Koala retrovirus infection and disease in South Australian koala (Phascolarctos cinereus) populations. In Proceedings of the Second Koala Retrovirus Workshop, ed. D. E. Alquezar-Planas, D. P. Higgins, C. L. Singleton, and A. D. Greenwood

Abstract

Koala retrovirus (KoRV) infection, endogenous in all northern koalas (Phascolarctos cinereus), has been found to occur at lower, but increasing, prevalence in the Kangaroo Island and Mount Lofty Ranges koala populations in South Australia. Proviral and viral loads are also lower than in Queensland koalas, which may be due to exogenous spread of infection, or may be related to the variable presence of viral genes and fragmented expression that has been found in positive Mount Lofty Ranges koalas. However, high proviral loads and full expression across the KoRV genome in South Australian koalas has been found in individuals with neoplasia, particularly lymphoma, which can be as extensive and as severe as that observed in northern koalas. KoRV-A is the predominant subtype and no association with chlamydial status has been found except that high viral loads correlate with severity of chlamydiosis. Based on the complexity of KoRV infections in South Australian koalas, further research is needed to understand the differences in transmission and pathogenesis that occur.