EVIDENCE FOR NUMEROUS OMP1 ALLELES OF PORCINE CHLAMYDIA-TRACHOMATIS AND NOVEL CHLAMYDIAL SPECIES OBTAINED BY PCR

A nested PCR for genus-specific amplification of the Chlamydia omp1 lo cus was established, This PCR detected single template molecules in 20 0-mu l specimen aliquots. Amplified chlamydial omp1 alleles were typed by heminested species PCRs and allele PCRs, We applied this method to 407 specimens from several host animals with various clinical conditi ons, and we detected prevalences of chlamydiae from 6 to 50%, Amplicon s from peacock enteritis and equine infertility specimens were not typ eable according to present omp1 allelic criteria for the chlamydial sp ecies, DNA sequencing revealed novel omp1 alleles which were 29.9 and 47.6% divergent in the deduced peptide sequences from the most closely related chlamydiae, Phylogenetic reconstruction indicated segregation of these alleles from the current four chlamydial species (90 and 97% bootstrap support), thus strongly suggesting the existence of additio nal chlamydial species. Allele typing of amplicons from swine with int estinal, urogenital, and respiratory infections demonstrated several u nique omp1 allelic variants of Chlamydia trachomatis. These novel alle les had deduced peptide sequences which were 11.6 to 19% divergent fro m porcine C. trachomatis S45. Mutations were clustered in the C-termin al region of variable segment IV of the omp1 locus encoding subspecies and serovar determinants of the chlamydial major outer membrane prote in, thus implying that there are numerous serovars of porcine C. trach omatis. These results demonstrate the need for routine application of sensitive genus-specific detection of chlamydiae in animal specimens a nd suggest a more prominent role than anticipated for chlamydiae in an imal diseases.