Ocular adnexal lymphoma: a clinicopathologic study of a large cohort of patients with no evidence for an association with Chlamydia psittaci

Non-Hodgkin lymphomas are among the most common primary tumors occurring in the ocular adnexa. Herein, we present a 14-year single-institution experience in 62 patients with primary ocular adnexal lymphomas (OALs). Association with Chlamydia psittaci infection is examined in 57 tumor specimens. Extranodal marginal zone lymphoma (EMZL) was the most frequent histologic subtype (89%). The majority of patients with EMZL (84%) presented with stage E-extranodal (IE), however only 16% had an advanced stage. All stage IE patients were treated with local radiotherapy, whereas patients with disseminated disease received systemic therapy with or without local irradiation. All but 1 patient with EMZL achieved complete remission (CR). During a median follow-up of 52 months (range, 3-153 months), the estimated 5-year overall survival (OS) and freedom from progression (FFP) were 96% and 79%, respectively. During the follow-up, 22% of patients relapsed, mainly in extranodal sites, and 4% transformed to diffuse large B-cell lymphoma. None of the patients exhibited local orbital failure in the radiation field. None of the OAL specimens harbored C psittaci DNA. Our study demonstrates that EMZLs, accounting for the majority of primary OALs, are characterized by an indolent natural history with frequent, continuous extranodal relapses. In South Florida, OALs are not associated with C psittaci infections.

Characterization of vaginal microflora of healthy, nonpregnant women by chaperonin-60 sequence-based methods

OBJECTIVE

The purpose of this study was to use a novel method that was based on the application of chaperonin-60 sequencing to describe the vaginal microflora of 16 healthy women.

STUDY DESIGN

Asymptomatic women consented for vaginal swabs to be collected at the time of a clinical pelvic examination. Total genomic DNA was isolated from the vaginal swabs. Degenerate, universal polymerase chain reaction primers were used to amplify an approximately 555 base pair region of the universal chaperonin-60 gene, which is found in all eubacteria and eukaryotes, from the total genomic DNA and libraries of cloned polymerase chain reaction products were constructed. Library clones were sequenced, and the resulting sequences were assigned to taxonomic groups on the basis of similarity to reference sequence data. Presence of Chlamydophila psittaci sequences in the samples was confirmed by species-specific polymerase chain reaction.

RESULTS

Sixteen of the 23 women who were enrolled had normal flora by Nugent's score of <4 and had adequate polymerase chain reaction product for assessment. Vaginal flora libraries were dominated by a variety of sequences with similarity to Lactobacillus spp L. crispatus, L. iners, L. gasseri, L. jensenii, and L. buchneri. Other sequences that were identified included representatives of Gardnerella spp, sequences with similarity to Porphyromonas spp and Megasphaera spp and sequences identical to C psittaci.

CONCLUSION

Culture-independent, chaperonin-60 sequence-based molecular methods can lead to the identification of greater diversity within defined taxa compared with those that are identified by standard culture-based methods and to the identification of novel organisms that were not previously associated with vaginal flora.

Frequency of spontaneous mutations that confer antibiotic resistance in Chlamydia spp

Mutations in rRNA genes (rrn) that confer resistance to ribosomal inhibitors are typically recessive or weakly codominant and have been mostly reported for clinical strains of pathogens possessing only one or two rrn operons, such as Helicobacter pylori and Mycobacterium spp. An analysis of the genome sequences of several members of the Chlamydiaceae revealed that these obligate intracellular bacteria harbor only one or two sets of rRNA genes. To study the contribution of rRNA mutations to the emergence of drug resistance in the Chlamydiaceae, we used the sensitivities of Chlamydia trachomatis L2 (two rrn operons) and Chlamydophila psittaci 6BC (one rrn operon) to the aminoglycoside spectinomycin as a model. Confluent cell monolayers were infected in a plaque assay with about 10(8) wild-type infectious particles and then treated with the antibiotic. After a 2-week incubation time, plaques formed by spontaneous spectinomycin-resistant (Spc(r)) mutants appeared with a frequency of 5 x 10(-5) for C. psittaci 6BC. No Spc(r) mutants were isolated for C. trachomatis L2, although the frequencies of rifampin resistance were in the same range for both strains (i.e., 10(-7)). The risk of emergence of Chlamydia strains resistant to tetracyclines and macrolides, the ribosomal drugs currently used to treat chlamydial infections, is discussed.

