bluuebunny/crossref_metadata_2025_split huggingface dataset:
DNA and a CpG Oligonucleotide Derived fromBabesia bovisAre Mitogenic for Bovine B Cells
Authors: Brown Wendy C. , Estes D. Mark , Chantler Sue Ellen , Kegerreis Kimberly A. , Suarez Carlos E. 
Published: December 2019

ABSTRACTDNAs from bacteria and variety of nonvertebrate organisms, including nematodes, mollusks, yeasts, and insects, cause polyclonal activation of murine B lymphocytes. Similar studies have not been reported for bovine B cells, and to date no studies have reported mitogenic properties of protozoal DNA for any species. However, we and others have observed that protozoal parasite antigens can induce the proliferation of lymphocytes from nonexposed donors. Extending these studies, we now show that the mitogenic property of protozoal antigen preparations is in part attributable to parasite DNA and thatBabesia bovisDNA is directly mitogenic for bovine B cells. DNase treatment ofB. bovisextracts abrogatedB. bovis-induced proliferation of peripheral blood mononuclear cells from nonexposed cattle. Like DNAs from other organisms that were mitogenic for murine B cells,B. bovisDNA is largely nonmethylated and induced a dose-dependent proliferation of bovine B cells, which was reduced upon methylation. Furthermore,B. bovisandE. coliDNAs enhanced immunoglobulin secretion by cultured B cells, inducing moderate increases in immunoglobulin G1 and stronger increases in immunoglobulin G2. Because certain nonmethylated CpG motifs present in bacterial DNA are known to stimulate proliferation of murine and human B cells, an 11-kb fragment ofB. bovisDNA was analyzed for CG dinucleotide content and for the presence of known immunostimulatory sequences (ISS) centered on a CG motif. The frequency of CG dinucleotides was approximately one-half of the expected frequency, and several CpG hexameric sequences with known activity for murine B cells were identified. An oligodeoxynucleotide containing one of these ISS (AACGTT), which is present within the rhoptry-associated protein-1 (rap-1) open reading frame, was shown to stimulate B-cell proliferation. These ISS may be involved in host immune modulation during protozoal infection and may be useful as vaccine adjuvants.
Antrum- and Corpus Mucosa-Infiltrating CD4+Lymphocytes inHelicobacter pyloriGastritis Display a Th1 Phenotype
Authors: Sommer Frank , Faller Gerhard , Konturek Peter , Kirchner Thomas , Hahn Eckhart G. , Zeus Jürgen , Röllinghoff Martin , Lohoff Michael 
Published: December 2019

ABSTRACTIn this study, cytokine patterns produced by CD4+T cells isolated from antrum or corpus gastral biopsy specimens of 10 patients withHelicobacter pylori-positive gastritis were compared. To this end, expression of intracellular cytokines (interleukin-4 [IL-4] and gamma interferon) and of CD4 was assessed by flow cytometry. Ten to 60% of the isolated CD4+T cells produced gamma interferon upon stimulation. With the exception of one patient, IL-4-positive CD4+cells were not detected. Therefore, CD4+cells infiltrating antrum and corpus stomach mucosa duringH. pyloriinfection show a Th1 phenotype. This polarized Th1-type response may contribute to the inability of the immune system to eradicateH. pyloriinfection.
The Type IV Leader Peptidase/ N -Methyltransferase of
Vibrio vulnificus
Controls Factors Required for Adherence to HEp-2 Cells and Virulence in Iron-Overloaded Mice
Authors: Paranjpye Rohinee N. , Lara J. Cano , Pepe Jeffrey C. , Pepe Cynthia M. , Strom Mark S. 
Published: December 2019

ABSTRACT

Vibrio vulnificus
expresses a number of potential virulence determinants that may contribute to its ability to cause a severe and rapidly disseminating septicemia in susceptible hosts. We have cloned and characterized two genes encoding products related to components of the type IV pilus biogenesis and general secretory (type II) pathways by complementation of a type IV peptidase/ N -methyltransferase (PilD) mutant of
Pseudomonas aeruginosa
with a
V. vulnificus
genomic library. One of the genes (
vvpD
) encodes a protein homologous to PilD and other members of the type IV peptidase family that completely restores this activity in a
P. aeruginosa
mutant deficient in the expression of PilD. The other gene (
vvpC
) encodes a homolog of PilC from
P. aeruginosa
, where it is essential for assembly of type IV pili. Phenotypic characterization of a
V. vulnificus vvpD
mutant, constructed by allelic exchange, showed that VvpD is required for the expression of surface pili, suggesting that the pili observed on
V. vulnificus
are of the type IV class. This mutant was also unable to secrete at least three extracellular degradative enzymes, and the localization of one of these (the cytolysin/hemolysin) to the periplasmic space indicates that these proteins are normally exported via the type II secretion pathway. Loss of VvpD resulted in significant decreases in CHO cell cytotoxicity, adherence to HEp-2 cells, and virulence in a mouse model. Capsule formation and serum resistance were not affected in the
vvpD
mutant, indicating that in addition to capsule, virulence of
V. vulnificus
requires type IV pili and/or extracellular secretion of several exoenzymes.
Cloning and Sequencing ofyajCandsecDHomologs ofBrucella abortusand Demonstration of Immune Responses to YajC in Mice Vaccinated withB. abortusRB51
Authors: Vemulapalli Ramesh , Duncan A. Jane , Boyle Stephen M. , Sriranganathan Nammalwar , Toth Thomas E. , Schurig Gerhardt G. 
Published: December 2019

