Abstract
Development of polioencephalomyelitis in mice infected with lactate dehydrogenase-elevating virus (LDV) requires expression of N-tropic ecotropic MuLV retroviruses. 129/Sv mice are resistant to N-tropic MuLV expression and therefore do not develop LDV-induced polioencephalomyelitis. The Fv1 gene determines the susceptibility to retrovirus replication. We sequenced the open reading frame of the Fv1nr allele of 129/Sv mice. It differs by only one nucleotide, modifying one amino acid in the encoded protein, from the Fv1n allele of susceptible AKR and C58 animals. Weexcluded that the resistance of (129/Svmice to LDV-induced polioencephalomyelitis resulted from the absence of endogenous N-tropic retrovirus, by infecting (129/Sv × C58/J) F1 animals. Therefore it is possible that the amino acid that defines the Fv1nr allele is responsible for resistance of 129/Sv mice to N-tropic MuLV expression and to LDV-induced polioencephalomyelitis.