Induction of neutralizing antibody response against koala retrovirus (KoRV) and reduction in viral load in koalas following vaccination with recombinant KoRV envelope protein

• Published in: npj vaccines Vol. 3; no. 1; p. 30
• Main Authors: Olagoke, O, Miller, D, Hemmatzadeh, F, Stephenson, T, Fabijan, J, Hutt, P, Finch, S, Speight, N, Timms, P
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 02.08.2018; Nature Publishing Group
• Subjects: 631/250/255; 631/250/590; 631/326/590/2294; 631/326/596/1787; 692/699/255/2514; Antiretroviral drugs; Biomedical and Life Sciences; Biomedicine; Immunoglobulins; Infectious Diseases; Medical Microbiology; Proteins; Public Health; Vaccine; Vaccines; Virology; Australia
• ISSN: 2059-0105; 2059-0105
• DOI: 10.1038/s41541-018-0066-4

Koala retrovirus (KoRV) infects the majority of Australia’s koalas ( Phascolarctos cinereus ) and has been linked to several life-threatening diseases such as lymphoma and leukemia, as well as Chlamydia and thus poses a threat to the continued survival of this species. While quarantine and antiretroviral drug treatment are possible control measures, they are impractical, leaving vaccination as the only realistic option. In this study, we examined the effect of a recombinant envelope protein-based anti-KoRV vaccine in two groups of South Australian koalas: KoRV infected or KoRV free. We report a successful vaccination response in the koalas with no vaccine-associated side effects. The vaccine induced a significant humoral immune response as well as the production of neutralizing antibodies in both groups of koalas. We also identified B-cell epitopes that were differentially recognized in KoRV-infected versus KoRV-free koalas following vaccination. Importantly, we also showed that vaccination had a therapeutic effect on koalas infected exogenously with KoRV by reducing their circulating viral load. Together, this study highlights the possibility of successfully developing a vaccine against KoRV infection in koalas. Koala retrovirus: Hopes for an effective vaccine A vaccine candidate for Koala retrovirus elicits a protective antibody response and reduces the viral load in already-infected koalas. Koala retrovirus (KoRV), first identified in the last 20 years, is a life-threatening, endemic pathogen affecting Australian koalas. In pursuit of an effective KoRV vaccine, the University of the Sunshine Coast’s Peter Timms led a group of Australian scientists to develop a candidate based on the transmembrane section of the virus’ envelope protein. The six koalas vaccinated in the study all generated a strong antibody response to the envelope protein, and a strong neutralizing antibody response was reported during in vitro tests. Vaccinated koalas with pre-existing KoRV infection benefited from an average 79% reduction in viral load when measured 12 weeks after vaccination. Further research should be prioritized to provide much-needed protection to Australia’s koalas.