T cells bearing Vβ8 are preferentially infected with exogenous mouse mammary tumor virus

We previously reported that a mouse mammary tumor virus (MMTV(II-TES14)), encoding a superantigen specific for TCR Vβ14, can infect lymph node (LN) cells of mice in an I-E-independent manner. Here we examined the kinetics of cell types infected with exogenous MMTV in the draining LN after s.c. injection of II-TES milk containing MMTV(II-TES14). The infectivity was assessed in LN cells sorted into each cell subset by a semiquantitative analysis of MMTV provirus using PCR with a primer specific for MMTV(II-TES14). Only B cells in the LN were infected by the MMTV on day 6 after injection, but CD8 ⁺ T cells and, to a lesser extent, CD4 ⁺ T cells were also found to be detectably infected on day 14 after the injection of II-TES milk. Among the T cells we examined, Vβ8 T cells were most preferentially infected with MMTV, but no Vβ314 T cells specific for MMTV(II-TES14) superantigen were infected on day 14 after infection. The transfer of Vβ8 T cells sorted from mice injected with II-TES milk 14 days previously resulted in the deletion of CD4 ⁺Vβ14 T cells and in the MMTV infection of normal B6 mice. No MMTV infection of T cells occurred in IgM knockout mice, which lack a mature B cell compartment. These results suggest that MMTV surviving in B cells is transferred to Vβ8 T cells, which may play an important role in MMTV longevity.