Abstract
Binding characteristics of mouse spinal cord and spleen cells to naturally occurring, ecotropic (paralytogenic and lymphomagenic 1504M virus) and amphotropic (lymphomagenic 1504A virus) retroviruses of wild mice were investigated. 125I-labeled ecotropic (N-tropic) virus bound efficiently to both spinal cord and spleen cells from SWR/J mice (Fv-1n), but labeled amphotropic (N-tropic) virus bound efficiently only to spleen cells. The extent of binding of 1504M virus to the spinal cord cells was related to the time of incubation and to the amount of labeled input virus. 1504M virus bound to both glial and neuronal subpopulations of the spinal cord with almost equal efficiency. Binding of 125I-labeled 1504M virus to SWR/J mouse spinal cord cells was competitively inhibited by unlabeled homologous virus, whereas an excess of unlabeled 1504A virus inhibited only 10% of the ecotropic virus binding. Unlabeled 1504M virus almost completely inhibited the low-level binding of 125I-labeled 1504A virus to spinal cord cells. The different extent of binding of 1504M virus to spinal cord cells from different strains of mice (SWR/J, NIH Swiss, BALB/c-Jax, Lake Casitas wild, and CD-1) correlated with the susceptibility to paralysis in these strains of mice after inoculation with 1504M virus. Although the spinal cord cells of BALB/c mice contained a moderate amount of 1504M virus receptor sites, these mice were resistant to virus-induced paralysis because of their Fv-1b genotype. Our results indicate that the receptor sites for wild mouse ecotropic retrovirus are strain and organ specific and suggest that the presence of such receptors in central nervous system tissue may be a prerequisite for a successful virus infection and paralysis induction in Fv-1n mice.