METHODS OF IDENTIFYING ANTIGEN GENE SEQUENCES

Abstract: The present invention relates to methods of identifying gene sequences of potential vaccine antigens. Also included are gene sequences and the polypeptides encoded by the gene sequences as well as the use of such sequences to induce a protective immune response in animals. Particularly, the invention relates to identifying potential antigen gene sequences of Mycoplasma, preferably Mycoplasma hyopneumoniae. In one aspect of the present invention there is provided a method of identifying expression proteins translated from a nucleotide sequence in an expression vector, said method comprising the use of a marker co-expressed with a protein translated from the nucleotide sequence. In a further aspect of the present invention there is provided a method of identifying a therapeutic antigenic gene sequence encoding a therapeutic antigenic protein of a disease, from a sample of nucleotide sequences. Preferably the marker is a polyHis tag.

Description: METHODS OF IDENTIFYING ANTIGEN GENE SEQUENCES The present invention relates to methods of identifying gene sequences of potential vaccine antigens. Also included are gene sequences and the polypeptides encoded by the gene sequences as well as the use of such sequences to induce a protective immune response in animals. Particularly, the invention relates to identifying potential antigen gene sequences of Mycoplasma, preferably Mycoplasma hyopneumoniae. INTRODUCTION The success of a vaccine to a pathogen resides in identifying a suitable antigen of a pathogen which is readily accessible to a host immune system. Once identified, it can form the basis for protection against the pathogen. In recent years a number of vaccines have been commercialised by Animal Health companies. Many of the vaccines are based on inactivated whole cell bacterins. Although these vaccines provide a reasonable level of efficacy there is considerable scope for improvement. Therefore the presently available vaccines could be improved on by developing vaccines that were not based on whole cells or fractions of whole cells. Other means of generating vaccines against pathogens includes the use of crude inactivated antigen mixtures of various proteins. However, the problem with these methods is that they present to the host a variety of antigens, none of which may provide suitable overall protection since the proteins most readily accessible to a host immune system are swamped by the other antigens. Moreover, some pathogens are difficult or expensive to grow because of their fastidious requirements. Some pathogens are also harmful to handle. Therefore, a vaccine which does not require the growing of the cells or bacteria and the processing of whole cells or fractions of whole cells would provide a safer, cheaper and possibly more efficacious vaccine. One way of achieving a cleaner and more specific vaccine is by using recombinant protective antigens. By providing specific antigens, only those antigens readily accessible to the host immune system may be used. There is the problem of identifying potential antigens. One way is to create a gene library. However, from the library, it is very time consuming to determine those sequences which may include a potential protective antigen. To efficiently screen through a large number of potential antigen genes for their efficacy in providing some level of protection from disease it is useful to initially clone them as expressing clones. In this way the need for tedious and time consuming clone analysis and subsequent expression subcloning is avoided. The whole process of antigen discovery is speeded up. Applicants now provide a novel method to ensure that the clones initially investigated were expressing recombinant protein. Previously, expression libraries have been screened for clones expressing all or part of a specific protein by using an antibody specific for or enriched for the protein of interest. Identifying the DNA sequences that code for the proteins, also makes it possible, using appropriate expression vehicles, to form recombinant DNA molecules and to transform appropriate hosts (eg., prokaryotic or eukaryotic hosts) with those recombinant DNA molecules. Culturing of the transformed hosts then permits the hosts to express the DNA sequences and to produce the desired proteins. Administering the produced and subsequently isolated proteins, active ingredients or combinations thereof (eg., by injection), in an amount sufficient to elicit a protective immune response, provides a means for immunising against infections. One pathogen for which vaccines have been commercialised by Animal Health companies is Mycoplasma hyopneumoniae. This pathogen causes Enzootic pneumonia in pigs. It rarely causes death, but often results in severe morbidity and reduced performance manifesting in significant depression in feed conversion efficiency resulting in reduced weight gain in pigs. The animals show symptoms of coughing and fever and are often prone to secondary infection by opportunistic microorganisms. Numerous attempts to provide a vaccine against Mycoplasma hyopneumoniae have not been terribly successful. Particularly, the use of heat inactivated, live or extract of Mycoplasma have proven to be ineffective in providing protection. Some vaccines based on inactivated whole cell bacterins have shown some level of efficacy but there is scope for improvement. Additionally, Mycoplasma hyopneumoniae is difficult and expensive to grow because of its fastidious requirements. Therefore the presently available vaccines could be improved on by developing vaccines that were not based on whole cells or fractions of whole cells. Accordingly, it is an object of the present invention to overcome or at least alleviate some of the problems of the prior art. SUMMARY OF THE INVENTION In one aspect of the present invention there is provided a method of identifying expression proteins translated from a nucleotide sequence in an expression vector, said method comprising the use of a marker co-expressed with a protein translated from the nucleotide sequence. In a preferred embodiment of the present invention there is provided a use of a polyHis tag for identifying expression proteins encoded by a nucleotide sequence in an expression vector wherein said polyHis tag is co-expressed with said protein. In another aspect of the present invention there is provided a method for identifying expression proteins encoded by a nucleotide sequence from a mixture of nucleotide sequences, said method comprising the steps of: providing an expression vector including a marker; introducing a nucleotide sequence from the mixture into the expression vector; and identifying an expression protein expressed by the expression vector by determining the presence of a fusion protein comprising the marker co- expressed with the expression protein. In a preferred embodiment the marker is a polyHis tag. In a further preferred embodiment, the expression vector is transfected into a host cell for expression of a marker-fusion protein comprising an expression protein. Preferably the marker fusion protein is a polyHis tag-fusion protein comprising a polyHis tag and an expression protein. Introduction of a population of expression vectors into the host cell may create a genomic or cDNA library which may be screened. In a further preferred embodiment of the method there is included a step of purifying the expression protein using the marker expressed in the fusion protein. Preferably the marker is a polyHis tag. There is provided in another aspect, a purified recombinant protein identified according to the above method. Preferably the recombinant protein is an expression protein. In another aspect, there is provided a purified nucleotide sequence which encodes a recombinant protein identified according to the above method. In another aspect of the present invention there is provided an expression vector including a marker, preferably a polyHis tag for use in identifying expression proteins encoded by a nucleotide sequence. In yet another aspect of the invention, there is provided a host including an expression vector, said vector including a marker, preferably a polyHis tag for use in identifying an expression protein. In a further aspect of the present invention, there is provided a method of identifying gene sequences encoding antigenic proteins from a sample of nucleotide sequences, said method comprising the steps of: providing an expression vector including a marker; introducing a nucleotide sequence from the sample into the expression vector; identifying an antigenic expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker co- expressed with the expression protein translated by the nucleotide sequence; and identifying the antigenic expression protein. Preferably the marker is a polyHis tag. In a preferred embodiment, the method further includes determining the gene sequence of the antigenic protein encoded by the expression vector. In another