ABSTRACTTo identifyBrucellaantigens that are potentially involved in stimulating a protective cell-mediated immune response, a gene library ofBrucella abortus2308 was screened for the expression of antigens reacting with immunoglobulin G2a antibodies from BALB/c mice vaccinated withB. abortusRB51. One selected positive clone (clone MCB68) contained an insert of 2.6 kb; nucleotide sequence analysis of this insert revealed two open reading frames (ORFs). The deduced amino acid sequences of the first and second ORFs had significant similarities with the YajC and SecD proteins, respectively, of several bacterial species. Both the YajC and SecD proteins were expressed inEscherichia colias fusion proteins with maltose binding protein (MBP). In Western blots, sera from mice vaccinated withB. abortusRB51 recognized YajC but not SecD. Further Western blot analysis with purified recombinant YajC protein indicated that mice inoculated withB. abortus19 or 2308 orB. melitensisRM1 also produced antibodies to YajC. In response to in vitro stimulation with recombinant MBP-YajC fusion protein, splenocytes from mice vaccinated withB. abortusRB51 were able to proliferate and produce gamma interferon but not interleukin-4. This study demonstrates, for the first time, the involvement of YajC protein in an immune response to an infectious agent.
Cloning, Expression, and Sequencing of a Cell Surface Antigen Containing a Leucine-Rich Repeat Motif from
Bacteroides forsythus
ATCC 43037
Authors: Sharma Ashu , Sojar Hakimuddin T. , Glurich Ingrid , Honma Kiyonobu , Kuramitsu Howard K. , Genco Robert J. 
Published: December 2019

ABSTRACT

Bacteroides forsythus
is a recently recognized human periodontopathogen associated with advanced, as well as recurrent, periodontitis. However, very little is known about the mechanism of pathogenesis of this organism. The present study was undertaken to identify the surface molecules of this bacterium that may play roles in its adherence to oral tissues or triggering of a host immune response(s). The gene (
bspA
) encoding a cell surface-associated protein of
B. forsythus
with an apparent molecular mass of 98 kDa was isolated by immunoscreening of a
B. forsythus
gene library constructed in a lambda ZAP II vector. The encoded 98-kDa protein (BspA) contains 14 complete repeats of 23 amino acid residues that show partial homology to leucine-rich repeat motifs. A recombinant protein containing the repeat region was expressed in
Escherichia coli
, purified, and utilized for antibody production, as well as in vitro binding studies. The purified recombinant protein bound strongly to fibronectin and fibrinogen in a dose-dependent manner and further inhibited the binding of
B. forsythus
cells to these extracellular matrix (ECM) components. In addition, adult patients with
B. forsythus
-associated periodontitis expressed specific antibodies against the BspA protein. We report here the cloning and expression of an immunogenic cell surface-associated protein (BspA) of
B. forsythus
and speculate that it mediates the binding of bacteria to ECM components and clotting factors (fibronectin and fibrinogen, respectively), which may be important in the colonization of the oral cavity by this bacterium and is also a target for the host immune response.
Function and Protective Capacity ofTreponema pallidumsubsp.pallidumGlycerophosphodiester Phosphodiesterase
Authors: Cameron Caroline E. , Castro Christa , Lukehart Sheila A. , Van Voorhis Wesley C. 
Published: December 2019

