Weak bases affect late stages of Mayaro virus replication cycle in vertebrate cells

This paper describes the effect of two weak bases (ammonium chloride and chloroquine) on the morphogenesis of Mayaro virus. When Mayaro virus-infected TC7 (monkey kidney) cells were treated with these agents it was observed that weak bases caused a significant reduction in virus yield. Also, cellular protein synthesis, which is inhibited by Mayaro virus infection, recovered to nearly normal levels, However, the synthesis of Mayaro virus proteins was affected. These phenomena were dose-dependent. The process of Mayaro virus infection in vertebrate cells is very rapid, Virus precursors are not observed in cell cytoplasm and budding through the plasma membrane seems to be the only way of virus release. Electron microscopy of cells infected with Mayaro virus and treated with weak bases revealed an accumulation of virus structures in cell cytoplasm, The study also noted an inhibition of budding through the plasma membrane and the appearance of virus particles inside intracytoplasmic vacuoles. These observations indicate an impairment at the final stages of the virus replication cycle.