aspect of the invention there is provided a method of screening a library of nucleotide sequences, said method including the steps of: providing a source of nucleotide sequences; providing an expression vector including a marker; creating a library by introducing a nucleotide sequence into the expression vector; identifying an expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker co-expressed with the expression protein translated by the nucleotide sequence; and determining the nucleotide sequence of the expression protein. Preferably the marker is a polyHis tag. In another aspect, there is provided a method of screening to identify expression clones in an expression library wherein said method includes: providing a source of nucleotide sequence; providing an expression vector including a marker; introducing the nucleotide sequence into the expression vector; transforming the expression vector into a host to create an expression library; and locating an expression clone by detecting the expression of a fusion protein, comprising a marker, preferably a polyHis tag co-expressed with an expression protein. In a further aspect of the present invention there is provided a method of identifying a therapeutic antigenic gene sequence encoding a therapeutic antigenic protein of a disease, from a sample of nucleotide sequences, said method comprising the steps of: providing an expression vector including a marker; introducing a nucleotide sequence from the sample into the expression vector; identifying an antigenic expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker, co- expressed with the expression protein translated by the nucleotide sequence; inoculating an animal with the expression vector which expresses the antigenic expression protein; challenging the animal with the disease; identifying an expression vector and expression protein that provides a therapeutic effect induced by vaccination; and determining the gene sequence of the antigenic expression protein encoded by the expression vector. Preferably the marker is a polyHis tag. In a further preferred embodiment of the invention, there is provided a method of screening a library of nucleotide sequences for a nucleotide sequence encoding polypeptides of Mycoplasma, preferably Mycoplasma hyopneumoniae, said method comprising the steps of: providing a source of nucleotide sequences from a sample of Mycoplasma; providing an expression vector including a marker; introducing a nucleotide sequence into the expression vector; identifying a Mycoplasma expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker, preferably a polyHis tag, co-expressed with the expression protein translated by a nucleotide sequence; and determining the nucleotide sequence of the expression protein of Mycoplasma, preferably Mycoplasma hyopneumoniae. Preferably the marker is a polyHis tag. In a preferred embodiment, the gene sequence encodes an antigenic polypeptide of Mycoplasma, preferably Mycoplasma hyopneumoniae. In yet another aspect of the present invention, there is provided a nucleotide sequence, mutant, analogue, derivative or functionally active fragment thereof encoding a polypeptide of Mycoplasma, preferably Mycoplasma hyopneumoniae, said nucleotide sequence identified by the methods described above. Preferably the nucleotide sequence comprises a sequence according to any one of Figures 1 to 42, and mutants, analogues derivatives or functionally active fragments thereof. More specifically, the nucleotide sequence is according to SEQ ID NO:1 , SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO:11 , SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:21 , SEQ ID NO:23, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:31 , SEQ ID NO:33, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:41 , SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:49, SEQ ID NO:51 , SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:57, SEQ ID NO:59, SEQ ID N0.61 , SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67, SEQ ID NO:69, SEQ ID NO:71 , SEQ ID NO:73, SEQ ID NO:75, SEQ ID NO:77, SEQ ID NO:79, SEQ ID NO:81 or SEQ ID NO:83 or a mutant, analogue, derivatives or functionally active fragments thereof. In an even further aspect of the present invention, there is provided a polypeptide encoded by the nucleotide sequence mutant, analogue, derivatives or functionally active fragments thereof encoding a polypeptide of Mycoplasma, preferably Mycoplasma hyopneumoniae, said nucleotide sequence identified by the methods described above. Preferably the polypeptide is encoded by a nucleotide sequence encoded by a sequence according to any one of Figures 1 to 42, mutant, analogues, derivatives or functionally active fragment thereof. More specifically the polypeptide has an amino acid sequence according to SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:10, SEQ ID NO:12, SEQ ID NO:14, SEQ ID NO:16, SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:28, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:40, SEQ ID NO:42, SEQ ID NO:44, SEQ ID NO:46, SEQ ID NO:48, SEQ ID NO:50, SEQ ID NO:52, SEQ ID NO:54, SEQ ID NO:56, SEQ ID NO:58, SEQ ID NO:60, SEQ ID NO 62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68, SEQ ID NO:70, SEQ ID NO:72, SEQ ID NO 74, SEQ ID NO: 76, SEQ ID NO:78, SEQ ID NO:80, SEQ ID NO:82 or SEQ ID NO:84 or a mutant, analogue, derivatives or functionally active fragments thereof. In a further aspect of the present invention, there is included compositions comprising the polypeptides or nucleotide sequences described above. Furthermore in other aspects, there is included pharmaceutical compositions and vaccine compositions of the polypeptide or nucleotide sequences described above. Other aspects of the invention include monoclonal antibodies generated against the polypeptides. Also included as a further aspect of the invention is a method of treating Mycoplasma infection, said method including administering an effective amount of an antigen polypeptide of Mycoplasma encoded by a nucleotide sequence or nucleotide sequence encoding the polypeptide identified by the methods above. Preferably, the antigen polypeptide is encoded by a nucleotide sequence according to any one of Figures 1 to 42 or a mutant, analogue, derivative or functionally active fragment thereof. More specifically the nucleotide sequence is according to SEQ ID NO:1 , SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO:11 , SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:21 , SEQ ID NO:23, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:31 , SEQ ID NO:33, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:41 , SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:49, SEQ ID NO:51 , SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:61 , SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67, SEQ ID NO:69, SEQ ID NO:71 , SEQ ID NO:73, SEQ ID NO:75, SEQ ID NO:77, SEQ ID NO:79, SEQ ID NO:81 or SEQ ID NO:83 or a mutant, analogue, derivatives or functionally active fragments thereof. Throughout the description and claims of this specification, the word "comprise" and variations of the word, such as "comprising" and "comprises", is not intended to exclude other additives, components, integers or steps. BRIEF DESCRIPTION OF FIGURES Figure 1 shows the nucleotide (SEQ ID NO:1) and amino acid sequence (SEQ ID NO:2) of Mycoplasma represented by clone pAD612. Figure 2 shows the nucleotide (SEQ ID NO:3) and amino acid sequence (SEQ ID NO:4) of Mycoplasma represented by clone pAD633. Figure 3 shows the nucleotide (SEQ ID NO:5) and amino acid sequence (SEQ:ID NO:6) of Mycoplasma represented by clone pAD639. Figure 4 shows the nucleotide (SEQ ID NO:7) and amino acid sequence (SEQ ID NO:8) of Mycoplasma represented by clone pAD640. Figure 5 shows the nucleotide (SEQ ID NO:9) and amino acid sequence (SEQ ID NO:10) of Mycoplasma represented by clones pAD641 and pAD1033. Figure 6 shows the nucleotide (SEQ ID NO:11) and amino acid sequence (SEQ ID NO: 12) of Mycoplasma represented by clone pAD653. Figure 7 shows the nucleotide (SEQ ID NO: 13) and amino acid sequence (SEQ ID NO: 14) of Mycoplasma represented by clones pAD657 and pAD964. Figure 8 shows the nucleotide (SEQ ID NO: 15) and amino acid sequence (SEQ ID NO: 16) of Mycoplasma represented by clones pAD659 and pAD910. Figure 9 shows the nucleotide (SEQ ID NO: 17) and amino acid sequence (SEQ ID NO: 18) of Mycoplasma represented by clone pAD662. Figure 10 shows the nucleotide (SEQ ID NO: 19) and amino acid sequence (SEQ ID NO:20) of Mycoplasma represented by clone pAD681. Figure 11 shows the nucleotide (SEQ ID NO:21) and amino acid sequence (SEQ ID NO:22) of Mycoplasma represented by clone pAD700. Figure 12 shows the nucleotide (SEQ ID NO:23) and amino acid sequence (SEQ ID NO:24) of Mycoplasma represented by clone pAD711. Figure 13 shows the nucleotide (SEQ ID NO:25) and amino acid sequence (SEQ ID NO:26) of Mycoplasma represented by clone pAD721. Figure 14 shows the nucleotide (SEQ ID NO:27) and