HLA-DQ_β chain can present mouse endogenous provirus MTV-9 product and clonally delete Tcr V_β5⁺ and V_β11⁺ T cells in transgenic mice

The elusive Mls gene(s) are mouse mammary tumor virus genes. The endogenous cotolerogen involved in the clonal deletion of Tcr V_β5.1, 5.2, and 11 in H-2E⁺ mouse strains has been narrowed down to MTV-9. We demonstrate that similar to H-2E_α molecules, human DQw6_β chain mediated clonal deletion of Tcr V_β5.1, 5.2, and 11 also requires the MTV-9 gene product. This shows that human class II molecules can present mouse retroviral antigen. Further, backcross analysis involving [B10.M(DQb)×DBA/1] suggest a second cotolerogen in the B10.M background in the clonal deletion of V_β5-bearing T cells.