Chlamydia Species Research Articles

Manipulation of the Host Cell Cytoskeleton by Chlamydia.

Chlamydiae are obligate intracellular pathogens. They undergo a biphasic developmental cycle differentiating between the infectious but metabolically quiescent elementary body and the vegetative, but non-infectious reticulate body. Chlamydia spends a significant portion of its development in the non-infectious stage, demanding an effective strategy of manipulating the host cells to ensure its intracellular survival and replication. A common target of all Chlamydia species studied so far is the host cell cytoskeleton, with past and recent findings revealing crucial roles in invasion, inclusion maintenance, nutrient acquisition, and egress. The molecular details of how Chlamydia co-opts the cytoskeleton is becoming clearer, with bacterial factors and their corresponding host cell targets identified.

Evidence for Chlamydia in Crohns Disease

Chlamydia causes enteritis in young pigs and calves, and granulomas within intestinal lymphatics. Recently we called attention to the lymphangitis and lymphatic obstruction that occurs in Crohn’s disease. We searched resected tissues from patients for evidence of chlamydia and sera for evidence of previous exposure to chlamydia. Immunohistochemistry and real-time PCR were employed to seek chlamydia in preserved tissues. In the IHC, antibody to C. trachomatis served as primary antibody; in the PCR, primers specific for Chlamydiaceae were employed. Commercial ELISA kits measured anti-chlamydia IgG and IgA against C. trachomatis antigen in sera derived from a population of patients different from that which yielded the tissue specimens. IHC revealed focal positive staining for chlamydia in tissues of 5 of 19 patients. Positive reacting cells occurred within dense inflammation, in sparsely scattered macrophages in the submucosa and subserosa. Tissues from 3 of 22 control subjects were positive. Real-time PCR done on ileal, colonic, and regional lymph node tissues revealed evidence of chlamydia in 3 of 33 patients. Serology for anti-chlamydia IgG revealed 2 positive values in 24 patients, while serology for anti-chlamydia IgA revealed 4 positives among the 24 patients, and 1 positive in the 15 controls. One patient and one control had both elevated IgG and IgA titers. The 4 patients with elevated IgA titers were from a single family of 6 with Crohn’s disease, which had been previously described. Additional consideration needs to be given to the chlamydia species, including those of animal origin, which leave behind little evidence of their previous involvement.

Enhanced Direct Major Histocompatibility Complex Class I Self-Antigen Presentation Induced by Chlamydia Infection.

The direct major histocompatibility complex (MHC) class I antigen presentation pathway ensures intracellular peptides are displayed at the cellular surface for recognition of infected or transformed cells by CD8(+) cytotoxic T lymphocytes. Chlamydia spp. are obligate intracellular bacteria and, as such, should be targeted by CD8(+) T cells. It is likely that Chlamydia spp. have evolved mechanisms to avoid the CD8(+) killer T cell responses by interfering with MHC class I antigen presentation. Using a model system of self-peptide presentation which allows for posttranslational control of the model protein's stability, we tested the ability of various Chlamydia species to alter direct MHC class I antigen presentation. Infection of the JY lymphoblastoid cell line limited the accumulation of a model host protein and increased presentation of the model-protein-derived peptides. Enhanced self-peptide presentation was detected only when presentation was restricted to defective ribosomal products, or DRiPs, and total MHC class I levels remained unaltered. Skewed antigen presentation was dependent on a bacterial synthesized component, as evidenced by reversal of the observed phenotype upon preventing bacterial transcription, translation, and the inhibition of bacterial lipooligosaccharide synthesis. These data suggest that Chlamydia spp. have evolved to alter the host antigen presentation machinery to favor presentation of defective and rapidly degraded forms of self-antigen, possibly as a mechanism to diminish the presentation of peptides derived from bacterial proteins.

