Figure 1

BXD strains exhibit variable kinetics of weight loss and survival after infection with Influenza A virus. Mice from 53 BXD and parental strains were infected intra-nasally with 2 × 10³ FFU of PR8 virus. Weight loss and survival of infected mice was followed over a period of 13 days. Mortality includes mice that were sacrificed because they had lost more than 25% of body weight. Three phenotypic groups can be distinguished: in the first group (A), all infected mice within a given BXD strain survived, in the second group (B) less than 50% of infected mice within a given BXD strain died, in the third group (C), more than 50% of infected mice within a given BXD strain died. From the weight loss curve of the second and third group it also becomes obvious that non-surviving mice were all approaching the 75% body weight loss endpoint before dying.