Characterisation of Chlamydia pneumoniae and other novel chlamydial infections in captive snakes

Chlamydiosis has been described in both free-ranging and captive reptiles. The infection usually manifests as granulomatous inflammation in inner organs such as spleen, heart, lung and liver but might also occur in asymptomatic reptiles. The aim of this study was to investigate and characterise Chlamydia pneumoniae and potential other novel chlamydial infections in the choana and cloaca samples of 137 clinically healthy captive snakes from six private collections. Forty eight samples from 29 animals were found to be positive by a Chlamydiaceae family-specific qPCR. By Chlamydia species-specific ArrayTube Microarray, 43 samples were positive, with 36 of these being identified as C. pneumoniae. The prevalence of Chlamydia ranged from 5 to 33%. PCR and sequencing of the Chlamydiales 16S rRNA signature sequence of 21 Chlamydia positive samples revealed the presence of seven novel 16S rRNA genotypes. BLAST-n and phylogenetic analysis of the near-full length 16S rRNA gene sequence of each of these novel 16S rRNA sequences revealed that five genotypes share closest sequence identity to 16S rRNA sequences from C. pneumoniae (98.6-99.2%), suggesting that these sequences are novel C. pneumoniae strains. One genotype is 96.9% similar to C. pneumoniae strains suggesting it may originate from a yet undescribed chlamydial species within the genus Chlamydia. This study further highlights the broad host range for C. pneumoniae and suggests that reptiles may still contain a significant and largely uncharacterised level of chlamydial genetic diversity that requires further investigation.