CHLAMYDIA ANTIGENS AND CORRESPONDING DNA FRAGMENTS AND USES THEREOF

Abstract: The present invention provides a method of nucleic acid, including DNA, immunization of a host, including humans, against disease caused by infection by a strain of Chlamydia, specifically C. pneumoniae, employing a vector containing a nucleotide sequence encoding full-length, 5'-truncated or 3'-truncated 76kDa protein of a strain of Chlamydia pneumoniae and a promoter to effect expression of the 76kDa protein gene in the host. Modifications are possible within the scope of this invention.

Description: TITLE OF INVENTION CHLAMYDIA ANTIGENS AND CORRESPONDING DNA FRAGMENTS AND USES THEREOF REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application No. 60/132,270, filed May 3, 1999, and U.S. Provisional Application No. 60/141,276 filed June 30, 1999. FIELD OF INVENTION The present invention relates to the Chlamydia 76kDa protein and corresponding DNA molecules, which can be used to prevent and treat Chlamydia infection m mammals, such as humans . BACKGROUND OF THE INVENTION Chlamydiae are prokaryotes. They exhibit morpnologic and structural similarities to gram-negative bacteria including a trilammar outer membrane, which contains lipopolysaccharide and several membrane proteins that are structurally and functionally analogous to proteins found m E coli . They are obligate intra-cellular parasites with a unique biphasic life cycle consisting of a metabolically inactive but infectious extracellular stage and a replicating but non-mfectious intracellular stage. The replicative stage of the life-cycle takes place within a membrane-bound inclusion which sequesters the bacteria away from the cytoplasm of the infected hosn cell . C. pneumoniae is a common human pathogen, originally described as the T AR strain of Chlamydia psi ttaci but subsequently recognised to be a new species. C. pneumoniae is antigenically, genetically and morphologically distinct from other Chlamydia species (C. trachomat s , C. pecorum and C. psi ttaci ) . It shows 10% or less DNA sequence homology with either of C. trachomati s or C. si ttaci . C. pneumoniae is a common cause of community acquired pneumonia, only less frequent than Streptococcus pneumoniae and Mycoplasma pneumoniae (Grayston et al . (1995) Journal of Infectious Diseases 168:1231; Campos et al . (1995) Investigation of Ophthalmology and Visual Science 36:1477) . It can also cause upper respiratory tract symptoms and disease, including bronchitis and sinusitis (Grayston et al . (1995) Journal of Infectious Diseases 168:1231; Grayston et al (1990) Journal of Infectious Diseases 161:618; Marrie (1993) Clinical Infectious Diseases. 18:501; Wang et al (1986) Chlamydial infections Cambridge University Press, Cambridge, p. 329. The great majority of the adult population (over 60%) has antibodies to C. pneumoniae (Wang et al (1986) Chlamydial infections. Cambridge University Press, Cambridge, p. 329), indicating past infection which was unrecognized or asymptomatic. C. pneumoniae infection usually presents as an acute respiratory disease (i.e., cough, sore throat, hoarseness, and fever; abnormal chest sounds on auscultation) . For most patients, the cough persists for 2 to 6 weeks, and recovery is slow. In approximately 10% of these cases, upper respiratory tract infection is followed by bronchitis or pneumonia. Furthermore, during a C. pneumoniae epidemic, subsequent co- mfection with pneumococcus has been noted m about half of these pneumonia patients, particularly m the infirm and the elderly. As noted above, there is more and more evidence that C. pneumoniae infection is also linked to diseases other than respiratory infections. The reservoir for the organism is presumably people. In contrast to C. psi ttaci infections, there is no known bird or animal reservoir. Transmission has not been clearly defined. It may result from direct contact with secretions, from fomites, or from airborne spread. There is a long incubation period, which may last for many months. Based on analysis of epidemics, C. pneumoniae appears to spread slowly through a population (case-to-case interval averaging 30 days) because infected persons are inefficient transmitters of the organism. Susceptibility to C. pneumoniae is universal. Reinfections occur during adulthood, following the primary infection as a child. C. pneumoniae appears to be an endemic disease throughout the world, noteworthy for superimposed intervals of increased incidence (epidemics) that persist for 2 to 3 years. C. trachomatis infection does not confer cross- immunity to C. pneumoniae . Infections are easily treated with oral antibiotics, tetracyclme or erythromycm (2 g/d, for at least 10 to 14 d) . A recently developed drug, azithromycm, is highly effective as a single-dose therapy against Chlamydial infections . In most instances, C. pneumoniae infection is often mild and without complications, and up to 90% of infections are subacute or unrecognized. Among children m industrialized countries, infections have been thought to be rare up to the age of 5 y, although a recent study (E Normann et al , Chlamydia pneumoniae m children with acute respiratory tract infections, Acta Paediatrica, 1998, Vol 87, Iss 1, pp 23-27) has reported that many children m this age group show PCR evidence of infection despite being seronegative, and estimates a prevalence of 17-19% 2-4 y olds. In developing countries, the seroprevalence of C. pneumoniae antibodies among young children is elevated, and there are suspicions that C. pneumoniae may be an important cause of acute lower respiratory tract disease and mortality for infants and children m tropical regions of the world. From seroprevalence studies and studies of local epidemics, the initial C. pneumoniae infection usually happens between the ages of 5 and 20 y. In the USA, for example, there are estimated to be 30,000 cases of childhood pneumonia each year caused by C. pneumoniae Infections may cluster among groups of children or young adults ( e . g. , school pupils or military conscripts) . C. pneumoniae causes 10 to 25% of community-acquired lower respiratory tract infections (as reported from Sweden, Italy, Finland, and the USA) . During an epidemic, C. pneumonia infection may account for 50 to 60% of the cases of pneumonia. Durmg these periods, also, more episodes of mixed infections with S . pneumoniae have been reported. Reinfection during adulthood is common; the clinical presentation tends to be milder. Based on population seroprevalence studies, there tends to be increased exposure with age, which is particularly evident among men. Some investigators have speculated that a persistent, asymptomatic C. pneumoniae infection state is common. In adults of middle age or older, C. pneumoniae infection may progress to chronic bronchitis and sinusitis. A study m the USA revealed that the incidence of pneumonia caused by C. pneumoniae m persons younger than 60 years is 1 case per 1,000 persons per year; but m the elderly, the disease incidence rose three-fold. C. pneumoniae infection rarely leads to hospitalization, except m patients with an underlying illness. Of considerable importance is the association of atherosclerosis and C. pneumoniae infection. There are several epidemiological studies showing a correlation of previous infections with C. pneumoniae and heart attacks, coronary artery and carotid artery disease (Saikku et al . (1988) Lancet ; ii : 983 ; Thorn et al . (1992) JAMA 268:68; Lmnanmaki et al . (1993), Circulation 87:1030; Saikku et al . (1992)Annals Internal Medicine 116:273; Melnick et al (1993) American Journal of Medicine 95:499) . Moreover, the organisms has been detected in atheromas and fatty streaks of the coronary, carotid, peripheral arteries and aorta (Shor et al . (1992) South African. Medical Journal 82:158; Kuo et al . (1993) Journal of Infectious Diseases 167:841; Kuo et al . (1993) Arteriosclerosis and Thrombosis 13:1500; Campbell et al (1995) Journal of Infectious Diseases 172:585; Chiu et al . Circulation, 1997 (In Press) ) . Viable C. pneumoniae has been recovered from the coronary and carotid artery (Ramirez et al (1996) Annals of Internal Medicine 125:979; Jackson et al . Abst . K121, p272, 36 th ICAAC, 15-18 Sept. 1996, New Orleans). Furthermore, it has been shown that C. pneumoniae can induce changes of atherosclerosis in a rabbit model (Fong et al (1997) Journal of Clinical Microbiolology 35:48) . Taken together, these results indicate that it is highly probable that C. pneumoniae can cause atherosclerosis in humans, though the epidemiological importance of Chlamydial atherosclerosis remains to be demonstrated . A number of recent studies have also indicated an association between C. pneumoniae infection and asthma. Infection has been linked to wheezing, asthmatic bronchitis, adult -onset asthma and acute exacerbations of asthma in adults, and small-scale studies have shown that prolonged antibiotic treatment was effective at greatly reducing the severity of the disease in some individuals (Hahn DL, et al . Evidence for Chlamydia pneumoniae infection in steroid-dependent asthma.Ann Allergy Asthma Immunol. 1998 Jan; 80(1) : 45-49.; Hahn DL, et al . Association of Chlamydia pneumoniae IgA antibodies with recently symptomatic asthma. Epidemiol Infect. 1996 Dec; 117(3) : 513-517; Bjornsson E, et al . Serology of Chlamydia in relation to asthma and bronchial hyperresponsiveness . Scand J Infect Dis. 1996; 28(1): 63-69.; Hahn DL . Treatment of Chlamydia pneumoniae infection m adult asthma: a before-after trial. J Fam Pract . 1995 Oct ; 41(4): 345-351.; Allegra L, et al . Acute exacerbations of asthma adults: role of Chlamydia pneumoniae infection. Eur Respir J. 1994 Dec; 7(12) : 2165- 2168.; Hahn DL, et al . Association of Chlamydia pneumoniae (strain TWAR) infection with wheezing, asthmatic bronchitis, and adult-onset asthma. JAMA. 1991 Jul 10; 266(2): 225-230). In light of these results a protective vaccine against C. pneumoniae infection would be of considerable importance. There is not yet an effective vaccine for any human Chlamydial infection. It is conceivable that an effective vaccine can be developed using physically or chemically inactivated Chlamydiae. However, such a vaccine does not have a high margin of safety. In general, safer vaccines are made by genetically manipulating the organism by attenuation or by recombinant means. Accordingly, a manor obstacle m creating an effective and safe vaccine against human Chlamydial infection has been the paucity of genetic information regarding Chlamydia, specifically C. pneumoniae . Studies with C. trachomati s and C. psi ttaci indicate that safe and effective vaccine against Chlamydia is an attainable goal. For example, mice which have recovered from a lung infection with C. trachomatis are protected from infertility induced by a subsequent vaginal challenge (Pal et al . (1996) Infection and Immunity .64 : 5341) . Similarly, sheep immunized with inactivated C. psi ttaci were protected from subsequent Chlamydial -induced abortions and stillbirths (Jones et al . (1995) Vaccine 13:715). Protection from Chlamydial infections has been associated with Thl immune responses, particularly the induction of INFg - producing CD4+T-cells (Igietsemes et al . (1993) Immunology 5:317) . The adoptive transfer of CD4+ cell lines or clones to nude or SCID mice conferred protection from challenge or cleared chronic disease (Igietseme et al (1993) Regional Immunology 5:317; Magee et al (1993) Regional Immunology 5: 305) , and in vivo depletion of CD4+ T cells exacerbated disease post-challenge (Landers et al (1991) Infection & Immunity 59:3774; Magee et al (1995) Infection & Immunity 63:516) . However, the presence of sufficiently high titres of neutralising antibody at mucosal surfaces can also exert a protective effect (Cotter et al . (1995) Infection and Immunity 63:4704). Antigenic variation within the species C. pneumoniae is not well documented due to insufficient genetic information, though variation is expected to exist based on C. trachomatis . Serovars of C. trachomatis are defined on the basis of antigenic variation m the major outer membrane protein (MOMP) , but published C. pneumoniae MOMP gene sequences show no variation between several diverse isolates of the organism (Campbell et al (1990) Infection and Immunity 58:93; McCafferty et al (1995) Infection and Immunity 63:2387-9; Knudsen et al (1996) Third Meeting of the European Society for Chlamydia Research, Vienna) . Melgosa et al . (Infect. Immun. 1994. 62:880) claimed to have cloned the gene encoding a 76 kDa antigen from a single strain of C. pneumoniae . An operon encoding the 9 kDa and 9kDa cyteme-rich outer membrane protein genes has been described (Watson et al . , Nucleic Acids Res (1990) 18:5299; Watson et al . , Microbiology (1995) 141:2489). Many antigens recognized by immune sera to C. pneumoniae are conserved across all Chlamydiae, but 98 kDa, 76 kDa and several other proteins may be C. pπeumo-πiae-specific (Perez Melgosa et al . , Infect. Immun. 1994. 62:880; Melgosa et al . , FEMS Microbiol Lett (1993) 112 :199;, Campbell et al., J Clin Microbiol (1990) 28 :1261; Iiηima et al . , J Clin Microbiol (1994) 32:583) . An assessment of the number and relative frequency of any C. pneumoniae serotypes, and the defining antigens, is not yet possible. The entire genome sequence of C. pneumoniae strain CWL-029 is now known (http : //chlamydia- www.Derkeley . edu : 4231/) and as further sequences become available a better understanding of antigenic variation may be gained. Many antigens recognised by immune sera to C. pneumoniae are conserved across all Chlamydiae, but 98kDa, 76 kDa and 54 kDa proteins appear to be C. pneumoniae-specifIC (Campos et al . (1995) Investigation of Ophthalmology and Visual Science 36:1477; Marrie (1993) Clinical Infectious Diseases. 18:501; Wiedmann-Al -Ahmad M, et al . Reactions of polyclonal and neutralizing antι-p54 monoclonal antibodies with an isolated, species-specific 54-kilodalton protein of Chlamydia pneumoniae. Clin Diagn Lab Immunol. 