Koalas in Victoria, Australia were re-established predominantly from an island colony after the mainland population collapsed in the early 1900s. The potential for a genetic bottleneck exists in these animals, potentially increasing their risk of experiencing disease. Chlamydia pecorum is a significant pathogen in koalas and is known to be present in Victorian koala populations. Although C. pecorum has been relatively well studied in vulnerable northern koala populations, research devoted to understanding this disease in Victorian populations has been limited. Recent studies utilising molecular techniques have successfully genotyped C. pecorum samples collected from koalas in New South Wales and Queensland, but only four samples from Victorian koalas have been genotyped, and the prevalence and clinical importance of C. pecorum in Victoria is poorly understood.
To address this we determined the prevalence of C. pecorum in koalas (n = 559) across six different regions in Victoria using qPCR targeting the 16S region. The overall prevalence of Chlamydia infection was 22%, although this varied between geographical regions. To facilitate genotype comparisons with northern populations, we sequenced the ompA gene of the C. pecorum samples (n = 100). The predominant C. pecorum in our samples was genotype B, occurring in 90% of cases in our study. This genotype has yet to be detected in northern koalas, but has been previously detected in South Australia. This data, along with clinical data, and data relating to bacterial load (determined by calculating C. pecorum genome copy numbers), is now being used to better understand the clinical significance of C. pecorum infection in Victorian koalas.
This research provides crucial information regarding prevalence and genotype of C. pecorum within Victoria koala populations, and will open up further avenues for comparisons between Victorian koalas and koalas in Queensland and New South Wales.