. and G. Peters, Biology and pathogenicity of Staphylococcus epidermidis, in Gram-positive pathogens, V. A. Fischetti, Editor. 2000, American Society for Microbiology: Washington, D.C. p. 442-449; von Eiff, C., et al., Lancet Infect Dis, 2(11): p. 677-85 (2002). Infection is thought to result from introduction of Staphylcoccus epidermidis from the patient's skin upon insertion of the prosthetic device. Colonization and subsequent biofilm formation can lead to bacteremia with the potential for hematogenous spread to other sites in the body. These infections are often difficult to treat, arising from the reduced killing of bacteria within a biofilm by antibiotics and also an increase in antibiotic resistance among clinical isolates. See Diekema, D. J., et al., Int J Antimicrob Agents, 20(6): p. 412-8 (2002); Edmond, M. B., et al., Clin Infect Dis, 29(2): p. 239-44 (1999); Lewis, K., Antimicrob Agents Chemother, 45(4): p. 999-1007 (2001); Raad, I. et al., Clin Infect Dis, 26(5): p.1182-7 (1998). Staphylcoccus epidermidis with reduced susceptibility to vancomycin have been reported. See Sanyal, D. and D. Greenwood, J Med Microbiol, 39(3): p. 204-10(1993); Sanyal, D., et al., Lancet, 337(8732): p. 54(1991). Difficulty treating these infections necessitates the use of immunization as a means to prevent infection.
Biofilm formation is a major virulence determinant for Staphylcoccus epidermidis infections. Consequently, research on Staphylcoccus epidermidis surface proteins has focused on those proteins involved in biofilm formation. These proteins have been subdivided into groups based on their involvement in the two major steps of biofilm formation: 1) primary attachment, staphylococca; surface protein-1 (SSP-1), autolysin (AtIE), Fbe (SdrG) and GehD and 2) bacterial cell accumulation, Bap homologous protein (Bhp), accumulation associated protein (AAP) and autolysin (AtIE). See von Eiff, C., et a., Lancet Infect Dis, 2002. 2(11): p. 677-85; Vuong, C., et al., J Infect Dis, 188(5): p. 706-18 (2003); Veenstra, G. J., et al., J Bacteriol., 178(2): p. 537-41 (1996); Rupp, M. E., et al., J Infect Dis, 183(7): p. 1038-42 (2001); Hussain, M., et al., Infect Immun, 65(2): p. 519-24 (1997); Nilsson, M., et al., Infect Immun, 66(6): p. 2666-73 (1998); Davis, S. L., et al., J Biol Chem, 276(30): p. 27799-805 (2001); and Bowden, M. G., et al., J Biol Chem, 277(45): p. 43017-43023 (2002). Comparatively less effort has been exerted towards the identification of surface proteins expressed upon exposure to the environmental cues within the host or those involved in host-parasite interactions.
Staphylcoccus epidermidis must undergo a transition from commensal to pathogen and adapt to its microenvironment within the host. For a commensal to transition to a pathogen it must gain access to host tissue, sense changes in its environment, alter gene expression so that it is able to evade host defenses, attach and adhere to host factors, grow and divide in the presence of different nutrients and host defenses. Proteins on the bacterial surface make initial contact with the new environment within the host. The many functions of these proteins include sensing the environment, scavenging and transporting nutrients, defending against the host immune system and binding host proteins. Surface exposed proteins can also serve as points of contact or recognition by the host immune system and can be targets for a humoral immune response against the bacterium. Josefsson, E., et al., J Infect Dis, 184(12): p. 1572-80 (2001); Swiatlo, E., et al., Infect Immun, 71(12): p. 7149-53 (2003); Grifantini, R., et al., Nat Biotechnol, 20(9): p. 914-21 (2002). Thus, there is an immediate need for identifying promising candidates among Staphylococcus epidermidis proteins for use in immunogenic compositions that induce immune responses to disease causing serotypes of Staphylococcus epidermidis. 
SUMMARY OF THE INVENTION
The present invention provides an immunogenic composition comprising a polypeptide having an amino acid sequence chosen from one or more of SEQ ID NO: 1 through SEQ ID NO: 32, a biological equivalent thereof, or a fragment thereof. In a particular embodiment, the polypeptide is immunoreactive with antibodies in the serum of rabbits infected with Staphylococcus epidermidis. In another embodiment, the polypeptide binds to one or more rabbit serum proteins.
In certain embodiments, the immunogenic composition further comprises a pharmaceutically acceptable carrier. In other embodiments, the immunogenic compositions of the invention also comprise one or more adjuvants. In still another embodiment, the immunogenic composition further comprises a Staphylococcus epidermidis polysaccharide antigen. In still another embodiment, the immunogenic composition further comprises a Staphylococcus aureus polysaccharide or polypeptide antigen.
The present invention provides immunogenic compositions, comprising a polypeptide isolated from Staphylococcus epidermidis. 
The present invention provides an immunogenic composition comprising a Staphylococcus epidermidis polypeptide wherein the polypeptide further comprises heterologous amino acids. In a particular embodiment, the polypeptide is a fusion polypeptide. In another embodiment, the polypeptide is a recombinant polypeptide. In still another embodiment, the invention provides an immunogenic composition comprising a Staphylococcus epidermidis polypeptide wherein the polypeptide comprises a neutralizing epitope of Staphylococcus epidermidis. In a certain embodiment, the polypeptide is a lipoprotein.
The present invention further provides immunogenic compositions, comprising a Staphylococcus epidermidis polypeptide, wherein the polypeptide is encoded by a polynucleotide comprising a nucleotide sequence having at least about 95% identity to a nucleotide sequence chosen from one of SEQ ID NO: 33 through SEQ ID NO: 64 or a degenerate variant thereof, or a fragment thereof. In a particular embodiment, the Staphylococcus epidermidis polynucleotide sequence is selected from the group consisting of SEQ ID NO: 40, SEQ ID NO: 42, SEQ ID NO: 43, SEQ ID NO: 44, SEQ ID NO: 46, SEQ ID NO: 50, SEQ ID NO: 51, SEQ ID NO: 52, SEQ ID NO: 55, SEQ ID NO: 58, SEQ ID NO: 59, and SEQ ID NO: 62, or a degenerate variant thereof, or a fragment thereof.
The present invention provides an immunogenic composition, wherein the polynucleotide is derived from Staphylococcus epidermidis. In a particular embodiment, the polynucleotide further comprises heterologous nucleotides. In another embodiment, the polynucleotide is in an expression vector. In still another embodiment, the expression vector is plasmid DNA. In a certain embodiment, the polynucleotide is a recombinant polynucleotide. In another embodiment, the polynucleotide is operatively linked to one or more gene expression regulatory elements. In still another embodiment, the polynucleotide directs the expression of a neutralizing epitope of Staphylococcus epidermidis. 
The invention also provides an immunogenic composition comprising a Staphylococcus epidermidis polypeptide encoded by a polynucleotide, wherein the immunogenic composition further comprises a transfection facilitating agent. In a particular embodiment, said transfection facilitating agent is bupivicaine.
The present invention also provides a method of inducing an immune response against Staphylococcus epidermidis comprising administering to a mammal an immunogenic amount of a composition comprising: a polypeptide having an amino acid sequence chosen from one or more of SEQ ID NO: 1 through SEQ ID NO: 32 or a biological equivalent thereof, or a fragment thereof, and a pharmaceutically acceptable carrier.
In addition, the present invention provides a method of inducing an immune response against Staphylococcus epidermidis comprising administering to a mammal an immunogenic amount of a composition comprising: a polynucleotide having a nucleotide sequence chosen from one or more of SEQ ID NO: 33 through SEQ ID NO: 64, a degenerate variant thereof, or a fragment thereof and a pharmaceutically acceptable carrier.
In one embodiment, the invention provides an immunogenic composition comprising a polynucleotide having a nucleotide sequence chosen from one of SEQ ID NO: 33 through SEQ ID NO: 64, a degenerate variant thereof, or a fragment thereof and is comprised in an expression vector. In another embodiment, the polynucleotide is derived from Staphylococcus epidermidis. In still another embodiment the polynucleotide comprises heterologous nucleotides.
In a certain embodiment, the invention provides a method for the detection and/or identification of Staphylococcus epidermidis in a biological sample comprising: (a) contacting the sample with an oligonucleotide probe of a polynucleotide comprising the nucleotide sequence chosen from one of SEQ ID NO:33 through SEQ ID NO: 64, or a degenerate variant thereof, or a fragment thereof, under conditions permitting hybridization; and (b) detecting the presence of hybridization complexes in the sample, wherein hybridization complexes indicate the presence of Staphylococcus epidermidis in the sample.
In other embodiments, the invention provides a method for the detection and/or identification of antibodies to Staphylococcus epidermidis in a biological sample comprising: (a) contacting the sample with a polypeptide comprising an amino acid sequence chosen from one of SEQ ID NO: 1 through SEQ ID NO: 32 or a biological equivalent thereof, or a fragment thereof, under conditions permitting immune complex formation; and detecting the presence of immune complexes in the sample, wherein immune complexes indicate the presence of Streptococcus pneumoniae in the sample.
In a particular embodiment, the immunogenic composition comprises a Staphylococcus epidermidis polypeptide sequence selected from the group consisting of SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 23, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 30, a biological equivalent thereof, or a fragment thereof. In another embodiment, the immunogenic composition comprises a Staphylococcus epidermidis polynucleotide sequence selected from the group consisting of SEQ ID NO: 40, SEQ ID NO: 42, SEQ ID NO: 43, SEQ ID NO: 44, SEQ ID NO: 46, SEQ ID NO: 50, SEQ ID NO: 51, SEQ ID NO: 52, SEQ ID NO: 55, SEQ ID NO: 58, SEQ ID NO: 59, SEQ ID NO: 62, or a degenerate variant thereof, or a fragment thereof.
In yet another embodiment, the invention provides a method of inducing an immune response against Staphylococcus aureus comprising administering to a mammal an immunogenic amount of a composition comprising: a Staphylococcus epidermidis polypeptide sequence selected from the group consisting of SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 23, SEQ ID NO: 26, SEQ ID NO: 27, SEQ ID NO: 30, a biological equivalent thereof, or a fragment thereof.
In a particular embodiment, the invention provides a method of inducing an immune response against Staphylococcus aureus comprising administering to a mammal an immunogenic amount of a composition comprising: a Staphylococcus epidermidis polynucleotide sequence selected from the group consisting of SEQ ID NO: 40, SEQ ID NO: 42, SEQ ID NO: 43, SEQ ID NO: 44, SEQ ID NO: 46, SEQ ID NO: 50, SEQ ID NO: 51, SEQ ID NO: 52, SEQ ID NO: 55, SEQ ID NO: 58, SEQ ID NO: 59, SEQ ID NO: 62, or a degenerate variant thereof, or a fragment thereof.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 depicts protein expression profiles of cell wall fractions from S. epidermidis 0-47 grown in TSB (1A and 1C) or 70% rabbit serum (1B and 1D), which were compared by 2D gel electrophoresis. Proteins were separated on pH 4-7 IPG strips in the first dimension followed by SDS-PAGE in the second dimension, transferred to nitrocellulose and detected by fluorescent stain (1A and 1C). Immunoreactive proteins were visualized with immune sera (1B and 1D) from rabbits infected with S. epidermidis 0-47. Molecular weight markers are labeled to the left.
FIG. 2 depicts fluorescent stained blot (2A) and immunoblot (2B) of a cell surface fraction from S. epidermidis 0-47 grown in 70% rabbit serum separated on pH 4-7 IPG strips in the first dimension and SDS-PAGE in the second dimension. The proteins in the spots were identified by mass spec analysis.
FIG. 3 depicts proteins, which were eluted from the surface of S. epidermidis 0-47 grown in TSB or 70% rabbit serum with increasing concentrations of NaCl or 4.OM urea. Asteriks indicate enriched proteins eluted from the surface of S. Epi grown in the presence of serum. Bacteria were washed 3× with TBS then sequentially with 0.5 M and 1.0 M NaCl and 4.0 M urea. Protein concentrations were determined for each of the samples and 0.75 μg was run on a 4-20% gradient gel. No protein was detected by protein assay in the samples eluted from the surface of TSB-grown bacteria (lanes 2-5), so 25 μl was loaded onto the gel. Lane 1, rabbit serum; Lanes 2 and 6—0.15M NaCl eluate; Lanes 3 and 7—0.5M NaCl, Lanes 4 and 8—1.0 M NaCl; Lane 5 and 9—4.0 M urea.
FIG. 4 depicts a 2D transfer of cell surface proteins from S. epidermidis, which was fluorescently stained for protein (4A) and probed with biotinylated serum proteins (4B) eluted from S. epidermidis grown in 70% rabbit serum. The spots were visualized with a streptavidin-alkaline phosphatase conjugate. The proteins in the spots were identified by mass spectroscopy.