Sequencing of the Chlamydophila psittaci ompA gene reveals a new genotype, E/B, and the need for a rapid discriminatory genotyping method

Twenty-one avian Chlamydophila psittaci isolates from different European countries were characterized using ompA restriction fragment length polymorphism, ompA sequencing, and major outer membrane protein serotyping. Results reveal the presence of a new genotype, E/B, in several European countries and stress the need for a discriminatory rapid genotyping method.

Regression of ocular adnexal lymphoma after Chlamydia psittaci-eradicating antibiotic therapy

PURPOSE

Some infectious agents contributing to lymphomagenesis have been considered targets for new therapeutic strategies. Chlamydia psittaci DNA has been detected in 80% of ocular adnexal lymphomas. The present pilot study was carried out to assess whether C psittaci-eradicating antibiotic therapy is associated with tumor regression in ocular adnexal lymphomas.

PATIENTS AND METHODS

Nine patients with C psittaci-positive marginal-zone B-cell lymphoma of the ocular adnexa at diagnosis or relapse were treated with doxycycline 100 mg, bid orally, for 3 weeks. The presence of C psittaci DNA in peripheral-blood mononuclear cells (PBMCs) was also assessed before and after treatment in seven patients. Objective lymphoma regression was assessed 1, 3, and 6 months after therapy conclusion and every 6 months during follow-up.

RESULTS

All patients completed antibiotic therapy with excellent tolerability. At 1 month from doxycycline assumption, chlamydial DNA was no longer detectable in PBMCs of all four positive patients. Objective response was complete in two patients, partial response (> 50%) was observed in two patients, and minimal response (< 50%) was observed in three patients. Duration of response in the seven responders was 12+, 29+, 31+, 8+, 7+, 2+, and 1+ months, respectively.

CONCLUSION

C psittaci-eradicating antibiotic therapy with doxycycline is followed by objective response in patients with ocular adnexal lymphoma, even after multiple relapses of the disease. A confirmatory, large, phase II trial is warranted to confirm whether this fast, cheap, and well-tolerated therapy could replace other more aggressive strategies as first-line treatment against ocular adnexal lymphomas.

Interaction between components of the type III secretion system of Chlamydiaceae

Members of the family Chlamydiaceae possess at least 13 genes, distributed throughout the chromosome, that are homologous with genes of known type III secretion systems (TTS). The aim of this study was to use putative TTS proteins of Chlamydophila pneumoniae, whose equivalents in other bacterial TTS function as chaperones, to identify interactions between chlamydial proteins. Using the BacterioMatch Two-Hybrid Vector system (Stratagene, La Jolla, Calif.), lcrH-2 and sycE, positions 1021 and 0325, respectively, from C. pneumoniae CM-1 were used as "bait" to identify target genes (positions 0324, 0705, 0708, 0808 to 0810, 1016 to 1020, and 1022) in close proximity on the chromosome. Interaction between the products of the lcrH-2 (1021) and lcrE (copN) (0324) genes was detected and confirmed by pull-down experiments and enzyme immunoassays using recombinant LcrH-2 and LcrE. As further confirmation of this interaction, the homologous genes from Chlamydia trachomatis, serovar E, and Chlamydophila psittaci, Texas turkey, were also cloned in the two-hybrid system to determine if LcrH-2 and LcrE would interact with their orthologs in other species. Consistent with their genetic relatedness, LcrH-2 from C. pneumoniae interacted with LcrE produced from the three species of Chlamydiaceae; LcrH-2 from C. psittaci reacted with LcrE from C. pneumoniae but not from C. trachomatis; and C. trachomatis LcrH-2 did not react with LcrE from the other two species. Deletions from the N and C termini of LcrE from C. pneumoniae identified the 50 C-terminal amino acids as essential for the interaction with LcrH-2. Thus, it appears that in the Chlamydiaceae TTS, LcrH-2 interacts with LcrE, and therefore it may serve as a chaperone for this protein.