Detection of atypical Chlamydiaceae in roe deer (Capreolus capreolus)

Investigations on fecal samples, vaginal swabs and sera from roe deer (Capreolus capreolus) in south-western France led to the detection of a non-classified Chlamydiaceae strain. A total of 85 vaginal swabs were sampled from roe deer that had been captured in 2012 (n=42) and 2013 (n=43). Using a Chlamydiaceae family-specific real-time PCR, only one vaginal swab out of the 42 samples done in 2012 tested positive and was subsequently identified as Chlamydia (C.) psittaci. In contrast, 6/43 vaginal swab samples were positive in 2013. Four of these positive samples came from a single group of roe deer, captured in the Fabas plain. Fecal samples from this group of 9 females were subsequently analyzed, with 6 of them testing positive with the Chlamydiaceae-specific PCR. All positive samples collected in 2013 were negative when re-tested with C. abortus-, C. pecorum- and C. suis-specific real-time PCR assays. Sera from this group of 9 females were analyzed with two immunoassays (recomLine and ELISA). Whereas intense positive reactions with C. pneumoniae antigens were observed for all sera when tested with the recomLine test, none was positive with the C. abortus specific ELISA test. Comparative sequence analysis of the 16S, 23S rRNA and ompA gene sequences from 3 animals, as well as the MLST analysis from 2 animals, showed that this roe deer group likely harbored the same bacterium related to members of the family Chlamydiaceae. Notably, the roe deer strain formed a separate entity different from the currently recognized chlamydial species, with C. trachomatis, C. suis and C. muridarum appearing as its closest relatives.

Genetic diversity in the plasticity zone and the presence of the chlamydial plasmid differentiates Chlamydia pecorum strains from pigs, sheep, cattle, and koalas.

BackgroundChlamydia pecorum is a globally recognised pathogen of livestock and koalas. To date, comparative genomics of C. pecorum strains from sheep, cattle and koalas has revealed that only single nucleotide polymorphisms (SNPs) and a limited number of pseudogenes appear to contribute to the genetic diversity of this pathogen. No chlamydial plasmid has been detected in these strains despite its ubiquitous presence in almost all other chlamydial species. Genomic analyses have not previously included C. pecorum from porcine hosts. We sequenced the genome of three C. pecorum isolates from pigs with differing pathologies in order to re-evaluate the genetic differences and to update the phylogenetic relationships between C. pecorum from each of the hosts.MethodsWhole genome sequences for the three porcine C. pecorum isolates (L1, L17 and L71) were acquired using C. pecorum-specific sequence capture probes with culture-independent methods, and assembled in CLC Genomics Workbench. The pairwise comparative genomic analyses of 16 pig, sheep, cattle and koala C. pecorum genomes were performed using several bioinformatics platforms, while the phylogenetic analyses of the core C. pecorum genomes were performed with predicted recombination regions removed. Following the detection of a C. pecorum plasmid, a newly developed C. pecorum-specific plasmid PCR screening assay was used to evaluate the plasmid distribution in 227 C. pecorum samples from pig, sheep, cattle and koala hosts.ResultsThree porcine C. pecorum genomes were sequenced using C. pecorum-specific sequence capture probes with culture-independent methods. Comparative genomics of the newly sequenced porcine C. pecorum genomes revealed an increased average number of SNP differences (~11 500) between porcine and sheep, cattle, and koala C. pecorum strains, compared to previous C. pecorum genome analyses. We also identified a third copy of the chlamydial cytotoxin gene, found only in porcine C. pecorum isolates. Phylogenetic analyses clustered porcine isolates into a distinct clade, highlighting the polyphyletic origin of C. pecorum in livestock.Most surprising, we also discovered a plasmid in the porcine C. pecorum genome. Using this novel C. pecorum plasmid (pCpec) sequence, a) we developed a pCpec screening assay to evaluate the plasmid distribution in C. pecorum from different hosts; and b) to characterise the pCpec sequences from available previously sequenced C. pecorum genome data. pCpec screening showed that the pCpec is common in all hosts of C. pecorum, however not all C. pecorum strains carry pCpec.ConclusionsThis study provides further insight into the complexity of C. pecorum epidemiology and novel genomic regions that may be linked to host specificity. C. pecorum plasmid characterisation may aid in improving our understanding of C. pecorum pathogenesis across the variety of host species this animal pathogen infects.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-2053-8) contains supplementary material, which is available to authorized users.

Prevalence of Chlamydia psittaci and Other Chlamydia Species in Wild Birds in Poland.