1997 Nov; 4(6) : 700-704) . Immunoblottmg of isolates with sera from patients does show variation of blotting patterns between isolates, indicating that serotypes C. pneumoniae may exist (Grayston et al . (1995) Journal of Infectious Diseases 168:1231; Ramirez et al (1996) Annals of Internal Medicine 125:979). However, the results are potentially confounded by the infection status of the patients, since immunoblot profiles of a patient's sera change with time pos -infection. An assessment of the number and relative frequency of any serotypes, and the defining antigens, is not yet possible. Accordingly, a need exists for identifying and isolating polynucleotide sequences of C. pneumoniae for use m preventing and treating Chlamydia infection. SUMMARY OF THE INVENTION The present invention provides purified and isolated polynucleotide molecules that encode the Chlamydia polypeptide designated 76kDa protein (SEQ ID No : 1) which can be used methods to prevent, treat, and diagnose Chlamydia infection. In one form of the invention, the polynucleotide molecules are DNA that encode the polypeptide of SEQ ID No : 2. Another form of the invention provides polypeptides corresponding to the isolated DNA molecules. The ammo acid sequence of the corresponding encoded polypeptide is shown as SEQ ID No : 2. Another form of the invention provides truncated polypeptides corresponding to truncated DNA molecules. In one embodiment, the truncated nucleotide and ammo acid sequences are shown as SEQ ID Nos : 3 and 4 respectively. In another embodiment, the truncated nucleotide and ammo acid sequences are shown as SEQ ID Nos : 5 and 6 respectively. Although Melgosa et al . has reported cloning a 76kDa protein from C. pneumoniae, comparison of the gene sequence as reported by Melgosa et al . to the published geneome sequence of C. pneumoniae (http : //chlamydia-www.berkeley . edu: 4231/) reveals that, m fact, the genomic sequence m this region contains at least two open reading frames (ORFs) , one m the 5' portion and one m the 3' portion. The sequence reported in Melgosa et al . is an m-frame fusion of the 5' end of the 5' ORF . Thus, Melgosa' s deduced protein is merely a 76kDa fusion protein and not the 76kDa protein observed by immunoblottmg from various C. pneumoniae isolates. By contrast, the 76kDa protein of the present mvention is the full-length protein encoded by the 3 'ORF m this region of the genome. Notably, further analysis of the genome sequence (http://chlan.ydia- www.berkeley. edu : 4231/) reveals at least one m-frame ATG upstream of the start codon of the 5' ORF, suggesting that the 5' ORF may form part of one or more larger ORFs. Those skilled m the art will readily understand that the invention, having provided the polynucleotide sequences encoding the Chlamydia 76kDa protein, also provides polynucleotides encoding fragments derived from such a polypeptide. Moreover, the invention is understood to provide mutants and derivatives of such polypeptides and fragments derived therefrom, which result from the addition, deletion, or substitution of non-essential ammo acids as described herein. Those skilled m the art would also readily understand that the invention, having provided the polynucleotide sequences encoding Chlamydia polypeptides, further provides monospecific antibodies that specifically bind to such polypeptides. The present invention has wide application and includes expression cassettes, vectors, and cells transformed or transfected with the polynucleotides of the invention. Accordingly, the present mvention further provides (l) a method for producing a polypeptide of the invention m a recombinant host system and related expression cassettes, vectors, and transformed or transfected cells; (ii) a vaccine, or a live vaccine vector such as a pox virus, Salmonella typhimurium, or Vibrio cholerae vector , containing a polynucleotide of the invention, such vaccines and vaccine vectors being useful for, e . g. , preventing and treating Chlamydia infection, in combination with a diluent or carrier, and related pharmaceutical compositions and associated therapeutic and/or prophylactic methods; (m) a therapeutic and/or prophylactic use of an RNA or DNA molecule of the invention, either m a naked form or formulated with a delivery vehicle, a polypeptide or combination of polypeptides, or a monospecific antibody of the mvention, and related pharmaceutical compositions; (iv) a method for diagnosing the presence of Chlamydia m a biological sample, which can involve the use of a DNA or RNA molecule, a monospecific antibody, or a polypeptide of the invention; and (v) a method for purifying a polypeptide of the invention by antibody-based affinity chromatography . BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be further understood from the following description with reference to embodiments shown m the drawings, in which: Figure 1 shows the full-length nucleotide sequence of the 76kDa protein gene (SEQ ID No: 1) and the deduced ammo acid sequence of the 76kDa protein from Chlamydia pneumoniae (SEQ ID No: 2) . Figure 2 shows the restriction enzyme analysis of the C. pneumoniae 76kDa protein gene. Figure 3 shows the nucleotide sequence containing a 3 '-truncated 76kDa protein gene and its corresponding deduced amino acid sequence from Chlamydia pneumoniae ; (note that nucleotides 1 to 665 and 2122 to 2238 are unrelated to the 76kDa protein gene) . Figure 4 shows the construction and elements of plasmid pCACPNM555a, containing the full-length 76kDa gene. Figure 5 shows the construction and elements of plasmid pCAI555, containing a 5' -truncated version of the 76kDa gene . Figure 6 shows the construction and elements of plasmid pCAD76kDa, containing a 3 '-truncated version of the 76kDa gene from Figure 3. Figure 7 illustrates protection against C. pneumoniae infection by pCACPNM555a following DNA immunization. Figure 8 illustrates protection against C. pneumoniae infection by pCAI555 following DNA immunization. Figure 9 illustrates protection against C. pneumoniae infection by pCAD76kDa following DNA immunization. For Figures 7 to 9, individual data points are shown for each animal (hollow diamonds) as well as mean and standard deviations for each group (solid squares) . DETAILED DESCRIPTION OF INVENTION The mvention is described with reference to the following sequences which are embodiments of the invention: SEQ ID NO: 1 is the full-length sequence of the 76kDa protein gene . SEQ ID NO : 2 is the deduced full-length ammo acid sequence of the 76kDa protein. SEQ ID NO: 3 is the 5' -truncated nucleotide sequence of the 76kDa protein gene. SEQ ID NO: 4 is the 5' -truncated amino acid sequence of the 76kDa protein. SEQ ID NO: 5 is the 3' -truncated nucleotide sequence of the 76kDa protein gene. SEQ ID NO: 6 is the 3 '-truncated amino acid sequence of the 76kDa protein, which forms the basis for immunoprotection by pCAD76kDa in Figure 9. SEQ ID NO: 7 is the sequence encoding a polypeptide containing a truncated 76kDa protein. Using this sequence as a template, a fragment was amplified by PCR to form part of construct pCAD76kDa. SEQ ID NO: 8 is the deduced ammo acid sequence of a truncated 76kDa protein, as expressed from pCAD76kDa. SEQ ID NO: 9 is the 5' primer used to clone the full- length 76kDa protein gene and to amplify the full-length 76kDa protein gene for pCACPNM555a. SEQ ID NO: 10 is the 3' primer used to clone the full-length 76kDa protein gene and to amplify the full-length 76kDa protein gene for pCACPNM555a. SEQ ID NO: 11 is the 5' primer used to amplify the 5' -truncated 76kDa protein gene fragment for pCAI555. SEQ ID NO: 12 is the 3' primer used to amplify the 5' -truncated 76kDa protein gene fragment for pCAI555. SEQ ID NO: 13 is the 5' primer used to amplify the 3 '-truncated 76kDa protein gene fragment for pCAD76kDa. SEQ ID NO: 14 is the 3' primer used to amplify the truncated 76kDa protein gene fragment for pCAD76kDa. An open reading frame (ORF) encoding the Chlamydial 76kDa protein has been identified from the C. pneumoniae genome. The gene encoding this protein and its fragments have been inserted mto expression plasmids and shown to confer immune protection against Chlamydial infection. Accordingly, this 76kDa protein and related polypeptides can be used to prevent and treat Chlamydia infection. According to a first aspect of the invention, isolated polynucleotides are provided which encode Chlamydia polypeptides, whose ammo acid sequences are shown m SEQ ID Nos : 2 , 4 and 6. The term "isolated polynucleotide" is defined as a polynucleotide removed from the environment in which it naturally occurs. For example, a naturally-occurring DNA molecule present m the genome of a living bacteria or as part of a gene bank is not isolated, but the same molecule separated from the remaining part of the bacterial genome, as a result of, e . g. , a cloning event (amplification), is isolated. Typically, an isolated DNA molecule is free from DNA regions { e . g. , coding regions) with which it is immediately contiguous at the 5' or 3 ' end, m the naturally occurring genome. Such isolated polynucleotides may be part of a vector or a composition and still be defined as isolated m that such a vector or composition is not part of the natural environment of such polynucleotide. The polynucleotide of the invention is either RNA or DNA (cDNA, genomic DNA, or synthetic DNA), or modifications, variants, homologs or fragments thereof. The DNA is either double-stranded or smgle-stranded, and, if smgle-stranded, is either the coding strand or the non-codmg (anti -sense) strand. Any one of the sequences that encode the polypeptides of the invention as shown m SEQ ID No : 1, 3 or 5 is (a) a coding sequence, (b) a ribonucleotide sequence derived from transcription of (a) , or (c) a coding sequence which uses the redundancy or degeneracy of the genetic code to encode the same polypeptides. By "polypeptide" or "protein" is meant any cham of ammo acids, regardless of length or post-translational modification { e . g. , glycosylation or phosphorylation). Both terms are used interchangeably m the present application. Consistent with the first aspect of the invention, ammo acid sequences are provided which are homologous to SEQ ID No : 2, 4 or 6. As used herein, "homologous ammo acid sequence" is any polypeptide which is encoded, m whole or m part, by a nucleic acid sequence which hybridizes at 25-35°C below critical melting temperature (Tm) , to any portion of the nucleic acid sequence of SEQ ID No: 1 , 3 or 5. A homologous ammo acid sequence is one that differs from an ammo acid sequence shown m SEQ ID No : 2 , 4 or 6 by one or more conservative ammo acid substitutions. Such a sequence also encompass serotypic variants (defined below) as well as sequences containing deletions or insertions which retain inherent characteristics of the polypeptide such as immunogenicity . Preferably, such a sequence is at least: 75%, more preferably 80%, and most preferably 90% identical to SEQ ID No: 2, 4 or 6. Homologous ammo acid sequences mclude sequences that are identical or substantially identical to SEQ ID No : 2, 4 or 6. By "ammo acid sequence substantially identical" is meant a sequence that is at least 90%, preferably 95%, more preferably 97%, and most preferably 99% identical to an ammo acid sequence of reference and that preferably differs from the sequence of reference by a majority of conservative ammo acid substitutions . Conservative ammo acid substitutions are substitutions among ammo acids of the same class. These classes include, for example, ammo acids having uncharged polar side chains, such as asparagme, glutamine, serine, threonine, and tyrosine; ammo acids having basic side chains, such as lysine, arginine, and histidme; ammo acids having acidic side chains, such as aspartic acid and glutamic acid; and ammo acids having nonpolar side chains, such as glycine, alanine, valme, leucme, lsoleucme, prol e, phenylalanine, methionine, tryptophan, and cysteine. Homology is measured using sequence analysis software such as Sequence Analysis Software Package of the Genetics Computer Group, University of Wisconsin Biotechnology Center, 1710 University Avenue, Madison, WI 53705. Ammo acid sequences are aligned to maximize identity. Gaps may be artificially introduced into the sequence to attain proper alignment. Once the optimal alignment has been set up, the degree of homology is established by recording all of the positions m which the ammo acids of both sequences are identical, relative to the total number of positions. Homologous polynucleotide sequences are defined a similar way. Preferably, a homologous sequence is one that is at least 45%, more preferably 60%, and most preferably 85% identical to the coding sequence of SEQ ID No: 1, 3 or 5. Consistent with the first aspect of the invention, polypeptides having a sequence homologous to SEQ ID No: 2 , 4 or 6 include naturally-occurring allelic variants, as well as mutants or any other non-naturally occurring variants that retain the inherent characteristics of the polypeptide of SEQ ID No: 2, 4 or 6. As is known m the art, an allelic variant is an alternate form of a polypeptide that is characterized as having a substitution, deletion, or addition of one or more ammo acids that does not alter the biological function of the polypeptide. By "biological function" is meant the function of the polypeptide m the cells m which it naturally occurs, even if the function is not necessary for the growth or survival of the cells. For example, the biological function of a porin is to allow the entry mto cells of compounds present m the extracellular medium. Biological function is distinct from antigenic property. A polypeptide can have more than one biological function. Allelic variants are very common m nature. For example, a bacterial species such as C. pneumoniae, is usually represented by a variety of strains that differ from each other by minor allelic variations. Indeed, a polypeptide that fulfills the same biological function m different strains can have an ammo acid sequence (and polynucleotide sequence) that is not identical m each of the strains. Despite this variation, an immune response directed generally against many allelic variants has been demonstrated. In studies of the Chlamydial MOMP antigen, cross-strain antibody binding plus neutralization of mfectivity occurs despite ammo acid sequence variation of MOMP from strain to strain, indicating that the MOMP, when used as an immunogen, is tolerant of ammo acid variations. Polynucleotides encoding homologous polypeptides or allelic variants are retrieved by polymerase chain reaction (PCR) amplification