ABSTRACTInfectious syphilis, caused by the spirochete bacteriumTreponema pallidumsubsp.pallidum, remains a public health concern worldwide. The immune-response evasion mechanisms employed byT. pallidumare poorly understood, and prior attempts to identify immunoprotective antigens for subsequent vaccine design have been unsuccessful. Previous investigations conducted in our laboratory identified theT. pallidumglycerophosphodiester phosphodiesterase as a potential immunoprotective antigen by using a differential immunologic expression library screen. In studies reported here, heterologous expression of theT. pallidumglycerophosphodiester phosphodiesterase inEscherichia coliyielded a full-length, enzymatically active protein. Characterization of the recombinant molecule showed it to be bifunctional, in that it exhibited specific binding to human immunoglobulin A (IgA), IgD, and IgG in addition to possessing enzymatic activity. IgG fractionation studies revealed specific binding of the recombinant enzyme to the Fc fragment of human IgG, a characteristic that may play a role in enabling the syphilis spirochete to evade the host immune response. In further investigations, immunization with the recombinant enzyme significantly protected rabbits from subsequentT. pallidumchallenge, altering lesion development at the sites of challenge. In all cases, animals immunized with the recombinant molecule developed atypical pale, flat, slightly indurated, and nonulcerative reactions at the challenge sites that resolved before lesions appeared in the control animals. Although protection in the immunized rabbits was incomplete, as demonstrated by the presence ofT. pallidumin the rabbit infectivity test, glycerophosphodiester phosphodiesterase nevertheless represents a significantly immunoprotectiveT. pallidumantigen and thus may be useful for inclusion in an antigen cocktail vaccine for syphilis.
Secreted Effector Proteins of
Salmonella dublin
Act in Concert To Induce Enteritis
Authors: Jones Michael A. , Wood Michael W. , Mullan Paul B. , Watson Patricia R. , Wallis Tim S. , Galyov Edouard E. 
Published: December 2019

ABSTRACT

The ability of enteropathogenic salmonellae to recruit inflammatory cells and induce secretory responses in the infected ileum is considered to be a main feature in
Salmonella
-induced enteritis. Interactions between the pathogen and intestinal epithelial cells result in a variety of cellular responses mediating inflammation and fluid secretion. It is becoming apparent that proteins secreted by the Inv-Spa type III secretion system of
Salmonella
spp. play a key role in the induction of these responses. We have recently demonstrated that the SopB effector protein is translocated into eukaryotic cells via a Sip-dependent pathway and mediates inflammation and fluid secretion in infected ileal mucosa. However, SopB did not appear to be the only effector involved, as inactivation of the
sopB
gene only partially impaired enteropathogenicity. We suggested that at least some of such protein effectors are likely to be proteins of the same class as SopB, i.e., secreted effector proteins translocated into eukaroyotic cells via a Sip-dependent pathway. In this work, we identify SopD, another secreted protein belonging to the family of Sop effectors of
Salmonella dublin
. Using the
cya
reporter system we showed that SopD is translocated into eukaroyotic cells. We assessed the potential involvement of SopD in enteropathogenicity and found that inactivation of
sopD
has an additive effect in relation to the
sopB
mutation.
Analysis of Clinical and Environmental Strains of Nontoxigenic
Vibrio cholerae
for Susceptibility to CTXΦ: Molecular Basis for Origination of New Strains with Epidemic Potential
Authors: Faruque Shah M. , Asadulghani  , Saha Manujendra N. , Alim A. R. M. Abdul , Albert M. John , Islam K. M. Nasirul , Mekalanos John J. 
Published: December 2019

ABSTRACT

Toxigenic
Vibrio cholerae
strains are lysogens of CTXΦ, a filamentous phage which encodes cholera toxin. The receptor for CTXΦ for invading
V. cholerae
cells is the toxin-coregulated pilus (TCP), the genes for which reside in a larger genetic element, the TCP pathogenicity island. We analyzed 146 CTX-negative strains of
V. cholerae
O1 or non-O1 isolated from patients or surface waters in five different countries for the presence of the TCP pathogenicity island, the regulatory gene
toxR
, and the CTXΦ attachment sequence
attRS
, as well as for susceptibility of the strains to CTXΦ, to investigate the molecular basis for the emergence of new clones of toxigenic
V. cholerae
. DNA probe or PCR assays for
tcpA
,
tcpI
,
acfB
,
toxR
, and
attRS
revealed that 6.85% of the strains, all of which belonged to the O1 serogroup, carried the TCP pathogenicity island,
toxR
, and multiple copies of
attRS
, whereas the remaining 93.15% of the strains were negative for TCP but positive for either one or both or neither of
toxR
and
attRS
. An analysis of the strains for susceptibility to CTXΦ, using a genetically marked derivative of the phage CTX-KmΦ, showed that all TCP-positive CTX-negative strains and 1 of 136 TCP-negative strains were infected by the phage either in vitro or in the intestines of infant mice. The phage genome integrated into the chromosome of infected
V. cholerae
O1 cells forming stable lysogens. Comparative analysis of rRNA gene restriction patterns revealed that the lysogens derived from nontoxigenic progenitors were either closely related to or distinctly different from previously described clones of toxigenic
V. cholerae
. To our knowledge, this is the first demonstration of lysogenic conversion of naturally occurring nontoxigenic
V. cholerae
strains by CTXΦ. The results of this study further indicated that strains belonging to the O1 serogroup of
V. cholerae
are more likely to possess the TCP pathogenicity island and hence to be infected by CTXΦ, leading to the origination of potential new epidemic clones.
Expression of the pMGA Genes of
Mycoplasma gallisepticum
Is Controlled by Variation in the GAA Trinucleotide Repeat Lengths within the 5′ Noncoding Regions
Authors: Glew Michelle D. , Baseggio Nina , Markham Philip F. , Browning Glenn F. , Walker Ian D. 
Published: December 2019