DETAILED DESCRIPTION OF THE INVENTION
Upon exposure to the bloodstream of the host, invading bacteria encounter environmental cues specific to the new environment. These cues are detected by the bacteria and signal adaptive changes in protein expression that may be detectable in cell wall purified proteins. Often, proteins and carbohydrates at the bacterial cell wall are candidates for inclusion in immunogenic compositions for treating or preventing bacterial infections. Whether an upregulated protein interacts with the host or plays a role in nutrient acquisition, it is important to the bacteria and therefore plays a role in survival of the bacteria and pathogenesis. Growth of bacteria in body fluids (ie. serum, peritoneal dialysate fluid, and urine) has been used as a model system to mimic some of the signals bacteria encounter within the host. See Wiltshire, M. D. and S. J. Foster, Infect Immun, 69(8): p. 5198-202 (2001); Shepard, B. D. and M. S. Gilmore, Infect Immun, 70(8): p. 4344-52 (2002); Smith, D. G., et al., Infect Immun, 59(2): p. 617-24 (1991); McDermid, K. P., et al., Infect Immun, 61(5): p.1743-9 (1993). One or more of these culture conditions was found to alter gene expression in Enterococcus faecalis, S. aureus and Staphylcoccus epidermidis and those proteins identified as being increased in expression in the altered culture conditions were found to belong to different classes of proteins having a variety of functions. See Wiltshire, M. D. and S. J. Foster, Infect Immun, 69(8): p. 5198-202 (2001); Shepard, B. D. and M.S. Gilmore, Infect Immun, 70(8): p. 4344-52 (2002).
The most common predisposing factor for a Staphylcoccus epidermidis infection is the implantation of a prosthetic device. An implanted prosthetic device becomes coated with plasma and matrix proteins including fibrinogen, vitronectin, von Willebrand factor and fibronectin. See von Eiff, C., et al., Eur J Clin Microbiol Infect Dis, 18(12): p. 843-6 (1999). These proteins often act as ligands for Staphylococcal epidermidis surface proteins, thus allowing the bacteria to bind and colonize the prosthetic device. Staphylcoccus epidermidis is known to express proteins that bind to fibrinogen, vitronectin and fibronectin. See Nilsson, M., et al., A fibrinogen-binding protein of Staphylococcus epidermidis. Infect Immun, 66(6), p. 2666-73 (1998); Davis, S. L., et al., J Biol Chem, 276(30), p. 27799-805 (2001); Williams, R. J., et al., Infect Immun, 70(12), p. 6805-10 (2002); Heilmann, C., et al., Mol Microbiol, 24(5), p. 1013-24 (1997). It is reasonable to expect that Staphylcoccus epidermidis will bind additional serum proteins in making the transition from commensal to pathogen.
The invention described hereinafter addresses the need for Staphylococcus epidermidis immunogenic compositions that effectively prevent or treat most or all of the disease caused by serotypes of Staphylococcus epidermidis. The invention further addresses the need for methods of diagnosing Staphylococcus epidermidis infection. The present invention has identified Staphylococcus epidermidis open reading frames, hereinafter ORFs, which encode antigenic polypeptides. More particularly, the Staphylococcus epidermidis ORFs encode polypeptides that serve as potential antigenic polypeptides in immunogenic compositions. In certain embodiments, the invention comprises Staphylococcus epidermidis polynucleotide ORFs encoding surface localized, exposed, secreted or membrane associated polypeptide antigens.
In other embodiments, the invention comprises vectors comprising ORF sequences and host cells or animals transformed, transfected or infected with these vectors. The invention also comprises transcriptional gene products of Staphylococcus epidermidis ORFs, such as, for example, mRNA, antisense RNA, antisense oligonucleotides and ribozyme molecules, which can be used to inhibit or control growth of the microorganism. The invention relates also to methods of detecting these nucleic acids or polypeptides and kits for diagnosing Staphylococcus epidermidis infection. The invention also relates to immunogenic compositions for the prevention and/or treatment of bacterial infection, in particular infection caused by or exacerbated by Staphylococcus epidermidis. In particular embodiments, the immunogenic compositions are used for the treatment or prevention of systemic diseases, which are induced or exacerbated by Staphylococcus epidermidis. In other embodiments, the immunogenic compositions are used for the treatment or prevention of non-systemic diseases, which are induced or exacerbated by Staphylococcus epidermidis. 
A. Staphylococcus epidermidis ORF Polynucleotides and Polypeptides
Isolated and purified Staphylococcus epidermidis ORF polynucleotides are identified which are used in the production of Staphylococcus epidermidis polypeptides for inclusion in immunogenic compoitions. More specifically, in certain embodiments, the ORFs encode Staphylococcus epidermidis surface localized, exposed, membrane associated or secreted polypeptides, particularly antigenic polypeptides. Thus, in one aspect, the present invention identifies isolated and purified polynucleotides (ORFs) that encode Staphylococcus epidermidis surface localized, exposed, membrane associated or secreted polypeptides for inclusion in immunogenic compositions. In particular embodiments, a polynucleotide of the present invention is a DNA molecule, wherein the DNA may be genomic DNA, chromosomal DNA, plasmid DNA or cDNA. In another embodiment, a polynucleotide is a recombinant polynucleotide, which encodes a Staphylococcus epidermidis polypeptide comprising an amino acid sequence that has at least 95% identity to an amino acid sequence of one of SEQ ID NO: 1 through SEQ ID NO: 32 or a fragment thereof. In another embodiment, an isolated and purified ORF polynucleotide comprises a nucleotide sequence that has at least 95% identity to one of the ORF nucleotide sequences of SEQ ID NO: 33 through SEQ ID NO: 64, a degenerate variant thereof, or a complement thereof. In one embodiment, an ORF polynucleotide of one of SEQ ID NO: 33 through SEQ ID NO: 64 is comprised in a plasmid vector and expressed in a prokaryotic host cell.
As used hereinafter, the term “polynucleotide” means a sequence of nucleotides connected by phosphodiester linkages. Polynucleotides are presented hereinafter in the direction from the 5′ to the 3′ direction. A polynucleotide of the present invention can comprise from about 10 to about several hundred thousand base pairs. In one embodiment, a polynucleotide comprises from about 10 to about 3,000 base pairs. Example lengths of particular polynucleotide are set forth hereinafter.
A polynucleotide as described herein can be a deoxyribonucleic acid (DNA) molecule, a ribonucleic acid (RNA) molecule, or analogs of the DNA or RNA generated using nucleotide analogs. The nucleic acid molecule can be single-stranded or double-stranded, but preferably is double-stranded DNA. Where a polynucleotide is a DNA molecule, that molecule can be a gene, a cDNA molecule or a genomic DNA molecule. Nucleotide bases are indicated hereinafter by a single letter code: adenine (A), guanine (G), thymine (T), cytosine (C), inosine (I) and uracil (U).
“Isolated” means altered “by the hand of man” from the natural state. If a composition or substance occurs in nature, in order for it to be considered “Isolated” it must have been changed or removed from its original environment, or both. For example, a polynucleotide or a polypeptide naturally present in a living animal is not “isolated,” but the same polynucleotide or polypeptide separated from the coexisting materials of its natural state is “isolated,” as the term is employed hereinafter.
As used herein, an “isolated” polynucleotide is free of sequences which naturally flank the nucleic acid (i.e., sequences located at the 5′ and 3′ ends of the nucleic acid) in the genomic DNA of the organism from which the nucleic acid is derived. For example, in various embodiments, the isolated Staphylococcus epidermidis nucleic acid molecule can contain less than about 5 kb, 4 kb, 3 kb, 2 kb, 1 kb, 0.5 kb or 0.1 kb of nucleotide sequences which naturally flank the nucleic acid molecule in genomic DNA of the cell from which the nucleic acid is derived. However, the Staphylococcus epidermidis nucleic acid molecule can be fused to other protein encoding or regulatory sequences and still be considered isolated.
ORF polynucleotides and thus the polypeptides described herein may be obtained using standard cloning and screening techniques from a cDNA library derived from mRNA. Polynucleotides of the invention can also be obtained from natural sources such as genomic DNA libraries (e.g., a Staphylococcus epidermidis library) or can be synthesized using well known and commercially available techniques.
Also encompassed herein are nucleic acid molecules that differ from the nucleotide sequences shown in SEQ ID NO:33 through SEQ ID NO:64 (and fragments thereof) due to degeneracy of the genetic code and thus encode the same Staphylococcus epidermidis polypeptide as that encoded by the nucleotide sequence shown in SEQ ID NO:33 through SEQ ID NO:64.
Orthologues and allelic variants of the Staphylococcus epidermidis polynucleotides can readily be identified using methods well known in the art. Allelic variants and orthologues of the polynucleotides will comprise a nucleotide sequence that is typically at least about 70-75%, more typically at least about 80-85%, and most typically at least about 90-95% or more homologous to the nucleotide sequence shown in SEQ ID NO:33 through SEQ ID NO:64, or a fragment of these nucleotide sequences. Such nucleic acid molecules can readily be identified as being able to hybridize under stringent conditions, to the nucleotide sequence shown in SEQ ID NO:33 through SEQ ID NO:64, or a fragment of these nucleotide sequences.
Moreover, the polynucleotides can comprise only a fragment of the coding region of a Staphylococcus epidermidis polynucleotide or gene, such as a fragment of one of SEQ ID NO:33 through SEQ ID NO:64. In certain embodiments, such fragments encode immunogenic fragments.
When these Staphylococcus epidermidis ORF polynucleotides of the invention are used for the recombinant production of Staphylococcus epidermidis polypeptides for inclusion in immunogenic compositions, the polynucleotide may include the coding sequence for the mature polypeptide, by itself, or the coding sequence for the mature polypeptide in reading frame with other coding sequences, such as those encoding a leader or secretory sequence, a pre-, or pro- or prepro-protein sequence, or other fusion peptide portions. For example, a marker sequence which facilitates purification of the fused polypeptide can be linked to the coding sequence (see Gentz et al., Proc. Natl. Acad. Sci. USA, 86:821-824, 1989, incorporated by reference hereinafter in its entirety). Thus, contemplated herein is the preparation of polynucleotides encoding fusion polypeptides permitting His-tag purification of expression products. The polynucleotide may also contain non-coding 5′ and 3′ sequences, such as transcribed, non-translated sequences, splicing and polyadenylation signals.
Thus, a polynucleotide encoding a polypeptide for inclusion in immunogenic compositions of the present invention, including homologs and orthologs from species other than Staphylococcus epidermidis, such as Staphylococcus aureus may be obtained by a process which comprises the steps of screening an appropriate library under stringent hybridization conditions with a labeled probe having the sequence of one of SEQ ID NO:33 through SEQ ID NO:64, a fragment thereof; and isolating full-length cDNA and genomic clones containing the polynucleotide sequence. Such hybridization techniques are well known to the skilled artisan. The skilled artisan will appreciate that, in many cases, an isolated cDNA sequence will be incomplete, in that the region coding for the polypeptide is cut short at the 5′ end of the cDNA. This is a consequence of reverse transcriptase, an enzyme with inherently low “processivity” (a measure of the ability of the enzyme to remain attached to the template during the polymerization reaction), failing to complete a DNA copy of the mRNA template during first strand cDNA synthesis.
Thus, in certain embodiments, the polynucleotide sequence information provided herein allows for the preparation of relatively short DNA (or RNA) oligonucleotide sequences having the ability to specifically hybridize to gene sequences of the selected polynucleotides disclosed hereinafter. The term “oligonucleotide” as used hereinafter is defined as a molecule comprised of two or more deoxyribonucleotides or ribonucleotides, usually more than three (3), and typically more than ten (10) and up to one hundred (100) or more (although preferably between twenty and thirty). The exact size will depend on many factors, which in turn depends on the ultimate function or use of the oligonucleotide. Thus, in particular embodiments, nucleic acid probes of an appropriate length are prepared based on a consideration of a selected nucleotide sequence, e.g., a sequence such as that shown in SEQ ID NO:33 through SEQ ID NO:64. The ability of such nucleic acid probes to specifically hybridize to a polynucleotide encoding a Staphylococcus epidermidis polypeptide lends them particular utility in a variety of embodiments. Most importantly, the probes can be used in a variety of assays for detecting the presence of complementary sequences in a given sample.
In certain embodiments, it is advantageous to use oligonucleotide primers. These primers may be generated in any manner, including chemical synthesis, DNA replication, reverse transcription, or a combination thereof. The sequence of such primers is designed using a polynucleotide described herein for use in detecting, amplifying or mutating a defined segment of an ORF polynucleotide that encodes a Staphylococcus epidermidis polypeptide from prokaryotic cells using polymerase chain reaction (PCR) technology.
In certain embodiments, it is advantageous to employ a polynucleotide described herein in combination with an appropriate label for detecting hybrid formation. A wide variety of appropriate labels are known in the art, including radioactive, enzymatic or other ligands, such as avidin/biotin, which are capable of giving a detectable signal.
Polynucleotides which are identical or sufficiently identical to a nucleotide sequence contained in one of SEQ ID NO:33 through SEQ ID NO:64, or a fragment thereof, may be used as hybridization probes for cDNA and genomnic DNA or as primers for a nucleic acid amplification (PCR) reaction, to isolate full-length cDNAs and genomic clones encoding polypeptides described herein and to isolate cDNA and genomic clones of other genes (including genes encoding homologs and orthologs from species other than Staphylococcus epidermidis) that have a high sequence similarity to the polynucleotide sequences set forth in of SEQ ID NO:33 through SEQ ID NO:64, or a fragment thereof. Typically these nucleotide sequences are from at least about 70% identical to at least about 95% identical to that of the reference polynucleotide sequence. The probes or primers will generally comprise at least 15 nucleotides, preferably, at least 30 nucleotides and may have at least 50 nucleotides. Particularly preferred probes will have between 30 and 50 nucleotides.
There are several methods available and well known to those skilled in the art to obtain full-length cDNAs, or extend short cDNAs, for example those based on the method of Rapid Amplification of cDNA ends (RACE). See Frohman et al., Proc. Natl. Acad. Sci. USA 85, 8998-9002, 1988. Recent modifications of the technique, exemplified by the MarathonTM technology (Clontech Laboratories Inc.) for example, have significantly simplified the search for longer cDNAs. In the MarathonTM technology, cDNAs have been prepared from mRNA extracted from a chosen tissue and an “adaptor” sequence ligated onto each end. Nucleic acid amplification (PCR) is then carried out to amplify the “missing” 5′ end of the cDNA using a combination of gene specific and adaptor specific oligonucleotide primers. The PCR reaction is then repeated using “nested” primers, that is, primers designed to anneal within the amplified product (typically an adaptor specific primer that anneals further 3′ in the adaptor sequence and a gene specific primer that anneals further 5′ in the known gene sequence). The products of this reaction can then be analyzed by DNA sequencing and a full-length cDNA constructed either by joining the product directly to the existing cDNA to give a complete sequence, or carrying out a separate full-length PCR using the new sequence information for the design of the 5′ primer.
To provide certain of the advantages in accordance with the present invention, a preferred nucleic acid sequence employed for hybridization studies or assays includes probe molecules that are complementary to at least a 10 to about 70 nucleotides long stretch of a polynucleotide that encodes a Staphylococcus epidermidis polypeptide, such as that shown in one of SEQ ID NO:33 through SEQ ID NO:64. A size of at least 10 nucleotides in length helps to ensure that the fragment will be of sufficient length to form a duplex molecule that is both stable and selective. Molecules having complementary sequences over stretches greater than 10 bases in length are generally preferred, though, in order to increase stability and selectivity of the hybrid, and thereby improve the quality and degree of specific hybrid molecules obtained. One will generally prefer to design nucleic acid molecules having gene-complementary stretches of 25 to 40 nucleotides, 55 to 70 nucleotides, or even longer where desired. Such fragments can be readily prepared by, for example, directly synthesizing the fragment by chemical means, by application of nucleic acid reproduction technology, such as the PCR technology of (U.S. Pat. No. 4,683,202, incorporated hereinafter by reference) or by excising selected DNA fragments from recombinant plasmids containing appropriate inserts and suitable restriction enzyme sites.
In another embodiment, it is contemplated that an isolated and purified polynucleotide comprises a nucleotide sequence that is identical or complementary to a segment of at least 10 contiguous bases of one of SEQ ID NO:33 through SEQ ID NO:64, wherein the polynucleotide hybridizes to a polynucleotide that encodes a Staphylococcus epidermidis polypeptide. Preferably, the isolated and purified polynucleotide comprises a base sequence that is identical or complementary to a segment of at least 25 to about 70 contiguous bases of one of SEQ ID NO:33 through SEQ ID NO:64. For example, the polynucleotide can comprise a segment of bases identical or complementary to 40 or 55 contiguous bases of the disclosed nucleotide sequences.
Accordingly, a polynucleotide probe molecule can be used for its ability to selectively form duplex molecules with complementary stretches of the gene. Depending on the application envisioned, one will desire to employ varying conditions of hybridization to achieve varying degree of selectivity of the probe toward the target sequence (see Table 1 below). For applications requiring a high degree of selectivity, one will typically desire to employ relatively stringent conditions to form the hybrids. For some applications, for example, where one desires to prepare mutants employing a mutant primer strand hybridized to an underlying template or where one seeks to isolate a Staphylococcus epidermidis homologous polypeptide coding sequence from other cells, functional equivalents, or the like, less stringent hybridization conditions are typically needed to allow formation of the heteroduplex (see Table 1). Cross-hybridizing species can thereby be readily identified as positively hybridizing signals with respect to control hybridizations. Thus, hybridization conditions are readily manipulated, and thus will generally be a method of choice depending on the desired results.
For some applications, for example, where one desires to prepare mutants employing a mutant primer strand hybridized to an underlying template or where one seeks to isolate a homologous polypeptide coding sequence from other cells, functional equivalents, or the like, less stringent hybridization conditions are typically needed to allow formation of the heteroduplex. Cross-hybridizing species are thereby readily identified as positively hybridizing signals with respect to control hybridizations. In any case, it is generally appreciated that conditions can be rendered more stringent by the addition of increasing amounts of formamide, which serves to destabilize the hybrid duplex in the same manner as increased temperature. Thus, hybridization conditions are readily manipulated, and thus will generally be a method of choice depending on the desired results.
Also described herein are polynucleotides capable of hybridizing under reduced stringency conditions, more preferably stringent conditions, and most preferably highly stringent conditions, to polynucleotides described hereinafter. Examples of stringency conditions are shown in Table 1 below: highly stringent conditions are those that are at least as stringent as, for example, conditions A-F; stringent conditions are at least as stringent as, for example, conditions G-L; and reduced stringency conditions are at least as stringent as, for example, conditions M-R.







TABLE 1







Stringency Conditions













Hybrid
Hybridization
Wash


Stringency
Polynucleotide
Length
Temperature and
Temperature


Condition
Hybrid
(bp)I
BufferH
and BufferH





A
DNA:DNA
>50
65° C.; 1xSSC -or-
65° C.;





42° C.; 1xSSC, 50%
0.3xSSC





formamide


B
DNA:DNA
<50
TB; 1xSSC
TB; 1xSSC


C
DNA:RNA
>50
67° C.; 1xSSC -or-
67° C.;





45° C.; 1xSSC, 50%
0.3xSSC





formamide


D
DNA:RNA
<50
TD; 1xSSC
TD; 1xSSC


E
RNA:RNA
>50
70° C.; 1xSSC -or-
70° C.;





50° C.; 1xSSC, 50%
0.3xSSC





formamide


F
RNA:RNA
<50
TF; 1xSSC
TF; 1xSSC


G
DNA:DNA
>50
65° C.; 4xSSC -or-
65° C.;





42° C.; 4xSSC, 50%
1xSSC





formamide


H
DNA:DNA
<50
TH; 4xSSC
TH; 4xSSC


I
DNA:RNA
>50
67° C.; 4xSSC -or-
67° C.;





45° C.; 4xSSC, 50%
1xSSC





formamide


J
DNA:RNA
<50
TJ; 4xSSC
TJ; 4xSSC


K
RNA:RNA
>50
70° C.; 4xSSC -or-
67° C.;





50° C.; 4xSSC, 50%
1xSSC





formamide


L
RNA:RNA
<50
TL; 2xSSC
TL; 2xSSC


M
DNA:DNA
>50
50° C.; 4xSSC -or-
50° C.;





40° C.; 6xSSC, 50%
2xSSC





formamide


N
DNA:DNA
<50
TN; 6xSSC
TN; 6xSSC


O
DNA:RNA
>50
55° C.; 4xSSC -or-
55° C.;





42° C.; 6xSSC, 50%
2xSSC





formamide


P
DNA:RNA
<50
TP; 6xSSC
TP; 6xSSC


Q
RNA:RNA
>50
60° C.; 4xSSC -or-
60° C.;





45° C.; 6xSSC, 50%
2xSSC





formamide


R
RNA:RNA
<50
TR; 4xSSC
TR; 4xSSC





(bp)I: The hybrid length is that anticipated for the hybridized region(s) of the hybridizing polynucleotides. When hybridizing a polynucleotide to a target polynucleotide of unknown sequence, the hybrid length is assumed to be that of the hybridizing polynucleotide. When polynucleotides of known sequence are hybridized, the hybrid length can be determined by aligning the sequences of the polynucleotides and identifying the region or regions of optimal sequence complementarity.


BufferH: SSPE (1xSSPE is 0.15M NaCl, 10 mM NaH2PO4, and 1.25 mM EDTA, pH 7.4) can be substituted for SSC (1xSSC is 0.15M NaCl and 15 mM sodium citrate) in the hybridization and wash buffers; washes are performed for 15 minutes after hybridization is complete.


TB through TR: The hybridization temperature for hybrids anticipated to be less than 50 base pairs in length should be 5-10° C. less than the melting temperature (Tm) of the hybrid, where Tm is determined according to the following equations. For hybrids less than 18 base pairs in length, Tm(° C.) = 2(# of A + T bases) + 4(# of G + C bases). For hybrids between 18 and 49 base pairs in length,Tm(° C.) = 81.5 + 16.6(log10[Na+]) + 0.41(% G + C) − (600/N), where N is the number of bases in the hybrid, and [Na+] is the concentration of sodium ions in the hybridization buffer ([Na+] for 1xSSC = 0.165 M).






