Infectivity of three Mayaro Virus (Genus Alphavirus, Family Togaviridae) geographic isolates in human cell lines

Mayaro virus (MAYV) is an emergent arthropod-borne virus that causes an acute febrile illness accompanied by arthralgia, similar to chikungunya virus. Increasing urbanization of MAYV outbreaks in the Americas has led to concerns that this virus could further expand its geographic range. Given the potential importance of this pathogen, we sought to fill some critical gaps in knowledge regarding MAYV infectivity and geographic variation. This study describes the cytopathogenicity of MAYV in human dermal fibroblasts, human skeletal muscle satellite cells, human embryonic kidney cells (HEK), peripherally derived human macrophages, and Vero cells. MAYV strain isolated from Bolivia (MAYV-U) infected cells more rapidly compared to MAYV strains isolated in Peru and Brazil (MAYV-P; MAYV-B), with high titers (1x10 8 pfu/ml) peaking at 37 hours post infection. MAYV-U also caused the most cytopathic effect in a time dependent manner. Furthermore, differently from the other two prototypic strains, MAYV-U harbors unique mutations in the E2 protein, D60G and S205F, likely to interact with the host cell receptor, which may explain the observed differences in infectivity. We further demonstrate that pre-treatment of cells with interferon-{beta} inhibited viral replication in a dose-dependent manner. Together, these findings advance our understanding of MAYV infection of human target cells and provide initial data regarding MAYV phenotypic variation according to geography.