To do this, 10BiT reporter mice (which possess a BAC transgene containing the Il10 gene locus with the Thy1.1 cDNA insertion30) were infected with LCMV Cl13, and on day 16 post infection (p.i.), we sort-purified Thy1.1+(IL-10+)CD4 T cells specific for the I-Ab restricted GP61-80 epitope of LCMV (Fig. 1a). This evidence concerns the gene CD4 and infection.