Additional examples of stringency conditions for polynucleotide hybridization are provided in Sambrook et al., 1989, Molecular Cloning: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., chapters 9 and 11, and Ausubel et al., 1995, Current Protocols in Molecular Biology, eds., John Wiley & Sons, Inc., sections 2.10 and 6.3-6.4, incorporated hereinafter by reference.
B. Staphylococcus epidermidis Polypeptides
In particular embodiments, the present invention provides isolated and purified Staphylococcus epidermidis polypeptides for use in immunogenic compositions. Preferably, a Staphylococcus epidermidis polypeptide used in an immunogenic composition of the invention is a recombinant polypeptide. In certain embodiments, a Staphylococcus epidermidis polypeptide comprises the amino acid sequence that has at least 95% identity to the amino acid sequence of one of SEQ ID NO: 1 through SEQ ID NO: 32, a biological equivalent thereof, or a fragment thereof.
A Staphylococcus epidermidis polypeptide used in an immunogenic composition of the present invention encompasses a polypeptide that comprises: 1) the amino acid sequence shown in one of SEQ ID NO: 1 through SEQ ID NO: 32; 2) functional and non-functional naturally occurring variants or biological equivalents of Staphylococcus epidermidis polypeptides of SEQ ID NO: 1 through SEQ ID NO: 32; 3) recombinantly produced variants or biological equivalents of Staphylococcus epidermidis polypeptides of SEQ ID NO: 1 through SEQ ID NO: 32; and 4) polypeptides isolated from organisms other than Staphylococcus epidermidis (orthologues of Staphylococcus epidermidis polypeptides).
A biological equivalent or variant of such a Staphylococcus epidermidis polypeptide encompasses 1) a polypeptide isolated from Staphylococcus epidermidis; and 2) a polypeptide that contains substantially homology to a Staphylococcus epidermidis polypeptide.
Biological equivalents or variants of Staphylococcus epidermidis include both functional and non-functional Staphylococcus epidermidis polypeptides. Functional biological equivalents or variants are naturally occurring amino acid sequence variants of a Staphylococcus epidermidis polypeptide that maintains the ability to elicit an immunological or antigenic response in a subject. Functional variants will typically contain only conservative substitutions of one or more amino acids of one of SEQ ID NO: 1 through SEQ ID NO: 32, or substitution, deletion or insertion of non-critical residues in non-critical regions of the polypeptide (e.g., not in regions containing antigenic determinants or protective epitopes).
The present invention further provides non-Staphylococcus epidermidis orthologues of Staphylococcus epidermidis polypeptides. Orthologues of Staphylococcus epidermidis polypeptides are polypeptides that are isolated from non-Staphylococcus epidermidis organisms and possess antigenic capabilities of the Staphylococcus epidermidis polypeptide. Orthologues of a Staphylococcus epidermidis polypeptide can readily be identified as comprising an amino acid sequence that is substantially homologous to one of SEQ ID NO: 1 through SEQ ID NO: 32.
Modifications and changes can be made in the structure of a polypeptide of the present invention and still obtain a molecule having Staphylococcus epidermidis antigenicity. For example, certain amino acids can be substituted for other amino acids in a sequence without appreciable loss of antigenicity. Because it is the interactive capacity and nature of a polypeptide that defines that polypeptide's biological functional activity, certain amino acid sequence substitutions can be made in a polypeptide sequence (or, of course, its underlying DNA coding sequence) and nevertheless obtain a polypeptide with like properties.
In making such changes, the hydropathic index of amino acids can be considered. The importance of the hydropathic amino acid index in conferring interactive biologic function on a polypeptide is generally understood in the art (Kyte and Doolittle, J Mol Biol, 157: p. 105-132, 1982). It is known that certain amino acids can be substituted for other amino acids having a similar hydropathic index or score and still result in a polypeptide with similar biological activity. Each amino acid has been assigned a hydropathic index on the basis of its hydrophobicity and charge characteristics. Those indices are: isoleucine (+4.5); valine (+4.2); leucine (+3.8); phenylalanine (+2.8); cysteine/cystine (+2.5); methionine (+1.9); alanine (+1.8); glycine (−0.4); threonine (−0.7); serine (−0.8); tryptophan (−0.9); tyrosine (−1.3); proline (−1.6); histidine (−3.2); glutamate (−3.5); glutamine (−3.5); aspartate (−3.5); asparagine (−3.5); lysine (−3.9); and arginine (−4.5).
It is believed that the relative hydropathic character of the amino acid residue determines the secondary and tertiary structure of the resultant polypeptide, which in turn defines the interaction of the polypeptide with other molecules, such as enzymes, substrates, receptors, antibodies, antigens, and the like. It is known in the art that an amino acid can be substituted by another amino acid having a similar hydropathic index and still obtain a functionally equivalent polypeptide. In such changes, the substitution of amino acids whose hydropathic indices are within +/−2 is preferred, those that are within +/−1 are particularly preferred, and those within +/−0.5 are even more particularly preferred.
Substitution of like amino acids can also be made on the basis of hydrophilicity, particularly where the biological functional equivalent polypeptide or peptide thereby created is intended for use in immunological embodiments. U.S. Pat. No. 4,554,101, incorporated hereinafter by reference, states that the greatest local average hydrophilicity of a polypeptide, as governed by the hydrophilicity of its adjacent amino acids, correlates with its immunogenicity and antigenicity, i.e. with a biological property of the polypeptide.
As detailed in U.S. Pat. No. 4,554,101, the following hydrophilicity values have been assigned to amino acid residues: arginine (+3.0); lysine (+3.0); aspartate (+3.0±1); glutamate (+3.0±1); serine (+0.3); asparagine (+0.2); glutamine (+0.2); glycine (0); proline (−0.5±1); threonine (−0.4); alanine (−0.5); histidine (−0.5); cysteine (−1.0); methionine (−1.3); valine (−1.5); leucine (−1.8); isoleucine (−1.8); tyrosine (−2.3); phenylalanine (−2.5); tryptophan (−3.4). It is understood that an amino acid can be substituted for another having a similar hydrophilicity value and still obtain a biologically equivalent, and in particular, an immunologically equivalent polypeptide. In such changes, the substitution of amino acids whose hydrophilicity values are within ±2 is preferred, those that are within ±1 are particularly preferred, and those within ±0.5 are even more particularly preferred.
As outlined above, amino acid substitutions are generally therefore based on the relative similarity of the amino acid side-chain substituents, for example, their hydrophobicity, hydrophilicity, charge, size, and the like. Exemplary substitutions which take various of the foregoing characteristics into consideration are well known to those of skill in the art and include: arginine and lysine; glutamate and aspartate; serine and threonine; glutamine and asparagine; and valine, leucine and isoleucine (See Table 2, below). The present invention thus contemplates immunogenic compositions comprising functional or biological equivalents of a Staphylococcus epidermidis polypeptide as set forth above.







TABLE 2







Amino Acid Substitutions










Original
Exemplary Residue



Residue
Substitution







Ala
Gly; Ser



Arg
Lys



Asn
Gln; His



Asp
Glu



Cys
Ser



Gln
Asn



Glu
Asp



Gly
Ala



His
Asn; Gln



Ile
Leu; Val



Leu
Ile; Val



Lys
Arg



Met
Leu; Tyr



Ser
Thr



Thr
Ser



Trp
Tyr



Tyr
Trp; Phe



Val
Ile; Leu










Biological or functional equivalents of a polypeptide can also be prepared using site-specific mutagenesis. Site-specific mutagenesis is a technique useful in the preparation of second generation polypeptides, or biologically functional equivalent polypeptides or peptides, derived from the sequences thereof, through specific mutagenesis of the encoding DNA. As noted above, such changes can be desirable where amino acid substitutions are desirable. The technique further provides a ready ability to prepare and test sequence variants, for example, incorporating one or more of the foregoing considerations, by introducing one or more nucleotide sequence changes into the DNA. Site-specific mutagenesis allows the production of mutants through the use of specific oligonucleotide sequences which encode the DNA sequence of the desired mutation, as well as a sufficient number of adjacent nucleotides, to provide a primer sequence of sufficient size and sequence complexity to form a stable duplex on both sides of the deletion junction being traversed. Typically, a primer of about 17 to 25 nucleotides in length is preferred, with about 5 to 10 residues on both sides of the junction of the sequence being altered.
In general, the technique of site-specific mutagenesis is well known in the art. As will be appreciated, the technique typically employs a phage vector which can exist in both a single stranded and double stranded form. Typically, site-directed mutagenesis in accordance herewith is performed by first obtaining a single-stranded vector which includes within its sequence a DNA sequence which encodes all or a portion of the Staphylococcus epidermidis polypeptide sequence selected. An oligonucleotide primer bearing the desired mutated sequence is prepared (e.g., synthetically). This primer is then annealed to the singled-stranded vector, and extended by the use of enzymes such as E. coli polymerase I Klenow fragment, in order to complete the synthesis of the mutation-bearing strand. Thus, a heteroduplex is formed wherein one strand encodes the original non-mutated sequence and the second strand bears the desired mutation. This heteroduplex vector is then used to transform appropriate cells such as E. coli cells and clones are selected which include recombinant vectors bearing the mutation. Commercially available kits come with all the reagents necessary, except the oligonucleotide primers.
A Staphylococcus epidermidis polypeptide or polypeptide antigen used in an immunogenic composition of the present invention is understood to be any Staphylococcus epidermidis polypeptide comprising substantial sequence similarity, structural similarity and/or functional similarity to a Staphylococcus epidermidis polypeptide comprising the amino acid sequence of one of SEQ ID NO: 1 through SEQ ID NO: 32. In addition, such a Staphylococcus epidermidis polypeptide or polypeptide antigen is not limited to a particular source. Thus, the invention provides for the general detection and isolation of the polypeptides from a variety of sources.
It is contemplated in the present invention, that a Staphylococcus epidermidis polypeptide may advantageously be cleaved into fragments for use in further structural or functional analysis, or in the generation of reagents such as Staphylococcus epidermidis-related polypeptides and Staphylococcus epidermidis-specific antibodies. This can be accomplished by treating purified or unpurified Staphylococcus epidermidis polypeptides with a peptidase such as endoproteinase glu-C (Boehringer, Indianapolis, Ind.). Treatment with CNBr is another method by which peptide fragments may be produced from natural Staphylococcus epidermidis polypeptides. Recombinant techniques also can be used to produce specific fragments of a Staphylococcus epidermidis polypeptide.
Fragments of the Staphylococcus epidermidis polypeptides are also included in the immunogenic compositions of the invention. A fragment is a polypeptide having an amino acid sequence that is entirely the same as part, but not all, of the amino acid sequence. The fragment can comprise, for example, at least 7 or more (e.g., 8, 10, 12, 14, 16, 18, 20, or more) contiguous amino acids of an amino acid sequence of one of SEQ ID NO: 1 through SEQ ID NO: 32. Fragments may be “freestanding” or comprised within a larger polypeptide of which they form a part or region, most preferably as a single, continuous region. In one embodiment, the fragments include at least one epitope of the mature polypeptide sequence.
“Fusion protein” refers to a protein or polypeptide encoded by two, often unrelated, fused genes or fragments thereof. For example, fusion proteins or polypeptides comprising various portions of constant region of immunoglobulin molecules together with another human protein or part thereof have been described. In many cases, employing an immunoglobulin Fc region as a part of a fusion protein or polypeptide is advantageous for use in therapy and diagnosis resulting in, for example, improved pharmacokinetic properties (see e.g., International Application EP-A 0232 2621). On the other hand, for some uses it is desirable to be able to delete the Fc part after the fusion protein or polypeptide has been expressed, detected and purified.
It is contemplated that Staphylococcus epidermidis polypeptides may be isolated from Staphylococcus epidermidis or prepared recombinantly as described herein.
C. Staphylococcus epidermidis Polynucleotide and Polypeptide Variants
“Variant” as the term is used hereinafter, is a polynucleotide or polypeptide that differs from a reference polynucleotide or polypeptide respectively, but retains essential properties. A typical variant of a polynucleotide differs in nucleotide sequence from another, reference polynucleotide. Changes in the nucleotide sequence of the variant may or may not alter the amino acid sequence of a polypeptide encoded by the reference polynucleotide. Nucleotide changes may result in amino acid substitutions, additions, deletions, fusions and truncations in the polypeptide encoded by the reference sequence, as discussed below. A typical variant of a polypeptide differs in amino acid sequence from another, reference polypeptide. Generally, differences are limited so that the sequences of the reference polypeptide and the variant are closely similar overall and, in many regions, identical. A variant and reference polypeptide may differ in amino acid sequence by one or more substitutions, additions, deletions in any combination. A substituted or inserted amino acid residue may or may not be one encoded by the genetic code. A variant of a polynucleotide or polypeptide may be a naturally occurring such as an allelic variant, or it may be a variant that is not known to occur naturally. Non-naturally occurring variants of polynucleotides and polypeptides may be made by mutagenesis techniques or by direct synthesis.
“Identity,” as known in the art, is a relationship between two or more polypeptide sequences or two or more polynucleotide sequences, as determined by comparing the sequences. In the art, “identity” also means the degree of sequence relatedness between polypeptide or polynucleotide sequences, as the case may be, as determined by the match between strings of such sequences. “Identity” and “similarity” can be readily calculated by known methods, including but not limited to those described in (Computational Molecular Biology, Lesk, A. M., ed., Oxford University Press, New York, 1988; Biocomputing: Informatics and Genome Projects, Smith, D. W., ed., Academic Press, New York, 1993; Computer Analysis of Sequence Data, Part I, Griffin, A. M., and Griffin, H. G., eds., Humana Press, New Jersey, 1994; Sequence Analysis in Molecular Biology, von Heinje, G., Academic Press, 1987; and Sequence Analysis Primer, Gribskov, M. and Devereux, J., eds., M Stockton Press, New York, 1991; and Carillo, H., and Lipman, D., SIAM J. Applied Math., 48: 1073 (1988). Methods to determine identity are designed to give the largest match between the sequences tested. Methods to determine identity and similarity are codified in publicly available computer programs. Computer program methods to determine identity and similarity between two sequences include, but are not limited to, the GCG program package (Devereux et al., Nucleic Acids Research 12(1):387, 1984), BLASTP, BLASTN, TBLASTN and FASTA (Altschul et al., J. Molec. Biol. 215:403-410,1990). The BLASTX program is publicly available from NCBI and other sources (BLAST Manual, Altschul, S., et al., NCBI NLM NIH Bethesda, Md. 20894; Altschul et al., J. Molec. Biol. 215:403-410, 1990.). The well known Smith-Waterman algorithm may also be used to determine identity.
By way of example, a polynucleotide sequence described herein may be identical to the reference sequence of one of SEQ ID NO: 33 through SEQ ID NO: 64, that is be 100% identical, or it may include up to a certain integer number of nucleotide alterations as compared to the reference sequence. Such alterations are selected from the group consisting of at least one nucleotide deletion, substitution, including transition and transversion, or insertion, and wherein said alterations may occur at the 5′ or 3′ terminal positions of the reference nucleotide sequence or anywhere between those terminal positions, interspersed either individually among the nucleotides in the reference sequence or in one or more contiguous groups within the reference sequence. The number of nucleotide alterations is determined by multiplying the total number of nucleotides in one of SEQ ID NO: 33 through SEQ ID NO: 64 by the numerical percent of the respective percent identity (divided by 100) and subtracting that product from said total number of nucleotides in one of SEQ ID NO: 33 through SEQ ID NO: 64.
For example, an isolated Staphylococcus epidermidis polynucleotide comprising a polynucleotide sequence that has at least 70% identity to the nucleic acid sequence of one of SEQ ID NO: 33 through SEQ ID NO: 64; a degenerate variant thereof or a fragment thereof, wherein the polynucleotide sequence may include up to nn nucleic acid alterations over the entire polynucleotide region of the nucleic acid sequence of one of SEQ ID NO: 33 through SEQ ID NO: 64, wherein nn is the maximum number of alterations and is calculated by the formula:

nn≦xn−(xn·y),

in which xn is the total number of nucleic acids of one of SEQ ID NO: 33 through SEQ ID NO: 64 and y has a value of 0.70, wherein any non-integer product of xn and y is rounded down to the nearest integer prior to subtracting such product from xn. Of course, y may also have a value of 0.80 for 80%, 0.85 for 85%, 0.90 for 90% 0.95 for 95%, etc. Alterations of a polynucleotide sequence encoding one of the polypeptides of SEQ ID NO: 1 through SEQ ID NO: 32 may create nonsense, missense or frameshift mutations in this coding sequence and thereby alter the polypeptide encoded by the polynucleotide following such alterations.

Similarly, a polypeptide sequence described herein may be identical to the reference sequence of SEQ ID NO: 1 through SEQ ID NO: 32, that is be 100% identical, or it may include up to a certain integer number of amino acid alterations as compared to the reference sequence such that the % identity is less than 100%. Such alterations are selected from the group consisting of at least one amino acid deletion, substitution, including conservative and non-conservative substitution, or insertion, and wherein said alterations may occur at the amino- or carboxy-terminal positions of the reference polypeptide sequence or anywhere between those terminal positions, interspersed either individually among the amino acids in the reference sequence or in one or more contiguous groups within the reference sequence. The number of amino acid alterations for a given % identity is determined by multiplying the total number of amino acids in one of SEQ ID NO: 1 through SEQ ID NO: 32 by the numerical percent of the respective percent identity (divided by 100) and then subtracting that product from said total number of amino acids in one of SEQ ID NO: 1 through SEQ ID NO: 32, or:

na≦xa−(xa·y),

wherein na is the number of amino acid alterations, xa is the total number of amino acids in one of SEQ ID NO: 1 through SEQ ID NO: 32, and y is, for instance 0.70 for 70%, 0.80 for 80%, 0.85 for 85% etc., and wherein any non-integer product of xa and y is rounded down to the nearest integer prior to subtracting it from xa.

