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PubMed1994

Lipopolysaccharide smooth-rough phase variation in bacteria of the genus Chlamydia.

In two strains of Chlamydia psittaci and in Chlamydia trachomatis serotype L1, we have detected a so-far-unknown antigen which (i) is resistant to heat and proteolytic digestion, (ii) can be extracted with phenol-water into the water phase, (iii) gives a ladder-like banding pattern in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, (iv) is immunogenic in rabbits and mice, and (v) contains immunoreactivity of lipid A, a common and characteristic component of gram-negative lipopolysaccharides (LPS). Thus, chlamydiae contain, in addition to the known rough-type LPS, another LPS type which is phenotypically smooth (S-LPS). S-LPS was observed preferentially in chlamydiae grown in the yolk sac of embryonated eggs; it was, however, also detected by immunofluorescence in tissue culture-grown chlamydiae with a monoclonal antibody against S-LPS.

Animals↗

PubMed1998

Phospholipid composition of purified Chlamydia trachomatis mimics that of the eucaryotic host cell.

Chlamydia trachomatis is an obligate intracellular eubacterial parasite capable of infecting a wide range of eucaryotic host cells. Purified chlamydiae contain several lipids typically found in eucaryotes, and it has been established that eucaryotic lipids are transported from the host cell to the parasite. In this report, we examine the phospholipid composition of C. trachomatis purified from host cells grown under a variety of conditions in which the cellular phospholipid composition was altered. A mutant CHO cell line, with a thermolabile CDP-choline synthetase, was used to show that decreased host cell phosphatidylcholine levels had no significant effect on C. trachomatis growth. However, less phosphatidylcholine was transported to the parasite and purified elementary bodies contained decreased levels of phosphatidylcholine. Brefeldin A, fumonisin B1, and exogenous sphingomyelinase were used to alter levels of host cell sphingomyelin. None of the agents had a significant effect on C. trachomatis replication. Treatment with fumonisin B1 and exogenous sphingomyelinase resulted in decreased levels of host cell sphingomyelin. This had no effect on glycerophospholipid trafficking to chlamydiae; however, sphingomyelin trafficking was reduced and elementary bodies purified from treated cells had reduced sphingomyelin content. Exposure to brefeldin A, which had no adverse effect on chlamydia growth, resulted in an increase in cellular levels of sphingomyelin and a concomitant increase in the amount of sphingomyelin in purified chlamydiae. Under the experimental conditions used, brefeldin A treatment had only a small effect on sphingomyelin trafficking to the host cell surface or to C. trachomatis. Thus, the final phospholipid composition of purified C. trachomatis mimics that of the host cell in which it is grown.

Animals↗

PubMed2000

Identification of an antigen localized to an apparent septum within dividing chlamydiae.

The process of chlamydial cell division has not been thoroughly investigated. The lack of detectable peptidoglycan and the absence of an FtsZ homolog within chlamydiae suggest an unusual mechanism for the division process. Our laboratory has identified an antigen (SEP antigen) localized to a ring-like structure at the apparent septum within dividing chlamydial reticulate bodies (RB). Antisera directed against SEP show similar patterns of antigen distribution in Chlamydia trachomatis and Chlamydia psittaci RB. In contrast to localization in RB, SEP in elementary bodies appears diffuse and irregular, suggesting that the distribution of the antigen is developmental-stage specific. Treatment of chlamydiae with inhibitors of peptidoglycan synthesis or culture of chlamydiae in medium lacking tryptophan leads to the formation of nondividing, aberrant RB. Staining of aberrant RB with anti-SEP reveals a marked redistribution of the antigen. Within C. trachomatis-infected cells, ampicillin treatment leads to high levels of SEP accumulation at the periphery of aberrant RB, while in C. psittaci, treatment causes SEP to localize to distinct punctate sites within the bacteria. Aberrancy produced via tryptophan depletion results in a different pattern of SEP distribution. In either case, the reversal of aberrant formation results in the production of normal RB and a redistribution of SEP to the apparent plane of bacterial division. Collectively these studies identify a unique chlamydial-genus-common and developmental-stage-specific antigen that may be associated with RB division.

Animals↗

PubMed2005

Production of a proteolytically active protein, chlamydial protease/proteasome-like activity factor, by five different Chlamydia species.

