Given that chronic musculoskeletal disease is associated with infection by a number of different arthritogenic alphaviruses,2 we evaluated if mice infected with MAYV or RRV also have elevated MHC-II+ macrophages and CD4+ T cells in joint tissue during the chronic phase, and if joint macrophages harbor MAYV and/or RRV RNA. The gene discussed is CD4; the disease is musculoskeletal system disorder.