D. Vectors, Host Cells And Recombinant Staphylococcus epidermidis Polypeptides

In one embodiment, the present invention provides expression vectors comprising ORF polynucleotides that encode Staphylococcus epidermidis polypeptides for use in immunogenic compositions. The Staphylococcus epidermidis expression vectors comprise ORF polynucleotides that encode Staphylococcus epidermidis polypeptides comprising the amino acid residue sequence of one of SEQ ID NO: 1 through SEQ ID NO: 32. Alternatively, the expression vectors comprise a polynucleotide comprising the nucleotide base sequence of one of SEQ ID NO: 33 through SEQ ID NO: 64. In other embodiments, the expression vectors of the invention comprise a polynucleotide operatively linked to an enhancer-promoter. In still other embodiments, the expression vectors comprise a polynucleotide operatively linked to a prokaryotic promoter. Alternatively, the expression vectors comprise a polynucleotide operatively linked to an enhancer-promoter that is a eukaryotic promoter. The expression vectors further comprise a polyadenylation signal that is positioned 3′ of the carboxy-terminal amino acid and within a transcriptional unit of the encoded polypeptide.
Expression of proteins in prokaryotes is most often carried out in E. coli with vectors containing constitutive or inducible promoters directing the expression of either fusion or non-fusion proteins. Fusion vectors add a number of amino acids to a protein encoded therein, usually to the amino terminus of the recombinant protein. Such fusion vectors typically serve three purposes: 1) to increase expression of recombinant protein; 2) to increase the solubility of the recombinant protein; and 3) to aid in the purification of the recombinant protein by acting as a ligand in affinity purification. Often, in fusion expression vectors, a proteolytic cleavage site is introduced at the junction of the fusion moiety and the recombinant protein to enable separation of the recombinant protein from the fusion moiety subsequent to purification of the fusion protein. Such enzymes, and their cognate recognition sequences, include Factor Xa, thrombin and enterokinase.
Typical fusion expression vectors include pGEX (Pharmacia Biotech Inc; Smith and Johnson, Gene 67:31-40,1988), pMAL (New England Biolabs, Beverly; Mass.) and pRIT5 (Pharmacia, Piscataway, N.J.) which fuse glutathione S-transferase (GST), maltose E binding protein, or protein A, respectively, to the target recombinant protein.
In one embodiment, the coding sequence of the Staphylococcus epidermidis polynucleotide is cloned into a pGEX expression vector to create a vector encoding a fusion protein comprising, from the N-terminus to the C-terminus, GST-thrombin cleavage site-Staphylococcus epidermidis polypeptide. The fusion protein can be purified by affinity chromatography using glutathione-agarose resin. Recombinant Staphylococcus epidermidis polypeptide unfused to GST can be recovered by cleavage of the fusion protein with thrombin.
Examples of suitable inducible non-fusion E. coli expression vectors include pTrc (Amann et al., Gene 69:301-315,1988), pET lid (Studier et al. “Gene Expression Technology” Methods in Enzymology 185, 60-89,1990), pBAD and pCRT7. Target gene expression from the pTrc vector relies on host RNA polymerase transcription from a hybrid trp-lac fusion promoter. Target gene expression from the pET lid vector relies on transcription from a T7 gn1 0-lac fusion promoter mediated by a coexpressed viral RNA polymerase J7 gnl. This viral polymerase is supplied by host strains BL21 (DE3) or HMS I 74(DE3) from a resident prophage harboring a T7 gnl gene under the transcriptional control of the lacUV 5 promoter.
One strategy to maximize recombinant protein expression in E. coli is to express the protein in a host bacterium with an impaired capacity to proteolytically cleave the recombinant protein. Another strategy is to alter the nucleic acid sequence of the nucleic acid to be inserted into an expression vector so that the individual codons for each amino acid are those preferentially utilized in E. coli. Such alteration of nucleic acid sequences of the invention can be carried out by standard DNA mutagenesis or synthesis techniques.
In another embodiment, the Staphylococcus epidermidis polynucleotide expression vector is a yeast expression vector. Examples of vectors for expression in yeast S. cerevisiae include pYepSec I (Baldari, et al., Embo J, 6: p. 229-234,1987), pMFa (Kurjan and Herskowitz, Cell, p. 933-943,1982), pJRY88 (Schultz et al., Gene, 54: p. 113-123,1987), and pYES2 (Invitrogen Corporation, San Diego, Calif.).
Alternatively, a Staphylococcus epidermidis polynucleotide can be expressed in insect cells using, for example, baculovirus expression vectors. Baculovirus vectors available for expression of proteins in cultured insect cells (e.g., Sf 9 cells) include the pAc series (Smith et al., Mol Cell Biol, 3: p. 2156-2165,1983) and the pVL series (Lucklow and Summers, Virology, 170: p. 31-39, 1989).
In yet another embodiment, a nucleic acid of the invention is expressed in mammalian cells using a mammalian expression vector. Examples of mammalian expression vectors include pCDM8 (Seed, Nature, 329: p. 840, 1987) and pMT2PC (Kaufman et al., EMBO J, 6: p. 187-195,1987). When used in mammalian cells, the expression vector's control functions are often provided by viral regulatory elements.
As used hereinafter, a promoter is a region of a DNA molecule typically within about 100 nucleotide pairs in front of (upstream of) the point at which transcription begins (i.e., a transcription start site). That region typically contains several types of DNA sequence elements that are located in similar relative positions in different genes. As used hereinafter, the term “promoter” includes what is referred to in the art as an upstream promoter region, a promoter region or a promoter of a generalized eukaryotic RNA Polymerase II transcription unit.
Another type of discrete transcription regulatory sequence element is an enhancer. An enhancer provides specificity of time, location and expression level for a particular encoding region (e.g., gene). A major function of an enhancer is to increase the level of transcription of a coding sequence in a cell that contains one or more transcription factors that bind to that enhancer. Unlike a promoter, an enhancer can function when located at variable distances from transcription start sites so long as a promoter is present.
As used hereinafter, the phrase “enhancer-promoter” means a composite unit that contains both enhancer and promoter elements. An enhancer-promoter is operatively linked to a coding sequence that encodes at least one gene product. As used hereinafter, the phrase “operatively linked” means that an enhancer-promoter is connected to a coding sequence in such a way that the transcription of that coding sequence is controlled and regulated by that enhancer-promoter. Means for operatively linking an enhancer-promoter to a coding sequence are well known in the art. As is also well known in the art, the precise orientation and location relative to a coding sequence whose transcription is controlled, is dependent inter alia upon the specific nature of the enhancer-promoter. Thus, a TATA box minimal promoter is typically located from about 25 to about 30 base pairs upstream of a transcription initiation site and an upstream promoter element is typically located from about 100 to about 200 base pairs upstream of a transcription initiation site. In contrast, an enhancer can be located downstream from the initiation site and can be at a considerable distance from that site.
An enhancer-promoter used in a vector construct described herein can be any enhancer-promoter that drives expression in a cell to be transfected. By employing an enhancer-promoter with well-known properties, the level and pattern of gene product expression can be optimized.
For example, commonly used promoters are derived from polyoma, Adenovirus 2, cytomegalovirus and Simian Virus 40. For other suitable expression systems for both prokaryotic and eukaryotic cells see chapters 16 and 17 of Sambrook et al., “Molecular Cloning: A Laboratory Manual” 2nd, ed, Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989, incorporated hereinafter by reference.
In another embodiment, the recombinant mammalian expression vector is capable of directing expression of the nucleic acid preferentially in a particular cell type (e.g., tissue-specific regulatory elements are used to express the nucleic acid). Tissue-specific regulatory elements are known in the art. Non-limiting examples of suitable tissue-specific promoters include the albumin promoter (liver-specific; Pinkert et al., Genes Dev, 1: p. 268-277,1987), lymphoid-specific promoters (Calame and Eaton, Adv Immunol, 43: p. 235-275,1988), in particular, promoters of T cell receptors (Winoto and Baltimore, EMBO J, 8: p. 729-733,1989) and immunoglobulins (Banerji et al., Cell, 33: p. 729-740,1983), (Queen and Baltimore, Cell, 33: p. 741-748,1983), neuron-specific promoters (e.g., the neurofilament promoter; Byrne and Ruddle, PNAS, 86: p. 5473-5477, 1989), pancreas-specific promoters (Edlund et al., Science, 230: p. 912-916, 1985), and mammary gland-specific promoters (e.g., milk whey promoter; U.S. Pat. No. 4,873,316 and International Application EP 264,166). Developmentally-regulated promoters are also encompassed, for example the murine hox promoters (Kessel and Gruss, Science, 249: p. 374-379, 1990) and the α-fetoprotein promoter (Campes and Tilghman, Genes Dev, 3: p. 537-546,1989).
Also provided herein is a recombinant expression vector comprising a DNA molecule encoding a Staphylococcus epidermidis polypeptide cloned into the expression vector in an antisense orientation. That is, the DNA molecule is operatively linked to a regulatory sequence in a manner which allows for expression (by transcription of the DNA molecule) of an RNA molecule which is antisense to Staphylococcus epidermidis mRNA. Regulatory sequences operatively linked to a nucleic acid cloned in the antisense orientation can be chosen which direct the continuous expression of the antisense RNA molecule in a variety of cell types. For instance viral promoters and/or enhancers, or regulatory sequences can be chosen which direct constitutive, tissue specific or cell type specific expression of antisense RNA. The antisense expression vector can be in the form of a recombinant plasmid, phagemid or attenuated virus in which antisense nucleic acids are produced under the control of a high efficiency regulatory region, the activity of which can be determined by the cell type into which the vector is introduced.
The recombinant expression vectors described herein may be inserted into any suitable host cell. The terms “host cell” and “recombinant host cell” are used interchangeably hereinafter. It is understood that such terms refer not only to the particular subject cell, but to the progeny or potential progeny of such a cell. Because certain modifications may occur in succeeding generations due to either mutation or environmental influences, such progeny may not, in fact, be identical to the parent cell, but are still included within the scope of the term as used hereinafter. A host cell can be any prokaryotic or eukaryotic cell. For example, a Staphylococcus epidermidis polypeptide can be expressed in bacterial cells such as E. coli, insect cells (such as Sf9, Sf21), yeast or mammalian cells (such as Chinese hamster ovary cells (CHO), VERO, chick embryo fibroblasts, BHK cells or COS cells). Other suitable host cells are known to those skilled in the art.
Vector DNA is introduced into prokaryotic or eukaryotic cells via conventional transformation, infection or transfection techniques. As used hereinafter, the terms “transformation” and “transfection” are intended to refer to a variety of art-recognized techniques for introducing foreign nucleic acid (e.g., DNA) into a host cell, including calcium phosphate or calcium chloride co-precipitation, DEAE-dextran-mediated transfection, lipofection, ultrasound or electroporation. Suitable methods for transforming or transfecting host cells can be found in Sambrook, et al. (“Molecular Cloning: A Laboratory Manual” 2nd, ed, Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989), and other laboratory manuals.
A host cell described herein, such as a prokaryotic or eukaryotic host cell in culture, is used to produce (i.e., express) a Staphylococcus epidermidis polypeptide. Accordingly, also described herein are methods for producing a Staphylococcus epidermidis polypeptide using such host cells. In one embodiment, the method comprises culturing the host cell (into which a recombinant expression vector encoding a Staphylococcus epidermidis polypeptide has been introduced) in a suitable medium until the Staphylococcus epidermidis polypeptide is produced. In another embodiment, the method further comprises isolating the Staphylococcus epidermidis polypeptide from the medium or the host cell.
A coding sequence of an expression vector is operatively linked to a transcription termination region. RNA polymerase transcribes an encoding DNA sequence through a site where polyadenylation occurs. Typically, DNA sequences located a few hundred base pairs downstream of the polyadenylation site serve to terminate transcription. Those DNA sequences are referred to hereinafter as transcription-termination regions. Those regions are required for efficient polyadenylation of transcribed messenger RNA (mRNA). Transcription-termination regions are well known in the art. Examples of such transcription-termination regions are the polyadenylation signal of SV40 and the protamine gene.
An expression vector comprises a polynucleotide that encodes a Staphylococcus epidermidis polypeptide. Such a polypeptide is meant to include a sequence of nucleotide bases encoding a Staphylococcus epidermidis polypeptide sufficient in length to distinguish the segment from a polynucleotide segment encoding a non-Staphylococcus epidermidis polypeptide. Such a polypeptide can also encode biologically functional polypeptides or peptides which have variant amino acid sequences, such as with changes selected based on considerations such as the relative hydropathic score of the amino acids being exchanged. These variant sequences are those isolated from natural sources or induced in the sequences disclosed hereinafter using a mutagenic procedure such as site-directed mutagenesis.
In certain embodiments, the expression vectors described herein comprise polynucleotides that encode polypeptides comprising the amino acid residue sequence of one of SEQ ID NO: 1 through SEQ ID NO: 32. An expression vector can include a Staphylococcus epidermidis polypeptide coding region itself of any of the Staphylococcus epidermidis polypeptides noted above or it can contain coding regions bearing selected alterations or modifications in the basic coding region of such a Staphylococcus epidermidis polypeptide. Alternatively, such vectors or fragments can encode larger polypeptides or polypeptides which nevertheless include the basic coding region. In any event, it should be appreciated that due to codon redundancy as well as biological functional equivalence, this aspect is not limited to the particular DNA molecules corresponding to the polypeptide sequences noted above.
Exemplary vectors include the mammalian expression vectors of the pCMV family including pCMV6b and pCMV6c (Chiron Corp., Emeryville Calif.). In certain cases, and specifically in the case of these individual mammalian expression vectors, the resulting constructs can require co-transfection with a vector containing a selectable marker such as pSV2neo. Via co-transfection into a dihydrofolate reductase-deficient Chinese hamster ovary cell line, such as DG44, clones expressing Staphylococcus epidermidis polypeptides by virtue of DNA incorporated into such expression vectors can be detected.
A DNA molecule can be incorporated into a vector by a number of techniques that are well known in the art. For instance, the vector pUC18 has been demonstrated to be of particular value in cloning and expression of genes. Likewise, the related vectors M13mp18 and M13mp19 can be used in certain embodiments of the invention, in particular, in performing dideoxy sequencing.
An expression vector described herein is useful both as a means for preparing quantities of the Staphylococcus epidermidis polypeptide-encoding DNA itself, and as a means for preparing the encoded polypeptide and peptides. It is contemplated that where Staphylococcus epidermidis polypeptides are made by recombinant means, one can employ either prokaryotic or eukaryotic expression vectors as shuttle systems.
In another aspect, the recombinant host cells are prokaryotic host cells. Preferably, the recombinant host cells of the invention are bacterial cells of the DH5 α strain of Escherichia coli. In general, prokaryotes are preferred for the initial cloning of DNA sequences and constructing the vectors useful in the invention. For example, E. coli K12 strains can be particularly useful. Other microbial strains that can be used include E. coli B, and E. coliX 1976 (ATCC No. 31537). These examples are, of course, intended to be illustrative rather than limiting.
The aforementioned strains, as well as E. coli W3110 (ATCC No. 273325), E. coli BL21 (DE3), E. coli Top10, bacilli such as Bacillus subtilis, or other enterobacteriaceae such as Salmonella typhimurium (or other attenuated Salmonella strains as described in U.S. Pat. No. 4,837,151) or Serratia marcesans, and various Pseudomonas species can be used.
In general, plasmid vectors containing replicon and control sequences, which are derived from species compatible with the host cell are used in connection with these hosts. The vector ordinarily carries a replication site, as well as marking sequences which are capable of providing phenotypic selection in transformed cells. For example, E. coli can be transformed using pBR322, a plasmid derived from an E. coli species (Bolivar, et al. 1977). pBR322 contains genes for ampicillin and tetracycline resistance and thus provides easy means for identifying transformed cells. The pBR plasmid, or other microbial plasmid or phage must also contain, or be modified to contain, promoters which can be used by the microbial organism for expression of its own polypeptides.
Those promoters most commonly used in recombinant DNA construction include the β-lactamase (penicillinase) and lactose promoter systems (Chang, et al. 1978; Itakura., et al. 1977, Goeddel, et al. 1979; Goeddel, et al. 1980) and a tryptophan (TRP) promoter system (EP 0036776; Siebwenlist et al. 1980). While these are the most commonly used, other microbial promoters have been discovered and utilized, and details concerning their nucleotide sequences have been published, enabling a skilled worker to introduce functional promoters into plasmid vectors (Siebwenlist, et al. 1980).
In addition to prokaryotes, eukaryotic microbes such as yeast can also be used. Saccharomyces cerevisiae or common baker's yeast is the most commonly used among eukaryotic microorganisms, although a number of other strains are commonly available. For expression in Saccharomyces, the plasmid YRp7, for example, is commonly used (Stinchcomb, et al. 1979; Kingsman, et al. 1979; Tschemper, et al. 1980). This plasmid already contains the trpI gene which provides a selection marker for a mutant strain of yeast lacking the ability to grow in tryptophan, for example ATCC No. 44076 or PEP4-1 (Jones, 1977). The presence of the trpI lesion as a characteristic of the yeast host cell genome then provides an effective environment for detecting transformation by growth in the absence of tryptophan.
Suitable promoter sequences in yeast vectors include the promoters for 3-phosphoglycerate kinase (Hitzeman., et al. 1980) or other glycolytic enzymes (Hess, et al. 1968; Holland, et al. 1978) such as enolase, glyceraldehyde-3-phosphate dehydrogenase, hexokinase, pyruvate decarboxylase, phosphofructokinase, glucose-6-phosphate isomerase, 3-phosphoglycerate mutase, pyruvate kinase, triosephosphate isomerase, phosphoglucose isomerase, and glucokinase. In constructing suitable expression plasmids, the termination sequences associated with these genes are also introduced into the expression vector downstream from the sequences to be expressed to provide polyadenylation of the mRNA and termination. Other promoters, which have the additional advantage of transcription controlled by growth conditions are the promoter region for alcohol dehydrogenase 2, isocytochrome C, acid phosphatase, degradative enzymes associated with nitrogen metabolism, and the aforementioned glyceraldehyde-3-phosphate dehydrogenase, and enzymes responsible for maltose and galactose utilization. Any-plasmid vector containing a yeast-compatible promoter, origin or replication and termination sequences are suitable.
In addition to microorganisms, cultures of cells derived from multicellular organisms can also be used as hosts. In principle, any such cell culture is workable, whether from vertebrate or invertebrate culture. However, interest has been greatest in vertebrate cells, and propagation of vertebrate cells in culture (tissue culture) has become a routine procedure in recent years. Examples of such useful host cell lines are AtT-20, VERO, HeLa, NSO, PER C6, Chinese hamster ovary (CHO) cell lines, and W138, BHK, COSM6, COS-7, 293 and MDCK cell lines. Expression vectors for such cells ordinarily include (if necessary) an origin of replication, a promoter located upstream of the gene to be expressed, along with any necessary ribosome binding sites, RNA splice sites, polyadenylation site, and transcriptional terminator sequences.
