Zoonotic potential of Chlamydophila.

The purpose of this article is to present the diseases induced in humans and animals by the different species of Chlamydophila, after providing an overview on the history of these infectious agents and their taxonomy. The route of transmission and the available methods for prevention and control in the different animal species are reviewed.

Preliminary phylogenetic identification of virulent Chlamydophila pecorum strains.

Chlamydophila pecorum is an obligate intracellular bacterium associated with different pathological conditions in ruminants, swine and koala, which is also found in the intestine of asymptomatic animals. A multi-virulence locus sequence typing (MVLST) system was developed using 19 C. pecorum strains (8 pathogenic and 11 non-pathogenic intestinal strains) isolated from ruminants of different geographical origins. To evaluate the ability of MVLST to distinguish the pathogenic from the non-pathogenic strains of C. pecorum, the sequences of 12 genes were analysed: 6 potential virulence genes (ompA, incA, incB, incC, mip and copN), 5 housekeeping genes (recA, hemD, aroC, efp, gap), and the ORF663 gene encoding a hypothetical protein (HP) that includes a variant 15-nucleotides coding tandem repeat (CTR). MVLST provided high discriminatory power (100%) in allowing to distinguish 6 of 8 pathogenic strains in a single group, and overall more discriminatory than MLST targeting housekeeping genes. ompA was the most polymorphic gene and the phylogenetic tree based only on its sequence differentiated 4 groups with high bootstrap values. The number of CTRs (rich in serine, proline and lysine) in ORF663 detected in the pathogenic strains was generally lower than that found in the intestinal strains. MVLST appears to be a promising method for the differential identification of virulent C. pecorum strains, and the ompA, incA and ORF663 genes appear to be good molecular markers for further epidemiological investigation of C. pecorum.

Identification and characterisation of coding tandem repeat variants in incA gene of Chlamydophila pecorum.

Bacteria of the family Chlamydiaceae are obligate intracellular pathogens of human and animals. Chlamydophila pecorum is associated with different pathological conditions in ruminants, swine and koala. To characterize a coding tandem repeat (CTR) identified at the 3' end of incA gene of C. pecorum, 51 strains of different chlamydial species were examined. The CTR were observed in 18 of 18 tested C. pecorum isolates including symptomatic and asymptomatic animals from diverse geographical origins. The CTR were also found in two strains of C. abortus respectively isolated from faeces from a healthy ewe and from a goat belonging to asymptomatic herds, but were absent in C. abortus strains isolated from clinical disease specimens, and in tested strains of C. psittaci, C. caviae, C. felis and C. trachomatis. The number of CTR repeats is variable and encode several motifs that are rich in alanine and proline. The CTR-derived variable structure of incA, which encode the Chlamydiaceae-specific type III secreted inclusion membrane protein, IncA, may be involved in the adaptation of C. pecorum to its environment by allowing it to persist in the host cell.