Real-time reverse transcriptase PCR for the endogenous koala retrovirus reveals an association between plasma viral load and neoplastic disease in koalas

• DOI: 10.1099/vir.0.80547-0
• Publication Date: 2005-02-19T01:05:31Z
• Authors: Rachael Tarlinton; Joanne Meers; Jon Hanger; Paul Young
• Keywords: Identification; 630; Phascolarctos-cinereus; Mice; 03 medical and health sciences; C1; Virology; Neoplasms; Animals; Gene-expression; Viremia; 270304 Infectious Agents; 0303 health sciences; 270802 Diagnostic Applications; Reverse Transcriptase Polymerase Chain Reaction; 780105 Biological sciences; Endogenous Retroviruses; 3. Good health; 270199 Biochemistry and Cell Biology not elsewhere classified; Herv-k; Particles; Biotechnology & Applied Microbiology; 270303 Virology; 270708 Conservation and Biodiversity; RNA, Viral; Leukemia-virus; Infection; Phascolarctidae; 0605 Microbiology

Koala retrovirus (KoRV) is a newly described endogenous retrovirus and is unusual in that inserts comprise a full-length replication competent genome. As koalas are known to suffer from an extremely high incidence of leukaemia/lymphoma, the association between this retrovirus and disease in koalas was examined. Using quantitative real-time reverse transcriptase PCR it was demonstrated that KoRV RNA levels in plasma are significantly increased in animals suffering from leukaemia or lymphoma when compared with healthy animals. Increased levels of KoRV were also seen for animals with clinical chlamydiosis. A significant positive association between viral RNA levels and age was also demonstrated. Real-time PCR demonstrated as much as 5 log variation in KoRV proviral DNA levels in genomic DNA extracted from whole blood from different animals. Taken together these data indicate that KoRV is an active endogenous retrovirus and suggests that it may be causally linked to neoplastic disease in koalas.