of genomic bacterial DNA extracted by conventional methods. This involves the use of synthetic oligonucleotide primers matching upstream and downstream of the 5' and 3' ends of the encoding domain. Suitable primers are designed according to the nucleotide sequence information provided m SEQ ID No : 1 , 3 or 5. The procedure is as follows: a primer is selected which consists of 10 to 40, preferably 15 to 25 nucleotides. It is advantageous to select primers containing C and G nucleotides m a proportion sufficient to ensure efficient hybridization; i.e., an amount of C and G nucleotides of at least 40%, preferably 50% of the total nucleotide content. A standard PCR reaction contains typically 0.5 to 5 Units of Taq DNA polymerase per 100 μL, 20 to 200 μM deoxynucleotide each, preferably at equivalent concentrations, 0.5 to 2.5 mM magnesium over the total deoxynucleotide concentration, 10^ to 10^ target molecules, and about 20 pmol of each primer. About 25 to 50 PCR cycles are performed, with an annealing temperature 15°C to 5°C below the true Tm of the primers. A more stringent annealing temperature improves discrimination against incorrectly annealed primers and reduces incorporation of incorrect nucleotides at the 3' end of primers. A denaturation temperature of 95°C to 97°C is typical, although higher temperatures may be appropriate for dematuration of G+C-rich targets. The number of cycles performed depends on the starting concentration of target molecules, though typically more than 40 cycles is not recommended as non-specific background products tend to accumulate . An alternative method for retrieving polynucleotides encoding homologous polypeptides or allelic variants is by hybridization screening of a DNA or RNA library. Hybridization procedures are well-known in the art and are described m Ausubel et al . , (Ausubel et al . , Current Protocols m Molecular Biology, John Wiley & Sons Inc., 1994), Silhavy et al . (Silhavy et al . Experiments with Gene Fusions, Cold Spring Harbor Laboratory Press, 1984), and Davis et al . (Davis et al . A Manual for Genetic Engineering: Advanced Bacterial Genetics, Cold Spring Harbor Laboratory Press, 1980)) . Important parameters for optimizing hybridization conditions are reflected in a formula used to obtain the critical melting temperature above which two complementary DNA strands separate from each other (Casey & Davidson, Nuci . Acid Res. ( 1917 ) 4:1539) . For polynucleotides of about 600 nucleotides or larger, this formula is as follows: Tm = 81.5 + 0.41 x (% G+C) + 16.6 log (cation ion concentration) - 0.63 x (% formamide) - 600/base number. Under appropriate stringency conditions, hybridization temperature (Th) is approximately 20 to 40°C, 20 to 25°C, or, preferably 30 to 40°C below the calculated Tm. Those skilled m the art will understand that optimal temperature and salt conditions can be readily determined. For the polynucleotides of the invention, stringent conditions are achieved for both pre-hybridizing and hybridizing incubations d) within 4-16 hours at 42°C, 6 x SSC containing 50% formamide, or (ii) within 4-16 hours at 65°C an aqueous 6 x SSC solution (1 M NaCl, 0.1 M sodium citrate (pH 7.0)) . Typically, hybridization experiments are performed at a temperature from 60 to 68°C, e.g. 65°C. At such a temperature, stringent hybridization conditions can be achieved 6xSSC, preferably m 2xSSC or lxSSC, more preferably 0.5xSSc, 0.3xSSC or 0. lxSSC (m the absence of formamide). lxSSC contains 0.15 M NaCl and 0.015 M sodium citrate. Useful homologs and fragments thereof that do not occur naturally are designed usmg known methods for identifying regions of an antigen that are likely to tolerate ammo acid sequence changes and/or deletions. As an example, homologous polypeptides from different species are compared; conserved sequences are identified. The more divergent sequences are the most likely to tolerate sequence changes. Homology among sequences may be analyzed usmg, as an example, the BLAST homology searching algorithm of Altschul et al . , Nucleic Acids Res.; 25:3389-3402 (1997). Alternatively, sequences are modified such that they become more reactive to T- and/or B-cells, based on computer-assisted analysis of probable T- or B-cell epitopes Yet another alternative is to mutate a particular ammo acid residue or sequence withm the polypeptide m vi tro, then screen the mutant polypeptides for their ability to prevent or treat Chlamydia infection according to the method outlined below. A person skilled m the art will readily understand that by following the screening process of this invention, it will be determined without undue experimentation whether a particular homolog of SEQ ID No: 2, 4 or 6 may be useful the prevention or treatment of Chlamydia infection. The screening procedure comprises the steps : (I) immunizing an animal, preferably mouse, with the test homolog or fragment; (ii) inoculating the immunized animal with Chlamydia; and (m) selecting those homologs or fragments which confer protection against Chlamydia. By "conferring protection" is meant that there is a reduction severity of any of the effects of Chlamydia infection, m comparison with a control animal which was not immunized with the test homolog or fragment. Consistent with the first aspect of the invention, polypeptide derivatives are provided that are partial sequences of SEQ ID No : 2, 4 or 6, partial sequences of polypeptide sequences homologous to SEQ ID No: 2, 4 or 6 , polypeptides derived from full-length polypeptides by internal deletion, and fusion proteins. It is an accepted practice m the field of immunology to use fragments and variants of protein immunogens as vaccines, as all that is required to induce an immune response to a protein is a small ( e . g. , 8 to 10 ammo acid) immunogenic region of the protein. Various short synthetic peptides corresponding to surface-exposed antigens of pathogens other than Chlamydia have been shown to be effective vaccine antigens against their respective pathogens, e . g. an 11 residue peptide of murine mammary tumor virus (Casey & Davidson, Nucl . Acid Res. (1977) 4:1539), a 16-resιdue peptide of Semliki Forest virus (Sm ders et al . , 1991. J. Gen. Virol. 72:557-565), and two overlapping peptides of 15 residues each from canine parvovirus (Langeveld et al . , Vaccine 12 (15) : 1473 -1480 , 1994). Accordingly, it will be readily apparent to one skilled m the art, having read the present description, that partial sequences of SEQ ID No: 2, 4 or 6 or their homologous ammo acid sequences are inherent to the full-length sequences and are taught by the present invention. Such polypeptide fragments preferably are at least 12 ammo acids m length. Advantageously, they are at least 20 ammo acids, preferably at least 50 ammo acids, and more preferably at least 75 ammo acids and most preferably at least 100 ammo acids m length. Polynucleotides of 30 to 600 nucleotides encoding partial sequences of sequences homologous to SEQ ID No: 2, 4 or 6 are retrieved by PCR amplification using the parameters outlined above and usmg primers matching the sequences upstream and downstream of the 5 ' and 3 ' ends of the fragment to be amplified. The template polynucleotide for such amplification is either the full length polynucleotide homologous to SEQ ID No: 1, 3 or 5 , or a polynucleotide contained a mixture of polynucleotides such as a DNA or RNA library. As an alternative method for retrieving the partial sequences, screening hybridization is carried out under conditions described above and usmg the formula for calculating Tm. Where fragments of 30 to 600 nucleotides are to be retrieved, the calculated Tm is corrected by subtracting (600/polynucleotιde size m base pairs) and the stringency conditions are defined by a hybridization temperature that is 5 to 10°C below Tm. Where oligonucleotides shorter than 20-30 bases are to be obtamed, the formula for calculating the Tm is as follows: Tm = 4 x (G+C) + 2 (A+T) . For example, an 18 nucleotide fragment of 50% G+C would have an approximate Tm of 54 °C. Short peptides that are fragments of SEQ ID No : 2, 4 or 6 or its homologous sequences, are obtained directly by chemical synthesis (E. Gross and H. J. Memhofer, 4 The Peptides: Analysis, Synthesis, Biology; Modern Techniques of Peptide Synthesis, John Wiley & Sons (1981), and M. Bodanzki , Principles of Peptide Synthesis, Sprmger-Verlag (1984)) . Useful polypeptide derivatives, e . g. , polypeptide fragments, are designed using computer-assisted analysis of ammo acid sequences. This would identify probable surface- exposed, antigenic regions (Hughes et al . , 1992. Infect. Immun. 60(9) :3497) . Analysis of 6 ammo acid sequences contained m SEQ ID No: 2, 4 or 6, based on the product of flexibility and hydrophobicity propensities using the program SEQSEE (Wishart DS, et al . "SEQSEE: a comprehensive program suite for protein sequence analysis." Comput Appl Biosci . 1994 Apr ; 10 (2) : 121-32) , can reveal potential B- and T-cell epitopes which may be used as a basis for selecting useful immunogenic fragments and variants. This analysis uses a reasonable combination of external surface features that is likely to be recognized by antibodies. Probable T-cell epitopes for HLA-A0201 MHC subclass may be revealed by an algorithms that emulate an approach developed at the NIH (Parker KC, et al . "Peptide binding to MHC class I molecules: implications for antigenic peptide prediction." Immunol Res 1995; 14(1) : 34-57) . Epitopes which induce a protective T cell -dependent immune response are present throughout the length of the polypeptide. However, some epitopes may be masked by secondary and tertiary structures of the polypeptide. To reveal such masked epitopes large internal deletions are created which remove much of the original protein structure and exposes the masked epitopes. Such internal deletions sometimes effect the additional advantage of removing immunodommant regions of high variability among strains. Polynucleotides encoding polypeptide fragments and polypeptides having large internal deletions are constructed using standard methods (Ausubel et al . , Current Protocols m Molecular Biology, John Wiley & Sons Inc., 1994) . Such methods include standard PCR, inverse PCR, restriction enzyme treatment of cloned DNA molecules, or the method of Kunkel et al . (Kunkel et al . Proc. Natl. Acad. Sci. USA (1985) 82:448). Components for these methods and instructions for their use are readily available from various commercial sources such as Stratagene. Once the deletion mutants have been constructed, they are tested for their ability to prevent or treat Chlamydia infection as described above. As used herein, a fusion polypeptide is one that contams a polypeptide or a polypeptide derivative of the invention fused at the N- or C-termmal end to any other polypeptide (hereinafter referred to as a peptide tail) . A simple way to obtain such a fusion polypeptide is by translation of an m-frame fusion of the polynucleotide sequences, .e., a hybrid gene. The hybrid gene encoding the fusion polypeptide is inserted mto an expression vector which is used to transform or transfect a host cell . Alternatively, the polynucleotide sequence encoding the polypeptide or polypeptide derivative is inserted mto an expression vector m which the polynucleotide encoding the peptide tail is already present. Such vectors and instructions for their use are commercially available, e . g. the pMal-c2 or pMal-p2 system from New England Biolabs, which the peptide tail is a maltose binding protein, the glutathione-S-transferase system of Pharmacia, or the His-Tag system available from Novagen. These and other expression systems provide convenient means for further purification of polypeptides and derivatives of the invention. An advantageous example of a fusion polypeptide is one where the polypeptide or homolog or fragment of the invention is fused to a polypeptide having adjuvant activity, such as subunit B of either cholera toxin or E. coli heat- labile toxin. Another advantageous fusion is one where the polypeptide, homolog or fragment is fused to a strong T-cell epitope or B-cell epitope. Such an epitope may be one known m the art ( e . g. the Hepatitis B virus core antigen, D.R. Millich et al . , "Antibody production to the nucleocapsid and envelope of the Hepatitis B virus primed by a single synthetic T cell site", Nature. 1987. 