Drosophila-host genetic control of susceptibility to Drosophila C virus.

Interactions between Drosophila C virus (DCV) and its natural host, Drosophila melanogaster, were investigated using 15 geographical population samples infected by intraabdominal inoculation. These strains derived from natural populations of D. melanogaster differed in susceptibility to the DCVc. One strain was "partially tolerant". Isofemale lines obtained from one susceptible and one partially tolerant strain were studied. The partially tolerant phenotype was dominant, and there was no difference between F1 progeny of direct and reciprocal crosses. Analysis of F2 progeny showed that neither sex-linked genes nor maternal effects are involved in susceptibility to DCVc. The partially tolerant strain phenotype was dominant and segregated with chromosome III. Two nonexclusive hypotheses are proposed to explain chromosome III gene action.