A comparative ultrastructural and molecular biological study on Chlamydia psittaci infection in alpha-1 antitrypsin deficiency and non-alpha-1 antitrypsin deficiency emphysema versus lung tissue of patients with hamartochondroma

BACKGROUND

Chlamydiales are familiar causes of acute and chronic infections in humans and animals. Human pulmonary emphysema is a component of chronic obstructive pulmonary disease (COPD) and a condition in which chronic inflammation manifested as bronchiolitis and intra-alveolar accumulation of macrophages is common. It is generally presumed to be of infectious origin. Previous investigations based on serology and immunohistochemistry indicated Chlamydophila pneumoniae infection in cases of COPD. Furthermore, immunofluorescence with genus-specific antibodies and electron microscopy suggested involvement of chlamydial infection in most cases of pulmonary emphysema, but these findings could not be verified by PCR. Therefore, we examined the possibility of other chlamydial species being present in these patients.

METHODS

Tissue samples from patients having undergone lung volume reduction surgery for advanced alpha-1 antitrypsin deficiency (AATD, n = 6) or non-alpha-1 antitrypsin deficiency emphysema (n = 34) or wedge resection for hamartochondroma (n = 14) were examined by transmission electron microscopy and PCR.

RESULTS

In all cases of AATD and 79.4% of non-AATD, persistent chlamydial infection was detected by ultrastructural examination. Intra-alveolar accumulation of macrophages and acute as well as chronic bronchiolitis were seen in all positive cases. The presence of Chlamydia psittaci was demonstrated by PCR in lung tissue of 66.7% AATD vs. 29.0% non-AATD emphysema patients. Partial DNA sequencing of four positive samples confirmed the identity of the agent as Chlamydophila psittaci. In contrast, Chlamydophila pneumoniae was detected only in one AATD patient. Lung tissue of the control group of non-smokers with hamartochondroma was completely negative for chlamydial bodies by TEM or chlamydial DNA by PCR.

CONCLUSIONS

These data indicate a role of Chlamydophila psittaci in pulmonary emphysema by linking this chronic inflammatory process to a chronic infectious condition. This raises interesting questions on pathogenesis and source of infection.

Tryptophan recycling is responsible for the interferon-gamma resistance of Chlamydia psittaci GPIC in indoleamine dioxygenase-expressing host cells

Comparative genomics indicates that vast differences in Chlamydia sp. host range and disease characteristics can be traced back to subtle variations in gene content within a region of the chromosome termed the plasticity zone. Genes required for tryptophan biosynthesis are located in the plasticity zone; however, the complement of genes encoded varies depending on the chlamydial species examined. Of the sequenced chlamydia genomes, Chlamydia psittaci GPIC contains the most complete tryptophan biosynthesis operon, encoding trpRDCFBA. Immediately downstream of the trp operon are genes encoding kynureninase and ribose phosphate pyrophosphokinase. Here, we show that, in GPIC, these genes are transcribed as a single transcript, the expression of which is regulated by tryptophan. Complementation analyses, using various mutant Escherichia coli isolates, indicate that the tryptophan biosynthesis, kynureninase and ribose phosphate pyrophosphokinase gene products are functional. Furthermore, growth of C. psittaci GPIC in HeLa cells, cultured in tryptophan-free medium, could be rescued by the addition of anthranilate, kynurenine or indole. In total, our results indicate that this complement of genes enables GPIC to recycle tryptophan and thus accounts for the interferon-gamma resistant phenotype displayed in indoleamine-2,3-dioxygenase-expressing host cells.