329:547-549), or one which has been identified m another polypeptide of the invention based on computer-assisted analysis of probable T- or B-cell epitopes. Consistent with this aspect of the invention is a fusion polypeptide comprising T- or B-cell epitopes from SEQ ID No: 2, 4 or 6 or its homolog or fragment, wherem the epitopes are derived from multiple variants of said polypeptide or homolog or fragment, each variant differing from another m the location and sequence of its epitope withm the polypeptide. Such a fusion is effective m the prevention and treatment of Chlamydia infection since it optimizes the T- and B-cell response to the overall polypeptide, homolog or fragment. To effect fusion, the polypeptide of the invention is fused to the N- , or preferably, to the C-termmal end of the polypeptide having adjuvant activity or T- or B-cell epitope. Alternatively, a polypeptide fragment of the invention is inserted internally withm the ammo acid sequence of the polypeptide having adjuvant activity. The T- or B-cell epitope may also be inserted internally with the ammo acid sequence of the polypeptide of the invention. Consistent with the first aspect, the polynucleotides of the invention also encode hybrid precursor polypeptides containing heterologous signal peptides, which mature mto polypeptides of the invention. By "heterologous signal peptide" is meant a signal peptide that is not found m naturally-occurring precursors of polypeptides of the invention. Polynucleotide molecules according to the invention, including RNA, DNA, or modifications or combinations thereof, have various applications. A DNA molecule is used, for example, (1) m a process for producing the encoded polypeptide a recombinant host system, (11) m the construction of vaccine vectors such as poxviruses, which are further used m methods and compositions for preventing and/or treating Chlamydia infection, (m) as a vaccine agent (as well as an RNA molecule) , a naked form or formulated with a delivery vehicle and, (iv) m the construction of attenuated Chlamydia strains that can over-express a polynucleotide of the invention or express it m a non-toxic, mutated form. Accordingly, a second aspect of the invention encompasses (l) an expression cassette containing a DNA molecule of the invention placed under the control of the elements required for expression, m particular under the control of an appropriate promoter; (n) an expression vector containing an expression cassette of the invention; (m) a procaryotic or eucaryotic cell transformed or transfected with an expression cassette and/or vector of the mvention, as well as (iv) a process for producing a polypeptide or polypeptide derivative encoded by a polynucleotide of the invention, which involves culturing a procaryotic or eucaryotic cell transformed or transfected with an expression cassette and/or vector of the invention, under conditions that allow expression of the DNA molecule of the invention and, recovering the encoded polypeptide or polypeptide derivative from the cell culture. A recombinant expression system is selected from procaryotic and eucaryotic hosts. Eucaryotic hosts include yeast cells ( e . g. , Saccharomyces cerevisiae or Pichia pastoris) , mammalian cells ( e . g. , COS1, NIH3T3, or JEG3 cells), arthropods cells (e.g., Spodoptera frugiperda (SF9) cells), and plant cells. A preferred expression system is a procaryotic host such as E . coli . Bacterial and eucaryotic cells are available from a number of different sources including commercial sources to those skilled m the art, e . g. , the American Type Culture Collection (ATCC; Rockville, Maryland) . Commercial sources of cells used for recombinant protein expression also provide instructions for usage of the cells. The choice of the expression system depends on the features desired for the expressed polypeptide. For example, it may be useful to produce a polypeptide of the invention m a particular lipidated form or any other form. One skilled m the art would redily understand that not all vectors and expression control sequences and hosts would be expected to express equally well the polynucleotides of this invention. With the guidelines described below, however, a selection of vectors, expression control sequences and hosts may be made without undue experimentation and without departing from the scope of this invention. In selecting a vector, the host must be chosen that is compatible with the vector which is to exist and possibly replicate m it. Considerations are made with respect to the vector copy number, the ability to control the copy number, expression of other proteins such as antibiotic resistance. In selecting an expression control sequence, a number of variables are considered. Among the important variable are the relative strength of the sequence ( e . g. the ability to drive expression under various conditions) , the ability to control the sequence's function, compatibility between the polynucleotide to be expressed and the control sequence ( e . g. secondary structures are considered to avoid hairpm structures which prevent efficient transcription) . In selecting the host, unicellular hosts are selected which are compatible with the selected vector, tolerant of any possible toxic effects of the expressed product, able to secrete the expressed product efficiently if such is desired, to be able to express the product m the desired conformation, to be easily scaled up, and to which ease of purification of the final product. The choice of the expression cassette depends on the host system selected as well as the features desired for the expressed polypeptide. Typically, an expression cassette includes a promoter that is functional m the selected host system and can be constitutive or inducible; a ribosome binding site; a start codon (ATG) if necessary; a region encoding a signal peptide, e . g. , a lipidation signal peptide; a DNA molecule of the invention; a stop codon; and optionally a 3 ' terminal region (translation and/or transcription terminator) . The signal peptide encoding region is adjacent to the polynucleotide of the invention and placed m proper reading frame. The signal peptide-encodmg region is homologous or heterologous to the DNA molecule encoding the mature polypeptide and is compatible with the secretion apparatus of the host used for expression. The open reading frame constituted by the DNA molecule of the invention, solely or together with the signal peptide, is placed under the control of the promoter so that transcription and translation occur m the host system. Promoters and signal peptide encoding regions are widely known and available to those skilled m the art and include, for example, the promoter of Salmonella typhimuπum (and derivatives) that is inducible by arabmose (promoter araB) and is functional m Gram-negative bacteria such as E. coli (as described m U.S. Patent No. 5,028,530 and m Cagnon et al . , (Cagnon et al . , Protein Engineering (1991) 4 (7): 843)); the promoter of the gene of bacteπophage T7 encoding RNA polymerase, that is functional m a number of E. coli strains expressing T7 polymerase (described m U.S. Patent No. 4,952,496); OspA lipidation signal peptide ; and RlpB lipidation signal peptide (Takase et al . , J. Bact . (1987) 169:5692) . The expression cassette is typically part of an expression vector, which is selected for its ability to replicate m the chosen expression system. Expression vectors ( e . g. , plasmids or viral vectors) can be chosen, for example, from those described m Pouwels et al . (Cloning Vectors: A Laboratory Manual 1985, Supp . 1987) . Suitable expression vectors can be purchased from various commercial sources. Methods for transformmg/transfectmg host cells with expression vectors are well-known m the art and depend on the host system selected as described m Ausubel et al . , (Ausubel et al . i Current Protocols m Molecular Biology, John Wiley & Sons Inc. , 1994) . Upon expression, a recombinant polypeptide of the invention (or a polypeptide derivative) is produced and remains the intracellular compartment, is secreted/excreted m the extracellular medium or the periplasmic space, or is embedded m the cellular membrane. The polypeptide is recovered m a substantially purified form from the cell extract or from the supernatant after centrifugation of the recombinant cell culture. Typically, the recombinant polypeptide is purified by antibody-based affinity purification or by other well-known methods that can be readily adapted by a person skilled m the art, such as fusion of the polynucleotide encoding the polypeptide or its derivative to a small affinity binding domain. Antibodies useful for purifying by immunoaff ity the polypeptides of the invention are obtained as described below. A polynucleotide of the invention can also be useful as a vaccine. There are two major routes, either using a viral or bacterial host as gene delivery vehicle (live vaccine vector) or administering the gene a free form, e . g. , inserted into a plasmid. Therapeutic or prophylactic efficacy of a polynucleotide of the invention is evaluated as described below. Accordingly, a third aspect of the invention provides (I) a vaccine vector such as a poxvirus, containing a DNA molecule of the invention, placed under the control of elements required for expression; (11) a composition of matter comprising a vaccine vector of the invention, together with a diluent or carrier; specifically (m) a pharmaceutical composition containing a therapeutically or prophylactically effective amount of a vaccine vector of the invention; (iv) a method for inducing an immune response against Chlamydia m a mammal ( e . g. , a human; alternatively, the method can be used veterinary applications for treating or preventing Chlamydia infection of animals, e . g. , cats or birds) , which involves administering to the mammal an immunogenically effective amount of a vaccine vector of the invention to elicit a protective or therapeutic immune response to Chlamydia ; and particularly, (v) a method for preventing and/or treating a Chlamydia ( e . g. , C. trachomatis , C. psi ttaci , C. pneumonia, C. pecorum) infection, which involves administering a prophylactic or therapeutic amount of a vaccine vector of the invention to an infected individual. Additionally, the third aspect of the invention encompasses the use of a vaccine vector of the invention the preparation of a medicament for preventing and/or treating Chlamydia infection. As used herein, a vaccine vector expresses one or several polypeptides or derivatives of the invention. The vaccine vector may express additionally a cytokine, such as mterleukm-2 (IL-2) or mterleukm-12 (IL-12), that enhances the immune response (adjuvant effect) . It is understood that each of the components to be expressed is placed under the control of elements required for expression m a mammalian cell. Consistent with the third aspect of the mvention is a composition comprising several vaccine vectors, each of them capable of expressing a polypeptide or derivative of the mvention. A composition may also comprise a vaccine vector capable of expressing an additional Chlamydia antigen, or a subumt, fragment, homolog, mutant, or derivative thereof; optionally together with or a cytokine such as JL-2 or IL-12. Vaccination methods for treatmg or preventing infection m a mammal comprises use of a vaccine vector of the invention to be administered by any conventional route, particularly to a mucosal ( e . g. , ocular, intranasal, oral, gastric, pulmonary, intestinal, rectal, vaginal, or urinary tract) surface or via the parenteral ( e . g. , subcutaneous, intradermal, intramuscular, intravenous, or intraperitoneal) route. Preferred routes depend upon the choice of the vaccine vector. Treatment may be effected m a single dose or repeated at intervals. The appropriate dosage depends on various parameters understood by skilled artisans such as the vaccine vector itself, the route of administration or the condition of the mammal to be vaccinated (weight, age and the like) . Live vaccine vectors available m the art include viral vectors such as adenoviruses and poxviruses as well as bacterial vectors, e . g . , Shigella, Salmonella , Vibrio cholerae, Lactobacillus, Bacille bilie de Calmette-Guerm (BCG) , and Streptococcus . An example of an adenovirus vector, as well as a method for constructing an adenovirus vector capable of expressing a DNA molecule of the invention, are described U.S. Patent No. 4,920,209. Poxvirus vectors include vaccinia and canary pox virus, described m U.S. Patent No. 4,722,848 and U.S. Patent No. 5,364,773, respectively. (Also see, e . g. , Tartaglia et al . , Virology (1992) 188:217) for a description of a vaccinia virus vector and Taylor et a-Z , Vaccine (1995) 13:539 for a reference of a canary pox. ) Poxvirus vectors capable of expressing a polynucleotide of the invention are obtamed by homologous recombination as described m Kieny et al . , Nature (1984) 312:163 so that the polynucleotide of the invention is inserted m the viral genome under appropriate conditions for expression m mammalian cells. Generally, the dose of vaccine viral vector, for therapeutic or prophylactic use, can be of from about lxlO 4 to about lxlO 11 , advantageously from about lxlO 7 to about lxlO 10 , preferably of from about lxlO 7 to about lxlO 9 plaque-forming units per kilogram. Preferably, viral vectors are administered parenterally; for example, m 3 doses, 4 weeks apart. It is preferable to avoid adding a chemical adjuvant to a composition containing a viral vector of the invention and thereby minimizing the immune response to the viral vector itself . Non-toxicogenic Vibrio cholerae mutant strains that are useful as a live oral vaccine are known. Mekalanos et al . , Nature (1983) 306:551 and U.S. Patent No. 4,882,278 describe strains which have a substantial amount of the coding sequence of each of the two ctxA alleles deleted so that no functional cholerae toxin is produced. WO 92/11354 describes a strain m which the irgA locus is inactivated by mutation; this mutation can be combined m a single strain with ctxA mutations. WO 94/01533 describes a deletion mutant lacking functional ctxA and attRSl DNA sequences. These mutant strains are genetically engineered to express heterologous antigens, as described m WO 94/19482. An effective vaccine dose of a Vibrio cholerae strain capable of expressing a polypeptide or polypeptide derivative encoded by a DNA molecule of the invention contains about 1x10 s to about lxlO 9 , preferably about 1x10 s to about lxlO 8 , viable bacteria m a volume appropriate for the selected route of administration. Preferred routes of administration include all mucosal routes; most preferably, these vectors are administered mtranasally or orally. Attenuated Salmonella typhimurium strains, genetically engineered for recombinant expression of heterologous antigens or not, and their use as oral vaccines are described m Nakayama et al . (Bio/Technology (1988) 6:693) and WO 92/11361. Preferred routes of administration include all mucosal routes; most preferably, these vectors are administered mtranasally or orally. Other bacterial strains used as vaccine vectors m the context of the present invention are described for Shigella flexneπ m High et al . , EMBO (1992) 11:1991 and Sizemore et al . , Science (1995) 270:299; for Streptococcus gordonii m Medaglmi et al . , Proc. Natl. Acad. Sci. USA (1995) 92:6868; and for Bacille Calmette Guerm Flynn J.L., Cell. Mol. Biol. (1994) 40 (suppl. I) :31, WO 88/06626, WO 90/00594, WO 91/13157, WO 92/01796, and WO 92/21376. In bacterial vectors, the polynucleotide of the invention is inserted mto the bacterial genome or remains m a free state as part of a plasmid. The composition comprising a vaccine bacterial vector of the present invention may further contain an adjuvant. A number of adjuvants are known to those skilled in the art. Preferred adjuvants are selected as provided below. Accordingly, a fourth aspect of the invention provides (I) a composition of matter comprising a polynucleotide of the invention, together with a diluent or carrier; (n) a pharmaceutical composition comprising a therapeutically or prophylactically effective amount of a polynucleotide of the invention; (m) a method for inducing an immune response against