Impact of MHC class I gene on resistance to murine AIDS.

Development of murine AIDS in mice following infection with LP-BM5 murine leukaemia virus (MuLV) is highly strain dependent, with strain differences determined by genes within and outside H-2. Among H-2 genes, the Dd gene is the most closely associated with resistance to LP-BM5 MuLV infection. However, the Dd-mediated resistance is highly influenced by outside H-2 genes, i.e. A lineage strains are more resistant than mice strains of B6/B10 lineage. In this study, the mice having BALB background were analysed and, similarly to A lineage mice, only Dd gene products were found to be required to provide resistance to LP-BM5 MuLV infection. Furthermore, BALB/c Kh mice bearing both Dd and Ld genes clearly showed obviously higher resistance than BALB/c-H-2dm2 mice solely having the Dd gene. In addition, in the long-term observation of the effect of the Dd gene on B6/B10 background mice, D8 mice having the Dd gene as a transgene and expressing a high level Dd gene product showed higher resistance than naturally recombinant B10.A(18R) mice. These results suggest that the MAIDS resistance associated with the D end loci is dependent on the level of expression of an MHC class I gene.