FV-1 restriction of age-dependent paralytic lactic dehydrogenase virus infection

A genetic analysis was made of the susceptibility of inbred mice to a paralytic disease elicited by the ip injection of a neuroparalytic strain of lactic dehydrogenase virus. The frequency of disease in susceptible inbred mice was X-ray dose and age dependent. Analysis of the susceptibility of appropriate F₁ hybrids and their backcross progeny showed that susceptibility was not linked to the major histocompatibility complex but segregated with the Fv-1 linkage group. Linkage group analysis showed that resistance to paralytic infection was linked to a single gene outside the major histocompatibility complex. By determining the segregation of Gpd-1 isozyme variants among backcross progeny it was shown that inheritance of the Fv-1^b allele resulted in virtually absolute restriction of susceptibility. Genetic evidence was obtained indicating that mice that mice that had multiple copies of N-tropic C-type retroviruses in their genomes, and that were permissive for retrovirus expression (Fv-1^n/n), were susceptible to paralytic LDV infection. Strains that carried few copies of N-tropic C-type retroviruses in their genomes, or that inherited the Fv-1^b allele, were resistant. A significant maternal resistance effect was demonstrable in some backcross generations that appeared to be mediated by H-2^b in the major histocompatibility complex.