Where expression of recombinant Staphylococcus epidermidis polypeptides is desired and a eukaryotic host is contemplated, it is most desirable to employ a vector such as a plasmid that incorporates a eukaryotic origin of replication. Additionally, for the purposes of expression in eukaryotic systems, one desires to position the Staphylococcus epidermidis encoding sequence adjacent to and under the control of an effective eukaryotic promoter such as promoters used in combination with Chinese hamster ovary cells. To bring a coding sequence under control of a promoter, whether it is eukaryotic or prokaryotic, the 5′ end of the translation initiation region of the proper translational reading frame of the polypeptide must be positioned between about 1 and about 50 nucleotides 3′ of or downstream with respect to the promoter chosen. Furthermore, where eukaryotic expression is anticipated, one would typically desire to incorporate into the transcriptional unit a polynucleotide which encodes the Staphylococcus epidermidis polypeptide.
Means of transforming or transfecting cells with exogenous polynucleotide such as DNA molecules are well known in the art and include techniques such as calcium-phosphate- or DEAE-dextran-mediated transfection, protoplast fusion, electroporation, liposome mediated transfection, direct microinjection and adenovirus infection (see e.g., Sambrook, Fritsch and Maniatis, 1989).
The most widely used method is transfection mediated by either calcium phosphate or DEAE-dextran. Although the mechanism remains obscure, it is believed that the transfected DNA enters the cytoplasm of the cell by endocytosis and is transported to the nucleus. Depending on the cell type, up to 90% of a population of cultured cells can be transfected at any one time. Because of its high efficiency, transfection mediated by calcium phosphate or DEAE-dextran is the method of choice for experiments that require transient expression of the foreign DNA in large numbers of cells. Calcium phosphate-mediated transfection is also used to establish cell lines that integrate copies of the foreign DNA, which are usually arranged in head-to-tail tandem arrays into the host cell genome.
In the protoplast fusion method, protoplasts derived from bacteria carrying high numbers of copies of a plasmid of interest are mixed directly with cultured mammalian cells. After fusion of the cell membranes (usually with polyethylene glycol), the contents of the bacteria are delivered into the cytoplasm of the mammalian cells and the plasmid DNA is transported to the nucleus. Protoplast fusion is not as efficient as transfection for many of the cell lines that are commonly used for transient expression assays, but it is useful for cell lines in which endocytosis of DNA occurs inefficiently. Protoplast fusion frequently yields multiple copies of the plasmid DNA tandemly integrated into the host chromosome.
The application of brief, high-voltage electric pulses to a variety of mammalian and plant cells leads to the formation of nanometer-sized pores in the plasma membrane. DNA is taken directly into the cell cytoplasm either through these pores or as a consequence of the redistribution of membrane components that accompanies closure of the pores. Electroporation can be extremely efficient and can be used both for transient expression of cloned genes and for establishment of cell lines that carry integrated copies of the gene of interest. Electroporation, in contrast to calcium phosphate-mediated transfection and protoplast fusion, frequently gives rise to cell lines that carry one, or at most a few, integrated copies of the foreign DNA.
Liposome transfection involves encapsulation of DNA and RNA within liposomes, followed by fusion of the liposomes with the cell membrane. The mechanism of how DNA is delivered into the cell is unclear but transfection efficiencies can be as high as 90%.
Direct microinjection of a DNA molecule into nuclei has the advantage of not exposing DNA to cellular compartments such as low-pH endosomes. Microinjection is therefore used primarily as a method to establish lines of cells that carry integrated copies of the DNA of interest.
The use of adenovirus as a vector for cell transfection is well known in the art. Adenovirus vector-mediated cell transfection has been reported for various cells (Stratford-Perricaudet, et al. 1992).
A transfected cell can be prokaryotic or eukaryotic. Preferably, the host cells of the invention are prokaryotic host cells. Where it is of interest to produce a Staphylococcus epidermidis polypeptide, cultured prokaryotic host cells are of particular interest.
Also contemplated herein is a process or method of preparing Staphylococcus epidermidis polypeptides comprising transforming, transfecting or infecting cells with a polynucleotide that encodes a Staphylococcus epidermidis polypeptide to produce transformed host cells; and maintaining the transformed host cells under biological conditions sufficient for expression of the polypeptide. In a particular embodiment, the transformed host cells are prokaryotic cells. Alternatively, the host cells are eukaryotic cells. More particularly, the prokaryotic cells are bacterial cells of the DH5-α strain of Escherichia coli. Alternatively, the polynucleotide transfected into the transformed cells comprise the nucleic acid sequence of one of SEQ ID NO: 33 through SEQ ID NO: 64. Additionally, transfection is accomplished using an expression vector disclosed above. A host cell used in the process is capable of expressing a functional, recombinant Staphylococcus epidermidis polypeptide.
Following transfection, the cell is maintained under culture conditions for a period of time sufficient for expression of a Staphylococcus epidermidis polypeptide. Culture conditions are well known in the art and include ionic composition and concentration, temperature, pH and the like. Typically, transfected cells are maintained under culture conditions in a culture medium. Suitable media for various cell types are well known in the art. In certain embodiments, culture temperature is from about 20° C. to about 50° C., more preferably from about 30° C. to about 40° C. and, even more preferably about 37° C.
The pH is preferably from about a value of 6.0 to a value of about 8.0, more preferably from about a value of about 6.8 to a value of about 7.8 and, most preferably about 7.4. Osmolality is preferably from about 200 milliosmols per liter (mosm/L) to about 400 mosm/l and, more preferably from about 290 mosm/L to about 310 mosm/L. Other biological conditions needed for transfection and expression of an encoded protein are well known in the art.
Transfected cells are maintained for a period of time sufficient for expression of a Staphylococcus epidermidis polypeptide. A suitable time depends inter alia upon the cell type used and is readily determinable by a skilled artisan. Typically, maintenance time is from about 2 to about 14 days.
Recombinant Staphylococcus epidermidis polypeptide is recovered or collected either from the transfected cells or the medium in which those cells are cultured. Recovery comprises isolating and purifying the Staphylococcus epidermidis polypeptide. Isolation and purification techniques for polypeptides are well known in the art and include such procedures as precipitation, filtration, chromatography, electrophoresis and the like.
E. Immunogenic Compositions
The present invention provides immunogenic compositions comprising one or more Staphylococcus epidermidis polypeptides selected as described in the Examples below, and physiologically acceptable carriers. In certain embodiments, the immunogenic compositions comprise one or more Staphylococcus epidermidis polypeptides comprising the amino acid residue sequence of one or more of SEQ ID NO: 1 through SEQ ID NO: 32. In other embodiments, the immunogenic compositions of the invention comprise polynucleotides that encode Staphylococcus epidermidis polypeptides, and physiologically acceptable carriers. For example, the immunogenic compositions of the present invention comprise Staphylococcus epidermidis polypeptides comprising the amino acid sequence of one or more of SEQ ID NO: 1 through SEQ ID NO: 32. Alternatively, the immunogenic compositions comprise polynucleotides comprising the nucleotide sequence of one or more of SEQ ID NO: 33 through SEQ ID NO: 64.
Various tests are used to assess the in vitro immunogenicity of the polypeptides of the invention. For example, an in vitro opsonic assay is conducted by incubating together a mixture of Staphylococcus epidermidis cells, heat inactivated human serum containing specific antibodies to the polypeptide in question, and an exogenous complement source. Opsonophagocytosis proceeds during incubation of freshly isolated human polymorphonuclear cells (PMN's) and the antibody/complement/Staphylococcus cell mixture. Bacterial cells that are coated with antibody and complement are killed upon opsonophagocytosis. Colony forming units (cfu) of surviving bacteria that escape from opsonophagocytosis are determined by plating the assay mixture. Titers are reported as the reciprocal of the highest dilution that gives ≧50% bacterial killing, as determined by comparison to assay controls. Specimens that demonstrate less than 50% killing at the lowest serum dilution tested (1:8), are reported as having an OPA titer of 4. The highest dilution tested is 1:2560. Samples with ≧50% killing at the highest dilution are repeated, beginning with a higher initial dilution. The method described above is a modification of Gray's method (Gray, Conjugate Vaccines Supplement, p. 694-697,1990).
A test serum control, which contains test serum plus bacterial cells and heat inactivated complement, is included for each individual serum. This control is used to assess whether the presence of antibiotics or other serum components are capable of killing the bacterial strain directly (i.e. in the absence of complement or PMN's). A human serum with known opsonic titer is used as a positive human serum control. The opsonic antibody titer for each unknown serum is calculated as the reciprocal of the initial dilution of serum giving 50% cfu reduction compared to the control without serum.
A whole cell ELISA assay is also used to assess in vitro immunogenicity and surface exposure of the polypeptide antigen, wherein the bacterial strain of interest (Staphylococcus epidermidis) is coated onto a plate, such as a 96 well plate, and test sera from an immunized animal is reacted with the bacterial cells. If any antibody, specific for the test polypeptide antigen, is reactive with a surface exposed epitope of the polypeptide antigen, it can be detected by standard methods known to one skilled in the art.
Any polypeptide demonstrating the desired in vitro activity is then tested in an in vivo animal challenge model. In certain embodiments, immunogenic compositions are used in the immunization of an animal (e.g., a mouse) by methods and routes of immunization known to those of skill in the art (e.g., intranasal, parenteral, oral, rectal, vaginal, transdermal, intraperitoneal, intravenous, subcutaneous, etc.). Following immunization of the animal with a particular Staphylococcus epidermidis immunogenic composition, the animal is challenged with Staphylococcus epidermidis and assayed for resistance to Staphylococcus epidermidis infection.
The Staphylococcus epidermidis polynucleotides and polypeptides are incorporated into immunogenic compositions suitable for administration to a subject, e.g., a human. Such compositions typically comprise the nucleic acid molecule or protein, together with a pharmaceutically acceptable carrier. As used hereinafter the language “pharmaceutically acceptable carrier” is intended to include any and all solvents, dispersion media, coatings, antibacterial and antifungal agents, isotonic and absorption delaying agents, and the like, compatible with pharmaceutical administration. The use of such media and agents for pharmaceutically active substances is well known in the art. Except insofar as any conventional media or agent is incompatible with the active compound, such media can be used in the compositions of the invention. Supplementary active compounds can also be incorporated into the compositions.
An immunogenic composition of the invention is formulated to be compatible with its intended route of administration. Examples of routes of administration include parenteral (e.g., intravenous, intradermal, subcutaneous, intraperitoneal), transmucosal (e.g., oral, rectal, intranasal, vaginal, respiratory) and transdermal (topical). Solutions or suspensions used for parenteral, intradermal, or subcutaneous application can include the following components: a sterile diluent such as water for injection, saline solution, fixed oils, polyethylene glycols, glycerine, propylene glycol or other synthetic solvents; antibacterial agents such as benzyl alcohol or methyl parabens; antioxidants such as ascorbic acid or sodium bisulfite; chelating agents such as ethylenediaminetetraacetic acid; buffers such as acetates, citrates or phosphates and agents for the adjustment of tonicity such as sodium chloride or dextrose. pH can be adjusted with acids or bases, such as hydrochloric acid or sodium hydroxide. The parenteral preparation can be enclosed in ampoules, disposable syringes or multiple dose vials made of glass or plastic.
Pharmaceutical compositions suitable for injectable use include sterile aqueous solutions (where water soluble) or dispersions and sterile powders for the extemporaneous preparation of sterile injectable solutions or dispersion. For intravenous administration, suitable carriers include physiological saline, bacteriostatic water, Cremophor ELTM (BASF, Parsippany, N.J.) or phosphate buffered saline (PBS). In all cases, the composition must be sterile and should be fluid to the extent that easy syringability exists. It must be stable under the conditions of manufacture and storage and must be preserved against the contaminating action of microorganisms such as bacteria and fungi. The carrier can be a solvent or dispersion medium containing, for example, water, ethanol, polyol (for example, glycerol, propylene glycol, and liquid polyetheylene glycol, and the like), and suitable mixtures thereof. The proper fluidity can be maintained, for example, by the use of a coating such as lecithin, by the maintenance of the required particle size in the case of dispersion and by the use of surfactants. Prevention of the action of microorganisms can be achieved by various antibacterial and antifungal agents, for example, parabens, chlorobutanol, phenol, ascorbic acid, and the like. In many cases, isotonic agents are included, for example, sugars, polyalcohols such as manitol, sorbitol, sodium chloride in the composition. Prolonged absorption of the injectable compositions can be brought about by including in the composition an agent which delays absorption, for example, aluminum monostearate and gelatin.
Sterile injectable solutions can be prepared by incorporating the active compound (e.g., a Staphylococcus epidermidis polypeptide or anti-Staphylococcus epidermidis antibody) in the required amount in an appropriate solvent with one or a combination of ingredients enumerated above, as required, followed by filtered sterilization. Generally, dispersions are prepared by incorporating the active compound into a sterile vehicle that contains a basic dispersion medium and the required other ingredients from those enumerated above. In the case of sterile powders for the preparation of sterile injectable solutions, the preferred methods of preparation are vacuum drying and freeze-drying which yields a powder of the active ingredient plus any additional desired ingredient from a previously sterile-filtered solution thereof.
Oral compositions generally include an inert diluent or an edible carrier. They can be enclosed in gelatin capsules or compressed into tablets. For the purpose of oral therapeutic administration, the active compound can be incorporated with excipients and used in the form of tablets, troches, or capsules. Oral compositions can also be prepared using a fluid carrier for use as a mouthwash, wherein the compound in the fluid carrier is applied orally and swished and expectorated or swallowed. Pharmaceutically compatible binding agents, and/or adjuvant materials can be included as part of the composition. The tablets, pills, capsules, troches and the like can contain any of the following ingredients, or compounds of a similar nature: a binder such as microcrystalline cellulose, gum tragacanth or gelatin; an excipient such as starch or lactose, a disintegrating agent such as alginic acid, Primogel, or corn starch; a lubricant such as magnesium stearate or Sterotes; a glidant such as colloidal silicon dioxide; a sweetening agent such as sucrose or saccharin; or a flavoring agent such as peppermint, methyl salicylate, or orange flavoring.
For administration by inhalation, the compounds are delivered in the form of an aerosol spray from pressured container or dispenser which contains a suitable propellant, e.g., a gas such as carbon dioxide, or a nebulizer. Systemic administration can also be by transmucosal or transdermal means. For transmucosal or transdermal administration, penetrants appropriate to the barrier to be permeated are used in the formulation. Such penetrants are generally known in the art, and include, for example, for transmucosal administration, detergents, bile salts, and fusidic acid derivatives. Transmucosal administration can be accomplished through the use of nasal sprays or suppositories. For transdermal administration, the active compounds are formulated into ointments, salves, gels, or creams as generally known in the art.
The compounds can also be prepared in the form of suppositories (e.g., with conventional suppository bases such as cocoa butter and other glycerides) or retention enemas for rectal delivery.
In one embodiment, the active compounds are prepared with carriers that will protect the compound against rapid elimination from the body, such as a controlled release formulation, including implants and microencapsulated delivery systems.
Biodegradable, biocompatible polymers can be used, such as ethylene vinyl acetate, polyanhydrides, polyglycolic acid, collagen, polyorthoesters, and polylactic acid. Methods for preparation of such formulations will be apparent to those skilled in the art. The materials can also be obtained commercially from Alza Corporation and Nova Pharmaceuticals, Inc. Liposomal suspensions (including liposomes targeted to infected cells with monoclonal antibodies to viral antigens) can also be used as pharmaceutically acceptable carriers. These can be prepared according to methods known to those skilled in the art, for example, as described in U.S. Pat. No. 4,522,811, which is incorporated hereinafter by reference.
It is especially advantageous to formulate oral or parenteral compositions in dosage unit form for ease of administration and uniformity of dosage. Dosage unit form as used hereinafter refers to physically discrete units suited as unitary dosages for the subject to be treated; each unit containing a predetermined quantity of active compound calculated to produce the desired therapeutic effect in association with the required pharmaceutical carrier. The specification for the dosage unit forms of the invention are dictated by and directly dependent on the unique characteristics of the active compound and the particular therapeutic effect to be achieved, and the limitations inherent in the art of compounding such an active compound for the treatment of individuals.
Combination immunogenic compositions are provided by including two or more of the polypeptides of the invention, as well as by combining one or more of the polypeptides of the invention with one or more known non-Staphylococcus epidermidis polypeptides such as Staphylococcus aureus polypeptides.
The following twelve Staphylococcus epidermidis polypeptide sequences SEQ ID NO: 8, SEQ ID NO: 10, SEQ ID NO: 11, SEQ ID NO: 12, SEQ ID NO: 14, SEQ ID NO: 18, SEQ ID NO: 19, SEQ ID NO: 20, SEQ ID NO: 23, SEQ ID NO: 26, SEQ ID NO: 27, and SEQ ID NO: 30 have polypeptide sequences with at least 90% identity to the homologs from Staphylococcus aureus. Therefore, these twelve polypeptides may also be used in immunogenic compositions against Staphylococcus aureus. In addition, the following twelve Staphylococcus epidermidis polynucleotide sequences encoding the the polypeptides with at least 90% identity to the Staphylococcus aureus homologs may also be used in immunogenic compositions: SEQ ID NO: 40, SEQ ID NO: 42, SEQ ID NO: 43, SEQ ID NO: 44, SEQ ID NO: 46, SEQ ID NO: 50, SEQ ID NO: 51, SEQ ID NO: 52, SEQ ID NO: 55, SEQ ID NO: 58, SEQ ID NO: 59, and SEQ ID NO: 62, or a degenerate variant thereof, or a fragment thereof.
In other embodiments, combination immunogenic compositions are provided by combining one or more of the polypeptides of the invention with one or more known S. epidermidis polysaccharides or polysaccharide-protein conjugates. See, for example, the Staphylococcus epidermidis and Staphylococcus aureus capsular polysaccharide adhesin, PNSG, poly-N-succinyl beta-1-6 N-acetyl glucosamine (also known as PIA, PS/A, PNAG). See Mckenney, D., et al., Infect. Immun. 66:4711 (1998) and Mckenney, D., et al., Science 284:1523 (1998), the disclosures of which are hereby incorporated by reference in their entirety.
