Ross River virus (RRV), the most common cause of mosquito-borne disease in Australia, results in a debilitating musculoskeletal inflammatory disease in humans. The clinical manifestations typically presented include maculopapular rash, fever, myalgia and polyarthralgia. Viraemia usually clears within a week after infection and it is unclear how patients still experience long-term symptoms such as myalgia and polyarthralgia after recovery from the initial infection1. Many mouse model studies have demonstrated that the virus is able to replicate to high titres in bones, joints and skeletal muscle associated tissues2. Furthermore, it has been shown that RRV RNA can be detected in the synovium extracted from the joints of RRV disease patients five-weeks post initial clinical presentation3.
To determine if persisting levels of infectious virus and/or viral genome is a contributing factor to RRV-induced chronic disease, we aimed to determine the cell types which are permissive to RRV infection and demonstrate their potential as reservoirs for long-term viral replication and/or maintenance of viral RNA. To investigate this, we are conducting long-term RRV infections using cell types present in joints and surrounding tissues. Cell types such as chondrocytes, macrophages, myocytes, osteoclast and osteoblasts are of interest as they are present at the site of inflammation in joints and muscle. Infected cells kept in culture for at least 60 days will be used to assess persistence of both infectious virus by plaque assay and viral RNA through qPCR and northern blot studies. While sampling is still ongoing, virus has been detected in RRV-infected human primary chondrocytes up to 11 days post infection. Collectively, the data produced will for the first time demonstrate that RRV and/or its genome can persist in cells from joints and muscle.