amino acid sequence (SEQ ID NO:28) of Mycoplasma represented by clone pAD727. Figure 15 shows the nucleotide (SEQ ID NO:29) and amino acid sequence (SEQ ID NO:30) of Mycoplasma represented by clone pAD742. Figure 16 shows the nucleotide (SEQ ID NO:31) and amino acid sequence (SEQ ID NO:32) of Mycoplasma represented by clone pAD760. Figure 17 shows the nucleotide (SEQ ID NO:33) and amino acid sequence (SEQ ID NO:34) of Mycoplasma represented by clones pAD774. Figure 18 shows the nucleotide (SEQ ID NO:35) and amino acid sequence (SEQ ID NO:36) of Mycoplasma represented by clone pAD784. Figure 19 shows the nucleotide (SEQ ID NO:37) and amino acid sequence (SEQ ID NO:38) of Mycoplasma represented by clone pAD789. Figure 20 shows the nucleotide (SEQ ID NO:39) and amino acid sequence (SEQ ID NO:40) of Mycoplasma represented by clones pAD908, pAD981 , pAD1013 and pAD1049. Figure 21 shows the nucleotide (SEQ ID NO:41) and amino acid sequence (SEQ ID NO:42) of Mycoplasma represented by clones pAD913. Figure 22 shows the nucleotide (SEQ ID NO:43) and amino acid sequence (SEQ ID NO:44) of Mycoplasma represented by clone pAD920. Figure 23 shows the nucleotide (SEQ ID NO:45) and amino acid sequence (SEQ ID NO:46) of Mycoplasma represented by clone pAD922. Figure 24 shows the nucleotide (SEQ ID NO:47) and amino acid sequence (SEQ ID NO:48) of Mycoplasma represented by clones pAD923 and pAD925. Figure 25 shows the nucleotide (SEQ ID NO:49) and amino acid sequence (SEQ ID NO:50) of Mycoplasma represented by clone pAD950. Figure 26 shows the nucleotide (SEQ ID NO:51) and amino acid sequence (SEQ ID NO:52) of Mycoplasma represented by clone pAD951. Figure 27 shows the nucleotide (SEQ ID NO:53) and amino acid sequence (SEQ ID NO:54) of Mycoplasma represented by clone pAD977. Figure 28 shows the nucleotide (SEQ ID NO:55) and amino acid sequence (SEQ ID NO:56) of Mycoplasma represented by clone pAD983. Figure 29 shows the nucleotide (SEQ ID NO:57) and amino acid sequence (SEQ ID NO:58) of Mycoplasma represented by clone pAD984. Figure 30 shows the nucleotide (SEQ ID NO:59) and amino acid sequence (SEQ ID NO:60) of Mycoplasma sequence 30 represented by clone pAD994. Figure 31 shows the nucleotide (SEQ ID NO:61) and amino acid sequence (SEQ ID NO:62) of Mycoplasma represented by clone pAD1005. Figure 32 shows the nucleotide (SEQ ID NO:63) and amino acid sequence (SEQ ID NO:64) of Mycoplasma represented by clone pAD1016. Figure 33 shows the nucleotide (SEQ ID NO:65) and amino acid sequence (SEQ ID NO:66) of Mycoplasma represented by clone pAD1020. Figure 34 shows the nucleotide (SEQ ID NO:67) and amino acid sequence (SEQ ID NO:68) of Mycoplasma represented by clone pAD1027. Figure 35 shows the nucleotide (SEQ ID NO:69) and amino acid sequence (SEQ ID NO:70) of Mycoplasma represented by clone pAD1037. Figure 36 shows the nucleotide (SEQ ID NO:71) and amino acid sequence (SEQ ID NO:72) of Mycoplasma represented by clone pAD1038. Figure 37 shows the nucleotide (SEQ ID NO:73) and amino acid sequence (SEQ ID NO:74) of Mycoplasma represented by clones pAD1040. Figure 38 shows the nucleotide (SEQ ID NO:75) and amino acid sequence (SEQ ID NO:76) of Mycoplasma represented by clone pAD702. Figure 39 shows the nucleotide (SEQ ID NO:77) and amino acid sequence (SEQ ID NO:78) of Mycoplasma represented by clone pAD763. Figure 40 shows the nucleotide (SEQ ID NO:79) and amino acid sequence (SEQ ID NO:80) of Mycoplasma represented by clone pAD766. Figure 41 shows the nucleotide (SEQ ID NO:81) and amino acid sequence (SEQ ID NO:82) of Mycoplasma represented by clone pAD957. Figure 42 shows the nucleotide (SEQ ID NO:83) and amino acid sequence (SEQ ID NO:84) of Mycoplasma represented by clone pAD996. DETAILED DESCRIPTION OF THE INVENTION In one aspect of the present invention there is provided a method of identifying expression proteins translated from a nucleotide sequence in an expression vector, said method comprising the use of a marker co-expressed with a protein translated from the nucleotide sequence. In a preferred embodiment, the marker is any marker which can be detected. Detection may be by a monoclonal antibody or specific polyclonal antiserum. Preferably the marker is small, preferably less than 30 amino acids. Most preferably, the marker is a polyHis tag. Although the tag may also be any one of the following such as: (a) the FLAG tag, an 8 amino acid tag sequence which is available in plasmid vectors from Sigma-Aldrich Inc. USA, (b) the l-SPY epitope 6 amino acid tag available in vectors from Amrad Corporation Ltd., Australia, (c) the Hemagglutinin epitope 9 amino acid tag (Clontech Laboratories Inc. USA); and (d) the c-Myc epitope 12 amino acid tag (Clontech Laboratories Inc. USA). When the marker is a polyHis tag, the number of histidine residues is preferably in the range of 4 to 8 histidine residues, most preferably, there are 6 histidine residues. At least four amino acid residues may precede the polyHis tag providing a total of at least 10 amino acids providing there are at least 4 to 8 contiguous histidine residues. To efficiently screen through a large number of potential antigen genes for their efficacy in providing some level of protection from disease it is useful to initially clone them as expressing clones. In this way the need for tedious and time consuming clone analysis and subsequent expression subcloning is avoided. The whole process of antigen discovery is speeded up. Applicants provide a novel method to ensure that the clones initially investigated were expressing recombinant protein. This is particularly the case when dealing with a gene library. Within any random library, there are a majority of clones which are in the incorrect orientation for expression or in the wrong reading frame to express a protein. The use of a marker, preferably a polyHis tag in an expression vector allows for the efficient identification of expressing clones which express a marker, preferably a polyHis tag fusion protein. In clones that are not producing a recombinant marker-fusion protein or preferably a polyHis fusion protein, or only a short recombinant protein, the small marker or polyHis protein that is encoded is rapidly degraded within the host cell and any marker or polyHis protein that remains binds very weakly to membranes used for colony screening. Thus non-productive clones give a negative result in colony screening whereas clones producing a longer tagged recombinant protein can give a positive signal. Thus a general genomic expression library can be reduced significantly in complexity and therefore allow faster and more efficient screening and subsequent utilisation of desired clones. Such clones expressing the proteins are deemed as potential protective antigens and because of the strategy used to construct and screen the clones the originally isolated clones could be immediately used in vaccine trials, both in the form of purified plasmid DNA for genetic vaccination, or as a purified marker-fusion recombinant protein, preferably a polyHis purified recombinant fusion protein. Where the marker is a polyHis tag region, it may be derived from any source that contains the region. For instance, the regions of the vectors pQE30, pQE31 and pQE32 (Qiagen Pty. Ltd. Australia) encoding the polyHis tag may be used. Other sources of polyHis tag may be obtained from Novagen Inc., USA, (pET-1.9-33) or by synthetically making a polyHis tag. In another aspect of the present invention there is provided a method for identifying expression proteins translated from a nucleotide sequence from a mixture of nucleotide sequences, said method comprising the steps of: providing an expression vector including a marker; introducing a nucleotide sequence from the mixture into the expression vector; and identifying an expression protein expressed by the expression vector by determining the presence of a fusion protein comprising the marker co- expressed with the expression protein. Preferably, the marker is a polyHis tag. The following specific examples are directed to a polyHis tag marker and polyHis tag fusion proteins. However, any marker which can be detected and co-expressed with the protein in an expressing clone may be used. Accordingly, the present invention is not restricted to polyHis tags. This marker is illustrative only and should not be taken in any way as a restriction on the generality of the invention described. As described above, identification of expression proteins, particularly from clones derived from a gene library, can expedite the identification of nucleotide sequences encoding potential antigens to pathogens. The mixture of nucleotide sequences may be derived from any source such as from a tissue sample, microorganism, cell or any component which contains nucleic acid. Preferably the nucleic acid is genomic, mitochondrial, recombinant or mRNA. A sample of DNA may be firstly subjected to any means which fragments the DNA such as by sonication or by enzyme digestion such as restriction enzyme digestion. Alternatively, the