Infectivity of three Mayaro Virus 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 for geographic expansion and spillover. Given the potential importance of this pathogen, we sought to fill 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. We found that regional differences between these viruses do not affect replication kinetics, with high titers peaking at 37 h post infection. MAYV-U, did however, cause the most cytopathic effect in a time-dependent manner. Compared to the other two prototypic isolates, MAYV-U harbors unique mutations in the E2 protein, D60G and S205F, that are likely to interact with the host cell receptor and could affect infectivity. We further demonstrate that pre-treatment of cells with interferon-β 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 variation according to geography.