We have previously identified a chlamydial protein, chlamydial protease/proteasome-like activity factor (CPAF), for degrading host transcription factors in cells infected with the human chlamydial species Chlamydia trachomatis or Chlamydia pneumoniae. We now report that functional CPAF was also produced during infection with the species Chlamydia muridarum, Chlamydia psittaci, and Chlamydia caviae, which primarily infect nonhuman hosts.

Animals↗

PubMed1991

Sequence analysis and lipid modification of the cysteine-rich envelope proteins of Chlamydia psittaci 6BC.

The envelopes of elementary bodies of Chlamydia spp. consist largely of disulfide-cross-linked major outer membrane protein (MOMP) and two cysteine-rich proteins (CRPs). The MOMP gene of Chlamydia psittaci 6BC has been sequenced previously, and the genes encoding the small and large CRPs from this strain were cloned and sequenced in this study. The CRP genes were found to be tandemly arranged on the chlamydial chromosome but could be independently expressed in Escherichia coli. The deduced 87-amino-acid sequence of the small-CRP gene (envA) contains 15 cysteine residues, a potential signal peptide, and a potential signal peptidase II-lipid modification site. Hydropathy plot and conformation analysis of the small-CRP amino acid sequence indicated that the protein was unlikely to be associated with a membrane. However, the small CRP was specifically labeled in host cells incubated with [3H]palmitic acid and may therefore be associated with a membrane through a covalently attached lipid portion of the molecule. The deduced 557-amino-acid sequence of the large-CRP gene (envB) contains 37 cysteine residues and a single putative signal peptidase I cleavage site. In one recombinant clone the large CRP appeared to be posttranslationally cleaved at two sites, forming a doublet in a manner similar to the large-CRP doublet made in native C. psittaci 6BC. Comparison of the deduced amino acid sequences of the CRPs from chlamydial strains indicated that the small CRP is moderately conserved, with 54% identity between C. psittaci 6BC and Chlamydia trachomatis, and the large CRP is highly conserved, with 71% identity between C. psittaci and C. trachomatis and 85% identity between C. psittaci 6BC and Chlamydia pneumoniae. The positions of the cysteine residues in both CRPs are highly conserved in Chlamydia spp. From the number of cysteine residues in the MOMP and the CRPs and the relative incorporation of [35S]cysteine into these proteins, it was calculated that the molar ratio of C. psittaci 6BC elementary body envelope proteins is about one large-CRP molecule to two small-CRP molecules to five MOMP molecules.

Amino Acid Sequence↗

PubMed1994

Enhancement of in vitro transcription by addition of cloned, overexpressed major sigma factor of Chlamydia psittaci 6BC.

Obligate parasitic bacteria of the genus Chlamydia possess a developmental cycle that takes place entirely within eucaryotic host cells. Because standard methods of genetic analysis are not available for chlamydiae, an in vitro transcription system has been developed to elucidate the mechanisms by which chlamydiae regulate gene expression. The in vitro system is specific for chlamydial promoters but is inefficient, presumably because the RNA polymerase is not saturated with sigma factor. Therefore, we prepared recombinant Chlamydia psittaci 6BC major sigma factor to enhance transcription in the in vitro system. The gene encoding the major sigma factor (sigA) was identified by using an rpoD box oligonucleotide and was subsequently cloned and sequenced. It was found to encode a potential 571-amino-acid protein (sigma 66) that is greater than 90% identical to the previously identified major sigma factors from the L2 and MoPn strains of Chlamydia trachomatis. sigA was recloned into a T7 RNA polymerase expression system to produce large quantities of sigma 66 in Escherichia coli. Overexpressed sigma 66 was identified by immunoblot by using monoclonal antibodies 2G10 (reactive) and 2F8 (nonreactive) generated against E. coli sigma 70. After purification by polyacrylamide gel electrophoresis, the recombinant protein was found to stimulate, by 10-fold or more, promoter-specific in vitro transcription by C. psittaci 6BC and C. trachomatis L2 RNA polymerases. Transcription was dependent on added chlamydial sigma 66, rather than on potentially contaminating E. coli sigma 70 or other fortuitous activators, since the monoclonal antibody 2G10, and not 2F8, inhibited transcription initiation. Recombinant omega(66) had no effect on transcription by E. coli core polymerase. The addition of recombinant omega(66) to the in vitro system should be useful for distinguishing omega(66)-dependent transcription of developmentally regulated chlamydial genes from omega(66)-independent transcription.