Avian chlamydiosis is a zoonotic disease occurring in humans, poultry, and exotic birds. It has been suggested that some wild bird species play an important role as reservoirs for Chlamydia, especially Chlamydia psittaci. Whereas C. psittaci is the predominant chlamydial agent in birds, in the present study we have determined the prevalence of different species of Chlamydia among selected wild bird species in Poland using a rapid and sensitive real-time PCR method. In total, 369 free-living birds from 35 bird species and 15 orders were examined. Samples from 27 birds (7.3%) were positive for chlamydial DNA in the PCR; 22 positive samples (81.5%) belonged to C. psittaci, three to Chlamydia trachomatis (11.1%), and two (7.4%) classified only to the genus Chlamydia. Most of C. psittaci-positive samples belonged to five orders: Anseriformes, Columbiformes, Gruiformes, Phasianiformes, and Passeriformes. All C. trachomatis samples were obtained from Eurasian coots (Gruiformes). Two Chlamydia-positive samples not classified to any Chlamydia species were obtained from a common wood pigeon (Columbiformes) and a common buzzard (Accipitriformes). Detection of C. psittaci and C. trachomatis in free-living bird populations force to think on significance of birds as reservoir of varied Chlamydia species and their epidemiological importance.

How common are chlamydia-related bacteria in early pregnancy and are they associated with miscarriage or preterm birth? Community-based prospective cohort study

BackgroundSerological case-control studies suggest that certain chlamydia-related bacteria (Chlamydiales) that cause cows to miscarry might do the same in human beings. Included in the order Chlamydiales are Waddlia chondrophila, Chlamydophila abortus, and Chlamydia trachomatis. We aimed to investigate the prevalence of Chlamydiales in pregnant women, and possible associations with miscarriage or preterm birth. MethodsWe tested stored urine samples from a carefully characterised cohort of 847 pregnant women recruited at mean 49·3 (SD 10·1) days’ gestation from 37 general practices in London, UK. Previous repeat testing of samples positive for Mycoplasma genitalium confirmed bacterial DNA integrity after storage. W chondrophila and pan-Chlamydiales specific real-time PCRs targeting the 16s rRNA gene were used to test samples. Samples positive on either of the two PCRs were subjected to DNA sequencing and Chlamydia trachomatis PCR. Outcomes were compared between infected and uninfected women with Fisher's exact test. Ethics review was conducted by Wandsworth, Croydon, and Riverside Research Ethics Committees. FindingsThe overall prevalence of Chlamydiales was 4·3% (36/847, 95% CI 3·0–5·8). Prevalence of W chondrophila was 0·6% (5/847, 0·2–1·4), Chlamydia trachomatis 1·7% (14/847, 0·9–2·8), and other Chlamydiales species 2·0% (17/847, 1·2–3·2). Infection with Chlamydia trachomatis (but not with other Chlamydiales or W chondrophila) was more common in women younger than 25 years, of black ethnicity, or with bacterial vaginosis. Follow-up was 99·9% (846/847) at 16 weeks’ gestation and 89·6% (759/847) at term. No infection was significantly associated with miscarriage (prevalence 10%, 84/827) or spontaneous preterm birth before 37 weeks’ (4%, 23/628) but numbers were small. One of three (33%) followed-up women infected with W chondrophila had a preterm birth compared with 22 (4%) of 625 uninfected women (p=0·11). Sequencing of 25 samples that were positive on W chondrophila or pan-Chlamydiales PCR revealed seven samples (28%) positive for Chlamydiales bacterium sequences that have been associated with respiratory tract infections in children. Interpretation4% of newly pregnant women tested positive for Chlamydiales, including species known to be pathogenic in mothers and neonates. Higher rates might have been found in vaginal samples and the study lacked power to test associations. Although W chondrophila might be associated with preterm birth, the prevalence was very low in this urban, community-based sample, suggesting that screening is unlikely to be cost-effective in such a population. FundingMedical Research Council.

Using Fluorescent Proteins to Visualize and Quantitate <em>Chlamydia </em>Vacuole Growth Dynamics in Living Cells

The obligate intracellular bacterium Chlamydia elicits a great burden on global public health. C. trachomatis is the leading bacterial cause of sexually transmitted infection and also the primary cause of preventable blindness in the world. An essential determinant for successful infection of host cells by Chlamydia is the bacterium's ability to manipulate host cell signaling from within a novel, vacuolar compartment called the inclusion. From within the inclusion, Chlamydia acquire nutrients required for their 2-3 day developmental growth, and they additionally secrete a panel of effector proteins onto the cytosolic face of the vacuole membrane and into the host cytosol. Gaps in our understanding of Chlamydia biology, however, present significant challenges for visualizing and analyzing this intracellular compartment. Recently, a reverse-imaging strategy for visualizing the inclusion using GFP expressing host cells was described. This approach rationally exploits the intrinsic impermeability of the inclusion membrane to large molecules such as GFP. In this work, we describe how GFP- or mCherry-expressing host cells are generated for subsequent visualization of chlamydial inclusions. Furthermore, this method is shown to effectively substitute for costly antibody-based enumeration methods, can be used in tandem with other fluorescent labels, such as GFP-expressing Chlamydia, and can be exploited to derive key quantitative data about inclusion membrane growth from a range of Chlamydia species and strains.

