Characterization of phenotypic properties of cloned RIE-1 cells resistant to reovirus type 1 infection (A) Cells were stained for reovirus antigen as previously described . Only the PI cells contain reovirus antigen as detected by immunohistochemistry (dark wells). Upper wells contain cloned mutant RIE-1 cells from two sets of RIE-1 mutant cell lines selected for reovirus resistance. The lower wells contain PI RIE-1 (left) and uninfected wild type RIE-1 (right). (B) Reovirus susceptible L-cell monolayers, maintained in 1 ml of completed medium, were used to detect the presence of virus in a 100 μl lysate obtained of mutant cells (upper two wells), PI RIE-1 cells (lower left) or uninfected parental RIE-1 cells (lower right). Note, that only L-cell monolayers exposed to a lysate from PI RIE-1 cells lysed within one week of exposure (gentian violet stain).