nucleotide sequences may derive from PCR of a portion of a DNA sequence described above. These sequences may be open reading frames (ORF). The expression vector preferably includes a polyHis tag. The polyHis tag may be derived from any source harbouring the polyHis tag as discussed above. Preferably the polyHis tag may be derived from standard vectors such as pQE30, pQE31 and pQE32 (Qiagen Pty. Ltd,, Australia). These vectors may be encode a T5 promoter, Lac operator and polyHis tag region. This region may cloned into an expression vector which is capable of expressing proteins encoded by the nucleotide sequences. Alternatively, the polyHis tag may be made synthetically. Preferably the marker or preferably a polyHis tag region is cloned into a eukaryotic expression vector. Most preferably, the vector is pCI (Promega Corporation, Australia) and preferably creates clones pCI30, pCI31 , and pCI32. This series of vectors allows the cloning of fragments downstream of the polyHis tag region in all three reading frames. The cytomegalovirus (CMV) immediate-early enhancer/promoter, chimeric intron, and SV40 late polyadenylation signal in these exemplified clones allow the vectors to be used as eukaryotic expression vectors in cell culture systems and genetic immunisations using purified plasmid DNA. The T5 promoter allows expression of cloned inserts in prokaryotes. The construction of these vectors is significant because they enable the screening of a library to identify a large number of clones that are expressing recombinant proteins. The nucleotide sequence(s) from the mixture such as from a digestion of genomic DNA may be introduced or cloned into the expression vector by any means known to the skilled addressee. The expression vector may be used to express protein in a host cell. In a preferred embodiment, the expression vector is transfected into a host cell for expression of the expression protein of polyHis fusion protein comprising a polyHis tag and an expression protein. Introduction of the expression vector into the host cell may create a genomic or cDNA library. The host cell may be any cell competent to receive the expression vector. Preferably the cell is prokaryotic. Most preferably it is Escherichia coli. Identification of the expression protein (and consequently any clones or host cells) expressing the protein can be determined by the presence of the polyHis tag on a polyHis tag fusion protein. The vectors in the present invention allow the general screening for all expressing clones on the basis of the polyHis tag. The polyHis tag may be identified by anti-polyHis antibodies or with metal-chelate conjugated probes such as nickel resin wherein the polyHis signals are developed by addition of a chromogenic substrate. In clones that are not producing a recombinant polyHis fusion protein, or only a short recombinant protein, the small polyHis protein that is encoded is rapidly degraded within the host cell and any polyHis protein that remains binds very weakly to membranes used for colony screening. Thus non-productive clones give a negative result in polyHis colony screening whereas clones producing a longer polyHis tagged recombinant protein can give a positive signal. Thus a general genomic expression library can be reduced significantly in complexity and therefore allow faster and more efficient screening and subsequent utilisation of desired clones. In a further preferred embodiment of the method there is included a step of purifying the expression protein using the polyHis tag expressed in the fusion protein. Once an expression protein expressed by an expression clone is identified using the polyHis tag, then this tag may also be used to purify any expression proteins. Any purification method may be used which is known by the skilled addressee. Affinity columns in affinity chromatography with anti- polyHis antibodies may be used. Generally, the expressed protein, identified by virtue of the polyHis tag, may be isolated by any means which relies on utilising the polyHis tag. There is provided in another aspect, a purified recombinant protein identified according to the above method. Once the protein is isolated, it may be used in any number of ways including vaccine trials in the form of purified proteins. The proteins can be immediately identified as potential antigens. Preferably, they will be protective antigens. In another aspect, there is provided a purified nucleotide sequence which encodes recombinant protein identified according to the above method. The proteins identified by the polyHis method described above are expressed by discrete nucleotide sequences, preferably recombinant sequences. By identifying the protein, a clone expressing the protein may be identified which harbours the nucleotide sequence. These clones may provide purified plasmid DNA, particularly the plasmid DNA may represent a potential protective antigen. In another aspect of the present invention there is provided an expression vector or a recombinant vector including a marker, preferably a polyHis tag for use in identifying expression proteins encoded by a nucleotide sequence. The expression vector may be any vector which produces expression of an expression protein. It may be a plasmid or cosmid. It may be introduced into clones for further expansion of the expression protein for the purposes of obtaining the protein for vaccination or identification purposes. In yet another aspect of the invention, there is provided a host including an expression vector, said vector including a marker, preferably a polyHis tag for use in identifying an expression protein encoded by a nucleotide sequence. The host cell may be any competent cell which can harbour an expression vector. Preferably, the host cell is prokaryotic or eukaryotic. In a further aspect of the present invention, there is provided a method of identifying gene sequences encoding antigenic proteins from a sample of nucleotide sequences, said method comprising the steps of: providing an expression vector including a marker, preferably a polyHis tag; introducing a nucleotide sequence from the sample into the expression vector; identifying an antigenic expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker, co- expressed with the expression protein translated by the nucleotide sequence; identifying the antigenic protein; and preferably determining the nucleotide sequence of the antigenic protein gene encoded by the expression vector. Identification of an antigenic protein may include identifying and preferably isolating a fusion protein having a polyHis tag and determining whether the fusion protein can elicit an immune response which is not generated by virtue of the polyHis tag. Determination of an immune response may be conducted by standard in vitro immunological tests using antisera from immune animals conducting ELISA's or antibody/antigen reactions. They may also be tested in vivo in protection trials in animals against further challenge. In another aspect of the invention there is provided a method of screening a library of nucleotide sequences, said method including the steps of: providing a source of nucleotide sequences; providing an expression vector including a marker, preferably a polyHis tag; creating a library by introducing a nucleotide sequence into the expression vector; identifying an expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker co-expressed with the expression protein translated by the nucleotide sequence; and determining the nucleotide sequence of the expression protein gene. In another aspect, there is provided a method of screening to identify expression clones in a library wherein said method includes: providing a source of nucleotide sequences; providing an expression vector including a marker, preferably a polyHis tag; introducing a nucleotide sequence into the expression vector; transforming the expression vector into a host to create an expression library; and locating an expression clone by detecting the expression of a fusion protein, comprising a marker, preferably a polyHis tag co-expressed with an expression protein. Identification of the expression proteins having a polyHis tag transcribed by the expression clones further identifies those clones (host cells) which express an open reading frame (ORF). Accordingly, the method identifies ORF's in a mixture of nucleotide sequences. This effectively speeds up the process of identifying useful nucleotide sequences encoding proteins which are potentially useful as antigens. It quickly identifies a clone which can be immediately expanded to provide sufficient sample of nucleotide sequence or plasmid DNA or recombinant protein for any use such as in genetic vaccines or for developing antibodies against a recombinant protein. In a further aspect of the present invention there is provided a method of identifying a therapeutic antigenic gene sequence encoding a therapeutic antigenic protein of a disease, from a sample of nucleotide sequences, said