Amino Acid Sequence↗

PubMed2003

In vitro and in vivo functional activity of Chlamydia MurA, a UDP-N-acetylglucosamine enolpyruvyl transferase involved in peptidoglycan synthesis and fosfomycin resistance.

Organisms of Chlamydia spp. are obligate intracellular, gram-negative bacteria with a dimorphic developmental cycle that takes place entirely within a membrane-bound vacuole termed an inclusion. The chlamydial anomaly refers to the fact that cell wall-active antibiotics inhibit Chlamydia growth and peptidoglycan (PG) synthesis genes are present in the genome, yet there is no biochemical evidence for synthesis of PG. In this work, we undertook a genetics-based approach to reevaluate the chlamydial anomaly by characterizing MurA, a UDP-N-acetylglucosamine enolpyruvyl transferase that catalyzes the first committed step of PG synthesis. The murA gene from Chlamydia trachomatis serovar L2 was cloned and placed under the control of the arabinose-inducible, glucose-repressible ara promoter and transformed into Escherichia coli. After transduction of a lethal DeltamurA mutation into the strain, viability of the E. coli strain became dependent upon expression of the C. trachomatis murA. DNA sequence analysis of murA from C. trachomatis predicted a cysteine-to-aspartate change in a key residue within the active site of MurA. In E. coli, the same mutation has previously been shown to cause resistance to fosfomycin, a potent antibiotic that specifically targets MurA. In vitro activity of the chlamydial MurA was resistant to high levels of fosfomycin. Growth of C. trachomatis was also resistant to fosfomycin. Moreover, fosfomycin resistance was imparted to the E. coli strain expressing the chlamydial murA. Conversion of C. trachomatis elementary bodies to reticulate bodies and cell division are correlated with expression of murA mRNA. mRNA from murB, the second enzymatic reaction in the PG pathway, was also detected during C. trachomatis infection. Our findings, as well as work from other groups, suggest that a functional PG pathway exists in Chlamydia spp. We propose that chlamydial PG is essential for progression through the developmental cycle as well as for cell division. Elucidating the existence of PG in Chlamydia spp. is of significance for the development of novel antibiotics targeting the chlamydial cell wall.

Alkyl and Aryl Transferases↗

PubMed2005

Analysis of putative Chlamydia trachomatis chaperones Scc2 and Scc3 and their use in the identification of type III secretion substrates.

The obligate intracellular pathogen Chlamydia trachomatis expresses a type III secretion system (T3SS) which has the potential to contribute significantly to pathogenesis. Based on a demonstrated role of type III secretion (T3S)-specific chaperones in the secretion of antihost proteins by gram-negative pathogens, we initiated a study of selected putative Chlamydia T3S chaperones in an effort to gain mechanistic insight into the Chlamydia T3SS and to potentially identify Chlamydia-specific secreted products. C. trachomatis Scc2 and Scc3 are homologous to SycD of Yersinia spp. Functional studies of the heterologous Yersinia T3SS indicated that although neither Scc2 nor Scc3 was able to fully complement a sycD null mutant, both have SycD-like characteristics. Both were able to associate with the translocator protein YopD, and Scc3 expression restored limited secretion of YopD in in vitro studies of T3S. CopB (CT578) and CopB2 (CT861) are encoded adjacent to scc2 and scc3, respectively, and have structural similarities with the YopB family of T3S translocators. Either Scc2 or Scc3 coprecipitates with CopB from C. trachomatis extracts. Expression of CopB or CopB2 in Yersinia resulted in their type III-dependent secretion, and localization studies with C. trachomatis-infected cells indicated that both were secreted by Chlamydia.

Bacterial Proteins↗

PubMed2006

Arginine-dependent gene regulation via the ArgR repressor is species specific in chlamydia.

Some, but not all, Chlamydia spp. are predicted to encode a homolog of ArgR, a master regulatory molecule that modulates arginine biosynthesis and catabolism in bacteria in response to intracellular arginine levels. While genes for arginine biosynthesis are apparently missing in Chlamydia, a putative arginine transport system encoded by glnP, glnQ, and artJ is present. We found that recombinant Chlamydia pneumoniae ArgR functions as an arginine-dependent aporepressor that bound specifically to operator sequences upstream of the glnPQ operon. ArgR was able to repress transcription in a promoter-specific manner that was dependent on the concentration of the corepressor l-arginine. We were able to locate ArgR operators upstream of glnPQ in C. pneumoniae and Chlamydophila caviae but not Chlamydia trachomatis, which corresponded to the predicted presence or absence of ArgR in these chlamydial species. Our findings indicate that only some members of the family Chlamydiaceae have an arginine-responsive mechanism of gene regulation that is predicted to control arginine uptake from the host cell. This is the first study to directly demonstrate a species-specific mechanism of transcriptional regulation in Chlamydia.

