Molecular characterization of Chlamydophila pneumoniae isolates from Western barred bandicoots

Abstract

Chlamydophila pneumoniae is an obligate intracellular respiratory pathogen that has been associated with pneumonia and chronic bronchitis, atherosclerosis, asthma and other chronic diseases in humans. However, C. pneumoniae is not restricted to humans, as originally thought, and can cause infections in several animal hosts. C. pneumoniae was isolated in cell culture from nine Western barred bandicoots (Perameles bougainville) from Australia. The sequences of five genomic regions were determined, including full-length sequences of the 16S rRNA and ompA genes and the ygeD-urk intergenic spacer, and partial sequences of the 23S rRNA and rpoB genes. Sequence analysis of the entire 16S rRNA and ompA genes from bandicoot isolates demonstrated that they were 98.2-98.3% similar to human isolates, 94.6-99.3% similar to the equine biovar and almost identical, with 99.5-99.9% similarity, to the koala biovar. Comparative genotyping of the variable domain 4 region of the ompA gene demonstrated that bandicoot isolates seemed to be identical to the animal genotype that has been recently identified in human carotid plaque specimens. Minor sequence polymorphism observed in ompA, 16S rRNA and rpoB genes of animal isolates, indicating genomic diversity within C. pneumoniae, may have important implications for diagnostic PCR assays leading to false negative results. Forty percent of selected published species-specific PCR assays were found to have sequence variability in primer and/or probe that might affect their performance in detecting bandicoot isolates of C. pneumoniae, or possibly other animal and human strains where minor sequence polymorphisms may be present. The data from this study support the previous observations that C. pneumoniae is not restricted to humans and may be widespread in an animal reservoir with a potential risk of transmission to humans.