method comprising the steps of: providing an expression vector including a marker; introducing a nucleotide sequence from the sample into the expression vector; identifying an antigenic expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker, co- expressed with the expression protein translated by the nucleotide sequence; inoculating an animal with the expression vector which expresses the antigenic expression protein; challenging the animal with the disease; identifying an expression vector and expression protein that provides a therapeutic effect induced by vaccination; and determining the gene sequence of the antigenic expression protein encoded by the expression vector. It is an advantage of the invention that it provides an efficient means of screening a library of nucleotide sequences and using identified clones for DNA vaccination trials to immediately assess the vaccine potential of clones. This aspect of easily using the identified clones to do vaccine trials far improves methods presently available. In a further preferred embodiment of the invention, there is provided a method of screening a library of a nucleotide sequence for a nucleotide sequence encoding polypeptides of Mycoplasma, preferably Mycoplasma hyopneumoniae, said method comprising the steps of: providing a source of nucleotide sequences from a sample of Mycoplasma; providing an expression vector including a marker, preferably a polyHis tag; introducing a nucleotide sequence into the expression vector; identifying a Mycoplasma expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker, preferably a polyHis tag, co-expressed with the expression protein translated by a nucleotide sequence; and determining the nucleotide sequence of the expression protein gene of Mycoplasma, preferably Mycoplasma hyopneumoniae. The source of nucleotide sequence from a sample of Mycoplasma may be of genomic, mitochondrial, recombinant or mRNA origin. Where the source is genomic, genomic DNA may be isolated from Mycoplasma by any means known to the skilled addressee. The Mycoplasma is preferably Mycoplasma hyopneumoniae. The methods of identification of the polyHis tag-Mycoplasma fusion protein are as described above. Preferably, the nucleotide sequence encodes an antigenic protein. Accordingly, there is a further step of determining whether the protein elicits an immune response. Preferably, the antigenic protein is a Mycoplasma antigenic protein. More preferably a Mycoplasma hyopneumoniae antigenic protein. The term "immune response" means a selective response mounted by the immune system in which specific antibodies and/or cytotoxic cells are produced against invading of foreign components such as microorganisms, parasites, transplanted tissue, proteins or antigens in general. The term "immune system" includes any cells and tissues which enable the mounting of a specific protective response to invading of foreign components such as microorganisms, parasites, transplanted tissue, proteins or antigens in general aimed at protecting the body from infection and in some cases setting up a long lasting specific immunity to re-infection. In yet another aspect of the present invention, there is provided a nucleotide sequence mutant, analogue, derivative or functionally active fragments thereof encoding a polypeptide of Mycoplasma, preferably Mycoplasma hyopneumoniae, said nucleotide sequence identified by the methods described above. Preferably the nucleotide sequence comprises a sequence according to any one of Figures 1 to 42, and mutants, analogues derivatives or functionally active fragments thereof. More specifically it comprises SEQ ID NO:1 , SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO:11 , SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:21 , SEQ ID NO:23, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:31 , SEQ ID NO:33, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:41 , SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:49, SEQ ID NO:51 , SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:61 , SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67, SEQ ID NO:69, SEQ ID NO:71 , SEQ ID NO:73, SEQ ID NO:75, SEQ ID NO:77, SEQ ID NO:79, SEQ ID NO:81 or SEQ ID NO:83 or a mutant, analogue, derivatives or functionally active fragments thereof. In another embodiment there is provided a recombinant vector including a nucleotide sequence described above, mutant analogue derivative or functionally active fragment thereof. Preferably the nucleotide sequence is according to any one of Figures 1 to 42, mutant analogue derivative or functionally active fragment thereof. More specifically it comprises SEQ ID NO:1 , SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO:11 , SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:21 , SEQ ID NO:23, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:31 , SEQ ID NO:33, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:41 , SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:49, SEQ ID NO:51 , SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:61 , SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67, SEQ ID NO:69, SEQ ID NO:71 , SEQ ID NO:73, SEQ ID NO:75, SEQ ID NO:77, SEQ ID NO:79, SEQ ID NO:81 or SEQ ID NO:83 or a mutant, analogue, derivatives or functionally active fragments thereof. The term "mutant, analogue, or derivative" refers to those sequences that may contain deletions, additions or substitutions of their sequences. Where these terms relate to a protein, the changes do not substantially change the activity of the protein. Where it relates to a changed nucleic acid molecule, the change does not result in a change in the reading frame of a protein coding region and preferably encodes a protein having no change, only a minor reduction or an increase in biological function. The term "fragments" relates to a portion of an amino acid or nucleic acid sequence that is less than full length but is capable of hybridizing to a full length sequence and being recognised as being part of a nucleic acid sequence capable of encoding an amino acid sequence which is a portion of the full length sequence. Due to the degeneracy of the genetic code, other nucleic acid sequences which encode the same or functionally equivalent amino acid sequence are included within the scope of the current invention. Such alterations of the nucleotide sequence may include substitutions of different nucleotides resulting in the same or a functionally equivalent gene product. Also included within the scope of this invention are nucleic acid sequences having deletions and/or additions and which result in a functionally equivalent gene product. In addition the gene product may include deletions, additions or substitutions of amino acid residues within the sequence which result in changes that still produce a functionally active product. In a further embodiment, there is provided a host cell including a recombinant vector described above. The host cell may be any cell competent to receive the recombinant vector. Preferably the host cell is prokaryotic, more preferably it is E. coli. In another aspect of the invention there is provided an amino acid sequence which encodes a polypeptide identified by the methods described above. The polypeptide may be a product of the expression vector or is an expression protein identified as a protein co-expressed with a marker preferably a polyHis marker. Preferably, the amino acid sequence is translated from a nucleotide sequence identified by the methods described above. In a preferred aspect, the amino acid sequence encodes a polypeptide of Mycoplasma, preferably Mycoplasma hyopneumoniae. More preferably, the amino acid sequence comprises a sequence according to any one of Figures 1 to 42 or a mutant, analogue, derivative, or functionally active fragment thereof. More specifically it comprises SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:10, SEQ ID NO:12, SEQ ID NO:14, SEQ ID NO:16, SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:28, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:40, SEQ ID NO:42, SEQ ID NO:44, SEQ ID NO:46, SEQ ID NO:48, SEQ ID NO:50, SEQ ID NO:52, SEQ ID NO:54, SEQ ID NO:56, SEQ ID NO:58, SEQ ID NO:60, SEQ ID NO 62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68, SEQ ID NO:70, SEQ ID NO:72, SEQ ID NO 74, SEQ ID NO: 76, SEQ ID NO:78, SEQ ID NO:80, SEQ ID NO:82 or SEQ ID NO:84 or a mutant, analogue, derivatives or functionally active fragments thereof. In an even further aspect of the present invention, there is provided a polypeptide encoded by the amino acid sequence mutant, analogue, derivative or functionally active fragment thereof as described above. Preferably the sequence encodes a polypeptide of Mycoplasma, preferably Mycoplasma hyopneumoniae, said amino acid sequence being identified by the methods described above. Preferably the polypeptide is encoded by an amino acid sequence according to any one of Figures 1 to 42, mutant, analogues, derivatives or functionally active fragment