Severe Chlamydophila psittaci pneumonia rapidly diagnosed by detection of antigen in sputum with an immunochromatography assay

We report a case of severe Chlamydophila (Chlamydia) psittaci pneumonia rapidly diagnosed by detection of antigen in sputum with an immunochromatography assay. The patient was admitted to our hospital because of shock, disturbance of consciousness, accidental hypothermia, and multiple organ dysfunction syndrome, and he recovered after administration of intravenous erythromycin and high-dose methylpredonisolone therapy. Psittacosis was confirmed by detection of 16S rRNA gene of C. psittasi in sputum with multiplex-polymerase chain reaction analysis. Serological responses to C. psittasi, C. trachomatis, and C. pneumoniae were also evaluated, and serological cross-reactivity was observed between each species. We consider that the commercially available immunochromatography assay for Chlamydia species can be helpful for rapid diagnosis of Chlamydia infection of the respiratory tract. Hereafter, further examination will be necessary regarding pretreatment of specimens or detection sensitivity and specificity.

A woman with a lobar infiltrate due to psittacosis detected by polymerase chain reaction

This report presents a case of community-acquired pneumonia due to Chlamydia psittaci presenting with a lobar infiltrate and diagnosed by a newly developed ompA gene-based polymerase chain reaction (PCR). This gene encodes a specific C. psittaci major outer membrane protein. This kind of PCR could reduce antibiotic consumption and expedite outbreak management.

[Ornithosis--an overlooked cause of atypical pneumonia]

A case illustrating the potential severity of infection with Chlamydia psittaci (ornithosis) is reported. The importance of considering Chlamydia psittaci as an option in patients with severe respiratory failure is emphasized with a view to early PCR diagnosis of ornithosis.

Missing links in the divergence of Chlamydophila abortus from Chlamydophila psittaci

Pathological and serological evidence and DNA-DNA reassociation data indicate that Chlamydophila psittaci and Chlamydophila abortus are separate species. C. psittaci causes avian systemic disease and C. abortus causes abortion. Both previously belonged to Chlamydia psittaci are associated with zoonotic and enzootic outbreaks. Genetic studies suggest that they are closely related and because of the recent availability of diverse C. psittaci strains and comparative data for several genes, it was possible to explore this relationship. The parrot C. psittaci strain 84/2334 was found to have DNA sequences that were identical to an extrachromosomal plasmid in duck C. psittaci strain N352, to rnpB in strain R54 from a brown skua and to the rrn intergenic spacer in parakeet strain Prk/Daruma (from Germany, Antarctica and Japan, respectively). Analysis of ompA and the rrn spacer revealed progressive diversification of the strains, with 84/2334 resembling what might have been a recent ancestor of C. abortus. Another C. psittaci strain (VS225) showed evidence of having undergone convergent evolution towards the C. abortus-like genotype, whereas strain R54 diverged independently. For the first time, these studies link C. abortus in an evolutionary context to the C. psittaci lineage. It has been concluded that C. abortus diverged from C. psittaci, and so strain R54 was designated a C. psittaci strain. It is recommended that characterization of C. psittaci and C. abortus strains should utilize more than a single method and more than a single gene.

Genome sequence of Chlamydophila caviae (Chlamydia psittaci GPIC): examining the role of niche-specific genes in the evolution of the Chlamydiaceae

The genome of Chlamydophila caviae (formerly Chlamydia psittaci, GPIC isolate) (1 173 390 nt with a plasmid of 7966 nt) was determined, representing the fourth species with a complete genome sequence from the Chlamydiaceae family of obligate intracellular bacterial pathogens. Of 1009 annotated genes, 798 were conserved in all three other completed Chlamydiaceae genomes. The C.caviae genome contains 68 genes that lack orthologs in any other completed chlamydial genomes, including tryptophan and thiamine biosynthesis determinants and a ribose-phosphate pyrophosphokinase, the product of the prsA gene. Notable amongst these was a novel member of the virulence-associated invasin/intimin family (IIF) of Gram-negative bacteria. Intriguingly, two authentic frameshift mutations in the ORF indicate that this gene is not functional. Many of the unique genes are found in the replication termination region (RTR or plasticity zone), an area of frequent symmetrical inversion events around the replication terminus shown to be a hotspot for genome variation in previous genome sequencing studies. In C.caviae, the RTR includes several loci of particular interest including a large toxin gene and evidence of ancestral insertion(s) of a bacteriophage. This toxin gene, not present in Chlamydia pneumoniae, is a member of the YopT effector family of type III-secreted cysteine proteases. One gene cluster (guaBA-add) in the RTR is much more similar to orthologs in Chlamydia muridarum than those in the phylogenetically closest species C.pneumoniae, suggesting the possibility of horizontal transfer of genes between the rodent-associated Chlamydiae. With most genes observed in the other chlamydial genomes represented, C.caviae provides a good model for the Chlamydiaceae and a point of comparison against the human atherosclerosis-associated C.pneumoniae. This crucial addition to the set of completed Chlamydiaceae genome sequences is enabling dissection of the roles played by niche-specific genes in these important bacterial pathogens.