Using Fluorescent Proteins to Visualize and Quantitate Chlamydia Vacuole Growth Dynamics in Living Cells.

The obligate intracellular bacterium Chlamydia elicits a great burden on global public health. C.trachomatis is the leading bacterial cause of sexually transmitted infection and also the primary cause of preventable blindness in the world. An essential determinant for successful infection of host cells by Chlamydia is the bacterium's ability to manipulate host cell signaling from within a novel, vacuolar compartment called the inclusion. From within the inclusion, Chlamydia acquire nutrients required for their 2-3 day developmental growth, and they additionally secrete a panel of effector proteins onto the cytosolic face of the vacuole membrane and into the host cytosol. Gaps in our understanding of Chlamydia biology, however, present significant challenges for visualizing and analyzing this intracellular compartment. Recently, a reverse-imaging strategy for visualizing the inclusion using GFP expressing host cells was described. This approach rationally exploits the intrinsic impermeability of the inclusion membrane to large molecules such as GFP. In this work, we describe how GFP- or mCherry-expressing host cells are generated for subsequent visualization of chlamydial inclusions. Furthermore, this method is shown to effectively substitute for costly antibody-based enumeration methods, can be used in tandem with other fluorescent labels, such as GFP-expressing Chlamydia, and can be exploited to derive key quantitative data about inclusion membrane growth from a range of Chlamydia species and strains.

In vitro activity of chloramphenicol, florfenicol and enrofloxacin against Chlamydia pecorum isolated from koalas (Phascolarctos cinereus).

To determine the in vitro susceptibilities of koala isolates of Chlamydia pecorum to enrofloxacin and chloramphenicol, which are frequently used to treat koalas with chlamydiosis, and florfenicol, a derivative of chloramphenicol. The in vitro susceptibilities were determined by culturing three stored isolates and seven clinical swabs of C. pecorum. Susceptibility testing was undertaken using cycloheximide-treated buffalo green monkey kidney cells in 96 well microtitre plates. The minimum inhibitory concentrations (MICs) for all isolates were 0.25-0.50 µg/mL (enrofloxacin), 1-2 µg/mL (chloramphenicol), and 1-2 µg/mL (florfenicol). Minimum bactericidal concentration (MBC) values for five isolates were also determined and were within one two-fold dilution of MICs. The MICs and MBCs of these antimicrobials were within ranges previously reported for other chlamydial species. When combined with previously published pharmacokinetic data, the in vitro susceptibility results support chloramphenicol as a more appropriate treatment option than enrofloxacin for koalas with chlamydiosis. The susceptibility results also indicate florfenicol may be an appropriate treatment option for koalas with chlamydiosis, warranting further investigation.

Structural characterization of muropeptides from Chlamydia trachomatis peptidoglycan by mass spectrometry resolves “chlamydial anomaly”

The "chlamydial anomaly," first coined by James Moulder, describes the inability of researchers to detect or purify peptidoglycan (PG) from pathogenic Chlamydiae despite genetic and biochemical evidence and antibiotic susceptibility data that suggest its existence. We recently detected PG in Chlamydia trachomatis by a new metabolic cell wall labeling method, however efforts to purify PG from pathogenic Chlamydiae have remained unsuccessful. Pathogenic chlamydial species are known to activate nucleotide-binding oligomerization domain-containing protein 2 (NOD2) innate immune receptors by as yet uncharacterized ligands, which are presumed to be PG fragments (muramyl di- and tripeptides). We used the NOD2-dependent activation of NF-κB by C. trachomatis-infected cell lysates as a biomarker for the presence of PG fragments within specific lysate fractions. We designed a new method of muropeptide isolation consisting of a double filtration step coupled with reverse-phase HPLC fractionation of Chlamydia-infected HeLa cell lysates. Fractions that displayed NOD2 activity were analyzed by electrospray ionization mass spectrometry, confirming the presence of muramyl di- and tripeptides in Chlamydia-infected cell lysate fractions. Moreover, the mass spectrometry data of large muropeptide fragments provided evidence that transpeptidation and transglycosylation reactions occur in pathogenic Chlamydiae. These results reveal the composition of chlamydial PG and disprove the "glycanless peptidoglycan" hypothesis.