thereof. More specifically it comprises SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:10, SEQ ID NO:12, SEQ ID NO:14, SEQ ID NO:16, SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:28, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:40, SEQ ID NO:42, SEQ ID NO:44, SEQ ID NO:46, SEQ ID NO:48, SEQ ID NO:50, SEQ ID NO:52, SEQ ID NO:54, SEQ ID NO:56, SEQ ID NO:58, SEQ ID NO:60, SEQ ID NO 62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68, SEQ ID NO:70, SEQ ID NO:72, SEQ ID NO 74, SEQ ID NO: 76, SEQ ID NO:78, SEQ ID NO:80, SEQ ID NO:82 or SEQ ID NO:84 or a mutant, analogue, derivatives or functionally active fragments thereof. The polypeptide may be isolated and purified by any methods known to the skilled addressee. Preferably, the methods of isolation utilise the polyHis tag which was used to identify expression protein or expression clones from a library of nucleotide sequences. In a further embodiment, there is provided a composition comprising the polypeptide or nucleotide sequence as described above. The composition may be a pharmaceutical composition comprising at least one polypeptide or nucleotide sequence as described above and a pharmaceutically acceptable carrier. The composition may also be a vaccine composition comprising at least one polypeptide or nucleotide sequence described above. The vaccine composition may be capable of eliciting an immune response wherein the polypeptide is an antigenic protein or a nucleotide sequence preferably of Mycoplasma, more preferably of Mycoplasma hyopneumoniae. In another aspect of the present invention, there is provided an antibody against a polypeptide described or identified according to the methods described above. Preferably the antibody is a monoclonal antibody. Various procedures are known in the art which may be used for the production of antibodies to epitopes of the polypeptides described above. Various host animals may be used in the production of these antibodies following immunisation with the polypeptides including but not restricted to rabbits, mice, goats etc. Adjuvants may be used to increase the immunological response, depending on the host species, and may include but are not restricted to Freunds (complete and incomplete). Monoclonal antibodies may be prepared by using techniques which enable the continuous production of antibody molecules by cell lines in vitro. These may include, but are not limited to, the hybridoma technique (Kohler and Milstein, Nature 256, 495, (1975)). Antibodies to the polypeptides may find use in the detection of antigenic polypeptides in various tissues, body fluids and cell lines, for example in screening assays for the antigen, and in the affinity purification of polypeptides, preferably antigenic polypeptides. The vaccine composition includes purified plasmid DNA including nucleotide sequences described above. In yet another aspect of the present invention, there is provided a method of treating an infection, said method including administering an effective amount of an antigenic polypeptide encoded by an amino acid sequence said polypeptide being identified by the methods described above. Preferably the infection is a Mycoplasma infection. More preferably, the infection is a Mycoplasma hyopneumoniae infection. Also it is preferred that the polypeptide is encoded by an amino acid sequence encoded by a nucleotide sequence according to any one of Figures 1 to 42, mutant, analogue, derivative or functionally active fragment thereof. More specifically the sequence comprises SEQ ID NO:1 , SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO:11 , SEQ ID NO.13, SEQ ID NO:15, SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:21 , SEQ ID NO 23, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO.31 , SEQ ID NO 33, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:41 , SEQ ID NO 43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:49, SEQ ID N0.51 , SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:61 , SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67, SEQ ID NO:69, SEQ ID NO:71 , SEQ ID NO:73, SEQ ID NO:75, SEQ ID NO:77, SEQ ID NO:79, SEQ ID NO:81 or SEQ ID NO:83 or a mutant, analogue, derivatives or functionally active fragments thereof. It is also preferred that the polypeptide has an amino acid sequence according to any one of Figures 1 to 42, mutant, analogue, derivative or functionally active fragment thereof. More specifically it comprises SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:10, SEQ ID NO:12, SEQ ID NO:14, SEQ ID NO:16, SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:28, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:40, SEQ ID NO:42, SEQ ID NO:44, SEQ ID NO:46, SEQ ID NO:48, SEQ ID NO:50, SEQ ID NO:52, SEQ ID NO:54, SEQ ID NO:56, SEQ ID NO:58, SEQ ID NO:60, SEQ ID NO 62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68, SEQ ID NO.70, SEQ ID NO:72, SEQ ID NO 74, SEQ ID NO: 76, SEQ ID NO:78, SEQ ID NO:80, SEQ ID NO:82 or SEQ ID NO:84 or a mutant, analogue, derivatives or functionally active fragments thereof. In yet another aspect of the present invention, there is provided a method of treating an infection, said method including administering to an animal in need, an effective amount of a DNA molecule including a nucleotide sequence identified by the methods described above. Preferably the infection is a Mycoplasma infection. More preferably, the infection is a Mycoplasma hyopneumoniae infection. Preferably, the nucleotide sequence is according to any one of Figures 1 to 42, mutant, analogue, derivative or functionally active fragment thereof or more specifically, SEQ ID NO:1 , SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO:11 , SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:21 , SEQ ID NO:23, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:31 , SEQ ID NO:33, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:41 , SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:49, SEQ ID NO:51 , SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:61 , SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67, SEQ ID NO:69, SEQ ID N0.71 , SEQ ID NO:73, SEQ ID NO:75, SEQ ID NO:77, SEQ ID NO:79, SEQ ID NO:81 or SEQ ID NO:83 or a mutant, analogue, derivatives or functionally active fragments thereof. The DNA may be administered by injection which allows for cells to take up DNA or it may be applied topically. Preferably, the DNA is injected into the skin layer subcutaneously, or intramuscularly. In another aspect of the present invention, there is provided a method of treating an infection, said method including administering an effective amount of an antibody specific to a polypeptide which has been identified by a method described above. Preferably the infection is a Mycoplasma infection. More preferably, the infection is a Mycoplasma hyopneumoniae infection. Preferably the polypeptide is encoded by an amino acid sequence according to any one of Figures to 1 to 42, a mutant, analogue, derivative or functionally active fragment thereof or more specifically SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:10, SEQ ID NO.12, SEQ ID NO:14, SEQ ID NO:16, SEQ ID N0.18, SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:28, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:40, SEQ ID NO:42, SEQ ID NO:44, SEQ ID NO:46, SEQ ID NO:48, SEQ ID NO:50, SEQ ID NO:52, SEQ ID NO:54, SEQ ID NO:56, SEQ ID NO:58, SEQ ID NO:60, SEQ ID NO 62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68, SEQ ID NO:70, SEQ ID NO:72, SEQ ID NO 74, SEQ ID NO: 76, SEQ ID NO:78, SEQ ID NO:80, SEQ ID NO:82 or SEQ ID NO:84 or a mutant, analogue, derivatives or functionally active fragments thereof. The present invention will now be more fully described with reference to the accompanying Examples and Figures. It should be understood, however, that the description following is illustrative only and should not be taken in any way as a restriction on the generality of the invention described. EXAMPLES EXAMPLE 1 : Construction of genomic libraries in pCI30, pCI31 and pCI32. Genomic DNA isolated from Mycoplasma hyopneumoniae was broken down into suitably sized fragments by sonication or partial restriction enzyme digestion. The DNA was then run on an agarose gel and size selected fractions cut from the gel and recovered. Vector DNA (pCI30, pCI31 , and pCI32) was digested with an appropriate restriction enzyme (Sma I or BamHI) treated with shrimp alkaline phosphatase to remove the terminal phosphates, then run on an agarose gel. The linearized band was cut out and the DNA recovered. Genomic DNA fragments and cut vector DNA were mixed at molar ratios of between 1 :1 and 5:1 and ligated using standard ligation conditions. The ligation mixtures were used to transform competent E. coli cells and thus produce a number of distinct genomic libraries. EXAMPLE 2: Screening of the genomic libraries. The genomic libraries were plated onto Luria-Bertoni (LB) broth agar containing ampicillin (100 μg/ml) and grown overnight at 37°C. Filter