ABSTRACT

We analyzed the segment of DNA which contains the expressed pMGA gene from one strain of
Mycoplasma gallisepticum
in normal (strain S6) cells and in cells in which pMGA1.1 gene expression had ceased as a consequence of in vitro culture in the presence of pMGA1.1-specific antibodies. Sequence analysis of isolates lacking pMGA1.1 expression revealed that this gene, which is typically expressed, exhibited sequence changes within a region 5′ to its promoter. Specifically, pMGA1.1
+
cells contained a (GAA)
12
motif upstream of the promoter, whereas in pMGA1.1
−
cells the corresponding region contained a (GAA)
10
motif; when such cells were grown in medium no longer containing pMGA-specific antibodies, pMGA1.1 was reexpressed and the 5′ (GAA)
12
motif was restored. Two other genes, pMGA1.9 and pMGA1.2, were also shown to acquire a (GAA)
12
motif in clones which expressed these genes. The results imply the evolution by the pMGA genes of
M. gallisepticum
of a novel transcriptional requirement which facilitates rapid and reversible switches in the pMGA expression pattern.
The Hemagglutination-Positive Phenotype ofMycoplasma synoviaeInduces Experimental Infectious Synovitis in Chickens More Frequently than Does the Hemagglutination-Negative Phenotype
Authors: Narat M. , Bencina D. , Kleven S. H. , Habe F. 
Published: December 2019

ABSTRACTInoculation with hemagglutination-positive (HA+) cultures ofMycoplasma synoviaeAAY-4 induced acute synovitis significantly more frequently (P= 0.001) in chicken tibiotarsal-tarsometatarsal joints than did inoculation with HA-negative (HA−) cultures derived from the same clone of AAY-4. Immunoblotting analyses showed that HA+cultures abundantly expressed two phase-variable hemadherence-associated surface membrane proteins of 53 kDa and 48 to 50 kDa defined by monoclonal antibodies. HA−cultures lacked the 53-kDa proteins and synthesized truncated 27- to 30-kDa forms of the 48- to 50-kDa proteins. Inoculation of cyclosporin A (CsA) into infected joints significantly decreased the frequency of acute synovitis (P= 0.001). Moreover, repeated intra-articular inoculation of CsA (three doses of 1 mg at 2-day intervals) significantly reduced the local antibody response toM. synoviaein the joints treated with CsA.
Chlamydia trachomatis
IncA Is Localized to the Inclusion Membrane and Is Recognized by Antisera from Infected Humans and Primates
Authors: Bannantine John P. , Stamm Walter E. , Suchland Robert J. , Rockey Daniel D. 
Published: December 2019

ABSTRACT

Chlamydia psittaci
produces a collection of proteins, termed IncA, IncB, and IncC, that are localized to the chlamydial inclusion membrane. In this report we demonstrate that IncA is also produced by
Chlamydia trachomatis. C. trachomatis
IncA is structurally similar to
C. psittaci
IncA and is also localized to the inclusion membrane. Immunoblot analysis demonstrated that sera from
C. trachomatis
-infected patients and from experimentally infected monkeys both recognized
C. trachomatis
IncA.
Population Structure of the Relapsing Fever Spirochete
Borrelia hermsii
as Indicated by Polymorphism of Two Multigene Families That Encode Immunogenic Outer Surface Lipoproteins
Authors: Hinnebusch B. Joseph , Barbour Alan G. , Restrepo Blanca I. , Schwan Tom G. 
Published: December 2019