Arginine↗

PubMed1991

Chlamydia pneumoniae elementary body antigenic reactivity with fluorescent antibody is destroyed by methanol.

Methanol, used for fixing chlamydia organisms to microscopic slides, was shown to eliminate the antigenic reactivity of Chlamydia pneumoniae elementary bodies with fluorescent antibodies. Acetone fixation had no adverse effect. Chlamydia trachomatis and Chlamydia psittaci were not affected by methanol fixation. The effect of methanol on C. pneumoniae is another characteristic that differentiates this species from the other two chlamydia species.

Antigens, Bacterial↗

PubMed1997

Phylogenetic analyses of Chlamydia psittaci strains from birds based on 16S rRNA gene sequence.

The nucleotide sequences of 16S ribosomal DNA (rDNA) were determined for 39 strains of Chlamydia psittaci (34 from birds and 5 from mammals) and for 4 Chlamydia pecorum strains. The sequences were compared phylogenetically with the gene sequences of nine Chlamydia strains (covering four species of the genus) retrieved from nucleotide databases. In the neighbor-joining tree, C. psittaci strains were more closely related to each other than to the other Chlamydia species, although a feline pneumonitis strain was distinct (983 to 98.6% similarity to other strains) and appeared to form the deepest subline within the species of C. psittaci (bootstrap value, 99%). The other strains of C. psittaci exhibiting similarity values of more than 99% were branched into several subgroups. Two pigeon strains and one turkey strain formed a distinct clade recovered in 97% of the bootstrapped trees. The other pigeon strains seemed to be distinct from the strains from psittacine birds, with 88% of bootstrap value. In the cluster of psittacine strains, three parakeet strains and an ovine abortion strain exhibited a specific association (level of sequence similarity, 99.9% or more; bootstrap value, 95%). These suggest that at least four groups of strains exist within the species C. psittaci. The 16S rDNA sequence is a valuable phylogenetic marker for the taxonomy of chlamydiae, and its analysis is a reliable tool for identification of the organisms.

Abortion, Veterinary↗

PubMed2002

Evaluation of dry and wet transported intravaginal swabs in detection of Chlamydia trachomatis and Neisseria gonorrhoeae infections in female soldiers by PCR.

Screening women for sexually transmitted diseases (STD) in nonclinic settings is highly desirable because many infections are asymptomatic. This is especially true for military women, for whom logistical, social, and other job-related obstacles present barriers to accessing medical care. We assessed the accuracy of intravaginal swabs transported by mail in a wet versus a dry state for PCR (Amplicor CT/NG test) detection of chlamydia and gonorrhea infections in a cross-sectional study of 793 active-duty military women attending an STD clinic. PCR tests of vaginal swabs (wet and dry) were compared to local clinical methods used on cervical swabs. Standard wet vaginal swab PCR testing detected more chlamydia (11.6%) than cervical enzyme immunoassay (9.3%). For detection of chlamydia using wet swabs, the sensitivity and specificity compared with adjudicated true positives were 94.6% (87 of 92) and 99.3% (696 of 701), respectively. Comparing dry swabs to true-positives for chlamydia, the sensitivity was 91.3% (84 of 92) and the specificity was 99.3% (696 of 701). Standard wet vaginal swab PCR detected more gonorrhea (3.3%) than routine cervical culture (2.1%). The sensitivity and specificity of PCR testing of wet swabs compared to true-positives (infected patients) were 96.3% (26 of 27) and 98.2% (752 of 766) for gonorrhea, respectively. For gonorrhea, the sensitivity and specificity of dry swabs compared to true-positives (infected patients) were 88.9% (24 of 27) and 98.3% (753 of 766), respectively. PCR testing of wet and dry transported intravaginal swabs to detect chlamydia and gonorrhea infections was an accurate diagnostic method for military women.

Adolescent↗

PubMed2004

Developing national outcome standards for the management of gonorrhoea and genital chlamydia in genitourinary medicine clinics.