lift replicas of the plates were made by placing dry, sterile nitrocellulose membranes on top of the colonies then immediately removing it and placing it colony side up onto an LB plate containing ampicillin and IPTG (1 mM) and incubating for 4 hours at 37°C. The membranes were then processed by standard methods to lyse the bacteria, neutralise the membranes and bind protein to the membranes. The dry membranes were then probed either with anti-polyHis antibodies or with conjugated nickel resin and the polyHis signals developed by addition of chromogenic substrate. The developed membranes were keyed back to the original plates and the positive colonies picked in to 96 well, deep well plates containing rich growth media supplemented with ampicillin. The clones were then grown at 37°C. Replicas of these plates were taken and held at -70°C for long term storage. EXAMPLE 3: Sequence analysis of selected clones. A collection of polyHis positive clones from each library was selected. Plasmid DNA was prepared and DNA sequence information from the inserted fragment was generated by automated dideoxy sequencing using a primer homologous to a region just upstream of the site of insertion into the vector. The sequence data generated was compared with the publicly available GenBank database. Homologies between our positive sequences and database entries were noted and in many instances this information gave some indication of the possible function of the gene fragments which had been cloned. On the basis of this homology information a subgroup of the positive clones was selected which were likely to represent genes which encoded proteins that may be easily accessible to the host immune system during Mycoplasma hyopneumoniae infection or that for other reasons were regarded as likely to offer some level of protection. These selected positive clones encode candidate protective antigens. Some of the clones chosen for further study represent different sections of the same gene. EXAMPLE 4: Screening of candidate protective antigens A series of animal trials were conducted to investigate the therapeutic application of the identified genes. All the trials followed a similar protocol. Pigs from a M. hyopneumoniae free herd were vaccinated 3 times, at 2 week intervals, starting from 6 weeks of age. Each vaccination was with 500 μg of plasmid DNA, divided evenly between 2 shots, 1 shot into the tissue at the base of the back of each ear, delivered using a Biojector 2000 needless injection device with a No.2 syringe. 1-2 weeks after the third vaccination the pigs were challenged by intratracheal instillation of a 5 ml dose of 0.45 μM filtered lung homogenate derived from a pig with an active M. hyopneumoniae infection. 3-4 weeks after challenge the pigs were euthanased and the lungs removed for scoring of pneumonic lesions. The pneumonic lesions were scored by counting the number of lung lobes that were affected and by estimating the percentage of each lung lobe that was affected by disease. This scoring system gives two measures of disease status, a lobe score and a lesion score. For each trial the average results across each group are presented. The trial results of those groups of clones which had a positive therapeutic effect are presented. Other groups of clones did not give a positive therapeutic effect and these results are not presented. Trial 1 Vaccinated with a group of clones that included clones pAD612-789. Treatment Lobe score Lesion score Unvaccinated, unchallenged 0 0 Unvaccinated, challenged 4.4 120 Vaccinated, challenged 3.25 72.5 The vaccine containing clones pAD612-789 had a therapeutic effect. The lobe score in the vaccinated pigs was 26% lower than in the controls and the lesion score was 40% lower. Trial 2 Two different groups of clones tested as vaccines. Group 1 : pAD's 662, 774, 784, 922, and 964 Group 2: pAD's 612, 633, 639, 640, 641 , 653, 657, 659, 681 , 700, 711 , 721 , 727, 742, 760, 789, 908, 910, 911 , 913, 920, 923, 925, 950, 951 , 966, 967, 977, 981 , 983, 984, 994, 1001 , 1005, 1013, 1016, 1020, 1027, 1033, 1037, 1038, 1040, and 1049. Treatment Lobe score Lesion score Unvaccinated, unchallenged 0 0 Vector vaccinated, challenged 3.4 67 Group 1 vaccinated, challenged 1.6 38 Group 2 vaccinated, challenged 2.2 51 The overall severity of disease induced in trial 2 was less than in trial 1 indicating a milder challenge. Both groups of clones had a therapeutic effect. The Group 1 vaccine reduced the lobe score by 53% and the lesion score by 43%. The Group 2 vaccine reduced the lobe score by 35% and the lesion score by 24%, compared with the group vaccinated with the empty vector plasmid DNA. Trial 3 Group 1 : Same clones as Group 1 in trial 2. The DNA was delivered in the standard way as detailed for the biojector or by genegun. For genegun delivery 1.6 micron gold particles were used with each pig receiving 4 shots, each of 1.25 μg DNA, at each of the 3 vaccination time points. Vaccination was behind each ear and the inside of each hind leg. The delivery pressure was 500 psi. Treatment Lobe score Lesion score Unvaccinated, unchallenged 0 0 Vector vaccinated, challenged 4.2 109 Group 1 biojector vaccinated, challenged 2.5 67 Group 1 genegun vaccinated, challenged 2.2 48.5 This trial again demonstrated that the five clones in Group 1 produce a therapeutic effect when delivered as naked DNA. The biojector delivered vaccine gave a 40% reduction in lobe score and a 39% reduction in lesion score. The same collection of clones delivered by genegun gave a 48% reduction in lobe score and a 56% reduction in lesion score. Trial 4 Other combinations of the clones used in trial 2 were used in this trial. Group 3: pAD's 653, 711 , 727, 920, 951 , and 965 Group 4: pAD's 612, 639, 640, 1005, 1020, and 1038 Group 5: pAD's 742, 760, 923, 925, 994, 984, and 1037 A group of 5 other clones that had not previously been used in trials was also included. Group 6: pAD's 702, 763, 766, 957, and 996 Treatment Lobe score Lesion score Unvaccinated, unchallenged 0 0 Vector vaccinated, challenged 5.0 106 Group 3 vaccinated, challenged 2.8 54 Group 3 genegun vaccinated, challenged 2.6 87 Group 4 vaccinated, challenged 3.0 79 Group 5 vaccinated, challenged 3.6 74 Group 6 vaccinated, challenged 2.75 42.5 All of these groups of clones produced a therapeutic effect in that they reduced the severity of pneumonic lesions. The group 3 clones reduced the lobe score by 44% when delivered by biojector and by 48% when delivered by genegun, and the lesion score by 49% when delivered by biojector and 18% when delivered by genegun. The other three experimental vaccines were delivered only by biojector. The group 4 vaccine reduced the lobe score by 40% and the lesion score by 25%. The group 5 vaccine reduced the lobe score by 28% and the lesion score by 30%. The group 6 vaccine reduced the lobe score by 45% and the lesion score by 60%. This series of trials demonstrates that compared with unvaccinated or empty vector vaccinated pigs the collection of cloned genes detailed in this patent can produce a therapeutic effect by lowering the severity of lung lesions in the groups vaccinated with various combinations of the recombinant plasmids. On the basis of this demonstration of therapeutic effect a collection of 42 genes are claimed in the present invention. EXAMPLE 5: Screening of genomic libraries to recover the complete genes. The clones listed in example 4 contain only partial gene sequences. It is desirable to identify the nucleotide sequence of the complete genes, as these are likely to encode further epitopes that will be useful in vaccine design. The complete coding regions of the genes represented by the clones in example 4 were recovered by screening two genomic libraries. The genomic libraries were constructed by ligating fragments created by digestion with the restriction enzymes EcoRI and Bglll into pUC18 vector digested with EcoRI and BamHI respectively. Ligation products were recovered by transformation of the ligation mix into XL2-BlueMRF' competent cells (Stratagene) and plating onto Luria- Bertoni agar plates containing 100 μg/ml ampicillin. Colonies were picked into 96 well plates containing rich growth media, grown overnight and then plasmid DNA was prepared for each. Plasmid DNA from each was denatured and spotted on to nylon membranes. Representative membranes were then probed with digoxigenin labelled PCR products generated from the inserted DNA present in each of the clones listed in example 4. Hybridizing clones were identified and analysed by restriction enzyme digestion, PCR using gene specific primers and by nucleotide sequencing. The resulting gene sequences are detailed in figures 1-42. A number of these sequences represent the complete coding sequence of the genes but for many of the genes only a partial sequence is available. Finally it is to be understood that various other modifications and/or alterations may be made without departing from the spirit of the present invention as outlined herein.