ABSTRACT

The tick-borne relapsing fever spirochete
Borrelia hermsii
evades the mammalian immune system by periodically switching expression among members of two multigene families that encode immunogenic, antigenically distinct outer surface proteins. The type strain,
B. hermsii
HS1, has at least 40 complete genes and pseudogenes that participate in this multiphasic antigenic variation. Originally termed
vmp
(for variable major protein) genes, they have been reclassified as
vsp
(for variable small protein) and
vlp
(for variable large protein) genes, based on size and amino acid sequence similarities. To date, antigenic variation in
B. hermsii
has been studied only in the type strain, HS1. Nucleotide sequence comparisons of 23
B. hermsii
HS1 genes revealed five distinct groups, the
vsp
gene family and four subfamilies of
vlp
genes. We used PCR with family- and subfamily-specific primers, followed by restriction fragment length polymorphism analysis, to compare the
vsp
and
vlp
repertoires of HS1 and seven other
B. hermsii
isolates from Washington, Idaho, and California. This analysis, together with pulsed-field gel electrophoresis genome profiles, revealed that the eight isolates formed three distinct groups, which likely represent clonal lineages. Members of the three groups coexisted in the same geographic area, but they could also be isolated across large geographical distances. This population structure may result from immune selection by the host, as has been proposed for other pathogens with polymorphic antigens.
Interleukin-4-Dependent Immunoglobulin G1 Isotype Switch in the Presence of a Polarized Antigen-Specific Th1-Cell Response to the Trypanosome Variant Surface Glycoprotein
Authors: Schopf Lisa R. , Filutowicz Hanna , Bi Xiao-Juan , Mansfield John M. 
Published: December 2019

ABSTRACTThis study examines B-cell immunoglobulin (Ig) class-switching events in the context of parasite antigen-specific Th-cell responses in experimental African trypanosomiasis. Inbred mice were infected withTrypanosoma brucei rhodesiense, and the coordinate stimulation of Th-cell cytokine responses and B-cell responses to the trypanosome variant surface glycoprotein (VSG) was measured. The cytokines produced by T cells in response to VSG, at both the transcript and protein levels, were gamma interferon and interleukin-2 (IL-2) but not IL-4 or IL-5. Isotype profiles of antibodies specific for VSG showed that IgG1, IgG2a, and IgG3 switch responses predominated; no VSG-specific IgE responses were detected. To determine whether cryptic IL-4 responses played a role in promoting the unexpected IgG1 switch response, IL-4 knockout mice were infected; the cytokine responses and Ig isotype profiles of IL-4 knockout mice were identical to those of the wild-type control mice except for dramatically reduced IgG1 levels in response to VSG. Thus, these results revealed an IL-4-dependent component of the VSG-driven B-cell Cμ-to-Cγ1 switch. We speculate that an IL-4 response is mediated primarily by cells other than T lymphocytes since IL-4-secreting but parasite antigen-unresponsive, “background” cells were detected in all infected mice and since infectednudemice also displayed a detectable IgG1 switch response. Overall, our results suggest that B-cell clonal stimulation, maturation, and Ig class switching in African trypanosomiasis may be partially regulated by unusual mechanisms that do not include antigen-specific Th1 or Th2 cells.
Mucosal Immunogenicity of a Holotoxin-Like Molecule Containing the Serine-RichEntamoeba histolyticaProtein (SREHP) Fused to the A2Domain of Cholera Toxin
Authors: Sultan Faisal , Jin Ling-ling , Jobling Michael G. , Holmes Randall K. , Stanley Samuel L. 
Published: December 2019

ABSTRACTOne strategy for the induction of mucosal immune responses by oral immunization is to administer the antigen in conjunction with cholera toxin. Cholera toxin consists of one A polypeptide (CTA) which is noncovalently linked to five B subunits (CTB) via the A2portion of the A subunit (CTA2). Coupling of antigens to the nontoxic B subunit of cholera toxin may improve the immunogenicity of antigens by targeting them to GM1 ganglioside on M cells and intestinal epithelial cells. Here, we describe the construction of a translational fusion protein containing the serine-richEntamoeba histolyticaprotein (SREHP), a protective amebic antigen, fused to a maltose binding protein (MBP) and to CTA2. When coexpressed inEscherichia coliwith the CTB gene, these proteins assembled into a holotoxin-like chimera containing MBP-SREHP-CTA2and CTB. This holotoxin-like chimera (SREHP-H) inhibited the binding of cholera toxin to GM1 ganglioside. Oral vaccination of mice with SREHP-H induced mucosal immunoglobulin A (IgA) and serum IgG antiamebic antibodies and low levels of mucosal anti-CTB antibodies. Our studies confirm that the genetic coupling of antigens to CTA2and their coexpression inE. colican produce holotoxin-like molecules that are mucosally immunogenic without the requirement for supplemental cholera toxin, and they establish the SREHP-H protein as a candidate for evaluation as a vaccine to prevent amebiasis.