Like the immune-competent mice, Rag1−/− PEP-R619W mice had noticeably less weight loss throughout most of the early stages of the infection (Fig. 2A and 2B) and mice survived longer (Fig. 2C and 2D) compared to Rag1−/− PEP-WT mice at both 5e4 and 1e5 PFU MHV A59 infection. This evidence concerns the gene RAG1 and infection.