Bioluminescent Ross River Virus Allows Live Monitoring of Acute and Long-Term Alphaviral Infection by In Vivo Imaging.

Arboviruses like chikungunya and Ross River (RRV) are responsible for massive outbreaks of viral polyarthritis. There is no effective treatment or vaccine available against these viruses that induce prolonged and disabling arthritis. To explore the physiopathological mechanisms of alphaviral arthritis, we engineered a recombinant RRV expressing a NanoLuc reporter (RRV-NLuc), which exhibited high stability, near native replication kinetics and allowed real time monitoring of viral spread in an albino mouse strain. During the acute phase of the disease, we observed a high bioluminescent signal reflecting viral replication and dissemination in the infected mice. Using Bindarit, an anti-inflammatory drug that inhibits monocyte recruitment, we observed a reduction in viral dissemination demonstrating the important role of monocytes in the propagation of the virus and the adaptation of this model to the in vivo evaluation of treatment strategies. After resolution of the acute symptoms, we observed an increase in the bioluminescent signal in mice subjected to an immunosuppressive treatment 30 days post infection, thus showing active in vivo replication of remnant virus. We show here that this novel reporter virus is suitable to study the alphaviral disease up to the chronic phase, opening new perspectives for the evaluation of therapeutic interventions.