DETECTION OF CHLAMYDIA-PSITTACI DNA IN AVIAN CLINICAL-SAMPLES BY POLYMERASE CHAIN-REACTION

A polymerase chain reaction (PCR) assay was developed to detect Chlamy dia psittaci DNA in faeces and tissue samples from avian species. Prim ers were designed to amplify a 264 bp product derived from part of the 5' non-translated region and part of the coding region of the ompA ge ne which encodes the major outer membrane protein. Amplified sequences were confirmed by Southern hybridization using an internal probe. The sensitivity of the combined assay was found to be between 60 to 600 f g of chlamydial DNA (approximately 6 to 60 genome copies). The specifi city of the assay was confirmed since PCR product was not obtained fro m samples containing several serotypes of C. trachomatis, strains of C . pneumoniae, the type strain of C. pecorum, nor from samples containi ng microorganisms commonly found in the avian gut flora. In this study , 404 avian faeces and 141 avian tissue samples received by the Centra l Veterinary Laboratory over a 6 month period were analysed by PCR, an tigen detection ELISA and where possible, cell culture isolation. PCR performed favourably compared with ELISA and cell culture, or with ELI SA alone. The PCR assay was especially suited to the detection of C. p sittaci DNA in avian faeces samples. The test was also useful when app lied to tissue samples from small contact birds associated with a case of human psittacosis where ELISA results were negative and chlamydial isolation was a less favourable method due to the need for rapid diag nosis.