Since irradiated BM recipients still retain some endogenous hematopoietic stem cells, we repeated the LCMV-Cl13 infection in BM chimeras using TCRβ KO recipient mice instead (i.e., mice lacking endogenous αβT cells) and obtained similar results where chimeras with TdT KO T cells had a 3.74-fold increase in viral load by day 41 post-infection (S4H and S4I Fig). The gene discussed is DNTT; the disease is infection.