Small numbers of allotypically marked EF4.1 TCRβ-transgenic CD4+ T cells were transferred into wild-type (WT) C57BL/6 (B6) recipients and primed either by infection with Friend virus (FV) or by immunization with a human Adenovirus 5 (Ad5)-based vector expressing F-MLV gp70 (Ad5.pIX-gp70) (Bayer et al., 2010). This evidence concerns the gene CD4 and infection.