Isolation and characterization of conditional-lethal mutants of Sindbis virus

Abstract

Twenty-three temperature-sensitive conditional-lethal mutants of Sindbis virus, a group A arbovirus, have been isolated and characterized. These appear to be single-step mutants whose replication at high temperatures is blocked by the temperature-sensitive defect of a protein determined by the viral genome. Two categories of mutants are found: those that synthesize infectious RNA but not infectious virus at high temperatures (RNA+), and those that produce neither infectious RNA nor infectious virus (RNA-). RNA+ mutants are in general more heat labile at 60 ° than either RNA- mutants or the Sindbis strain from which they were isolated. The most probable explanation for this behavior is discussed. © 1966.