Quantitative detection of Chlamydia psittaci and C. pecorum by high-sensitivity real-time PCR reveals high prevalence of vaginal infection in cattle

Bovine vaginal cytobrush specimens were analyzed for the presence of Chlamydia spp. by a high-sensitivity, high-specificity quantitative PCR. The 53% prevalence of low-level Chlamydia psittaci and C. pecorum genital infection detected in virgin heifers suggests predominantely extragenital transmission of Chlamydia in cattle and conforms to the high seroprevalence of anti-Chlamydia antibodies.

High-sensitivity quantitative PCR platform

Real-time PCR methods have become widely used within the past few years. However, real-time PCR is rarely used to study chronic diseases with low pathogen loads, presumably because of insufficient sensitivity. In this report, we developed an integrated nucleic acid isolation and real-time PCR platform that vastly improved the sensitivity of the quantitative detection of the intracellular bacterium, Chlamydia spp., by fluorescence resonance energy transfer real-time PCR. Determinants of the overall detection sensitivity were analyzed by extracting nucleic acids from bovine milk specimens spiked with low amounts of chlamydial organisms. Nucleic acids were optimally preserved and recovered by collection in guanidinium stabilization buffer, binding to a matrix of glass fiber fleece, and elution in low volume. Step-down thermal cycling and an excess of hot-start Taq polymerase vastly improved the robustness and sensitivity of the real-time PCR while essentially maintaining 100% specificity. The amplification of Chlamydia 23S rRNA allowed for the differentiation of chlamydial species and was more robust at low target numbers than amplification of the omp1 gene. The best combined method detected single targets per a 100-microL specimen equivalent in a 5-microL real-time PCR input. In an initial application, this high-sensitivity real-time PCR platform demonstrated a high prevalence of chlamydial infection in cattle.

Evidence for a type III secretion system in Chlamydophila psittaci

In order to examine the presence of a type III secretion system in Chlamydophila psittaci, we focused on the SctW (CopN) coding region in a locus containing four genes encoding putative products with similarity to chaperones (Sccl), secretion pore components (Cds1 and Cds2) and secreted proteins (CopN) formerly identified in the type III secretion system of other gram-negative bacteria. SctW regulates type III secretion in gram-negative bacteria. SctW expression was examined in C. psittaci infected HeLa cells using SctW-specific polyclonal antibodies in an indirect immunofluorescence staining. SctW expression was detected 29 hours post inoculation and was absent in uninfected control cells. Immunoblotting of whole HeLa cell lysate 72 hours post inoculation with the SctW-specific polyclonal antibody also revealed the presence of SctW. Results demonstrated SctW of C. psittaci to be expressed in at least one stage of the intracellular bacterial life cycle. The present finding may contribute to the future identification of a functional type III secretion apparatus in C. psittaci.

Serological and molecular characterization of Chlamydophila psittaci strains using serovar-specific monoclonal antibodies and ompA sequence analysis

In the present study, 21 avian Chlamydophila psittaci field isolates from 4 different European countries (Belgium, Germany, Italy and The Netherlands) were characterized using serovar-specific monoclonal antibodies as well as ompA sequence analysis, enabling the comparison between the two characterization methods for future epidemiological studies. The 21 European isolates included 6 isolates from the order Psittaciformes, 6 isolates from the Anseriformes, 5 isolates from the order Columbiformes and 4 Galliformes respectively. Only 19 on 21 isolates could be serotyped while all isolates were successfully genotyped. In addition, genotyping revealed the presence of mixed infections in 5 on 21 isolates while serotyping could only detect one of these 5 mixed infections. Interestingly, genotyping indicated the existence of a new genotype designated E/B. The E/B genotype is closely related to the genotypes A, B and E but the ompA gene of E/B strains shows a guanosine on position 1006 and 1021 in combination with a cytidine on position 1022 to be unique. Genotype E/B isolates reacted with both the serovar E- and B-specific monoclonal antibody leading to the conclusion of a mixed infection while only one specific ompA sequence was present in the sample. For epidemiological studies genotyping by use of ompA sequence analysis is to be preferred as it is more sensitive than serotyping and can distinguish genotype B, E and E/B strains.

