| Research Abstract |
1 ) A total of 77 Chlamydia psittaci strains of avian, human, and mammalian origin were grouped into four serovars with 11 monoclonal antibodies recognizing the lipopolysaccharide and the major outer membrane protein antigens. The avian and human strains, which were closely related to each other, were distinct from the mamalian strains. Immunological typing of C. psittaci with monoclonal antibodies seems practical.
2 ) Immunochemical properties of the major outer membrane protein (MOMP) of 16 strains of Chlamydia psittaci isolated from psittacine birds, budgerigars, a pigeon, turkeys, humans, cats, a muskrat, sheep, and cattle and a strain of C. trachomatis, L2/434/Bu, were compared by sodium dodecyl sulfate- polyacrylamide gel electrophoresis and by immunoblotting analysis with hyperinnunized rabbit antisera to strains of parrot, turkey, feline, and bovine origin. The MOEPs of the strains showed variation in molecular weights and immunological specificities. Fifteen of the C. psittaci
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strains were classified into two avian and two mammalian types based on immunological specificity of the MOMP, whereas the other strain was not classified in this study. Immunological classification based on specificity of the MOMP by immunoblotting proved to be a valuable method to classify various strains of C. psittaci.
3 ) 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 SalI, DNA-DNA hybridization in solution with Sl 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. Less
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