To investigate the in vivo role of OASL1 in T-cell differentiation and viral defense upon chronic viral infection, we infected both WT and Oasl1 KO mice with LCMV CL-13 and monitored CD8+ T-cell numbers and phenotypes as well as viral titers in the blood for 35 days (d) post-infection (p.i.). The gene discussed is CD8A; the disease is viral infectious disease.