Dynamic diversity of the tryptophan pathway in chlamydiae: reductive evolution and a novel operon for tryptophan recapture

BACKGROUND

Complete genomic sequences of closely related organisms, such as the chlamydiae, afford the opportunity to assess significant strain differences against a background of many shared characteristics. The chlamydiae are ubiquitous intracellular parasites that are important pathogens of humans and other organisms. Tryptophan limitation caused by production of interferon-gamma by the host and subsequent induction of indoleamine dioxygenase is a key aspect of the host-parasite interaction. It appears that the chlamydiae have learned to recognize tryptophan depletion as a signal for developmental remodeling. The consequent non-cultivable state of persistence can be increasingly equated to chronic disease conditions.

RESULTS

The genes encoding enzymes of tryptophan biosynthesis were the focal point of this study. Chlamydophila psittaci was found to possess a compact operon containing PRPP synthase, kynureninase, and genes encoding all but the first step of tryptophan biosynthesis. All but one of the genes exhibited translational coupling. Other chlamydiae (Chlamydia trachomatis, C. muridarum and Chlamydophila pneumoniae) lack genes encoding PRPP synthase, kynureninase, and either lack tryptophan-pathway genes altogether or exhibit various stages of reductive loss. The origin of the genes comprising the trp operon does not seem to have been from lateral gene transfer.

CONCLUSIONS

The factors that accommodate the transition of different chlamydial species to the persistent (chronic) state of pathogenesis include marked differences in strategies deployed to obtain tryptophan from host resources. C. psittaci appears to have a novel mechanism for intercepting an early intermediate of tryptophan catabolism and recycling it back to tryptophan. In effect, a host-parasite metabolic mosaic has evolved for tryptophan recycling.

Detection and differentiation of chlamydiae by fluorescence in situ hybridization

Chlamydiae are important pathogens of humans and animals but diagnosis of chlamydial infections is still hampered by inadequate detection methods. Fluorescence in situ hybridization (FISH) using rRNA-targeted oligonucleotide probes is widely used for the investigation of uncultured bacteria in complex microbial communities and has recently also been shown to be a valuable tool for the rapid detection of various bacterial pathogens in clinical specimens. Here we report on the development and evaluation of a hierarchic probe set for the specific detection and differentiation of chlamydiae, particularly C. pneumoniae, C. trachomatis, C. psittaci, and the recently described chlamydia-like bacteria comprising the novel genera Neochlamydia and PARACHLAMYDIA: The specificity of the nine newly developed probes was successfully demonstrated by in situ hybridization of experimentally infected amoebae and HeLa 229 cells, including HeLa 229 cells coinfected with C. pneumoniae and C. trachomatis. FISH reliably stained chlamydial inclusions as early as 12 h postinfection. The sensitivity of FISH was further confirmed by combination with direct fluorescence antibody staining. In contrast to previously established detection methods for chlamydiae, FISH was not susceptible to false-positive results and allows the detection of all recognized chlamydiae in one single step.

Feline chlamydiosis in Italy: PCR amplification and analysis of the ompA and groEL-homolog genes

The ompA and groEL-homolog genes of Chlamydia psittaci were amplified from feline conjunctival swabs. The PCR products from positive samples for ompA and groEL genes were digested with the restriction enzyme Alu I and Hind III, respectively. In addition, the PCR products from both genes were sequenced. The results confirm the high homogeneity of the ompA gene of feline C. psittaci. The RFLP analysis of groEL-homolog gene could be useful to typing the strains of feline C. psittaci.