Chlamydia m a mammal by administration of an immunogenically effective amount of a polynucleotide of the invention to elicit a protective immune response to Chlamydia ; and particularly, (iv) a method for preventing and/or treating a Chlamydia ( e . g. , C. trachomatis, C. psi ttaci , C. pneumoniae, or C. pecorum) infection, by administering a prophylactic or therapeutic amount of a polynucleotide of the invention to an infected individual. Additionally, the fourth aspect of the mvention encompasses the use of a polynucleotide of the invention m the preparation of a medicament for preventing and/or treating Chlamydia infection. A preferred use includes the use of a DNA molecule placed under conditions for expression m a mammalian cell, especially m a plasmid that is unable to replicate mammalian cells and to substantially integrate m a mammalian genome. Use of the polynucleotides of the invention include their administration to a mammal as a vaccine, for therapeutic or prophylactic purposes. Such polynucleotides are used the form of DNA as part of a plasmid that is unable to replicate a mammalian cell and unable to integrate mto the mammalian genome. Typically, such a DNA molecule is placed under the control of a promoter suitable for expression m a mammalian cell. The promoter functions either ubiquitously or tissue- specifically . Examples of non-tissue specific promoters include the early Cytomegalovirus (CMV) promoter (described U.S. Patent No. 4,168,062) and the Rous Sarcoma Virus promoter (described m Norton & Coffin, Molec. Cell Biol. (1985) 5:281). An example of a tissue-specific promoter is the desmm promoter which drives expression m muscle cells (Li et al . , Gene (1989) 78:243, Li & Paulm, J. Biol. Chem. (1991) 266:6562 and Li & Paulm, J. Biol. Chem. (1993) 268:10403). Use of promoters is well-known to those skilled m the art. Useful vectors are described m numerous publications, specifically WO 94/21797 and Hartikka et al . , Human Gene Therapy (1996) 7:1205. Polynucleotides of the invention which are used as vaccines encode either a precursor or a mature form of the corresponding polypeptide. In the precursor form, the signal peptide is either homologous or heterologous. In the latter case, a eucaryotic leader sequence such as the leader sequence of the tissue-type plasminogen factor (tPA) is preferred. As used herein, a composition of the invention contains one or several polynucleotides with optionally at least one additional polynucleotide encoding another Chlamydia antigen such as urease subunit A, B, or both, or a fragment, derivative, mutant, or analog thereof. The composition may also contain an additional polynucleotide encoding a cytokine, such as mterleukm-2 (IL-2) or mterleukm-12 (IL-12) so that the immune response is enhanced. These additional polynucleotides are placed under appropriate control for expression. Advantageously, DNA molecules of the invention and/or additional DNA molecules to be included m the same composition, are present m the same plasmid. Standard techniques of molecular biology for preparing and purifying polynucleotides are used m the preparation of polynucleotide therapeutics of the invention. For use as a vaccine, a polynucleotide of the invention is formulated according to various methods outlined below. One method utililizes the polynucleotide a naked form, free of any delivery vehicles. Such a polynucleotide is simply diluted m a physiologically acceptable solution such as sterile saline or sterile buffered saline, with or without a carrier. When present, the carrier preferably is isotonic, hypotonic, or weakly hypertonic, and has a relatively low ionic strength, such as provided by a sucrose solution, e . g. , a solution containing 20% sucrose. An alternative method utilizes the polynucleotide m association with agents that assist m cellular uptake. Examples of such agents are (I) chemicals that modify cellular permeability, such as bupivacaine (see, e . g. , WO 94/16737), (ii) liposomes for encapsulation of the polynucleotide, or (m) cationic lipids or silica, gold, or tungsten microparticles which associate themselves with the polynucleotides . Anionic and neutral liposomes are well-known the art (see, e . g. , Liposomes: A Practical Approach, RPC New Ed, IRL press (1990), for a detailed description of methods for making liposomes) and are useful for delivering a large range of products, including polynucleotides. Cationic lipids are also known in the art and are commonly used for gene delivery. Such lipids mclude Lipofectin™ also known as DOTMA (N- [1- (2 , 3 -dioleyloxy) propyl] - N,N,N-trimethylammonium chloride), DOTAP (1 , 2 -bis (oleyloxy) -3 - (trimethylammonio) propane) , DDAB (dimethyldioctadecylammonium bromide) , DOGS (dioctadecylamidologlycyl spermine) and cholesterol derivatives such as DC-Choi (3 beta- (N- (N' ,N ' - dimethyl aminomethane) -carbamoyl) cholesterol) . A description of these cationic lipids can be found in EP 187,702, WO 90/11092, U.S. Patent No. 5,283,185, WO 91/15501, WO 95/26356, and U.S. Patent No. 5,527,928. Cationic lipids for gene delivery are preferably used m association with a neutral lipid such as DOPE (dioleyl phosphatidylethanolamine) , as described in WO 90/11092 as an example. Formulation containing cationic liposomes may optionally contain other transfection-facilitating compounds. A number of them are described in WO 93/18759, WO 93/19768, WO 94/25608, and WO 95/02397. They include spermine derivatives useful for facilitating the transport of DNA through the nuclear membrane (see, for example, WO 93/18759) and membrane- permeabilizing compounds such as GALA, Gramicidine S, and cationic bile salts (see, for example, WO 93/19768) . Gold or tungsten microparticles are used for gene delivery, as described in WO 91/00359, WO 93/17706, and Tang et al . Nature (1992) 356:152. The microparticle-coated polynucleotide is injected via intradermal or mtraepidermal routes using a needleless injection device ("gene gun"), such as those described in U.S. Patent No. 4,945,050, U.S. Patent No. 5,015,580, and WO 94/24263. The amount of DNA to be used in a vaccine recipient depends, e . g . , on the strength of the promoter used the DNA construct, the immunogenicity of the expressed gene product, the condition of the mammal intended for administration ( e . g. , the weight, age, and general health of the mammal) , the mode of administration, and the type of formulation. In general, a therapeutically or prophylactically effective dose from about 1 μg to about 1 mg, preferably, from about 10 μg to about 800 μg and, more preferably, from about 25 μg to about 250 μg, can be administered to human adults. The administration can be achieved m a single dose or repeated at intervals. The route of administration is any conventional route used m the vaccine field. As general guidance, a polynucleotide of the invention is administered via a mucosal surface, e . g. , an ocular, intranasal, pulmonary, oral, intestinal, rectal, vaginal, and urinary tract surface; or via a parenteral route, e . g. , by an intravenous, subcutaneous, intraperitoneal, intradermal, mtraepidermal , or intramuscular route. The choice of administration route depends on the formulation that is selected. A polynucleotide formulated m association with bupivacaine is advantageously administered mto muscles. When a neutral or anionic liposome or a cationic lipid, such as DOTMA or DC-Choi, is used, the formulation can be advantageously injected via intravenous, intranasal (aerosolization) , intramuscular, intradermal, and subcutaneous routes. A polynucleotide m a naked form can advantageously be administered via the intramuscular, intradermal, or subcutaneous routes . Although not absolutely required, such a composition can also contain an adjuvant. If so, a systemic adjuvant that does not require concomitant administration m order to exhibit an adjuvant effect is preferable such as, e.g., QS21, which is described U.S. Patent No. 5,057,546. The sequence information provided m the present application enables the design of specific nucleotide probes and primers that are used for diagnostic purposes. Accordingly, a fifth aspect of the invention provides a nucleotide probe or primer having a sequence found m or derived by degeneracy of the genetic code from a sequence shown m SEQ ID No: 1, 3 or 5 The term "probe" as used m the present application refers to DNA (preferably single stranded) or RNA molecules (or modifications or combinations thereof) that hybridize under the stringent conditions, as defined above, to nucleic acid molecules having SEQ ID No : 1, 3 or 5 or to sequences homologous to SEQ ID No : 1 , 3 or 5 , or to its complementary or anti-sense sequence. Generally, probes are significantly shorter than full-length sequences. Such probes contain from about 5 to about 100, preferably from about 10 to about 80, nucleotides. In particular, probes have sequences that are at least 75%, preferably at least 85%, more preferably 95% homologous to a portion of SEQ ID No : 1 , 3 or 5 or that are complementary to such sequences. Probes may contain modified bases such as mosme, methyl-5 -deoxycytidme, deoxyuπdme, dιmethylammo-5-deoxyuπdme, or dιammo-2, 6-punne. Sugar or phosphate residues may also be modified or substituted. For example, a deoxyπbose residue may be replaced by a polyamide (Nielsen et al . , Science (1991) 254:1497) and phosphate residues may be replaced by ester groups such as diphosphate, alkyl, arylphosphonate and phosphorothioate esters. In addition, the 2 ' -hydroxyl group on ribonucleotides may be modified by including such groups as alkyl groups. Probes of the invention are used m diagnostic tests, as capture or detection probes. Such capture probes are conventionally immobilized on a solid support, directly or indirectly, by covalent means or by passive adsorption. A detection probe is labeled by a detection marker selected from: radioactive isotopes, enzymes such as peroxidase, alkaline phosphatase, and enzymes able to hydrolyze a chromogenic, fluorogenic, or luminescent substrate, compounds that are chromogenic, fluorogenic, or luminescent, nucleotide base analogs, and biotm. Probes of the invention are used m any conventional hybridization technique, such as dot blot (Maniatis et al . , Molecular Cloning: A Laboratory Manual (1982) Cold Spring Harbor Laboratory Press, Cold Spring Harbor, New York), Southern blot (Southern, J. Mol. Biol. (1975) 98:503), northern blot (identical to Southern blot with the exception that RNA is used as a target) , or the sandwich technique (Dunn et al . , Cell (1977) 12:23) . The latter technique involves the use of a specific capture probe and/or a specific detection probe with nucleotide sequences that at least partially differ from each other. A primer is a probe of usually about 10 to about 40 nucleotides that is used to initiate enzymatic polymerization of DNA m an amplification process ( e . g. , PCR), an elongation process, or a reverse transcription method. Primers used m diagnostic methods involving PCR are labeled by methods known m the art . As described herein, the invention also encompasses d) a reagent comprising a probe of the invention for detecting and/or identifying the presence of Chlamydia m a biological material; (ii) a method for detecting and/or identifying the presence of Chlamydia m a biological material, m which (a) a sample is recovered or derived from the biological material, (b) DNA or RNA is extracted from the material and denatured, and (c) exposed to a probe of the invention, for example, a capture, detection probe or both, under stringent hybridization conditions, such that hybridization is detected; and (m) a method for detecting and/or identifying the presence of Chlamydia m a biological material, m which (a) a sample is recovered or derived from the biological material, (b) DNA is extracted therefrom, (c) the extracted DNA is primed with at least one, and preferably two, primers of the invention and amplified by polymerase chain reaction, and (d"> the amplified DNA fragment is produced. It is apparent that disclosure of polynucleotide sequences of SEQ ID No: 1, 3 or 5, its homologs and partial sequences enable their corresponding ammo acid sequences. Accordingly, a sixth aspect of the invention features a substantially purified polypeptide or polypeptide derivative having an ammo acid sequence encoded by a polynucleotide of the invention. A "substantially purified polypeptide" as used herein is defined as a polypeptide that is separated from the environment m which it naturally occurs and/or that is free of the majority of the polypeptides that are present m the environment which it was synthesized. For example, a substantially purified polypeptide is free from cytoplasmic polypeptides. Those skilled m the art would readily understand that the polypeptides of the invention may be purified from a natural source, i.e., a Chlamydia strain, or produced by recombinant means . Consistent with the sixth aspect of the invention are polypeptides, homologs or fragments which are modified or treated to enhance their immunogenicity m the target animal, m whom the polypeptide, homolog or fragments are intended to confer protection against Chlamydia. Such modifications or treatments include: ammo acid substitutions with an ammo acid derivative such as 3 -meth-yhistidme, 4-hydroxyprolme, 5- hydroxylysme etc., modifications or deletions which are carried out after preparation of the polypeptide, homolog or fragment, such as the modification of free ammo, carboxyl or hydroxyl side groups of the ammo acids . Identification of homologous polypeptides or polypeptide derivatives encoded by polynucleotides of the invention which have specific antigenicity is achieved by screening for cross-reactivity with an antiserum raised against the polypeptide of reference having an ammo acid sequence of SEQ ID No : 1, 3 or 5. The procedure is as follows: a monospecific hyperimmune antiserum is raised against a purified reference polypeptide, a fusion polypeptide (for example, an expression product of MBP, GST, or His-tag systems, the description and instructions for use of which are contained m Invitrogen product manuals for pcDNA3. l/Myc-His (+) A, B, and C and for the Xpress Tm System Protein Purification) , or a synthetic peptide predicted to be antigenic. Where an antiserum is raised against a