In other embodiments, combination immunogenic compositions are provided by combining one or more polypeptides of the invention with one or more known S. aureus polysaccharides or S. aureus polysaccharide-protein conjugates. For example, of the 12 known capsular serotypes of S. aureus, serotype 5 (CP5) and serotype 8 (CP8) account for approximately 85-90% of all clinical isolates . Most methicillin-resistant S. aureus isolates express CP5 ]. Antibodies to CP5 and CP8 induce type-specific opsonophagocytic killing by human polymorphonuclear neutrophils in vitro and confer protection in animals [Karakawa, W. W., Sutton, A., et al., Infect Immun 56(5):1090-1095 (1988); Fattom, A. I., Sarwar, J., et al., Infection & Immunity 64(5):1659-1665 (1996)]. Several laboratories have synthesized immunogenic conjugates consisting of CP5 and CP8 covalently linked to protein. These conjugates are highly immunogenic in mice and humans and induce antibodies that opsonize microencapsulated S. aureus for phagocytosis [Fattom, A., Schneerson, R, et al., Infect Immun 61(3):1023-1032 (1993); Gilbert, F. B., Poutrel, B., et al., Vaccine 12(4):369-374 (1994); Reynaud-Rondier, L., Voiland, A., et al., FEMS Microbiol Immunol 3(4):193-199 (1991)]. Monovalent immunogenic compositions containing CP5 conjugated to Pseudomonas aeruginosa recombinant exotoxin A are immunogenic and well tolerated in healthy adults and in patients with end-stage renal disease [Welch, P. G., Fattom, A., Moore, J. Jr., et al., J. Am. Soc. Nephrol. 7:247-253 [Abstract] (1996)]. In a double-blind trial involving patients with end-stage renal disease who were receiving hemodialysis, a bivalent conjugate vaccine composed of CP5 and CP8 covalently bound to Pseudomonas aeruginosa recombinant exotoxin A conferred partial immunity against S. aureus bacteremia for approximately 40 weeks, after which protection decreased as antibody levels decreased [Shinefield, H., Black, S., et al., N Engl J Med 346(7):491-496 (2002)]. The outcome of this trial indicates a need for an improved immunogenic composition that could contribute to broader and more complete protection.
As described above, in certain embodiments, combination immunogenic compositions are provided by combining one or more polypeptides of the invention with one or more known S. aureus polysaccharide-protein conjugates. The “protein component” of the carbohydrate-protein conjugates is known as a carrier protein. The term “carrier proteins”, as a group are preferably proteins that are non-toxic and non-reactogenic and obtainable in sufficient amount and purity. Carrier proteins should be amenable to standard conjugation procedures. In a particular embodiment of the present invention, CRM197 is used as the carrier protein. CRM19, (Wyeth, Sanford, N.C.) is a non-toxic variant (i.e., toxoid) of diphtheria toxin isolated from cultures of Corynebacterium diphtheria strain C7 (β197) grown in casamino acids and yeast extract-based medium. CRM197 is purified through ultra-filtration, ammonium sulfate precipitation, and ion-exchange chromatography. Other diphtheria toxoids are also suitable for use as carrier proteins. The immunogenic composition may further comprise an adjuvant, such as an aluminum-based adjuvant, such as aluminum phosphate, aluminum sulfate and aluminum hydroxide.
Other suitable carrier proteins include inactivated bacterial toxins such as tetanus toxoid, pertussis toxoid, cholera toxoid (e.g., as described in International Patent Application WO2004/083251 [38]), E. coli LT, E. coli ST, and exotoxin A from Pseudomonas aeruginosa. Bacterial outer membrane proteins such as outer membrane complex c (OMPC), porins, transferrin binding proteins, pneumolysis, pneumococcal surface protein A (PspA), pneumococcal adhesin protein (PsaA), or Haemophilus influenzae protein D, can also be used. Other proteins, such as ovalbumin, keyhole limpet hemocyanin (KLH), bovine serum albumin (BSA) or purified protein derivative of tuberculin (PPD) can also be used as carrier proteins.
Immunogenic compositions comprising polynucleotides are delivered to the recipient by a variety of vectors and expression systems. Such systems include, among others, chromosomal, episomal and virus-derived systems, e.g., vectors derived from bacterial plasmids, attenuated bacteria such as Salmonella (U.S. Pat. No. 4,837,151), from bacteriophage, from transposons, from yeast episomes, from insertion elements, from yeast chromosomal elements, from viruses such as vaccinia and other poxviruses, adenovirus, baculoviruses, papova viruses, such as SV40, fowl pox viruses, pseudorabies viruses and retroviruses, alphaviruses such as Venezuelan equine encephalitis virus (U.S. Pat. No. 5,643,576), sindbis virus and semiliki forest virus, nonsegmented negative-stranded RNA viruses such as vesicular stomatitis virus (U.S. Pat. No. 6,168,943), and vectors derived from combinations thereof, such as those derived from plasmid and bacteriophage genetic elements, such as cosmids and phagemids. The expression systems should include control regions that regulate as well as engender expression, such as promoters and other regulatory elements (such as a polyadenylation signal). Generally, any system or vector suitable to maintain, propagate or express polynucleotides to produce a polypeptide in a host may be used. The appropriate nucleotide sequence may be inserted into an expression system by any of a variety of well-known and routine techniques, such as, for example, those set forth in Sambrook et al., “Molecular Cloning: A Laboratory Manual” 2nd, ed, Cold Spring Harbor Laboratory, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, N.Y., 1989.
A pharmaceutically acceptable vehicle is understood to designate a compound or a combination of compounds entering into a pharmaceutical or immunogenic composition which does not cause side effects and which makes it possible, for example, to facilitate the administration of the active compound, to increase its life and/or its efficacy in the body, to increase its solubility in solution or alternatively to enhance its preservation. These pharmaceutically acceptable vehicles are well known and will be adapted by persons skilled in the art according to the nature and the mode of administration of the active compound chosen.
As defined hereinafter, an “adjuvant” is a substance that serves to enhance the immunogenicity of an “antigen” or the immunogenic compositions comprising one or more polypeptide antigens having an amino acid sequence chosen from one of SEQ ID NO: 1 through SEQ ID NO: 32. Thus, adjuvants are often given to boost or modulate the immune response and are well known to the skilled artisan. Examples of adjuvants contemplated in the present invention include, but are not limited to, aluminum salts (alum) such as aluminum phosphate and aluminum hydroxide, Mycobacterium tuberculosis, bacterial lipopolysaccharides, aminoalkyl glucosamine phosphate compounds (AGP), or derivatives or analogs thereof, which are available from Corixa (Hamilton, Mont.), and which are described in U.S. Pat. No. 6,113,918; one such AGP is 2-[(R)-3-Tetradecanoyloxytetradecanoylamino]ethyl 2-Deoxy-4-O-phosphono-3-O-[(R)-3-tetradecanoyoxytetradecanoyl]-2-[(R)-3-tetradecanoyoxytetradecanoylamino]-b-D-glucopyranoside, which is also known as 529 (formerly known as RC529), which is formulated as an aqueous form or as a stable emulsion, MPLTM (3-O-deacylated monophosphoryl lipid A) (Corixa) described in U.S. Pat. No. 4,912,094, synthetic polynucleotides such as oligonucleotides containing a CpG motif (U.S. Pat. No. 6,207,646), polypeptides, saponins such as Quil A or STIMULONTM QS-21 (Antigenics, Framingham, Mass.), described in U.S. Pat. No. 5,057,540, a pertussis toxin (PT), or an E. coli heat-labile toxin (LT), particularly LT-K63, LT-R72, CT-Si09, PT-K9/G129; see, e.g., International Patent Publication Nos. WO 93/13302 and WO 92/19265, cholera toxin (either in a wild-type or mutant form, e.g., wherein the glutamic acid at amino acid position 29 is replaced by another amino acid, preferably a histidine, in accordance with published International Patent Application number WO 00/18434). Similar cholera toxin mutants are described in published International Patent Application number WO 02/098368 (wherein the isoleucine at amino acid position 16 is replaced by another amino acid, either alone or in combination with the replacement of the serine at amino acid position 68 by another amino acid; and/or wherein the valine at amino acid position 72 is replaced by another amino acid). Other cholera toxin mutants are described in published International Patent Application number WO 02/098369 (wherein the arginine at amino acid position 25 is replaced by another amino acid; and/or an amino acid is inserted at amino acid position 49; and/or two amino acids are inserted at amino acid positions 35 and 36).
Various cytokines and lymphokines are suitable for use as adjuvants. One such adjuvant is granulocyte-macrophage colony stimulating factor (GM-CSF), which has a nucleotide sequence as described in U.S. Pat. No. 5,078,996. A plasmid containing GM-CSF cDNA has been transformed into E. coli and has been deposited with the American Type Culture Collection (ATCC), 1081 University Boulevard, Manassas, Va. 20110-2209, under Accession Number 39900. The cytokine Interleukin-12 (IL-12) is another adjuvant which is described in U.S. Pat. No. 5,723,127. Other cytokines or lymphokines have been shown to have immune modulating activity, including, but not limited to, the interleukins 1-alpha, 1-beta, 2, 4, 5,6, 7, 8, 10, 13, 14, 15, 16, 17 and 18, the interferons-alpha, beta and gamma, granulocyte colony stimulating factor, and the tumor necrosis factors alpha and beta, and are suitable for use as adjuvants.
A composition of the present invention is typically administered parenterally in unit dosage formulations containing standard, well-known nontoxic physiologically acceptable carriers, adjuvants, and vehicles as desired.
Injectable preparations, for example sterile injectable aqueous or oleaginous suspensions, are formulated according to the known art using suitable dispersing or wetting agents and suspending agents. The sterile injectable preparation can also be a sterile injectable solution or suspension in a nontoxic parenterally acceptable diluent or solvent, for example, as a solution in 1,3-butanediol.
Among the acceptable vehicles and solvents that may be employed are water, Ringer's solution, and isotonic sodium chloride solution. In addition, sterile, fixed oils are conventionally employed as a solvent or suspending medium. For this purpose any bland fixed oil can be employed including synthetic mono- or di-glycerides. In addition, fatty acids such as oleic acid find use in the preparation of injectables.
Preferred carriers include neutral saline solutions buffered with phosphate, lactate, Tris, and the like. Of course, when administering viral vectors, one purifies the vector sufficiently to render it essentially free of undesirable contaminants, such as defective interfering adenovirus particles or endotoxins and other pyrogens such that it does not cause any untoward reactions in the individual receiving the vector construct. A preferred means of purifying the vector involves the use of buoyant density gradients, such as cesium chloride gradient centrifugation.
A carrier can also be a liposome. Means for using liposomes as delivery vehicles are well known in the art (see, e.g. Gabizon et al., 1990; Ferruti et al., 1986; and Ranade, 1989).
The immunogenic compositions of this invention also comprise a polynucleotide sequence of this invention operatively associated with a regulatory sequence that controls gene expression. The polynucleotide sequence of interest is engineered into an expression vector, such as a plasmid, under the control of regulatory elements which will promote expression of the DNA, that is, promoter and/or enhancer elements. In a preferred embodiment, the human cytomegalovirus immediate-early promoter/enhancer is used (U.S. Pat. No. 5,168,062). The promoter may be cell-specific and permit substantial transcription of the polynucleotide only in predetermined cells.
The polynucleotides of the invention are introduced directly into the host either as “naked” DNA (U.S. Pat. No. 5,580,859) or formulated in compositions with facilitating agents, such as bupivicaine and other local anesthetics (U.S. Pat. No. 5,593,972) and cationic polyamines (U.S. Pat. No. 6,127,170), which are hereby incorporated by reference in their entirety.
In this polynucleotide immunization procedure, the polypeptides of the invention are expressed on a transient basis in vivo; no genetic material is inserted or integrated into the chromosomes of the host. This procedure is to be distinguished from gene therapy, where the goal is to insert or integrate the genetic material of interest into the chromosome. An assay is used to confirm that the polynucleotides administered by immunization do not give rise to a transformed phenotype in the host (U.S. Pat. No. 6,168,918).
H. Uses and Methods of the Invention
The Staphylococcus epidermidis polynucleotides, polypeptides and polypeptide homologues described herein are used in methods of immunization. The isolated polynucleotides are used to express Staphylococcus epidermidis polypeptides (e.g., via a recombinant expression vector in a host cell or in polynucleotide immunization applications).
As described in detail in the Examples herein, Staphylococcus epidermidis was grown in the presence of serum to stimulate the expression of proteins and carbohydrates at the bacterial cell wall that may be significant to systemic bacterial infection. As a result, thirty two polypeptides and the corresponding polynucleotides were identified as expressed by Staphylococcus epidermidis when grown in 70% serum. In addition, twenty-four of these proteins were found to be reactive with immune sera from rabbits infected with Staphylococcus epidermidis. 
The genes corresponding to the proteins expressed when Staphylococcus epidermidis was grown in serum were cloned and used to express the proteins recombinantly. The recombinant proteins were used to immunize mice and twenty five of twenty six proteins induced antibodies that reacted with whole cell lysates of Staphylococcus epidermidis. In addition, eighteen of these sera also reacted with whole cell lysates of Staphylococcus aureus. Finally, when immunized mice were challenged with Staphylococcus epidermidis it was found that eleven of the proteins had induced antibodies that reduced the amount of detectable bacteria found in the spleen after challenge.
The invention further provides immunogenic compositions comprising one or more polypeptides just described, which have an amino acid sequence chosen from one SEQ ID NO: 1 through SEQ ID NO: 32, a biological equivalent thereof or a fragment thereof. The immunogenic composition may further comprise a pharmaceutically acceptable carrier. In certain embodiments, the immunogenic composition will comprise one or more adjuvants.
In another embodiment, the invention provides immunogenic compositions comprising a polynucleotide having a nucleotide sequence chosen from one of SEQ ID NO: 33 through SEQ ID NO: 64, wherein the polynucleotide is comprised in a recombinant expression vector. Preferably the vector is plasmid DNA. The polynucleotide may further comprise heterologous nucleotides, e.g., the polynucleotide is operatively linked to one or more gene expression regulatory elements, and further comprise one or more adjuvants. In a preferred embodiment, the immunogenic polynucleotide composition directs the expression of one or more neutralizing epitopes of Staphylococcus epidermidis. 
Provided also are methods for immunizing a host against Staphylococcus epidermidis infection. In a preferred embodiment, the host is human. Thus, a host or subject is administered an immunizing amount of an immunogenic composition comprising a polypeptide having an amino acid sequence chosen from one of SEQ ID NO: 1 through SEQ ID NO: 32, a biological equivalent thereof or a fragment thereof and a pharmaceutically acceptable carrier. An immunizing amount of an immunogenic composition is determined by performing a dose response study in which subjects are immunized with gradually increasing amounts of the immunogenic composition and the immune response analyzed to determine the optimal dosage. Starting points for the study are inferred from immunization data in animal models. The dosage amount can vary depending upon specific conditions of the individual. The amount is determined in routine trials by means known to those skilled in the art.
An immunologically effective amount of the immunogenic composition in an appropriate number of doses is administered to the subject to elicit an immune response. Immunologically effective amount, as used herein, means the administration of that amount to a mammalian host (preferably human), either in a single dose or as part of a series of doses, sufficient to at least cause the immune system of the individual treated to generate a response that reduces the clinical impact of the bacterial infection. Ideally, the treated individual will not exhibit the more serious clinical manifestations of the Staphloccocal epidermidis or Staphlocccal aureus infection. The dosage amount can vary depending upon specific conditions of the individual, such as age and weight. This amount can be determined in routine trials by means known to those skilled in the art.
All patents and publications cited herein are hereby incorporated by reference.
EXAMPLES
The following examples were carried out using standard techniques, which are well known and routine to those of skill in the art, except where otherwise described in detail. All chemicals were obtained from Sigma (Sigma Chemical Co., St. Louis, Mo.) unless stated otherwise. The following examples are presented for illustrative purpose, and should not be construed in any way limiting the scope of this invention.
Example 1
Bacterial Growth in 70% Serum
The following examples were performed using the clinical isolate Staphylcoccus epidermidis 0-47. The unannotated genomic sequence was available for this isolate from Incyte Corporation of Palo Alto, Calif. See Heilmann, C., et al., Infect Immun, 64(1): p. 277-82 (1996). To stimulate the expression of proteins, which may be clinically relevant to pathogenicity, cultures of bacteria were grown overnight in either 100% tryptic soy broth (TSB) or 70:30 rabbit serum:TSB with shaking (200 rpm) at 37° C. The rabbit serum was obtained from Life Technologies, Rockville, Md. Bacteria were diluted from an overnight culture to an OD600 ̃0.1 and grown for 4 h until mid log phase. At mid log phase, the cells were harvested by centrifugation and further processed as described in the following examples.
Example 2
Preparation Of Cell Wall Fractions For 2-D Gel Electrophoresis
The cell walls of Staphylcoccus epidermidis 0-47 grown as described in Example 1 were isolated and then prepared for two-dimensional gel electrophoresis. Bacterial pellets were resuspended to an OD600 ̃20 and washed twice with rocking for 15 minutes at 4° C. using Tris buffered saline (TBS, 20 mM Tris, pH 8.0, 150 mM NaCl). Serum proteins bound to the surface of the bacteria were removed by washing for 15 minutes at 4° C. with 20 mM Tris, pH 8.0 containing 1M NaCl. Bacteria grown in TSB were treated in the same manner as the bacteria grown in serum. The bacteria were again pelleted by centrifugation. To create protoplasts, the bacteria were then resuspended to OD600 ̃40 in TBS containing 30% sucrose, 100 μg/ml lysostaphin, 10 μg/ml DNase, 1 μg/ml Pefablock (Boehringer Mannheim, Indianapolis, Ind.), 10 μg/ml lysozyme and 100 units/ml mutanolysin and incubated at 37° C. for 1 hour. The resulting protoplasts were pelleted by centrifugation at 5000 rpm for 10 minutes and the supernatant containing the cell wall material was decanted. The decanted supernatants containing the cell wall fractions were supplemented with Complete Mini protease inhibitor tablets (Roche Diagnostics, Indianapolis, Ind.) and dialyzed overnight against water at 4° C. using a 10,000 kD MWCO dialysis membrane (Pierce Biotechnology, Inc., Rockford, Ill.). After dialysis, the cell wall fractions were frozen at −20° C.
Following isolation, the cell wall fraction samples were prepared for 2-D gel electrophoresis as follows: the frozen cell wall extracts were thawed and precipitated with 70% acetone on ice for 4 hours. The protein precipitate was pelleted, dried in a SpeedVac (Thermo Savant, Holbrook, N.Y.) and solubilized with ReadyPrep (BioRad) SEQUENTIAL EXTRACTION REAGENT 3, which contains 5 M urea, 2 M thiourea, 2% (w/v) CHAPS, 2% (w/v) SB 3-10, 40 mM Tris and 0.2% Bio-Lyte 3/10.
The prepared cell wall fraction samples were loaded onto 11 cm immobilized pH gradient (IPG) strips, pH 4-7 (BioRad) by allowing each sample to re-hydrate a gel strip during an overnight incubation at room temperature. The sample size was 250 μg in a total volume of 200 μl. During the overnight incubation, the strips were covered with mineral oil (BioRad) to prevent evaporation. Following completion of rehydration of the strips, excess mineral oil was removed onto blotting paper that was saturated with water and the hydrated strips were then loaded into a pHaser Iso-electric focusing (IEF) apparatus (Genomic Solutions Inc., Ann Arbor, Mich.). The strips were prefocused with a current limit of 50 mA/strip with the voltage gradually increasing from 250 V to 5,000 V. Voltage was then held constant at 5,000 V for a total 50 kVh ( ̃16h). Second dimension SDS-PAGE was carried out using 12.5% Criterion precast gels (BioRad). For mass spectrometric analysis, gels were stained with Sypro Ruby protein gel stain (BioRad) according to the manufacturer's instructions.
Two-dimensional (2D) gel profiles of cell wall associated proteins from Staphylococcus epidermidis grown in TSB or 70% rabbit serum were compared. See FIG. 1. Growth in 70% rabbit serum resulted in a change in the protein expression profile of cell wall associated proteins from Staphylcoccus epidermidis that was easily detectable in fluorescent stained transfers of 2D gels (FIGS. 1A and 1B).
Eight proteins were detected by fluorescent stain to be differentially regulated between Staphylcoccus epidermidis grown in TSB or in the presence of rabbit serum. See Table 3 and FIG. 1. Most notable was an increase in the fluorescent staining of three protein streaks between 25 kDa and 37 kDa in the cells grown in 70% serum (FIG. 1B, spots e, g and h).







