A group of temperature-sensitive mutants of Moloney leukemia virus which is defective in cleavage of env precursor polypeptide in infected cells also induces hind-limb paralysis in newborn CFW/D mice.

A group of temperature sensitive mutants of Moloney murine leukemia virus (MoMuLV) designated as ts1, ts7, and ts11 rapidly and invariably induce hind-limb paralysis ranging from 28 to 52 days postinjection of neonatal CFW/D mice. These temperature-sensitive mutants are defective in the processing of the precursor of the env protein, gPr80env in infected cells, resulting in the accumulation of gPr80env in the infected cell and production of virions with reduced amounts of gp70, p15E, and p12E when compared to that of the wild-type virion. In contrast, two nonparalytogenic ts mutants, ts3 and ts10, like the wild-type virus, show normal processing of gPr80env in infected cells and production of virions with a similar amount of env proteins to that of the wild-type virion.