fusion polypeptide, two different fusion systems are employed. Specific antigenicity can be determined according to a number of methods, including Western blot (Towbin et al . , Proc. Natl. Acad. Sci. USA (1979) 76:4350), dot blot, and ELISA, as described below. In a Western blot assay, the product to be screened, either as a purified preparation or a total E. coli extract, is submitted to SDS-Page electrophoresis as described by Laemmli (Nature (1970) 227:680). After transfer to a nitrocellulose membrane, the material is further incubated with the monospecific hyperimmune antiserum diluted m the range of dilutions from about 1:5 to about 1:5000, preferably from about 1:100 to about 1:500. Specific antigenicity is shown once a band corresponding to the product exhibits reactivity at any of the dilutions m the above range. In an ELISA assay, the product to be screened is preferably used as the coating antigen. A purified preparation is preferred, although a whole cell extract can also be used. Briefly, about 100 μl of a preparation at about 10 μg protem/ml are distributed mto wells of a 96-well polycarbonate ELISA plate. The plate is incubated for 2 hours at 37°C then overnight at 4°C. The plate is washed with phosphate buffer saline (PBS) containing 0.05% Tween 20 (PBS/Tween buffer) . The wells are saturated with 250 μl PBS containing 1% bovine serum albumin (BSA) to prevent nonspecific antibody binding. After 1 hour incubation at 37°C, the plate is washed with PBS/Tween Duffer. The antiserum is serially diluted m PBS/Tween buffer containing 0.5% BSA. 100 μl of dilutions are added per well . The plate is incubated for 90 minutes at 37°C, washed and evaluated according to standard procedures. For example, a goat anti-rabbit peroxidase conjugate is added to the wells when specific antibodies were raised m rabbits. Incubation is carried out for 90 minutes at 37°C and the plate is washed. The reaction is developed with the appropriate substrate and the reaction is measured by colorimetry (absorbance measured spectrophotometπcally) . Under the above experimental conditions, a positive reaction is shown by O.D. values greater than a non immune control serum. In a dot blot assay, a purified product is preferred, although a whole cell extract can also be used. Briefly, a solution of the product at about 100 μg/ml is serially two-fold diluted in 50 mM Tris-HCl (pH 7.5). 100 μl of each dilution are applied to a nitrocellulose membrane 0.45 μm set m a 96- well dot blot apparatus (Biorad) . The buffer is removed by applying vacuum to the system. Wells are washed by addition of 50 mM Tris-HCl (pH 7.5) and the membrane is air-dried. The membrane is saturated m blocking buffer (50 mM Tris-HCl (pH 7.5) 0.15 M NaCl, 10 g/L skim milk) and incubated with an antiserum dilution from about 1:50 to about 1:5000, preferably about 1:500. The reaction is revealed accordmg to standard procedures. For example, a goat anti-rabbit peroxidase conjugate is added to the wells when rabbit antibodies are used. Incubation is carried out 90 minutes at 37°C and tne blot is washed. The reaction is developed with the appropriate substrate and stopped. The reaction is measured visually by the appearance of a colored spot, e . g. , by colorimetry. Under the above experimental conditions, a positive reaction is shown once a colored spot is associated with a dilution of at least about 1:5, preferably of at least about 1:500. Therapeutic or prophylactic efficacy of a polypeptide or derivative of the invention can be evaluated as described below. A seventh aspect of the invention provides (I) a composition of matter comprising a polypeptide of the invention together with a diluent or carrier; specifically (ii) a pharmaceutical composition containing a therapeutically or prophylactically effective amount of a polypeptide of the invention; (in) a method for inducing an immune response against Chlamydia m a mammal, by administering to the mammal an immunogenically effective amount of a polypeptide of the invention to elicit a protective immune response to Chlamydia ; and particularly, (iv) a method for preventing and/or treating a Chlamydia ( e . g. , C. trachomatis . C. psi ttaci , C. pneumoniae . or C. pecorum) infection, by administering a prophylactic or therapeutic amount of a polypeptide of the invention to an infected individual. Additionally, the seventh aspect of the invention encompasses the use of a polypeptide of the invention in the preparation of a medicament for preventing and/or treating Chlamydia infection. As used herein, the immunogenic compositions of the invention are administered by conventional routes known the vaccine field, m particular to a mucosal ( e . g. , ocular, intranasal, pulmonary, oral, gastric, intestinal, rectal, vaginal, or urinary tract) surface or via the parenteral (e.g., subcutaneous, intradermal, intramuscular, intravenous, or intraperitoneal) route. The choice of administration route depends upon a number of parameters, such as the adjuvant associated with the polypeptide. If a mucosal adjuvant is used, the intranasal or oral route is preferred. If a lipid formulation or an aluminum compound is used, the parenteral route is preferred with the sub-cutaneous or intramuscular route being most preferred. The choice also depends upon the nature of the vaccine agent. For example, a polypeptide of the invention fused to CTB or LTB is best administered to a mucosal surface . As used herein, the composition of the invention contains one or several polypeptides or derivatives of the invention. The composition optionally contams at least one additional Chlamydia antigen, or a subunit, fragment, homolog, mutant, or derivative thereof. For use m a composition of the invention, a polypeptide or derivative thereof is formulated mto or with liposomes, preferably neutral or anionic liposomes, microspheres, ISCOMS, or virus-like-particles (VLPs) to facilitate delivery and/or enhance the immune response. These compounds are readily available to one skilled m the art; for example, see Liposomes: A Practical Approach, RCP New Ed, IRL press (1990) . Adjuvants other than liposomes and the like are also used and are known m the art. Adjuvants may protect the antigen from rapid dispersal by sequestering it m a local deposit, or they may contain substances that stimulate the host to secrete factors that are chemotactic for macrophages and other components of the immune system. An appropriate selection can conventionally be made by those skilled m the art, for example, from those described below (under the eleventh aspect of the invention) . Treatment is achieved m a single dose or repeated as necessary at intervals, as can be determined readily by one skilled the art. For example, a priming dose is followed by three booster doses at weekly or monthly intervals . An appropriate dose depends on various parameters including the recipient ( e . g. , adult or infant), the particular vaccine antigen, the route and frequency of administration, the presence/absence or type of adjuvant, and the desired effect ( e . g. , protection and/or treatment) , as can be determined by one skilled m the art. In general, a vaccine antigen of the invention is administered by a mucosal route m an amount from about 10 μg to about 500 mg, preferably from about 1 mg to about 200 mg. For the parenteral route of administration, the dose usually does not exceed about 1 mg, preferably about 100 μg. When used as vaccine agents, polynucleotides and polypeptides of the invention may be used sequentially as part of a multistep immunization process. For example, a mammal is initially primed with a vaccine vector of the invention such as a pox virus, e . g. , via the parenteral route, and then boosted twice with the polypeptide encoded by the vaccine vector, e . g. , via the mucosal route. In another example, liposomes associated with a polypeptide or derivative of the invention is also used for priming, with boosting being carried out mucosally using a soluble polypeptide or derivative of the invention m combination with a mucosal adjuvant ( e . g. , LT) . A polypeptide derivative of the invention is also used m accordance with the seventh aspect as a diagnostic reagent for detecting the presence of anti - Chlamydia antibodies, e . g. , m a blood sample. Such polypeptides are about 5 to about 80, preferably about 10 to about 50 ammo acids m length. They are either labeled or unlabeled, depending upon the diagnostic method. Diagnostic methods involving such a reagent are described below. Upon expression of a DNA molecule of the mvention, a polypeptide or polypeptide derivative is produced and purified using known laboratory techniques. As described above, the polypeptide or polypeptide derivative may be produced as a fusion protein containing a fused tail that facilitates purification. The fusion product is used to immunize a small mammal, e . g. , a mouse or a rabbit, m order to raise antibodies against the polypeptide or polypeptide derivative (monospecific antibodies) . Accordingly, an eighth aspect of the invention provides a monospecific antibody that binds to a polypeptide or polypeptide derivative of the invention. By "monospecific antibody" is meant an antibody that is capable of reacting with a unique naturally-occurring Chlamydia polypeptide. An antibody of the invention is either polyclonal or monoclonal . Monospecific antibodies may be recombinant, e . g. , chimeric ( e . g. , constituted by a variable region of murine origin associated with a human constant region) , humanized (a human immunoglobulin constant backbone together with hypervaπable region of animal, e . g. , murine, origin), and/or single cham. Both polyclonal and monospecific antibodies may also be the form of immunoglobulin fragments, e . g. , F(ab) '2 or Fab fragments. The antibodies of the invention are of any isotype, e . g. , IgG or IgA, and polyclonal antibodies are of a single isotype or a mixture of lsotypes. Antibodies against the polypeptides, homologs or fragments of the present invention are generated by immunization of a mammal with a composition comprising said polypeptide, homolog or fragment. Such antibodies may be polyclonal or monoclonal . Methods to produce polyclonal or monoclonal antibodies are well known m the art. For a review, see "Antibodies, A Laboratory Manual, Cold Spring Harbor Laboratory, Eds. E. Harlow and D. Lane (1988), and D.E. Yelton et al . , 1981. Ann. Rev. Biochem. 50:657-680. For monoclonal antibodies, see Kohler & Milstem (1975) Nature 256:495-497. The antibodies of the invention, which are raised to a polypeptide or polypeptide derivative of the invention, are produced and identified using standard immunological assays, e . g. , Western blot analysis, dot blot assay, or ELISA (see, e . g. , Coligan et al . , Current Protocols m Immunology (1994" 1 John Wiley & Sons, Inc., New York, NY) . The antibodies are used m diagnostic methods to detect the presence of a Chlamydia antigen m a sample, such as a biological sample. The antibodies are also used m affinity chromatography for purifying a polypeptide or polypeptide derivative of the invention. As is discussed further below, such antibodies may be used m prophylactic and therapeutic passive immunization methods . Accordingly, a ninth aspect of the invention provides (l) a reagent for detecting the presence of Chlamydia m a biological sample that contains an antibody, polypeptide, or polypeptide derivative of the invention; and (ii) a diagnostic method for detecting the presence of Chlamydia m a biological sample, by contacting the biological sample with an antibody, a polypeptide, or a polypeptide derivative of the invention, such that an immune complex is formed, and by detecting such complex to indicate the presence of Chlamydia m the sample or the organism from which the sample is derived. Those skilled m the art will readily understand that the immune complex is formed between a component of the sample and the antibody, polypeptide, or polypeptide derivative, whichever is used, and that any unbound material is removed prior to detecting the complex. It is understood that a polypeptide reagent is useful for detecting the presence of ant - Chlamydia antibodies m a sample, e . g. , a blood sample, while an antibody of the invention is used for screening a sample, such as a gastric extract or biopsy, for the presence of Chlamydia polypeptides. For diagnostic applications, the reagent ( i . e . , the antibody, polypeptide, or polypeptide derivative of the invention) is either m a free state or immobilized on a solid support, such as a tube, a bead, or any other conventional support used m the field. Immobilization is achieved using direct or indirect means. Direct means include passive adsorption (non-covalent binding) or covalent binding between the support and the reagent. By "indirect means" is meant that an anti -reagent compound that interacts with a reagent is first attached to the solid support. For example, if a polypeptide reagent is used, an antibody that binds to it can serve as an anti-reagent, provided that it binds to an epitope that is not involved m the recognition of antibodies biological samples. Indirect means may also employ a ligand-receptor system, for example, where a molecule such as a vitamm is grafted onto the polypeptide reagent and the corresponding receptor immobilized on the solid phase. This is illustrated by the biotm-streptavid system. Alternatively, a peptide tail is added chemically or by genetic engineering to the reagent and the grafted or fused product immobilized by passive adsorption or covalent linkage of the peptide tail. Such diagnostic agents may be included m a kit which also comprises instructions for use. The reagent is labeled with a detection means which allows for the detection of the reagent when it is bound to its target. The detection means may be a fluorescent agent such as fluorescem isocyanate or fluorescem isothiocyanate, or an enzyme such as horse radish peroxidase or luciferase or alkaline phosphatase, or a radioactive element such as 125 I or 51 Cr. Accordingly, a tenth aspect of the invention provides a process for purifying, from a biological sample, a polypeptide or polypeptide derivative of the invention, which involves carrying out antibody-based affinity chromatography with the biological sample, wherem the antibody is a monospecific