Ross River virus (RRV) is a common mosquito-borne alphavirus that causes debilitating arthritis in thousands of Australians annually¹. The clinical manifestations typically presented include maculopapular rash, fever, myalgia and polyarthralgia. Interestingly, 5-50% of patients experience long-term joint and muscle pain after recovery even though viraemia usually clears one week after infection^1,2. Many mouse studies have demonstrated that RRV can replicate to high titres in bones, joints and skeletal muscle associated tissues³. Furthermore, RRV RNA has been detected in synovium of RRV disease patients up to five-weeks post initial clinical presentation⁴. Our goal is to determine if persisting levels of infectious virus and/or viral genome present in the joints contributes to alphavirus-induced chronic disease.

In this study, we will identify the cell types that can harbour long-term RRV viral replication and/or maintenance of viral RNA. Cells present in joint-associated tissues such as chondrocytes, macrophages, myocytes, osteoclasts and osteoblasts will be infected with RRV for up to 120 days. Viral genome transcription and/or host inflammatory responses will be measured every 1-2 weeks by gene expression analysis.

Preliminary data has shown that infectious RRV virus and viral RNA can be detected in human primary chondrocytes up to 11 and 122 days post-infection respectively. Additionally, we found changes in gene expression of several key soluble factors associated with disease pathogenesis (IL-6, MCP-1, TNF-a, etc.). Collectively, the data produced will, for the first time, demonstrate the persistence of RRV and/or its genome in cells of joints.