TABLE 3







List of Spots Identifieda












Protein
cMethod of



bSpot #
SEQ ID NO:
detection















 1, 2
12
I, S



 3
12
I, S



 3
19
I, S



 4c
11
I, S



 4
18
I, S



 5-7, 9
11
I, S



 8
21
I



10c
11
I, S



10
18
I, S



10
28
I, S



11
3
I, S



12
10
I, S



13
10
I, S



13
26
I, S



14
dNGID
I, S



15-16
10
I, S



17
25
I



18
4
I



19
17
I, S



19
23
I, S



20-23, 25
17
I, S



24
30
I, S



26
30
I, S



26
8
I, S



26
7
I, S



27, 30-32
2
I, S



28, 33
22
I, S



29
5
I, S



34
13
I, S



35
NGID
I



36
NGID
I



37
NGID
I, S



38
29
I, S



38
3
I, S



39
32
I, S



40
14
S



40
20
S



40
27
S



41
14
S



42
6
I



43
32
S



43
16
S



43
24
S



44
15
S







aList of spots detected on 2D blots by reactivity with immune sera or binding to serum components.



bSome spots contained more that one protein.



cMethod by which the spot was detected following transfer to nitrocellulose, reactive immune sera from infected rabbits, I, or binding serum components, S.



dNGID = no gene in database






Example 3
Binding of Immune Serum and Biotinylated Serum Proteins to Cell Wall Proteins
After completion of the first and second dimensions of electrophoresis, the protein content of the gels was transferred onto nitrocellulose for binding assays. Specifically, the protein content of the gels was electro-blotted to nitrocellulose membranes (BioRad) using a semi-dry blotting apparatus (Owl Separations Systems, Portsmouth, N.H.) at 12V for 1 hour. The protein containing nitrocellulose membranes (blots) were then stained with Sypro Ruby protein blot stain (BioRad) following the manufacturer's instructions and visualized in a FluorS Imager (BioRad). Each blot was incubated in blocking buffer (PBS with 0.05% Tween 20 and 5% dry milk) for 10 minutes at room temperature then incubated overnight with either a 1:2000 dilution of immune sera (Western blot) or 40 μg/ml biotinylated serum proteins (see below). Following overnight incubation, blots were washed 3× with wash buffer (PBS with 0.5% Tween 20) and incubated with either goat anti-rabbit IgG alkaline phosphatase conjugate (Biosource International, Camarillo, Calif.) or streptavidin alkaline phosphatase conjugate (Biosource) for 2 hours at room temperature in blocking buffer. Blots were again washed three times with wash buffer and visualized with BCIP/NBT membrane phosphatase substrate system (KPL, Inc., Gaithersburg, Md.). Pictures were taken in the FluorS. All analysis of 2D gels was performed using Melanie 3.0 software.
Protein concentration was assayed using the BioRad protein assay kit (BioRad).
Changes in the protein expression profile of cell wall associated proteins was more pronounced by considering the Western blots of the nitrocellulose membranes containing the proteins transferred from the 2D gels. In the Western blots, the nitrocellulose membranes were incubated with pooled immune sera from rabbits repeatedly infected with Staphylcoccus epidermidis 0-47. See FIGS. 1C and 1D. These upregulated proteins are also strongly immunoreactive, suggesting they were expressed during infection of the rabbits. Five other immunoreactive streaks or spots from the serum-grown cells were expressed at either lower or undetectable levels in TSB grown cells. See FIG. 1, spots a, b, c, d and f.
Example 4
Analysis of Serum Proteins that Interact With Staphylcoccus epidermidis Cell Wall Associated Proteins
Elution of Serum Proteins from Staphylcoccus epidermidis 
Staphylcoccus epidermidis 0-47 was grown in 70% rabbit serum at 37° C. to OD600 ̃0.8 and the cells were pelleted. The cells were resuspended at OD600 ̃20 and washed three times with TBS while rocking at 4° C. The bound serum proteins were eluted sequentially with 20 mM Tris, pH 8.0 containing either 0.5 M NaCl, 1.0 M NaCl or 4.0 M urea for 1 hour with rocking at 4° C. The bacteria were then removed by centrifugation and the supernatant collected. The supernatants contained the serum proteins eluted from the surface of the bacteria. Proteins eluted under the different conditions were analyzed by SDS-PAGE using 4-20% gradient Tris-glycine gels (Cambrex Biosciences Rockland, Inc., Rockland, Me.)
Biotinylation of Serum Proteins
The eluted serum proteins were dialyzed overnight against PBS at 4° C. IgG's were depleted by overnight incubation with protein G sepharose (Amersham-Pharmacia, Piscataway, N.J.) at 4° C. Assuming an average protein mass of 50 kDa in the eluted fraction, the proteins were labeled with a 15-molar excess of EZ-Link® NHS-biotin (Pierce Biotechnology) for 1.5 hour at 4° C. The reaction was quenched with excess glycine and dialyzed (10,0000 MWCO, Pierce) overnight against PBS.
Identification Of Serum Proteins Bound To The Surface Of Staphylcoccus epidermidis 
Serum proteins eluted from the bacteria under these conditions were compared by SDS-PAGE to normal rabbit serum and to the bacterial proteins eluted from the surface of Staphylcoccus epidermidis grown in TSB. See FIG. 3. Buffers containing 0.5 NaCl, 1 M NaCl and 4 M urea each eluted bound serum proteins from the bacterial cells. These eluted serum proteins represent a pool of proteins eluted from the bacterial surface that is enriched for serum proteins. Some bacterial proteins are likely present in this pool, however no bacterial proteins detectable by protein assay were eluted from bacteria grown in TSB. Although some faint protein bands were detected by silver stain to be eluted from TSB grown bacteria, they did not correspond to the more intensely stained proteins eluted from the surface of the bacteria grown in serum. Elution with 1 M NaCl was the least denaturing condition that eluted the most proteins and was used to elute proteins for the following examples.
In order to identify cell wall associated proteins involved in binding serum components, biotin labeled serum proteins were used to probe 2D transfers by incubating a solution of the labeled proteins with the nitrocellulose bound cell wall proteins transferred from a 2D gel. To isolate serum proteins that bind to Staphylcoccus epidermidis, bacteria grown in 70% rabbit serum were washed with 1 M NaCl. The eluted serum proteins were collected and dialyzed into PBS. Next, the naturally occurring immune IgG that may be present in the eluted serum proteins was depleted by incubation with protein G sepharose. Removal of IgG reduces the likelihood of identifying a protein that is reactive with host antibodies. The eluted serum proteins were then biotin labeled as described above and used to probe a 2D blot of Staphylcoccus epidermidis cell surface proteins. See FIGS. 4A and 4B. Thirty-four spots and regions were visualized by this method and are likely involved in the interaction of Staphylcoccus epidermidis with host serum proteins. Of the 34 spots consistently found to interact with serum components all but 4 were found to react with the immune sera from infected rabbits. See FIG. 2 and Table 3.
Staphylcoccus epidermidis grown in serum had serum proteins bound to bacterial surface proteins that were eluted with 0.5 M and 1 M NaCl. Under the same conditions few staphylococcal proteins were eluted from bacteria grown in TSB however it is possible that a staphylococcal protein expressed only in the serum is eluted by the high salt treatment.
Example 5
Mass Spectroscopy Identification of Serum Upregulated Proteins
Bacteria grown in 70% serum were used in subsequent proteomic experiments and analyses, working under the assumption that the changes detected during growth in serum may more accurately reflect alterations in gene expression made by the bacteria in response to environmental cues seen within a host. In the following mass spectroscopy studies, proteins isolated from spots on 2D gel electrophoresis separations were first subjected to time-of-flight mass spectroscopy. If a positive, unambiguous identification was obtained then no further mass spectrometric analysis was performed. See Table 4. In the cases where some ambiguity remained after time-of-flight mass spectroscopy, such as when multiple proteins resolved to the same spot on the 2D gel, then electrospray mass spectroscopy was performed to resolve the ambiguity. See Table 4.







TABLE 4







Proteins Identified by Mass Spectroscopy













Protein
DNA
2-D Gel



Orf
SEQ ID NO:
SEQ ID NO:
Spot Number
















121
1
33
38



305
2
34
27, 30-32



321
3
35
11



373
4
36
18



554
5
37
29



639
6
38
42



608
7
39
 26,



702
8
40
26



793
9
41
39



847
10
42
12, 13, 15, 16



854
11
43
4, 5-7, 9, 10



1015
12
44
1, 2, 3



1069
13
45
34



1238
14
46
40, 41



1382
15
47
44



1405
16
48
43



1450
17
49
19, 20-23, 25



1522
18
50
 4, 10



1545
19
51
 3



1653
20
52
 40,



1690
21
53
 8



1703
22
54
28, 33



2006
23
55
19



2180
24
56
43



2214
25
57
17



2482
26
58
13



2580
27
59
40



2649
28
60
10



2653
29
61
38



2736
30
62
24, 26



2907
31
63



2975
32
64
39, 43










Sample Preparation

Prior to performing mass spectrometry, the target protein spots were subjected to in-gel tryptic digestion. Protein spots were removed from the gel and cut into  ̃1 mm pieces. The gel pieces were washed three times with 0.2 ml of 50% (v/v) acetonitrile (Burdick & Jackson, Muskegon, Mich.) in 10 mM ammonium bicarbonate (J. T. Baker, Phillipsburg, N.J.) for 15 minutes with occasional vortexing. The gel pieces were dehydrated with acetonitrile for 5 minutes, lyophylized, and stored frozen at −20° C. Proteins in the gel were then digested with 50 μl of 12 ng/ml sequencing grade modified trypsin (Promega Corporation, Madison, Wis.) overnight at 37° C. The trypsin solution was then removed and the gel again dehydrated in 50 μl acetonitrile. The peptide-containing acetonitrile was then removed and the gel pieces washed in 50 μl 5% formic acid (Riedel-de Haën, Seelze, Germany) for 15 minutes at room temperature in a bath sonicator (Branson Cleaning Equipment Co., Shelton, Conn.). The peptide-containing supernatant was removed and combined with the initial acetonitrile wash. The gel was again washed in acetonitrile and the supernatant combined with two previous extraction steps and dried in a SpeedVac (Thermo Savant) to  ̃10 μl, then diluted to 100 μl with 0.1% (v/v) aqueous formic acid. The sample was then loaded onto a Zip-TipC18 P10 column (Waters Corporation, Milford, Mass.) and eluted in 50 μl of 50% acetonitrile/0.1% formic acid. Samples were transferred to a 96×2 well Teflon coated stainless steel plate (PerSeptive Biosystems, Framingham, Mass.) for mass fingerprinting analysis on the MALDI-ToF instrument (PerSeptive Biosystems) glass nanospray tips (New Objective Inc., Woburn, Mass.) to be sprayed in the orifice of the ion trap mass spectrometer.
Peptide Mass Fingerprinting Using ToF Mass Spectrometry
Each sample was applied to the Teflon coated stainless steel 96×2 well plate with the α-cyano-4-hydroxycinnamic acid thin-layer application. The samples were allowed to dry at room temperature. Mass spectral data were acquired on a Voyager DE-STR MALDI-ToF mass spectrometer (PerSeptive Biosystems) equipped with delayed extraction technology, and a reflector. The mass spectrometer was equipped with a nitrogen laser at 337 nm and a laser rate of 3 Hz. Accelerating voltage was set at 20 kV, mode of operation (reflector), extraction mode (delayed), polarity (positive), grid voltage (65%), mirror voltage ratio (1.12), extraction delay time (200 nsec), mass range (800-3500 Da), and laser shots per spectrum (200).
Static Nanospray Ion Trap-Mass Spectrometry
Mass spectral data were acquired on a ThermoFinnigan LCQ DECA quadrupole ion trap mass spectrometer (ThermoFinnigan, San Jose, Calif.) equipped with a nano-electrospray interface. The nano-electrospray interface consisted of a silica spray needle,  ̃27 mm length by 120/69 μm OD/ID, 2 μm orifice diameter (New Objective Inc.). The glass tip was mounted in a x,y,z axis holder (ThermoFinnigan) held on a base positioned at the front of the mass spectrometer detector. Electrical current was applied to the standard coating of the glass tip to supply an electrical connection for the electrospray interface through a metal connection on the static nanospray probe (ThermoFinnigan). The nanospray delivered a flow of 20-80 nl/min.
Two to five microliters of the tryptic digest was analyzed using a nanospray glass tip spraying directly into the orifice of the mass spectrometer. Peptide analyses were conducted on the LCQ-DECA ion trap mass spectrometer (Thermofinnigan) operating at a variable spray voltage of  ̃1 kV, and using a heated capillary temperature of 200° C. Data sets were acquired in automated MS/MS mode using the data acquisition software provided with the instrument. The acquisition method included 1 MS scan (400-1800 m/z) followed by MS/MS scans of the top three most abundant ions in the MS scan. The dynamic exclusion function was employed to increase the number of peptide ions that were analyzed (settings: 3 amu=exclusion width, 0.5 minutes=exclusion duration). The current experiment was analyzed in groups of samples and in a manual fashion.
Automated analysis of mass fingerprinting data was performed using MSFIT (Protein Prospector) and MASCOT (Matrix Science) software database search engines using Incyte's PathoSeq(c) Staphylcoccus epidermidis 0-47 database. The resultant spectra were processed with baseline correction, noise removal, and peak de-isotoping before utilizing the search engines. The database search parameters were set at the following levels: MW (1000-150 kDa), pl (3-10), Digest (trypsin), max. number of missed cleavages (2), missed cleavages pfactor (0.4), static modification (cysteine modified by acrylamide), N terminus (hydrogen), C terminus (free acid), variable mods (oxidation of methionine, N-terminus acetylation, phosphorylation of serine, threonine, and tyrosine), Mass (monoisotopic), min. number of peptides required to match (4) with a mass tolerance of 300 ppm, and the application of iterative calibration (Intelcast) with a mass tolerance of 15 ppm. Protein identifications were determined by MOWSE score and a 95% confidence score by MS-FIT and MASCOT respectively.
Automated analysis of MS/MS data was performed using SEQUEST incorporated into the Finnigan Bioworks data analysis package (ThermoFinnigan). See Eng, J. K., et al., J Amer Soc Mass Spec, 5(11): p. 976-89 (1994). The following variable modifications were allowed in the software: cysteine acrylamide modification and oxidation of methionine. The search parameters were set at the following designations: mass range (400-3500 Da), lower intensity MS signal (1e +5), peptide tolerance (2.0 Da), min. number of fragment ions (15), min. number of scans in a group (1), and maximum number of missed cleavages (2). All protein identifications were manually verified for accuracy.
Identification Of Proteins By Mass Spectrometry
Spots consistently detected on both fluorescent and immunostained transfers from Staphylcoccus epidermidis grown in 70% serum, were located and labeled for identification by mass spectrometry. See FIGS. 2A and 2B. A total of 40 immunoreactive spots were cut and subjected to mass spectrometric analysis for identification. See Table 4. The complete protein sequences are shown in the sequence listing (SEQ ID NOS:1-32). The protein-containing gel spots were cut out of a gel and identified by mass fingerprint analysis using MALDI-TOF followed by searching Incyte's PathSeq(c) Staphylcoccus epidermidis 0-47 database for the corresponding coding region. See Table 4. Spots with multiple protein hits or questionable signal were further analyzed using static nanospray. A total of 32 proteins was identified, with some spots containing more than one protein. See Tables 3 and 4. Twenty-four of the proteins identified were immunoreactive, 26 bound to serum components and 20 of the proteins were both immunoreactive and serum binding. This large overlap was expected, as most proteins on the surface of Staphylcoccus epidermidis involved in binding to serum factors would likely elicit an immune response.
Six proteins were consistently present in immunostained blots, but no corresponding spots were visibly present on the fluorescent stained transfers. See FIG. 2B, white circles and arrow. Although these proteins are likely expressed during an infection and elicit an immune response they are not expressed at levels that allow for their detection by fluorescent protein staining under the conditions used in these experiments.
Example 6
Prediction of Protein Function
The predicted function of the proteins was determined by comparison with complete genome homologs from ATCC12228. See Zhang, Y. Q., et a., Mol Microbiol, 49(6), p. 1577-93 (2003). The predicted functions shown in Table 5, are attributed to the respective ORFs by prior publications involving the specific protein or by homology to previously characterized proteins occurring in other organisms.







