Fig. 3.

Roles of the major histocompatibility complex (MHC) in combating virus infections. (a) Mouse susceptibility loci in the MHC are shown. Studies using congenic mice having intra-MHC recombination identified the contribution of specific MHC alleles to virus infection. Mostly, MHC class I genes play a crucial role against virus infection of mice. Only a small number of genes in the MHC and their relative positions on chromosome 17 are shown. (b) Genetic associations of the human MHC with susceptibility to virus infection. Only a small number of genes in the MHC, with their relative positions on chromosome 6, are shown. The genes encoding class I are depicted in red, class II in yellow and class III in green. TNF is the gene encoding tumor necrosis factor. C2 and C4 are complement genes.