Damage/Danger Associated Molecular Patterns (DAMPs) Modulate Chlamydia pecorum and C. trachomatis Serovar E Inclusion Development In Vitro.

Persistence, more recently termed the chlamydial stress response, is a viable but non-infectious state constituting a divergence from the characteristic chlamydial biphasic developmental cycle. Damage/danger associated molecular patterns (DAMPs) are normal intracellular components or metabolites that, when released from cells, signal cellular damage/lysis. Purine metabolite DAMPs, including extracellular ATP and adenosine, inhibit chlamydial development in a species-specific manner. Viral co-infection has been shown to reversibly abrogate Chlamydia inclusion development, suggesting persistence/chlamydial stress. Because viral infection can cause host cell DAMP release, we hypothesized DAMPs may influence chlamydial development. Therefore, we examined the effect of extracellular ATP, adenosine, and cyclic AMP exposure, at 0 and 14 hours post infection, on C. pecorum and C. trachomatis serovar E development. In the absence of de novo host protein synthesis, exposure to DAMPs immediately post or at 14 hours post infection reduced inclusion size; however, the effect was less robust upon 14 hours post infection exposure. Additionally, upon exposure to DAMPs immediately post infection, bacteria per inclusion and subsequent infectivity were reduced in both Chlamydia species. These effects were reversible, and C. pecorum exhibited more pronounced recovery from DAMP exposure. Aberrant bodies, typical in virus-induced chlamydial persistence, were absent upon DAMP exposure. In the presence of de novo host protein synthesis, exposure to DAMPs immediately post infection reduced inclusion size, but only variably modulated chlamydial infectivity. Because chlamydial infection and other infections may increase local DAMP concentrations, DAMPs may influence Chlamydia infection in vivo, particularly in the context of poly-microbial infections.

Phosphoproteomic analysis of the Chlamydia caviae elementary body and reticulate body forms.

Chlamydia are Gram-negative, obligate intracellular bacteria responsible for significant diseases in humans and economically important domestic animals. These pathogens undergo a unique biphasic developmental cycle transitioning between the environmentally stable elementary body (EB) and the replicative intracellular reticulate body (RB), a conversion that appears to require extensive regulation of protein synthesis and function. However, Chlamydia possess a limited number of canonical mechanisms of transcriptional regulation. Ser/Thr/Tyr phosphorylation of proteins in bacteria has been increasingly recognized as an important mechanism of post-translational control of protein function. We utilized 2D gel electrophoresis coupled with phosphoprotein staining and MALDI-TOF/TOF analysis to map the phosphoproteome of the EB and RB forms of Chlamydia caviae. Forty-two non-redundant phosphorylated proteins were identified (some proteins were present in multiple locations within the gels). Thirty-four phosphorylated proteins were identified in EBs, including proteins found in central metabolism and protein synthesis, Chlamydia-specific hypothetical proteins and virulence-related proteins. Eleven phosphorylated proteins were identified in RBs, mostly involved in protein synthesis and folding and a single virulence-related protein. Only three phosphoproteins were found in both EB and RB phosphoproteomes. Collectively, 41 of 42 C. caviae phosphoproteins were present across Chlamydia species, consistent with the existence of a conserved chlamydial phosphoproteome. The abundance of stage-specific phosphoproteins suggests that protein phosphorylation may play a role in regulating the function of developmental-stage-specific proteins and/or may function in concert with other factors in directing EB-RB transitions.

Characterisation of Chlamydia pneumoniae and other novel chlamydial infections in captive snakes

