Generation and characterization of a temperature-sensitive mutation in the NS-1 gene of the autonomous parvovirus minute virus of mice

In-phase single-codon insertion mutations were constructed in the open reading frames of the NS-1 and NS-2 genes of the autonomous parvovirus minute virus of mice. A viral mutant containing an isoleucine insertion exclusively within NS-1 between residues 229 and 230 was isolated that produced approximately 3 orders of magnitude fewer plaques at 39 degrees C than at 32 degrees C. Preliminary characterization of the mutant demonstrated that the NS-1 gene product is independently required for both genome amplification and the regulation of the temporal expression between the two viral transcription units during lytic infection.