Genetics of the idiotype of strain AKR antibodies to group A streptococcal carbohydrate; further evidence for a low degree of homology in the VH chromosomal region.

A new VH gene is described which governs the expression of idiotypes associated with the antibody response of strain AKR mice to Group A streptococcal carbohydrate (A-CHO). This VH gene, termed ACHd, is identified using guinea pig antisera to a pool of strain AKR antibodies to A-CHO. The genetic polymorphism is revealed by quantitative differences in idiotype expression between different inbred strains. In recombinant inbred strains linkage to the Ig-1d allotype allele of strain AKR is demonstrated. In a putative recombinant strain it appears that ACHd maps at a locus different from that of A5A+, another VH gene controlling idiotypes of anti-A-CHO antibodies. This represents a further example of pseudoallelism between related VH genes and lack of homology in the VH chromosomal region. Expression of the ACHd gene was independent of the Ly-2, 3 locus which is associated with kappa chain variants.