Rabies Virus Is Recognized by the NLRP3 Inflammasome and Activates Interleukin-1β Release in Murine Dendritic Cells

Inflammasome activation is important for the development of an effective host defense against many pathogens, including RNA viruses. However, the mechanism by which the inflammasome recognizes RNA viruses and its role in rabies virus (RABV) pathogenicity and immunogenicity remain poorly defined. To determine the function of the inflammasome in response to RABV infection, we infected murine bone marrow-derived dendritic cells (BMDCs) with RABV. Our results indicate that the infection of BMDCs with RABV induces both the production of pro-interleukin-1 beta (pro-IL-1 beta) and its processing, resulting in the secretion of active IL-1 beta through activation of the NLRP3-, ASC-, and caspase-1-dependent inflammasome. As previously shown for the induction of type I interferon by RABV, the induction of pro-IL-1 beta also depends upon IPS-1. We demonstrate that both the production of pro-IL-1 beta and activation of the inflammasome require viral replication. We also demonstrate that increased viral replication in BMDCs derived from IFNAR-deficient mice resulted in significantly more IL-1 beta release. Additionally, IL-1 receptor-deficient mice show an increase in RABV pathogenicity. Taken together, these results indicate an important role of the inflammasome in innate immune recognition of RABV.