TABLE 5







Predicted Functions of S. epidermidis proteins












Protein
bMethod of


Spot #
aPredicted function
SEQ ID NO:
detection













1, 2
dihydrolipoamide dehydrogenase
12
I, S


 3
′′
12
I, S



glutamate-1-semialdehyde 2,1-
19
I, S



aminomutase


 4
enolase
11
I, S



elongation factor TU (EF-TU)
18
I, S


5-7, 9
enolase
11
I, S


 8
phosphogluconate dehydrogenase
21
I


10
enolase
11
I, S



elongation factor TU (EF-TU)
18
I, S



Na+/H+ antiporter
28
I, S


11
alanine dehydrogenase
3
I, S


12
glyceraldehyde-3-phosphate dehydro (GAPDH)
10
I, S


13
′′
′′
I, S



elongation factor (EF-TS)
26
I, S


14
no match

I, S


15-16
glyceraldehyde-3-phosphate dehydro
10
I, S



(GAPDH)


17
acetyl-CoA C-acetyltransferase
25
I


18
cystathionine gamma-synthase
4
I


19
ferrichrome binding lipoprotein
17
I, S



oligopeptide permease
23
I, S


20-23,
ferrichrome binding lipoprotein
17
I, S


25


24
fructose-bisphosphate aldolase
30
I, S


26
′′
′′
I, S



hypothetical protein
8
I, S



hypothetical protein
7
I, S


27, 30-32
lipoprotein (SitC)
2
I, S


28, 33
amino acid-binding lipoprotein
22
I, S


29
putative hexulose-6-phosphate synthase
5
I, S


34
lipoate ligase
13
I, S


35
no match

I


36
no match

I


37
no match

I, S


38
immunodominant antigen A
29
I, S



Putative protein
1
I, S


39
extracellular matrix binding protein
32
I, S



(Embp)


40
cysteine synthase
14
S



fructose-bisphosphate aldolase
20
S



homologue



thioredoxine reductase
27
S


41
cysteine synthase
14
S


42
putative transaldolase
6
I


43
extracellular matrix binding protein
32
S



(Embp)



transketolase
16
S



hypothetical protein
24
S


44
glutamyl-tRNAGln amidotransferase
15
S



subunit





aThe predicted function of the proteins was determined by comparison with complete genome homologs from ATCC12228.


bMethod by which the spot was detected following transfer to nitrocellulose, reactive immune sera from infected rabbits, I, or binding serum components, S.






As discussed above, the expression profile of cell wall associated proteins from Staphylococcus epidermidis 0-47 grown in 70% rabbit serum was analyzed by 2D gel electrophoresis. The overall expression profile in serum was determined to be significantly different from that occurring following growth in TSB. Numerous proteins that were upregulated during growth in serum were identified by mass spectroscopy and their functions predicted by sequence comparison. See Table 5. Three proteins predicted to be involved in nutrient acquisition, 305,1450, and 1703 were all significantly increased. See Tables 4 and 5. All three proteins form streaks across the gel. See FIG. 4. Without being bound by theory, this may be the consequence of multiple charge isomers or related to their predicted lipoprotein composition. Additionally, all three proteins are highly reactive with immune sera from rabbits infected with Staphylcoccus epidermidis 0-47 suggesting that these proteins are also expressed in the host during an infection. See FIG. 2 and Table 5. In total, 24 of these proteins were identified as reactive with immune sera from infected rabbits. Not only are these proteins expressed during growth in serum, but they also elicited an immune response in an infected animal. See Example 8. Taken together, these data suggest that these antigens are all expressed during an infection. Expression of the transcripts from these ORFs within the bloodstream of an infected mouse was confirmed by RT-PCR for all of the identified proteins (data not shown).
Example 7
Cloning And Expression Of Recombinant Proteins
Genes were cloned using primers designed based on the proteins identified by mass spectrometry of the expressed proteins and the Staphylcoccus epidermidis 0-47 database. Individual genes were amplified by polymerase chain reaction (PCR) using Pfu Turbo DNA polymerase (Stratagene, La Jolla, Calif.) and adenine overhangs were added with Taq DNA polymerase (Roche Diagnostics). The reaction products were cloned into pCRT7/NT-TOPO or pBAD/TOPOThio (Invitrogen, Carlsbad, Calif.) following the manufacturer's instructions and transformed into E. coli Top10 (Invitrogen). Positive clones were detected by colony PCR using ReddyMix PCR mastermix (ABgene, Rochester, N.Y.) and sequenced to ensure that no spurious mutations had arisen. Plasmids from pCRT7 clones were purified and transformed into E. coli BL21 (DE3) (Invitrogen) for expression using the T7 polymerase. Proteins were expressed by growth of the positive clones in HySoy broth (1% HySoy, Quest Intl, Stockbridge, Ga.), 0.5% yeast extract, 100 mM NaCl, 50 mM Na2HPO4-7H2O, 40 mM NaH2PO4—H2O) supplemented with 100 μg/ml ampicillin at 37° C. with shaking (200 rpm) until OD600 ̃1.0. Protein expression was induced with either 1 mM IPTG (pCRT7) or 0.2% arabinose (pBAD) and the cultures were grown an additional 3 hours. The cells were then harvested by centrifugation and expression was assessed by SDS-PAGE of whole cell lysates.
Purification Of Recombinant Proteins
Cell pellets were resuspended in 100 ml TBS (20 mM Tris, pH 8.0, 150 mM NaCl) and lysed by one passage through a French pressure cell (SLM-Aminco, Rochester, N.Y.). Samples were then separated into a soluble fraction or insoluble pellet by centrifugation at 10,000×g for 10 minutes. The location of recombinant protein was assessed by SDS-PAGE. If a recombinant protein was in the soluble fraction, then the protein was loaded onto iminodiacetic acid agarose resin charged with Ni2+. See Table 6. Next, the column was washed with 30 mM imidazole in TBS. Bound proteins were eluted with 300 mM imidazole in TBS. If an additional purification step was required, the proteins were dialyzed into 20 mM Tris, pH 8.0, containing 50 mM NaCl, 1 mM EDTA and loaded onto a column packed with POROS-Q resin (Applied Biosystems, Foster City, Calif.). Bound proteins were eluted with a 50 mM to 500 mM NaCl gradient in 20 mM Tris, pH 8.0, 1 mM EDTA. Fractions containing the protein of interest were determined by SDS-PAGE and frozen at −20° C.
If a recombinant protein was found in the insoluble fraction, then the insoluble fraction was treated with 100 ml 1% Triton X-100 in TBS for 4 hours at 4° C. See Table 6. The insoluble proteins were pelleted by centrifugation and the supernatant discarded. The insoluble pellet was then extracted with 100 ml of 8 M urea in TBS for at least 8 hours at room temperature. Insoluble debris was pelleted and the protein was purified as above except all buffers contained 2M urea. Following purification Triton X-100 was added to a final concentration of 0.1%. The proteins were then dialyzed into TBS containing 0.1% Triton and stored at −20° C.
All liquid chromatography was performed using an AKTA explorer (Amersham-Pharmacia Biotech, Piscataway, N.J.). All SDS-PAGE was performed using 4-20% gradient Tris-glycine gels (Cambrex).







TABLE 6







Recombinant Protein Solubility











Protein
Location of Recombinant Protein













Orf
SEQ ID NO:
Soluble Fraction
Insoluble Fraction
















121
1

X



305
2
X



321
3

X



373
4

X



554
5
X



639
6
X



608
7

X



702
8

X



793
9

X



847
10
X



854
11

X



1015
12

X



1069
13

X



1238
14

X



1382
15

X



1405
16

X



1450
17
X



1522
18

X



1545
19

X



1653
20

X



1690
21
X



1703
22
X



2006
23
NT



2180
24

X



2214
25

X



2482
26
X



2580
27
X



2649
28

X



2653
29
X



2736
30

X



2907
31
NT



2975
32
NT







X indicates the protein was found in that fraction.



NT indicates not tested.






Example 8
Immunogenic Compositions Using Recombinant Staphylcoccus epidermidis Proteins
Four week-old female Balb/C mice (Charles River Laboratories, Wilmington, Mass.) were immunized at 0, 3 and 6 weeks with 10 μg recombinant protein formulated with 20 μg STIMULONTM QS-21 by subcutaneous injection. The mice were bled on week 0 prior to the first immunization and on week 8. Two days following the final bleed, the mice were challenged by intraperitoneal injection of 5×108 cfu Staphylcoccus epidermidis 0-47 grown overnight on Columbia salt agar (1× Columbia agar, 0.1% glucose, 1% yeast extract, 0.5% NaCl). Twenty-four hours following challenge, the mice were sacrificed and the bacteria were enumerated in the spleen and blood.
Active Immunization of Mice With Recombinant Proteins
Twenty-seven orfs encoding either serum-binding or immunoreactive proteins were cloned from Staphylococcus epidermidis 0-47 and the recombinant proteins were expressed in E. coli with a hexahistidine tag (The His-tag was used as a matter of convenience; an immunogenic composition of this invention would contain proteins expressed without a His-tag). See Table 7. These proteins were purified using a Ni2+ chelate column followed by ion exchange chromatography. The three remaining cloned orfs (2006, 2975 and 2907) were cloned but not expressed at levels sufficient for purification. Balb/C mice were immunized at 0, 3 and 6 weeks with individual recombinant proteins. The animals were bled at 0 and 8 weeks and challenged (i.p.) on week 8 with Staphylcoccus epidermidis 0-47. Twenty-four hours following challenge, the animals were euthanized and the number of bacteria present in the blood and spleen enumerated. This initial screen of immunogenic composition candidates was performed on groups of 5 animals to enable for the screening of numerous proteins. The resulting data are not statistically significant but they did provide valuable information as to the immunogenic composition potential of a large number of candidates. Eight of twenty-seven recombinant proteins reduced the number of bacteria recovered from the spleen and/or blood by one log or more. See Table 7 (NT=not tested).







TABLE 7







Reductions in Bacterial Counts Following Immunization












Log CFU




Protein
Reduction












Orf
SEQ ID NO:
Spleen
Blood
















121
1
NT
NT



305
2
0.8
1



321
3
0
1



373
4
0
0



554
5
0.5
0



639
6
0
0



608
7
0.5
0



702
8
0
0



793
9
NT
NT



847
10
0
0



854
11
1.5
0.7



1015
12
0
0



1069
13
1.1
0



1238
14
1
0.8



1382
15
0
0



1405
16
0
0



1450
17
0
0



1522
18
0
0



1545
19
0
0



1653
20
1
0



1690
21
0
0



1703
22
2
0



2006
23
NT
NT



2180
24
0
0



2214
25
1.2
0.9



2482
26
0
0



2580
27
0
0



2649
28
0.9
0



2653
29
0
0



2736
30
0
0



2907
31
NT
NT



2975
32
NT
NT







NT indicates not tested.






The sera obtained from the immunized mice were evaluated for antibody reactivity to the bacterial proteins. See Table 8. Twenty-three of twenty-four immune sera tested reacted with the native proteins, as determined by western blots of whole cell lysates of Staphylcoccus epidermidis grown to mid-log phase in rabbit serum. See Table 8 (NT=not tested).







TABLE 8







Antibody Reactivity to Staphylococcal Protein












Antibody Reactivity to




Protein
Staphylococcal Protein












Orf
SEQ ID NO:
S. epidermidis
S. aureus
















121
1
NT
NT



305
2
+
+



321
3
+
−



373
4
+
NT



554
5
−
NT



639
6
+
−



608
7
+
+



702
8
+
+



793
9
+
+



847
10
+
+



854
11
+



1015
12
+
+



1069
13
+
+



1238
14
+
NT



1382
15
+
+



1405
16
+
+



1450
17
+
+



1522
18
+
+



1545
19
+
+



1653
20
+
NT



1690
21
+
+



1703
22
+
+



2006
23
NT
NT



2180
24
NT
NT



2214
25
+
+



2482
26
+
+



2580
27
+
NT



2649
28
+
+



2653
29
−
NT



2736
30
+
+



2907
31
NT
NT



2975
32
NT
NT







NT indicates not tested.






As shown in Table 8, many of the animals immunized with Staphylcoccus epidermidis antigens also developed antibody responses to Staphylcoccus aureus. Therefore, immunogenic compositions against Staphylcoccus epidermidis antigens could be effective in the treatment or prevention of Staphylcoccus aureus as well as Staphylcoccus epidermidis. See Table 8.
A subset of the recombinant proteins used in immunogenic compositions above were used to immunize larger groups of mice. Groups of 10 female (4 week-old) Balb/C mice were immunized by subcutaneous injection with saline or 10 μg of antigen with 20 μg STIMULONTM QS-21 as adjuvant. Two weeks following the last immunization, the mice ere challenged with  ̃5×108 cfu S. epidermidis 0-47 by intraperitoneal injection. Twenty-four hours after challenge, bacteria were enumerated in the blood and spleen. See Table 9. Reduction in log CFU was determined as compared to a control of STIMULONTM QS-21 in saline. Data were analyzed by student's-T test with resulting p-values of *0.05 or **0.01.







TABLE 9







Proteins Used in Immunogenic Compositions










LOG CFU




REDUCTION









Orf
Spleen
Blood












305
0.5



321
0.7
1.2*


554
—


608
0.3


793
0.7


854
0.9


1069
1.6**


1238
1.2*
1.2*


1653
0.4


1703
0.8


2214
1.4*


2649
1.2*





*p-value <0.05


**p-value <0.01






The Staphylcoccus epidermidis proteins shown in Table 9 showed the greatest effectiveness when used in immunogenic compositions that reduced the severity of a bacterial infection following a subsequent challenge.
Example 9
Protection from Staphylcoccus aureus Challenge Following Immunization With Staphylcoccus epidermidis Proteins
As suggested by the antibody binding data in Example 8, (Table 8), immunogenic compositions against Staphylcoccus epidermidis antigens could be effective in the treatment or prevention of Staphylcoccus aureus. Therefore, a challenge was performed using Staphylcoccus aureus following immunization with immunogenic compositions of Staphylcoccus epidermidis antigens.
Four week-old female CD-1 mice (Charles River Laboratories, Wilmington, Mass.) were immunized at 0, 3 and 6 weeks with 10 μg recombinant protein in 20 μg STIMULONTM QS-21 by subcutaneous injection. The mice were bled on week 0 prior to the first immunization and on week 8. Two days following the final bleed the mice were challenged by intraperitoneal injection of 3×108 cfu S. aureus Reynolds grown overnight on Columbia salt agar (1× Columbia agar, 0.1% glucose, 1% yeast extract, 0.5% NaCl). Twenty-four hours following challenge, the mice were sacrificed and the bacteria were enumerated in the kidney.







TABLE 10







Challenge with Staphylococcus. aureus













Protein
Predicted
CFU



ORF
SEQ ID NO:
Function
reduction
















2653
29
immunodominant Ag A
0.9 log



321
3
alanine dehydrogenase
0.7 log



1015
12
dihydrolipoamide
none





dehydrogenase



608
7
unknown
0.6 log



1069
13
lipoate ligase
1.7 log



639
6
hypothetical
none










As shown in Table 10, certain Staphylcoccus epidermidis antigens were effective in inducing antibodies that recognized and bound to Staphylcoccus aureus. In addition, the induced antibodies had the beneficial effect of reducing the level of bacteria enumerated after a Staphylcoccus aureus challenge.
The percent identity of the amino acid sequence of the Staphylcoccus epidermidis polypeptide antigens of SEQ ID NOS:1 through SEQ ID NO:32 was compared to the amino acid sequence of their homologs from Staphylcoccus aureus. The results are shown in Table 11.







TABLE 11







Identity between Staphylococcus epidermidis and


Staphylococcus aureus










Polypeptide
a% Identity with Homolog


Orf
SEQ ID NO:
in S. aureus












121
1
33%


305
2
76%


321
3
85%


373
4
81%


554
5
87%


639
6
62%


608
7
89%


702
8
97%


793
9
23%


847
10
95%


854
11
94%


1015
12
96%


1069
13
82%


1238
14
94%


1382
15
93%


1405
16
82%


1450
17
71%


1522
18
96%


1545
19
91%


1653
20
95%


1690
21
89%


1703
22
82%


2006
23
90%


2180
24
87%


2214
25
73%


2482
26
91%


2580
27
91%


2649
28
78%


2653
29
62%


2736
30
92%


2907
31


2975
32
32%





Homology was determined between polypeptide sequences

## Claims

1. An immunogenic composition comprising one or more isolated polypeptides consisting of the amino acid sequence selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 13, and SEQ ID NO: 17, wherein the at least one of the one or more isolated polypeptides is a lipoprotein, and at least one of the one or more isolated polypeptides is derived from Staphylococcus epidermidis.

2. The immunogenic composition of claim 1, wherein the one or more isolated polypeptides are immunoreactive with antibodies in the serum of rabbits infected with Staphylococcus epidermidis.

3. The immunogenic composition of claim 2, wherein the one or more isolated polypeptides bind to one or more rabbit serum proteins.

4. The immunogenic composition according to claim 1, further comprising a pharmaceutically acceptable carrier.

5. The immunogenic composition according to claim 4, further comprising one or more adjuvants.

6. An immunogenic composition comprising one or more isolated polypeptides consisting of an heterologous amino acid sequence and an amino acid sequence selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 13, and SEQ ID NO: 17.

7. The immunogenic composition according to claim 6, wherein the at least one of the one or more isolated polypeptides is a fusion polypeptide.

8. The immunogenic composition according to claim 7, wherein the at least one of the one or more isolated polypeptides is a recombinant polypeptide.

9. The immunogenic composition according to claim 1, said composition further comprising a Staphylococcus epidermidis polysaccharide antigen.

10. The immunogenic composition according to claim 1, said composition further comprising a Staphylococcus aureus polysaccharide or polypeptide antigen.

11. An immunogenic composition comprising one or more isolated polypeptides consisting of the amino acid sequence selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 13, SEQ ID NO: 17 and SEQ ID NO: 22 and further comprising an isolated Staphylococcus epidermidis polypeptide consisting of SEQ ID NO: 14.

12. A method of inducing an immune response against Staphylococcus epidermidis comprising administering to a mammal an immunogenic amount of an immunogenic composition according to claim 1.

13. The method of claim 12, wherein the immunogenic composition further comprises an adjuvant.

14. The method of claim 12, wherein at least one of the one or more isolated polypeptides is a recombinant polypeptide.

15. The immunogenic composition according to claim 1, wherein one of the one or more isolated polypeptides consists of the amino acid sequence of SEQ ID NO: 2.

16. The immunogenic composition according to claim 1, wherein one of the one or more isolated polypeptides consists of the amino acid sequence of SEQ ID NO: 13.

17. The immunogenic composition according to claim 1, wherein one of the one or more isolated polypeptides consists of the amino acid sequence of SEQ ID NO: 17.

18. An immunogenic composition comprising one or more isolated polypeptides consisting of the amino acid sequence selected from the group consisting of SEQ ID NO: 2, SEQ ID NO: 13, and SEQ ID NO: 17 and further comprising an isolated Staphylococcus epidermidis polypeptide consisting of SEQ ID NO: 22.

19. A method of inducing an immune response against Staphylococcus epidermidis comprising administering to a mammal an immunogenic amount of an immunogenic composition according to claim 6 .

20. The method of claim 19, wherein at least one of the one or more isolated polypeptides is a fusion polypeptide.

21. The method of claim 19, wherein the immunogenic composition further comprises an adjuvant.