Mayaro virus replication restriction and induction of muscular inflammation in mice are dependent on age and type-I interferon response

Mayaro virus (MAYV) is an emergent Arbovirus belonging to the Alphavirus genus from theTogaviridaefamily which has been circulated in forest regions of American continent through small outbreaks. Recent studies warned for the risk of MAYV dispersion to new areas and for the potential establishment of an urban epidemic cycle. Similar to Chikungunya and other arthritogenic Alphavirus, MAYV-induced disease shows a high prevalence of arthralgia and myalgia that can persist for months. Despite this, knowledge regarding pathogenesis, characteristics of host immune response, and resolution of MAYV infections are still limited. Here we investigated the dependence of age, innate and adaptive immunity for the control of MAYV replication and induction of inflammation in mice. We observed that age and type I interferon response are related to restriction of MAYV infection and tissue inflammation in mice. Moreover, we showed that MAYV continues to replicate persistently in adult recombination activation gene-1 efficient mice (RAG1−/−), indicating that adaptive immunity is essential to MAYV clearance. Despite chronic replication, infected adult RAG1−/−mice did not develop an apparent signal of muscle damage at late infection. On the other hand, MAYV infection induces muscular and paw inflammation in young WT and adult Type I Interferon receptor deficient mice (IFNAR−/−). In addition, MAYV infection triggers an increase in the expression of pro-inflammatory mediators, such as TNF, IL-6, KC, IL-1β, MCP-1, and RANTES, in muscle tissue, and decreases TGF-β expression. Taken together, our study contributes to the comprehension of MAYV pathogenesis, and describes a translational mouse model for further studies of MAYV infection, as well for testing vaccine and therapeutic strategies against this virus.Author SummaryMAYV-induced disease presents a high prevalence of arthralgia and myalgia that potentially persist for months, which is characteristic of the arthritogenic Alphavirus group. However, information regarding MAYV infection and the molecular mechanism of pathogenesis is still scarce. Here we investigated the dependence of age, innate and adaptive immunity for the control of MAYV replication and induction of inflammation in mice. We observed that tissue inflammation and the restriction of MAYV replication in mice are affected by aging and type I interferon response. Besides, we also showed that adaptive immunity was important for MAYV clearance in adult mice. Histological analyses demonstrated that MAYV replication triggered muscular and paw inflammation in young WT and adult type-I interferon receptor deficient mice. In addition, the level of expression of several pro-inflammatory cytokines was increased in the muscle MAYV-infected mice. Our data provide an advance for understanding the molecular mechanism involved in MAYV pathogenesis, as well as describes anin vivomodel for further investigations on MAYV infection and for antiviral compounds and vaccine testing.