A cell-determined deficiency in the processing of gag proteins of murine leukemia virus 334C

Abstract

A murine leukemia virus was cloned by a method which yielded cell clones each chronically infected with a virus clone. One of these produced virus which had an abnormal protein pattern characterized by increased amounts of certain proteins normally present in trace amounts. Immunoreplica analysis showed that these proteins were related to the major capsid protein p30 and suggested that they were uncleaved precursor proteins or other high-molecular-weight proteins derived from the gag gene. The major species of RNA in this clone were the same size as those in a clone producing normal virus. When uninfected cells were infected with virus produced by this clone, the progeny had a normal protein pattern. Finally, this clone was abnormal in its growth characteristics in that the cells died rapidly upon becoming confluent. This cell clone, therefore, seems to have a cell-determined deficiency in the processing of leukemia virus proteins. Electron microscopy showed that this cell line produced an abnormally high proportion of virus particles which had an immature morphology.