BACKGROUND: Measuring clinical performance within a framework of clinical governance is increasingly important for monitoring improvements in patient care. Standards for quality indicators must, however, be achievable and evidence based. We describe an approach to the development of national standards for measuring outcomes of care for gonorrhoea and genital chlamydia in genitourinary medicine clinics. METHODS: Two standards for each infection, one reflecting quality of case management and one reflecting partner management were chosen by consensus. A systematic review of published and unpublished UK studies about gonorrhoea and chlamydia management was carried out and weighted averages calculated for each parameter, stratified by location. Genitourinary medicine practitioners around the country were also asked for their opinion about desirable values for each standard and the results compared. Variability in performance between centres was examined using Shewhart's control charts. RESULTS: We identified 17 reports about gonorrhoea outcomes and 14 about chlamydia. There was marked heterogeneity in results according to geographical location and different standards were set for clinics in and out of London. Opinions from practitioners suggested much higher standards than the values obtained from the systematic review. There was evidence for special cause variation related to management of gonorrhoea and chlamydia in London clinics. CONCLUSIONS: Standards set using expert opinion are unrealistic when compared to evidence of what is achievable. Evidence based methods should therefore be used to derive outcome standards for case management gonorrhoea and chlamydia. The control chart method identified clinics where investigation to find reasons for special cause variation in performance should be undertaken to change practice.

Ambulatory Care↗

PubMed2004

The chlamydia screening studies: rationale and design.

BACKGROUND: Screening has been recommended to reduce the prevalence and morbidity associated with genital chlamydia infection in the United Kingdom. METHODS: We describe the rationale and study design of the Chlamydia Screening Studies (ClaSS), a collaborative project designed to evaluate screening outside genitourinary medicine clinics. A non-selective, active screening approach in 16-39 year olds randomly sampled from 27 general practice lists in the Bristol and Birmingham areas formed the basis of interlinked studies: a case-control study was used to investigate factors to improve the targeting of screening; participants with chlamydia were invited to enroll in a randomised controlled trial to evaluate partner notification conducted in primary care; and laboratory based studies were used to assess the best specimens and tests. We also explored psychosocial effects of screening and partner notification and modelled the cost effectiveness of the programme. CONCLUSION: Results from four pilot practices show that mailing of specimens for chlamydia testing is feasible but that it is difficult to achieve high response rates with postal screening. The high prevalence of asymptomatic infection in men suggests that efforts to screen men for chlamydia should be strengthened.

Adolescent↗

PubMed2002

Geographic epidemiology of gonorrhoea and chlamydia on a large military installation: application of a GIS system.

OBJECTIVES: The geographic epidemiology of infectious diseases can help in identifying point source outbreaks, elucidating dispersion patterns, and giving direction to control strategies. We sought to establish a geographic information system (GIS) infectious disease surveillance system at a large US military post (Fort Bragg, North Carolina) using STDs as the initial outcome for the model. METHODS: Addresses of incident cases were plotted onto digitised base maps of Fort Bragg (for on-post addresses) and surrounding Cumberland County, NC (for off-post addresses) using MAPINFO Version 5. We defined 26 geographic sectors on the installation. Active duty soldiers attending the post preventive medicine clinic were enrolled between July 1998 and June 1999. RESULTS: Gonorrhoea (GC) was diagnosed in 210/2854 (7.4%) and chlamydia (CT) in 445/2860 (15.6%). African-American male soldiers were at higher risk for GC (OR = 4.6 (95% CL 3.0 to 7.2)) and chlamydia (OR = 2.0 (1.4 to 2.7)). For women, there were no ethnic differences in gonorrhoea prevalence, but chlamydia was higher in African-Americans (OR = 2.0 (1.4-2.7)). Rank and housing type were associated with gonorrhoea and chlamydia in men, but were not significant factors in women. For gonorrhoea, two geographic sectors had prevalences between 14.0%-16.5%, three between 10.3%-13.9%, three between 7.1%-10.2%, and five between 3.0%-7.1%. The geographic distribution demonstrated a core-like pattern where the highest sectors were contiguous and were sectors containing barracks housing lower enlisted grade personnel. In contrast, chlamydia prevalence was narrowly distributed. CONCLUSION: GIS based disease surveillance was easily and rapidly implemented in this setting and should be useful in developing preventive interventions.

Chlamydia Infections↗

PubMed2003

Sex differences in the experience of testing positive for genital chlamydia infection: a qualitative study with implications for public health and for a national screening programme.