Claims: CLAIMS 1. A method of identifying expression proteins translated from a nucleotide sequence in an expression vector, said method comprising co-expressing a marker with a protein translated from the nucleotide sequence. 2. A method for identifying expression proteins translated from a nucleotide sequence from a mixture of nucleotide sequences, said method comprising the steps of: providing an expression vector including a marker; introducing a nucleotide sequence from the mixture into the expression vector; and identifying an expression protein expressed by the expression vector by determining the presence of a fusion protein comprising the marker co- expressed with the expression protein. 3. A method according to claim 1 or 2 wherein the marker is a detectable marker. 4. A method according to any one of claims 1 to 3 wherein the marker is less than 30 amino acids and selected from the group including: (a) a polyHis tag; (b) the FLAG tag, (c) the l-SPY epitope tag; (d) the Hemagglutinin tag; and (e) the c-Myc epitope tag. 5. A method according to any one of claims 1 to 4 wherein the marker is a polyHis tag. 6. A method according to claim 5 wherein the polyHis tag comprises 4 to 8 contiguous histidine residues. 7. A method according to claim 6 wherein the polyHis tag comprises 6 contiguous histidine residues. 8. A method according to any one of claims 2 to 7 wherein the expression vector is a eukaryotic expression vector. 9. A method according to any one of claims 2 to 8 wherein the expression vector is further transfected into a host cell for expression of an expression protein. 10. A method according to any one of claims 1 to 9 wherein the expression protein, is identified by an anti-marker antibody or a metal chelate-chelate conjugated probe. 11. A method according to claim 10 wherein the anti-marker antibody is an anti-poly His antibody. 12. A method according to any one of claims 1 to 11 further including purifying the expression protein by utilizing the marker co-expressed with the expression protein said method including selecting the expression protein via the marker. 13. A purified recombinant protein identified by the methods according to any one of claims 1 to 12. 14. A purified nucleotide sequence which encodes a recombinant protein according to claim 13. 15. A method of screening to identify expression clones in a library said method comprising: providing a source of nucleotide sequences; providing an expression vector including a marker; introducing a nucleotide sequence into the expression vector; transforming the expression vector into a host cell to create an expression library; and locating an expression clone by detecting the expression of a fusion protein comprising a marker co-expressed with an expression protein. 16. A method of screening a library of nucleotide sequences to identify expressed nucleotide sequences, said method including the steps of: providing a source of nucleotide sequences; providing an expression vector including a marker; creating a library by introducing a nucleotide sequence into the expression vector; identifying an expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker co-expressed with the expression protein translated by the nucleotide sequence; and determining the nucleotide sequence of the expression protein. 17. A method of identifying antigenic gene sequences from a sample of nucleotide sequences, said method comprising the steps of: providing an expression vector including a marker; introducing a nucleotide sequence from the sample into the expression vector; identifying an antigenic expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker, co- expressed with the expression protein translated by the nucleotide sequence; identifying the antigenic expression protein; determining the gene sequence of the antigenic expression protein encoded by the expression vector. 18. A method of identifying a therapeutic antigenic gene sequence encoding a therapeutic antigenic protein of a disease, from a sample of nucleotide sequences, said method comprising the steps of: providing an expression vector including a marker; introducing a nucleotide sequence from the sample into the expression vector; identifying an antigenic expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker, co- expressed with the expression protein translated by the nucleotide sequence; inoculating an animal with the expression vector which expresses the antigenic expression protein; challenging the animal with the disease; identifying an expression vector and expression protein that provides a therapeutic effect induced by vaccination; and determining the gene sequence of the antigenic expression protein encoded by the expression vector. 19. A method according to any one of claims 15 to 18 wherein the library is a library of nucleotide sequences which translate to polypeptides of Mycoplasma, said method comprising the steps of: providing a source of nucleotide sequences from a sample of Mycoplasma; providing an expression vector including a marker; introducing a nucleotide sequence into the expression vector; identifying a Mycoplasma expression protein expressed by the expression vector by determining the presence of a fusion protein comprising a marker co-expressed with the expression protein translated by a nucleotide sequence; and determining the nucleotide sequence of the expression protein of Mycoplasma. 20. A method according to claim 19 wherein the Mycoplasma is Mycoplasma hyopneumoniae. 21. A method according to any one of claims 15 to 20 wherein the marker is a polyHis tag. 22. A nucleotide sequence identified by the method according to any one of claims 16 to 21. 23. A nucleotide sequence of Mycoplasma having a sequence according to any one of Figures 1 to 42, or SEQ ID NO: 1 , SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO:11 , SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:21 , SEQ ID NO:23, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:31 , SEQ ID NO:33, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:41 , SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:49, SEQ ID NO:51 , SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:61 , SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67, SEQ ID NO:69, SEQ ID NO:71 , SEQ ID N0.73, SEQ ID NO:75, SEQ ID NO:77, SEQ ID NO:79, SEQ ID NO:81 or SEQ ID NO:83 or mutants, analogues, derivatives or functionally active fragments thereof. 24. A recombinant vector including a nucleotide sequence according to claim 22 or 23. 25. A host cell including a recombinant vector according to claim 24. 26. An amino acid sequence which encodes a protein identified by a method according to any one of claims 1 to 12. 27. An amino acid sequence of Mycoplasma having a sequence according to any one of Figures 1 to 42, or SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:10, SEQ ID NO:12, SEQ ID NO:14, SEQ ID NO:16, SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:28, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:40, SEQ ID NO:42, SEQ ID NO:44, SEQ ID NO:46, SEQ ID NO:48, SEQ ID NO:50, SEQ ID NO:52, SEQ ID NO:54, SEQ ID NO:56, SEQ ID NO:58, SEQ ID NO:60, SEQ ID NO 62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68, SEQ ID NO:70, SEQ ID NO:72, SEQ ID NO 74, SEQ ID NO: 76, SEQ ID NO:78, SEQ ID NO:80, SEQ ID NO:82 or SEQ ID NO:84 or a mutant, analogue, derivative or functionally active fragment thereof. 28. An isolated and purified polypeptide encoded by an amino acid sequence according to claim 26. 29. An isolated and purified polypeptide encoded by an amino acid sequence according to claim 27. 30. An isolated and purified polypeptide translated from a nucleotide sequence according to claim 22 or 23. 31. An antibody specific for a polypeptide according to any one of claims 13, 28, 29 or 30. 32. An antibody according to claim 31 which is a monoclonal antibody. 33. A method of treating an infection, said method including administering an effective amount of an antigenic polypeptide according to any one of claims 28 to 30. 34. A method of treating an infection, said method including administering to an animal in need, an effective amount of a DNA molecule including a nucleotide sequence according to claim 22 or 23. 35. A method according to claim 34 wherein the DNA molecule is administered via a recombinant vector according to claim 24. 36. A method of treating an infection, said method including administering an effective amount of an antibody specific to a polypeptide, according to claim 31 or 32. 37. A method according to any one of claims 33 to 36 wherein the infection is a Mycoplasma infection. 38. A method according to claim 37 wherein the infection is a Mycoplasma hyopneumoniae infection. 39. A method according to claim 34 or 35 wherein the nucleotide sequence comprises a sequence according to any one of Figures 1 to 42, or SEQ ID NO:1 , SEQ ID NO:3, SEQ ID NO:5, SEQ ID NO:7, SEQ ID NO:9, SEQ ID NO.11 , SEQ ID NO:13, SEQ ID NO:15, SEQ ID NO:17, SEQ ID NO:19, SEQ ID NO:21 , SEQ ID NO:23, SEQ ID NO:25, SEQ ID NO:27, SEQ ID NO:29, SEQ ID NO:31 , SEQ ID NO:33, SEQ ID NO:35, SEQ ID NO:37, SEQ ID NO:39, SEQ ID NO:41 , SEQ ID NO:43, SEQ ID NO:45, SEQ ID NO:47, SEQ ID NO:49, SEQ ID NO:51 , SEQ ID NO:53, SEQ ID NO:55, SEQ ID NO:57, SEQ ID NO:59, SEQ ID NO:61 , SEQ ID NO:63, SEQ ID NO:65, SEQ ID NO:67, SEQ ID NO:69, SEQ ID NO:71 , SEQ ID NO:73, SEQ ID NO:75, SEQ ID NO:77, SEQ ID NO:79, SEQ ID NO:81 or SEQ ID NO:83 or a mutant, analogue, derivative or functionally active fragment thereof. 40. A method according to claim 33 or 36 wherein the polypeptide is encoded by an amino acid sequence according to any one of Figures 1 to 42, SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, SEQ ID NO:10, SEQ ID NO:12, SEQ ID NO:14, SEQ ID NO:16, SEQ ID NO:18, SEQ ID NO:20, SEQ ID NO:22, SEQ ID NO:24, SEQ ID NO:26, SEQ ID NO:28, SEQ ID NO:30, SEQ ID NO:32, SEQ ID NO:34, SEQ ID NO:36, SEQ ID NO:38, SEQ ID NO:40, SEQ ID NO:42, SEQ ID NO:44, SEQ ID NO:46, SEQ ID NO:48, SEQ ID NO:50, SEQ ID NO:52, SEQ ID NO:54, SEQ ID NO:56, SEQ ID NO:58, SEQ ID NO:60, SEQ ID NO 62, SEQ ID NO:64, SEQ ID NO:66, SEQ ID NO:68, SEQ ID NO:70, SEQ ID NO:72, SEQ ID NO 74, SEQ ID NO: 76, SEQ ID NO:78, SEQ ID NO:80, SEQ ID NO:82 or SEQ ID NO:84 or a mutant, analogue, derivative or functionally active fragment thereof.

Inventors: DORAN TIMOTHY JAMES, MOORE ROBERT JOHN, DORAN, TIMOTHY, JAMES, MOORE, ROBERT, JOHN
Applicants: COMMW SCIENT IND RES ORG, DORAN TIMOTHY JAMES, MOORE ROBERT JOHN, COMMONWEALTH SCIENTIFIC AND INDUSTRIAL RESEARCH ORGANISATION, DORAN, TIMOTHY, JAMES, MOORE, ROBERT, JOHN
Application year: 1999
Main classification: C07K1
IPC codes: A61K35, A61K38, A61K39, A61K48, A61P31, C07K1, C07K14, C07K16, C12N1, C12N5, C12N15, C12P21, C12Q1, G01N33