antibody of the invention. For use m a purification process of the invention, the antibody is either polyclonal or monospecific, and preferably is of the IgG type. Purified IgGs is prepared from an antiserum using standard methods (see, e . g. , Coligan et al . , Current Protocols m Immunology (1994) John Wiley & Sons, Inc., New York, NY.) . Conventional chromatography supports, as well as standard methods for grafting antibodies, are described , e.g., Antibodies: A Laboratory Manual, D. Lane, E. Harlow, Eds (1988) and outlined below. Briefly, a biological sample, such as an C. pneumoniae extract preferably in a buffer solution, is applied to a chromatography material, preferably equilibrated with the buffer used to dilute the biological sample so that the polypeptide or polypeptide derivative of the invention ( .e., the antigen) is allowed to adsorb onto the material. The chromatography material, such as a gel or a resm coupled to an antibody of the invention, is m either a batch form or a column. The unbound components are washed off and the antigen is then eluted with an appropriate elution buffer, such as a glycine buffer or a buffer containing a chaotropic agent, e . g. , guamdme HCl, or high salt concentration ( e . g. , 3 M MgCl 2 ) . Eluted fractions are recovered and the presence of the antigen is detected, e . g. , by measuring the absorbance at 280 nm. An eleventh aspect of the invention provides (I) a composition of matter comprising a monospecific antibody of the mvention, together with a diluent or carrier; (ii) a pharmaceutical composition comprising a therapeutically or prophylactically effective amount of a monospecific antibody of the invention, and (m) a method for treating or preventing a Chlamydia ( e . g. , C. trachomatis, C. psi ttaci , C. pneumoniae or C. pecorum) infection, by administering a therapeutic or prophylactic amount of a monospecific antibody of the invention to an infected individual . Additionally, the eleventh aspect of the invention encompasses the use of a monospecific antibody of the mvention the preparation of a medicament for treating or preventing Chlamydia infection. The monospecific antibody is either polyclonal or monoclonal, preferably of the IgA isotype (predominantly) In passive immunization, the antibody is administered to a mucosal surface of a mammal, e . g. , the gastric mucosa, e . g. , orally or mtragastπcally, advantageously, m the presence of a bicarbonate buffer. Alternatively, systemic administration, not requiring a bicarbonate buffer, is carried out. A monospecific antibody of the invention is administered as a single active component or as a mixture with at least one monospecific antibody specific for a different Chlamydia polypeptide. The amount of antibody and the particular regimen used are readily determined by one skilled m the art. For example, daily administration of about 100 to 1,000 mg of antibodies over one week, or three doses per day of about 100 to 1,000 mg of antibodies over two or three days, are effective regimens for most purposes . Therapeutic or prophylactic efficacy are evaluated usmg standard methods m the art, e . g. , by measuring induction of a mucosal immune response or induction of protective and/or therapeutic immunity, using, e . g. , the C. pneumoniae mouse model. Those skilled m the art will readily recognize that the C. pneumoniae strain of the model may be replaced with another Chlamydia strain. For example, the efficacy of DNA molecules and polypeptides from C. pneumoniae is preferably evaluated m a mouse model using C. pneumoniae strain. Protection is determined by comparing the degree of Chlamydia infection to that of a control group. Protection is shown when infection is reduced by comparison to the control group. Such an evaluation is made for polynucleotides, vaccine vectors, polypeptides and derivatives thereof, as well as antibodies of the invention. Adjuvants useful m any of the vaccine compositions described above are as follows. Adjuvants for parenteral administration include aluminum compounds , such as aluminum hydroxide , aluminum phosphate, and aluminum hydroxy phosphate. The antigen is precipitated with, or adsorbed onto, the aluminum compound according to standard protocols. Other adjuvants, such as RIBI (ImmunoChem, Hamilton, MT) , are used m parenteral administration . Adjuvants for mucosal administration include bacterial toxins, e . g. , the cholera toxin (CT) , the E. coli heat-labile toxin (LT) , the Clostridium difficile toxin A and the pertussis toxin (PT) , or combinations, subunits, toxoids, or mutants thereof such as a purified preparation of native cholera toxin subunit B (CTB) . Fragments, homologs, derivatives, and fusions to any of these toxins are also suitable, provided that they retain adjuvant activity. Preferably, a mutant having reduced toxicity is used. Suitable mutants are described, e . g. , m WO 95/17211 (Arg-7-Lys CT mutant) , WO 96/06627 (Arg-192-Gly LT mutant) , and WO 95/34323 (Arg-9-Lys and Glu-129-Gly PT mutant) . Additional LT mutants that are used m the methods and compositions of the invention include, e . g. , Ser-63-Lys, Ala-69Gly, Glu-110-Asp, and Glu-112- Asp mutants. Other adjuvants, such as a bacterial monophosphoryl lipid A (MPLA) of, e . g. , E. coli , Salmonella minnesota, Salmonella typhimurium, or Shigella flexneri ; saponins, or polylactide glycolide (PLGA) microspheres, is also be used m mucosal administration. Adjuvants useful for both mucosal and parenteral administrations include polyphosphazene (WO 95/02415) , DC-chol (3 b- (N- (N' ,N' -dimethyl aminomethane) -carbamoyl) cholesterol; U.S. Patent No. 5,283,185 and WO 96/14831) and QS-21 (WO 88/09336) . Any pharmaceutical composition of the invention containing a polynucleotide, a polypeptide, a polypeptide derivative, or an antibody of the invention, is manufactured m a conventional manner. In particular, it is formulated with a pharmaceutically acceptable diluent or carrier, e . g. , water or a saline solution such as phosphate buffer saline. In general, a diluent or carrier is selected on the basis of the mode and route of administration, and standard pharmaceutical practice. Suitable pharmaceutical carriers or diluents, as well as pharmaceutical necessities for their use m pharmaceutical formulations, are described m Remington ' s Pharmaceuti cal Sciences , a standard reference text m this field and m the USP/NF. The invention also includes methods m which Chlamydia infection are treated by oral administration of a Chlamydia polypeptide of the invention and a mucosal adjuvant, m combination with an antibiotic, an antacid, sucralfate, or a combination thereof. Examples of such compounds that can be administered with the vaccine antigen and the adjuvant are antibiotics, including, e . g. , macrolides, tetracyclmes , and derivatives thereof (specific examples of antibiotics that can be used include azithromycm or doxicyclm or immunomodulators such as cytokines or steroids) . In addition, compounds containing more than one of the above-listed components coupled together, are used. The invention also includes compositions for carrying out these methods, i.e., compositions containing a Chlamydia antigen (or antigens) of the invention, an adjuvant, and one or more of the above-listed compounds, m a pharmaceutically acceptable carrier or diluent. It has recently been shown that the 9kDa cysteine rich membrane protein contains a sequence cross-reactive with the murine alpha-myosm heavy chain epitope M7A-alpha, an epitope conserved m humans (Bachmaier et al . , Science (1999) 283:1335). This cross-reactivity is proposed to contribute to the development of cardiovascular disease, so it may be beneficial to remove this epitope, and any other epitopes cross-reactive with human antigens, from the protein if it is to be used as a vaccine. Accordingly, a further embodiment of the present invention includes the modification of the coding sequence, for example, by deletion or substitution of the nucleotides encoding the epitope from polynucleotides encoding the protein, as to improve the efficacy and safety of the protein as a vaccine. A similar approach may be appropriate for any protective antigen found to have unwanted homologies or cross-reactivities with human antigens. Amounts of the above-listed compounds used m the methods and compositions of the invention are readily determined by one skilled m the art. Treatment/immunization schedules are also known and readily designed by one skilled m » the art. For example, the non-vaccine components can be administered on days 1-14, and the vaccine antigen + adjuvant can be administered on days 7, 14, 21, and 28. EXAMPLES The above disclosure generally describes the present invention. A more complete understanding can be obtained by reference to the following specific examples. These examples are described solely for purposes of illustration and are not intended to limit the scope of the invention. Changes m form and substitution of equivalents are contemplated as circumstances may suggest or render expedient . Although specific terms have been employed herein, such terms are intended in a descriptive sense and not for purposes of limitation. Example 1 : This example illustrates the preparation of a plasmid vector pCACPNM555a containing the full length 76kDa protein gene . The full-length 76kDa protein gene was amplified from Chlamydia pneumoniae genomic DNA by polymerase chain reaction (PCR) using a 5' primer (5' ATAAGAATGCGGCCGCCACCATGGTTAATCCTATTGGTCCAGG 3') (SEQ ID No: 9) and a 3' primer (5' GCGCCGGATCCCTTGGAGATAACCAGAATATAGAG 3') (SEQ ID No: 10) . The 5' primer contains a Not I restriction site, a ribosome binding site, an initiation codon and a sequence close to the 5' end of the full-length 76kDa protein coding sequence. The 3' primer includes the sequence encoding the C-terminal sequence of the 76kDa protein and a Bam HI restriction site. The stop codon was excluded and an additional nucleotide was inserted to obtain an m- frame fusion with the Histidme tag. After amplification, the PCR fragment was purified using QIAquick™ PCR purification kit (Qiagen) and then digested with Not I and Bam HI and cloned mto the pCA-Myc-His eukaryotic expression vector describe m Example 2 (Fig. 4) with transcription under control of the human CMV promoter. Example 2 : This example illustrates the preparation of the eukaryotic expression vector pCA/Myc-His. Plasmid pcDNA3.1 ( - ) Myc-His C (Invitrogen) was restricted with Spe I and Bam HI to remove the CMV promoter and the remaining vector fragment was isolated. The CMV promoter and intron A from plasmid VR-1012 (Vical) was isolated on a Spe I / Bam HI fragment. The fragments were ligated together to produce plasmid pCA/Myc-His. The Not I/Bam HI restricted PCR fragment containing the full-length 76kDa protein gene was ligated into the Not I and Bam HI restricted plasmid pCA/Myc- His to produce plasmid pCACPNM555a (Fig 4) . The resulting plasmid, pCACPNM555a, was transferred by electroporation mto E. coli XL-1 blue (Stratagene) which was grown m LB broth containing 50 μg/ml of carbenicillin. The plasmid was isolated by Endo Free Plasmid Giga Kit™ (Qiagen) large scale DNA purification system. DNA concentration was determined by absorbance at 260 nm and the plasmid was verified after gel electrophoresis and Ethidium bromide staining and comparison to molecular weight standards. The 5' and 3' ends of the gene were verified by sequencing using a LiCor model 4000 L DNA sequencer and IRD-800 labelled primers. Example 3 : This example illustrates the immunization of mice to achieve protection against an intranasal challenge of C. pneumoniae . It has been previously demonstrated (Yang et. al . , 1993) that mice are susceptible to intranasal infection with different isolates of C. pneumoniae . Strain AR-39 (Grayston, 1989) was used m Balb/c mice as a challenge infection model to examine the capacity of Chlamydia gene products delivered as naked DNA to elicit a protective response against a sublethal C. pneumoniae lung infection. Protective immunity is defined as an accelerated clearance of pulmonary infection. Groups of 7 to 9 week old male Balb/c mice (7 to 10 per group) were immunized intramuscularly (ι.