[Chlamydial diseases of domestic animals--zoonotic potential of the agents and diagnostic issues]

The role of chlamydiae as agents of a number of important animal and human diseases is still the subject of intensive research. Recently, a proposal for taxonomic reclassification of this group of obligate intracellular bacteria was published, which was based on a large amount of new data on genetic relatedness. According to this proposal, the family Chlamydiaceae now comprises two genera (Chlamydia and Chlamydophila) with 9 largely host-related species. The previously accepted classification scheme had distinguished 4 species within the genus Chlamydia. The most important animal chlamydiosis with zoonotic character is psittacosis, a systemic disease in psittacine birds of acute, protracted, chronic or subclinical manifestation. The analogous infection in domestic and wild fowl is known as ornithosis. Avian strains of C. psittaci (new classification: Chlamydophila psittaci) can also infect humans, the symptoms being mainly unspecific and influenza-like, but severe pneumonia, endocarditis and encephalitis are also known. The main group of persons facing an elevated risk of infection includes those having frequent contact with domestic and companion birds at work or in their spare time. In Germany, the annual average of notified cases is approximately 100. Cases of transmission to humans were repeatedly reported in connection with enzootic abortion in sheep (causative agent: C. psittaci or Chlamydophila abortus, respectively). Various chlamydial species occur as pathogens and commensals as well in cattle, pigs, horses, and cats. The assessment of the actual epidemiological importance is, however, often difficult because of their almost ubiquitous spread. Likewise, those strains of C. pneumoniae (new classification: Chlamydophila pneumoniae) found in several animal species can not yet be assessed for pathogenic properties. The possibilities for diagnostic detection of chlamydiae have considerably improved following the introduction of molecular methods, particularly the polymerase chain reaction (PCR), which permits direct identification from clinical specimens and differentiation of species.

Isolation and characterisation of local strains of Chlamydophila abortus (Chlamydia psittaci serotype 1) from Tunisia

Chlamydiosis is one of the major diseases that can lead to abortion in ewes. Since 1997, in 5 regions of Tunisia, Chlamydia-related abortions have been reported in 15 sheep and goat flocks. One hundred and sixty-six sera and 50 vaginal swab samples were collected from adult ewes. Chlamydial antigens were detected in 29 (58%) of the vaginal swabs using Enzyme Linked Immunosorbent Assay (ELISA) while 9 (18%) were positive by cell culture. Five strains were recovered from 4 different sheep flocks. Monoclonal antibody profiles and restriction fragment length polymorphism (RFLP) analysis of the 16S-23S rRNA spacer region showed that these isolates were C. abortus. Using amplified fragment length polymorphism (AFLP), these Tunisian strains were shown to exhibit the same pattern as strains isolated in France.

Recombination in the ompA gene but not the omcB gene of Chlamydia contributes to serovar-specific differences in tissue tropism, immune surveillance, and persistence of the organism

Sequences of the major outer membrane protein (MOMP) gene (ompA) and the outer membrane complex B protein gene (omcB) from Chlamydia trachomatis, Chlamydia pneumoniae, and Chlamydia psittaci were analyzed for evidence of intragenic recombination and for linkage equilibrium. The Sawyer runs test, compatibility matrices, and index of association analyses provided substantial evidence that there has been a history of intragenic recombination at ompA including one instance of interspecies recombination between the C. trachomatis mouse pneumonitis strain and the C. pneumoniae horse N16 strain. Although none of these methods detected intragenic recombination within omcB, differences in divergence reported in earlier studies suggested that there has been intergenic recombination involving omcB, and the analyses presented in this study are consistent with this. For C. trachomatis, index-of-association analyses suggested a higher degree of recombination for C class than for B class strains and a higher degree of recombination in the downstream half of ompA. In concordance with these findings, many significant breakpoints were found in variable segments 3 and 4 of MOMP for the recombinant strains D/B120, G/UW-57, E/Bour, and LGV-98 identified in this study. We provide examples of how genetic diversity generated by repeated recombination in these regions may be associated with evasion of immune surveillance, serovar-specific differences in tissue tropism, and persistence.