Genetic diversity of avian and mammalian Chlamydia psittaci strains and relation to host origin

Abstract

Genetic relationships were reported for Chlamydia psittaci derived from psittacine birds, pigeons, turkeys, humans, cats, muskrats, cattle, and sheep and for C. trachomatis, including representative strains of the three biovars, through physical analysis of genomic DNA including DNA fingerprinting with restriction endonuclease Sall, DNA-DNA hybridization in solution with S1 nuclease, and Southern analysis with genomic DNA probes. A total of 26 strains were divided into four groups of C. psittaci and two groups of C. trachomatis, on the basis of DNA fingerprints. The six groups of Chlamydia spp. were related to host origin: two avian groups (Avl and Av2), one feline and muskrat group (Fel), one ruminant group (Rul), one C. trachomatis biovars trachoma and lymphogranuloma group (CtHu), and one C. trachomatis mouse biovar group (CtMo), although an ovine abortion strain belonged to the avian group Av2. DNA-DNA hybridization assay and Southern analysis with genomic DNA probes indicated three DNA homology groups in the genus Chlamydia: an avian-feline group (groups Avl, Av2, and Fel), a ruminant group (group Rul), and a C. trachomatis group (groups CtHu and CtMo). Furthermore, the Southern analysis indicated that the homologous sequences (DNA homology of at least 14%) within the avian-feline group were distributed along the whole genome, whereas the homologous sequences (DNA homology of less than 24%) among the three DNA homology groups were localized in distinct regions of the genome DNA. These results suggest that Chlamydia spp. are derived from a common ancestor and have diverged into various groups showing restricted host ranges as a natural characteristic and that the species C. psittaci should be differentiated into groups related to host origin and DNA homology.The genus Chiamydia comprises two species, Chiamydia psittaci and Chlamydia trachomatis (23). Differentiation of the two species is based on natural hosts, inclusion morphology, glycogen in inclusions, and folate biosynthesis (23). In the genus Chlamydia, interspecies DNA-DNA homology is less than 10%, while intraspecies DNA-DNA homology is almost 100% (12), although the mouse pneumonitis strain which is the mouse biovar of C. trachomatis showed only 30 to 60% DNA-DNA homology with other strains of the same species (29). The DNA-DNA homology of C. psittaci was, however, estimated for only two avian-related strains, California 10 (designated Frt-Hu/CallO in the present study) and 6BC (Prk/6BC in the present study) (12), despite the isolation of C. psittaci from a variety of animals and birds and despite a wide range of guanine and cytosine content (40 to 44 mol% G+C) (9). Immunological and biological analyses indicated phenotypic heterogeneity of C. psittaci (14,27). Recent analyses of DNA fingerprints also showed differences among several strains of C. psittaci (1,18,28).We have reported a series of studies for establishing a systematic classification of C. psittaci, such as immunological typing with monoclonal antibodies (8) and immunoblotting analysis ...

Genetic Diversity and Epizootiology ofChlamydophila psittaciPrevalent among the Captive and Feral Avian Species Based on VD2 Region ofompAGene

“…some isolates having the characteristic of both groups (9,13,34,43,46). Recent studies have also pointed toward this fact (42).…”

Emended description of the order Chlamydiales, proposal of Parachlamydiaceae fam. nov. and Simkaniaceae fam. nov., each containing one monotypic genus, revised taxonomy of the family Chlamydiaceae, including a new genus and five new species, and standards for the identification of organisms

“…Some of these influences are evident in the available DNA reassociation data for chlamydiae. For example, C. psittaci B577 has been reported to have similarities of 34 and 85% versus C. psittaci 6BCT; B577 has reported similarities of 27 and 46% with C. psittaci Cal-10 MN (Fukushi & Hirai, 1989) ( Table 1). Such wide variances in chlamydial data indicate that DNA-DNA reassociation is not the method of choice for conclusively determining relatedness among chlamydial populations.…”

“…t Fukushi & Hirai (1989). Note also that interspecies analyses were carried out with one Chlamydophila pecorum strain, and that Chlamydophila pecorum intraspecies analysis used three.…”

Recent Epidemiological Status of Feline Upper Respiratory Infections in Japan.

“…Nucleotide and amino acid sequence homologies between them were found to be 99.5% and 99.1%, respectively (data not shown), again suggesting high homogeneity of the ompA gene of feline C. psittaci. It has been described that there are two genotypes in feline C. psittaci, for instance, based on the RFLP analysis of genomic DNA; types Fe1a and Fe1b represented by Pn-1 and Cello strains, respectively [5,22]. In addition, it was pointed out that cats might have been infected with some antigenically different Chlamydia species on the basis of a serological study [21].…”