MATURATION OF MOLONEY MURINE LEUKEMIA-VIRUS

The accumulation of large numbers of budding particles of ts-3, a temperature-sensitive mutant of the Moloney strain of MuLV (Mo-MuLV), on the cell membrane at the non-permissive temperature and their release as immature particles within 30 min on temperature shift-down provide a large pool of freshly released, synchronous virions ideally suited for the investigation of the postreleased changes in the virions. Our studies indicate that freshly released virions at 34° show a twofold increase in infectivity and reverse transcriptase activity for the first 90-120 min after virion release. Upon further incubation, both infectivity and reverse transcriptase activity decreased. Furthermore, processing of the gag precursor was also observed. The above postreleased changes were found to be correlated with the morphologic transformation of immature to mature virions. © 1979.