To further characterize the effects of MHV68 infection on the CD8+ T cell phenotype, CD8bright and CD8dim T cells were individually isolated using a FACSAria flow sorter from splenocytes of infected animals by identification and subsequent purification of CD8bright or dim/CD4−/CD19−/NK1.1- cells and compared to CD8+/CD4−/CD19−/NK1.1− cells purified from non-infected animals. The gene discussed is CD4; the disease is infection.