In this study, we use C57BL/6 mice mutated using CRISPR/Cas9 to express the murine ortholog of the Ptpn22 pro-autoimmune allele (PEP-619WW) and LCMV-cl13 to define new mechanisms by which the autoimmunity associated allele of PTPN22 contributes to viral clearance and enhances anti-viral T cell and myeloid cell responses. The gene discussed is PTPN22; the disease is Autoimmunity.