Chlamydiosis has been described in both free-ranging and captive reptiles. The infection usually manifests as granulomatous inflammation in inner organs such as spleen, heart, lung and liver but might also occur in asymptomatic reptiles. The aim of this study was to investigate and characterise Chlamydia pneumoniae and potential other novel chlamydial infections in the choana and cloaca samples of 137 clinically healthy captive snakes from six private collections. Forty eight samples from 29 animals were found to be positive by a Chlamydiaceae family-specific qPCR. By Chlamydia species-specific ArrayTube Microarray, 43 samples were positive, with 36 of these being identified as C. pneumoniae. The prevalence of Chlamydia ranged from 5 to 33%. PCR and sequencing of the Chlamydiales 16S rRNA signature sequence of 21 Chlamydia positive samples revealed the presence of seven novel 16S rRNA genotypes. BLAST-n and phylogenetic analysis of the near-full length 16S rRNA gene sequence of each of these novel 16S rRNA sequences revealed that five genotypes share closest sequence identity to 16S rRNA sequences from C. pneumoniae (98.6–99.2%), suggesting that these sequences are novel C. pneumoniae strains. One genotype is 96.9% similar to C. pneumoniae strains suggesting it may originate from a yet undescribed chlamydial species within the genus Chlamydia. This study further highlights the broad host range for C. pneumoniae and suggests that reptiles may still contain a significant and largely uncharacterised level of chlamydial genetic diversity that requires further investigation.

Evidence of members of the Chlamydiales in bovine abortions in England and Wales

DESPITE the economical importance and welfare issues associated with bovine abortion, as well as the potential zoonotic implications, the rate of diagnosis remains low with a cause of abortion only...

Defining species-specific immunodominant B cell epitopes for molecular serology of Chlamydia species.

Urgently needed species-specific enzyme-linked immunosorbent assays (ELISAs) for the detection of antibodies against Chlamydia spp. have been elusive due to high cross-reactivity of chlamydial antigens. To identify Chlamydia species-specific B cell epitopes for such assays, we ranked the potential epitopes of immunodominant chlamydial proteins that are polymorphic among all Chlamydia species. High-scoring peptides were synthesized with N-terminal biotin, followed by a serine-glycine-serine-glycine spacer, immobilized onto streptavidin-coated microtiter plates, and tested with mono-specific mouse hyperimmune sera against each Chlamydia species in chemiluminescent ELISAs. For each of nine Chlamydia species, three to nine dominant polymorphic B cell epitope regions were identified on OmpA, CT618, PmpD, IncA, CT529, CT442, IncG, Omp2, TarP, and IncE proteins. Peptides corresponding to 16- to 40-amino-acid species-specific sequences of these epitopes reacted highly and with absolute specificity with homologous, but not heterologous, Chlamydia monospecies-specific sera. Host-independent reactivity of such epitopes was confirmed by testing of six C. pecorum-specific peptides from five proteins with C. pecorum-reactive sera from cattle, the natural host of C. pecorum. The probability of cross-reactivity of peptide antigens from closely related chlamydial species or strains correlated with percent sequence identity and declined to zero at <50% sequence identity. Thus, phylograms of B cell epitope regions predict the specificity of peptide antigens for rational use in the genus-, species-, or serovar-specific molecular serology of Chlamydia spp. We anticipate that these peptide antigens will improve chlamydial serology by providing easily accessible assays to nonspecialist laboratories. Our approach also lends itself to the identification of relevant epitopes of other microbial pathogens.

The prevalence and clinical significance of Chlamydia infection in island and mainland populations of Victorian koalas (Phascolarctos cinereus).

Chlamydia infection is known to impact the health of koalas (Phascolarctos cinereus) in New South Wales (NSW) and Queensland, but the clinical significance of Chlamydia infections in Victorian koalas is not well described. We examined the prevalence of Chlamydia infection and assessed associated health parameters in two Victorian koala populations known to be Chlamydia positive. The same testing regimen was applied to a third Victorian population in which Chlamydia had not been detected. We examined 288 koalas and collected samples from the urogenital sinus and conjunctival sacs. Detection and differentiation of Chlamydia species utilized real-time PCR and high-resolution melting curve analysis. Chlamydia pecorum was detected in two populations (prevalences: 25% and 41%, respectively) but only from urogenital sinus swabs. Chlamydia was not detected in the third population. Chlamydia pneumoniae was not detected. Chlamydia pecorum infection was positively associated with wet bottom (indicating chronic urinary tract disease) in one Chlamydia-positive population and with abnormal urogenital ultrasound findings in the other Chlamydia-positive population. The prevalence of wet bottom was similar in all populations (including the Chlamydia-free population), suggesting there is another significant cause (or causes) of wet bottom in Victorian koalas. Ocular disease was not observed. This is the largest study of Chlamydia infection in Victorian koalas, and the results suggest the potential for epidemiologic differences related to Chlamydia infections between Victorian koalas and koalas in Queensland and NSW and also between geographically distinct Victorian populations. Further studies to investigate the genotypes of C. pecorum present in Victorian koalas and to identify additional causes of wet bottom in koalas are indicated.