τn.) plus mtranasally (l.n.) with plasmid DNA containing the coding sequence of C. pneumoniae full-length 76kDa protein as described in Examples 1 and 2. Saline or the plasmid vector lacking an inserted Chlamydial gene was given to groups of control animals. For l.m. immunization alternate left and right quadriceps were injected with lOOμg of DNA m 50μl of PBS on three occasions at 0 , 3 and 6 weeks. For l.n. immunization, anaesthetized mice aspirated 50μl of PBS containing 50 μg DNA on three occasions at 0 , 3 and 6 weeks. At week 8, immunized mice were inoculated l.n. with 5 x 10 5 IFU of C. pneumoniae, strain AR39 m lOOμl of SPG buffer to test their ability to limit the growth of a sublethal C. pneumoniae challenge. Lungs were taken from mice at days 5 and 9 post- challenge and immediately homogenised m SPG buffer (7.5% sucrose, 5mM glutamate, 12.5mM phosphate pH7.5) . The homogenate was stored frozen at -70°C until assay. Dilutions of the homogenate were assayed for the presence of infectious Chlamydia by inoculation onto monolayers of susceptible cells. The inoculum was centrifuged onto the cells at 3000rpm for 1 hour, then the cells were incubated for three days at 35°C m the presence of lμg/ml cycloheximide . After incubation the monolayers were fixed with formalin and methanol then lmmunoperoxidase stained for the presence of Chlamydial inclusions usmg convalescent sera from rabbits infected with C. pneumoniae and metal -enhanced DAB as a peroxidase substrate. Figure 7 and Table 1 show that mice immunized l.n. and i.m. with pCACPNM555a had Chlamydial lung titers less than 30,000 IFU/lung (mean 23,550) m 5 of 6 cases at day 9 whereas the range of values for control mice sham immunized with salme were 20,800 to 323,300 IFU/lung (mean 206,375) for (Table 1). DNA immunisation per se was not responsible for the observed protective effect since two other plasmid DNA constructs, pCACPNM806 and pCACPNM760, failed to protect, with lung titers in immunised mice similar to those obtained for saline- lmmunized control mice. The constructs pCACPNM806 and pCACPNM760 are identical to pCACPNM555a except that the nucleotide sequence encoding the full-length 76kDa protein is replaced with C. pneumoniae nucleotide sequences encoding an unrelated sequence. Table 1 Example 4 : This example illustrates the preparation of a plasmid vector pCAI555 containing a 5' -truncated 76kDa protein gene. The 5' truncated 76kDa protein gene was amplified from Chlamydia pneumoniae genomic DNA by polymerase chain reaction (PCR) using a 5' primer (5' ATAAGAATGCGGCCGCCACCATGAGTCTGGCAGATAAGCTGGG 3') (SEQ ID No: 11 ) and a 3' primer (5' GCGCCGGATCCCTTGGAGATAACCAGAATATA 3') (SEQ ID No: 12) . The 5' primer contains a Not I restriction site, a ribosome binding site, an initiation codon and a sequence at the second Met codon of the 76kDa protein coding sequence. The 3' primer includes the sequence encoding the C-terminal sequence of the 3' 76kDa protein and a Bam HI restriction site. The stop codon was excluded and an additional nucleotide was inserted to obtain an in-frame fusion with the Histidine tag. RECTIFIED SHEET (RULE 91 ) After amplification, the PCR fragment was purified using QIAquick™ PCR purification kit (Qiagen) and then digested with Not I and Bam HI and cloned mto the pCA-Myc-His eukaryotic expression vector describe m Example 5 (Fig. 5) with transcription under control of the human CMV promoter. Example 5 : This example illustrates the preparation of the eukaryotic expression vector pCA/Myc-His. Plasmid pcDNA3.1 ( - ) Myc-His C (Invitrogen) was restricted with Spe I and Bam HI to remove the CMV promoter and the remaining vector fragment was isolated. The CMV promoter and mtron A from plasmid VR-1012 (Vical) was isolated on a Spe I / Bam HI fragment. The fragments were ligated together to produce plasmid pCA/Myc-His. The Not I/Bam HI restricted PCR fragment containing the 5' truncated 76kDa protein gene was ligated mto the Not I and Bam HI restricted plasmid pCA/Myc- His to produce plasmid pCAI555 (Fig 5) . The resulting plasmid, pCAI555, was transferred by electroporation mto E . coli XL-1 blue (Stratagene) which was grown m LB broth containing 50 μg/ml of carbenicillin. The plasmid was isolated by Endo Free Plasmid G ga Kit™ (Qiagen) large scale DNA purification system. DNA concentration was determined by absorbance at 260 nm and the plasmid was verified after gel electrophoresis and Ethidium bromide staining and comparison to molecular weight standards. The 5' and 3' ends of the gene were verified by sequencing using a LiCor model 4000 L DNA sequencer and IRD-800 labelled primers. Example 6 : This Example illustrates the immunization of mice to achieve protection against an intranasal challenge of C. pneumoniae . The procedures are described Example 3 above, except that the DNA plasmid used for immunization contains the coding sequence of C. pneumoniae 5' -truncated 76kDa protein, as described m Examples 4 and 5. Figure 8 and Table 2 show that mice immunized l.n. and i.m. with pCAI555 had Chlamydial lung titers less than 13000 IFU/lung (mean 6050) m 6 of 6 cases at day 9 whereas the range of values for control mice sham immunized with sal e were 106,100 IFU/lung (mean 39,625) for (Table 2). DNA immunisation per se was not responsible for the observed protective effect since two other plasmid DNA constructs, pCAI116 and pCAI178, failed to protect, with lung titers m immunised mice similar to those obtained for salme-immunized control mice. The constructs pCAI116 and pCAI178 are identical to pCAI555 except that the nucleotide sequence encoding the 5'- truncated 76kDa protein is replaced with a C .pneumoniae nucleotide sequence encoding an unprotective sequence and the nucleoside 5 ' -diphosphate phosphotransferase protein. Table 2 Example 7 This example illustrates the preparation of a plasmid vector pCAD76kDa containing a 3 '-truncated 76kDa protein gene. The 3 '-truncated 76kDa protein gene was amplified from Chlamydia pneumoniae genomic DNA by polymerase chain reaction (PCR) using a 5' primer (5' GCTCTAGACCGCCATGACAAAAAAACATTATGCTTGGG 3') (SEQ ID No: 13) and a 3' primer (5' CGGGATCCATAGAACTTGCTGCAGCGGG 3') (SEQ ID No: 14). The 5' primer contains a Xba I restriction site, a ribosome binding site, an initiation codon and a sequence 765bp upstream of the 5' end of the 76kDa protein coding sequence. The 3' primer includes a 21bp the sequence downstream of codon 452 of the 76kDa protein and a Bam HI restriction site. An additional nucleotide was inserted to obtain an in-frame fusion with the Histidine tag. Note that inclusion of the 765bp 5' region and the 21bp 3' regions were inadvertent. These sequences are not part of the 76kDa protein gene. Nevertheless, immunoprotection was achieved using this sequence (Example 6) . After amplification, the PCR fragment was purified using QIAquick™ PCR purification kit (Qiagen) and then digested with Xba I and Bam HI and cloned into the pCA-Myc-His eukaryotic expression vector describe in Example 8 (Fig. 6) with transcription under control of the human CMV promoter. Example 8 : This Example illustrates the preparation of the eukaryotic expression vector pCA/Myc-His. Plasmid pcDNA3.1 (-) Myc-His C (Invitrogen) was restricted with Spe I and Bam HI to remove the CMV promoter and the remaining vector fragment was isolated. The CMV promoter and intron A from plasmid VR-1012 (Vical) was isolated on a Spe I / Bam HI fragment. The fragments were ligated together to produce plasmid pCA/Myc-His . The Xba I/Bam HI restricted PCR fragment containing a 3 '-truncated 76kDa protein gene was ligated into the Xba I and Bam HI restricted plasmid pCA/Myc- His to produce plasmid pCAD76kDa (Fig. 6) . The resulting plasmid, pCAD76kDa, was transferred by electroporation into E. coli XL-1 blue (Stratagene) which was RECTIFIED SHEET (RULE 91 ) ISA/EP grown m LB broth containing 50 μg/ml of carbenicillin. The plasmid was isolated by Endo Free Plasmid Giga Kit™ (Qiagen) large scale DNA purification system. DNA concentration was determined by absorbance at 260 nm and the plasmid was verified after gel electrophoresis and Ethidium bromide staining and comparison to molecular weight standards. The 5' and 3' ends of the gene were verified by sequencing using a LiCor model 4000 L DNA sequencer and IRD-800 labelled primers. Example 9 : This example illustrates the immunization of mice to achieve protection against an intranasal challenge of C. pneumoniae . The procedures are as described m Example 3 above, except that the DNA plasmid used for immunization contains the coding sequence of C. pneumoniae 3 '-truncated 76kDa protein, as described Examples 7 and 8. Figure 9 and Table 3 show that mice immunized l.n. and i.m. with pC7AD76kDa had Chlamydial lung titers less than 2400 m 5 of 5 cases whereas the range of values for control mice were 1800-23100 IFU/lung (mean 11811) and 16600-26100 IFU/lung (mean 22100) for sham immunized with salme or immunized with the unmodified vector respectively (Table 2) . The lack of protection with the unmodified vector confirms that DNA per se was not responsible for the observed protective effect. This is further supported by the results obtained for one additional plasmid DNA construct, pdagA, that failed to protect, and for which the mean lung titers were similar to those obtamed for salme-immunized control mice. The construct pdagA is identical to pCAD76kDa except that the nucleotide sequence encoding the 3 '-truncated 76kDa protein is replaced with a C .pneumoniae nucleotide sequence encoding the protein dagA. Table 3

Claims: CLAIMS : 1. A nucleic acid molecule comprising a nucleic acid sequence which encodes a polypeptide selected from any of: (a) SEQ ID No: 2 (b) SEQ ID No. 4 (c) SEQ ID No. 6, (d) an immunogenic fragment comprising at least 12 consecutive ammo acids from a polypeptide of (a) ; and (e) a polypeptide of any one of (a) to (d) which has been modified to improve its immunogenicity, wherem said modified polypeptide is at least 75% identical m ammo acid sequence to the corresponding polypeptide of any one of (a) to (d) . 2. A nucleic acid molecule comprising a nucleic acid sequence selected from any of: (a) SEQ ID No (b) SEQ ID No (c) SEQ ID No (d) a sequence which encodes a polypeptide encoded by any one of SEQ ID Nos : 1 , 3 and 5 ; (e) a sequence comprising at least 38 consecutive nucleotides from any one of the nucleic acid sequences of (a) to (d) ; and (f) a sequence which encodes a polypeptide which is at least 75% identical m ammo acid sequence to the polypeptides encoded by any one of SEQ ID Nos: 1, 3 and 5. 3. A nucleic acid molecule comprising a nucleic acid sequence which is anti-sense to the nucleic acid molecule of claim 1. 4. A nucleic acid molecule comprising a nucleic acid sequence which encodes a fusion protein, said fusion protein comprising a polypeptide encoded by a nucleic acid molecule according to claim 1 and an additional polypeptide. 5. The nucleic acid molecule of claim 4 wherem the additional polypeptide is a heterologous signal peptide. 6. The nucleic acid molecule of claim 4 wherem the additional polypeptide has adjuvant activity. 7. A nucleic acid molecule according to any one of claims 1 to 6 , operatively linked to one or more expression control sequences. 8. A vaccine comprising at least one first nucleic acid according to any one of claims 1, 2, and 4 to 7 and a vaccine vector wherem each first nucleic acid is expressed as a polypeptide, the vaccine optionally comprising a second nucleic acid encoding an additional polypeptide which enhances the immune response to the polypeptide expressed by said first nucleic acid. 9. The vaccine of claim 8 wherem the second nucleic acid encodes an additional Chlamydia polypeptide. 10. A pharmaceutical composition comprising a nucleic acid according to any one of claims 1 to 7 and a pharmaceutically acceptable carrier. 11. A pharmaceutical composition comprising a vaccine according to claim 8 or 9 and a pharmaceutically acceptable carrier . 12. A unicellular host transformed with the nucleic acid molecule of claim 7. 13. A nucleic acid probe of 5 to 100 nucleotides which hybridizes under stringent conditions to the nucleic acid molecule of SEQ ID No : 1, or to a homolog or complementary or anti-sense sequence of said nucleic acid molecule. 14. A primer of 10 to 40 nucleotides which hybridizes under stringent conditions to the nucleic acid molecules of SEQ ID No : 1, or to a homolog or complementary or anti-sense sequence of said nucleic acid molecule. 15. A polypeptide encoded by a nucleic acid sequence accordmg to any one of claims 1, 2 and 4 to 7. 16. A polypeptide comprising an ammo acid sequence selected from any of : (a) SEQ ID No (b) SEQ ID No (c) SEQ ID No (d) an immunogenic fragment comprising at least 12 consecutive ammo acids from a polypeptide of (a) ; and (e) a polypeptide of any one of (a) to (d) which has been modified to improve its immunogenicity, wherem said modified polypeptide is at least 75% identical m ammo acid sequence to the corresponding polypeptide of any one of (a) to (d) . 17. A fusion polypeptide comprising a polypeptide of claim 15 or 16 and an additional polypeptide. 18. The fusion polypeptide of claim 17 wherem the additional polypeptide is a heterologous signal peptide. 19. The fusion protein of claim 17 where the additional polypeptide has adjuvant activity. 20. A method for producing a polypeptide of claim 15 or 16, comprising the step of culturing a unicellular host according to claim 12. 21. An antibody against the polypeptide of any one of claims 15 to 19. 22. A vaccine comprising at least one first polypeptide according to any one of claims 15 to 19 and a pharmaceutically acceptable carrier, optionally comprising a second polypeptide which enhances the immune response to the first polypeptide. 23. The vaccine of claim 22 wherem the second polypeptide comprises an additional Chlamydia polypeptide. 24. A pharmaceutical composition comprising a polypeptide according to any one of claims 15 to 19 and a pharmaceutically acceptable carrier. 25. A pharmaceutical composition comprising a vaccine according to claim 22 or 23 and a pharmaceutically acceptable carrier . 26. A pharmaceutical composition comprising an antibody according to claim 21 and a pharmaceutically acceptable carrier . 27. A method for preventing or treating Chlamydia infection using: (a) the nucleic acid of any one of claims 1 to 7 ; (b) the vaccine of any one of claims 8, 9, 22 and 23; (c) the pharmaceutical composition of any one of claims 10, 11, 24 to 26; (d) the polypeptide of any one of claims 15 to 19; or (e) the antibody of claim 21. 28. A method of detecting Chlamydia infection comprising the step of assaying a body fluid of a mammal to be tested, with a component selected from any one of : (a) the nucleic acid of any one of claims 1 to 7; (b) the polypeptide of any one of claims 15 to 19; and (c) the antibody of claim 21. 29. A diagnostic kit comprising instructions for use and a component selected from any one of : (a) the nucleic acid of any one of claims 1 to 7 ; (b) the polypeptide of any one of claims 15 to 19; and (c) the antibody of claim 21. 30. A method for identifying a polypeptide of claims 15 to 19 which induces an immune response effective to prevent or lessen the severity of Chlamydia infection m a mammal previously immunized with polypeptide, comprising the steps of (a) immunizing a mouse with the polypeptide; and (b) inoculating the immunized mouse with Chlamydia ; wherem the polypeptide which prevents or lessens the severity of Chlamydia infection m the immunized mouse compared to a non-immunized control mouse is identified. 31. An expression plasmid selected from the group consisting of pCACPNM555a, pCAI555 and pCAD76kDa. 32. A nucleic acid molecule selected from the group consisting of SEQ ID Nos : 1, 3, 5 and 7. 33. A polypeptide selected from the group consisting of SEQ ID Nos : 2 , 4 , 6 and 8. 34. An isolated 76kDa protein from Chlamydia . 35. An isolated 76kDa protein from Chlamydia pneumoniae

Inventors: DUNN PAMELA, MURDIN ANDREW D, OOMEN RAYMOND P, WANG JOE, DUNN, PAMELA, MURDIN, ANDREW, D., OOMEN, RAYMOND, P., WANG, JOE
Applicants: AVENTIS PASTEUR, DUNN PAMELA, MURDIN ANDREW D, OOMEN RAYMOND P, WANG JOE, AVENTIS PASTEUR LIMITED, DUNN, PAMELA, MURDIN, ANDREW, D., OOMEN, RAYMOND, P., WANG, JOE
Application year: 2000
Main classification: C12N15
IPC codes: A61K39, A61K48, A61P9, A61P11, A61P31, C07K14, C07K16, C07K19, C12N1, C12N5, C12N15, C12P21, C12Q1, G01N33