OBJECTIVES: To explore men's and women's accounts of chlamydia testing, with a view to understanding sex differences in attitudes and in behaviours of public health importance. METHODS: Semistructured interviews with 24 heterosexual patients (12 men; 12 women) diagnosed with genital chlamydia infection, at a large sexual health clinic in central London were transcribed and analysed using qualitative thematic analysis. RESULTS: Participants' expressions revealed important sex differences. Women felt anxious about their future reproductive health, feared stigmatisation, and blamed themselves for contracting chlamydia; whereas men generally reported less concern, were unwilling to disclose their condition to sexual partners, and some men projected attributions of blame onto their partners. Delays in seeking care appeared to be related to perceptions of chlamydia as a relatively minor infection, particularly in men. CONCLUSIONS: Health promotion needs to reflect sex and age differences, emphasising the negative consequences of delayed clinic attendance and exposure to repeat infections. For health professionals to respond appropriately and effectively to increasing numbers of chlamydia infections, there is a need to understand men's avoidant attitudes and behaviours in relation to sexual and reproductive health.

Adolescent↗

PubMed2006

Co-infection with genital gonorrhoea and genital chlamydia in female sex workers in Yunnan, China.

An observational study on prevalence of co-infection with gonorrhoea and chlamydia was conducted among female sex workers (FSWs) in Kunming, China.A total of 505 FSWs participated in the study. All eligible participants gave informed consent. Demographic, behavioural and clinical information of the participants was gathered by direct structured interviews. Tampon swabs were collected to test for Chlamydia trachomatis and Nesseria gonorrhoeae. One-hundred and twenty-four (24.6%) FSWs were co-infected with these two pathogens. Of the 191 FSWs with gonorrhea, 124 (64.9%, 95% confidence interval [CI] = 57.9-71.3%) were co-infected with chlamydia which was significantly higher than the proportion (41.9%, 95% CI = 36.4-47.6%) co-infected with gonorrhoea among 296 FSWs with chlamydia (P < 0.001). Only 47 of 191 (24.6%) FSWs with gonococcal infection and 28 of 124 (22.6%) with co-infection with gonorrhoea and chlamydia reported vaginal discharge. The results of the study justify the recommendation in the national sexually transmitted disease (STD) guidelines that patients infected with gonorrhoea also be treated routinely with an anti-chlamydial regimen. However, a periodic mass treatment may be considered in some circumstances in STD control programmes to rapidly reduce the infections in this population.

Adolescent↗

PubMed2005

Delivery of Chlamydia vaccines.

The plethora of ocular, genital and respiratory diseases of Chlamydia, including nongonococcal urethritis, cervicitis pelvic inflammatory disease, ectopic pregnancy, tubal factor infertility, conjunctivitis, blinding trachoma and interstitial pneumonia, and chronic diseases that may include atherosclerosis, multiple sclerosis, adult onset asthma and Alzheimer's disease, still pose a considerable public health challenge to many nations. Although antibiotics are effective against Chlamydia when effectively diagnosed, asymptomatic infections are rampart, making clinical presentation of complications often the first evidence of an infection. Consequently, the current medical opinion is that an effective prophylactic vaccine would constitute the best approach to protect the human population from the most severe consequences of these infections. Clinical and experimental studies have demonstration that Chlamydia immunity in animals and humans is mediated by T cells and a complementary antibody response, and the completion of the genome sequencing of several isolates of Chlamydia is broadening our knowledge of the immunogenic antigens with potential vaccine value. Thus, major advances have been made in defining the essential elements of a potentially effective subunit vaccine design and parameters for evaluation. However, the challenge to develop effective delivery systems and human compatible adjuvants that would boost the immune response to achieve long-lasting protective immunity remains an elusive objective in chlamydial vaccine research. In response to evolving molecular and cellular technologies and novel vaccinology approaches, considerable progress is being made in the construction of novel delivery systems, such as DNA and plasmid expression systems, viral vectors, living and nonliving bacterial delivery systems, the use of chemical adjuvants, lipoprotein constructs and the codelivery of vaccines and specific immuno-modulatory biological agonists targeting receptors for chemokines, Toll-like receptors, and costimulatory molecules. The application of these novel delivery strategies to Chlamydia vaccine design could culminate in timely achievement of an efficacious vaccine.

Animals↗