Emendation of the family Chlamydiaceae: Proposal of a single genus, Chlamydia, to include all currently recognized species

The family Chlamydiaceae (order Chlamydiales, phylum Chlamydiae) comprises important, obligate intracellular bacterial pathogens of humans and animals. Subdivision of the family into the two genera Chlamydia and Chlamydophila has been discussed controversially during the past decade. Here, we have revisited the current classification in the light of recent genomic data and in the context of the unique biological properties of these microorganisms. We conclude that neither generally used 16S rRNA sequence identity cut-off values nor parameters based on genomic similarity consistently separate the two genera. Notably, no easily recognizable phenotype such as host preference or tissue tropism is available that would support a subdivision. In addition, the genus Chlamydophila is currently not well accepted and not used by a majority of research groups in the field. Therefore, we propose the classification of all 11 currently recognized Chlamydiaceae species in a single genus, the genus Chlamydia. Finally, we provide emended descriptions of the family Chlamydiaceae, the genus Chlamydia, as well as the species Chlamydia abortus, Chlamydia caviae and Chlamydia felis.

Seroprevalence studies on animal chlamydiosis amongst ruminants in five states of India.

Background and Aim:Animal chlamydiosis, caused by different chlamydial species, is characterized by clinical or subclinical disease manifestations in cattle, buffalo, ovine, caprine and wild animal species. Animal chlamydiosis often remains underdiagnosed or undiagnosed, and its status in many parts of India is still unknown. Hence, the present study was conducted to determine the seroprevalence of animal chlamydiosis amongst ruminant livestock species of five states of India.Materials and Methods:Totally, 2127 randomly selected serum samples collected from ruminant livestock species viz. cattle (n=430), buffaloes (n=429), sheep (906) and goats (n=362), were tested by agar gel precipitation test for chlamydiosis between 2002 and 2011. Precipitating antigen was prepared from locally isolated strain of Chlamydia psittaci after treatment with sodium deoxycholate.Results:The chlamydial seroprevalence detected amongst ruminants in five states of India was: Himachal Pradesh: Cattle-10.90%, sheep-10.60% and goats- 22.46%; Punjab: Cattle-1.45%; Andhra Pradesh: Cattle-2.80%, buffaloes-0.93%, sheep-8.90% and goats-9.46%; Maharashtra: goats-8.33%; Jammu and Kashmir: sheep-12.50%. The mean seroprevalence values of each animal species are: Cattle-4.65%, buffaloes-0.93%, sheep-9.82% and goats-19.33%.Conclusion:The results indicate the endemic nature of animal chlamydiosis across five states in India. Hence, it requires further extensive studies in other parts of India also using chlamydial species-specific diagnostics to ascertain overall countrywide prevalence of the disease. The zoonotic nature of the chlamydiae of ruminant origin further adds significance to such prevalence studies.

Chlamydial plasmids and bacteriophages.

Chlamydia are absolute pathogens of humans and animals; despite being rather well recognised, they are still open for discovery. One such discovery is the occurrence of extrachromosomal carriers of genetic information. In prokaryotes, such carriers include plasmids and bacteriophages, which are present only among some Chlamydia species. Plasmids were found exclusively in Chlamydia (C.) trachomatis, C. psittaci, C. pneumoniae, C. suis, C. felis, C. muridarum and C. caviae. In prokaryotic organisms, plasmids usually code for genes that facilitate survival of the bacteria in the environment (although they are not essential). In chlamydia, their role has not been definitely recognised, apart from the fact that they participate in the synthesis of glycogen and encode proteins responsible for their virulence. Furthermore, in C. suis it was evidenced that the plasmid is integrated in a genomic island and contains the tetracycline-resistance gene. Bacteriophages specific for chlamydia (chlamydiaphages) were detected only in six species: C. psittaci, C. abortus, C. felis, C. caviae C. pecorum and C. pneumoniae. These chlamydiaphages cause inhibition of the developmental cycle, and delay transformation of reticulate bodies (RBs) into elementary bodies (EBs), thus reducing the possibility of infecting other cells in time. Plasmids and bacteriophages can be used in the diagnostics of chlamydioses; although especially in the case of plasmids, they are already used for detection of chlamydial infections. In addition, bacteriophages could be used as therapeutic agents to replace antibiotics, potentially addressing the problem of increasing antibiotic-resistance among chlamydia.