COMPARATIVE STUDIES OF WILD-TYPE AND COLD-MUTANT (TEMPERATURE-SENSITIVE) INFLUENZA-VIRUSES - INDEPENDENT SEGREGATION OF TEMPERATURE-SENSITIVITY OF VIRUS-REPLICATION FROM TEMPERATURE-SENSITIVITY OF VIRION TRANSCRIPTASE ACTIVITY DURING RECOMBINATION OF MUTANT A-ANN-ARBOR-6-60 WITH WILD-TYPE H3N2 STRAINS

RNA I of a cold-adapted and temperature-sensitive (ts) influenza virus mutant A/Ann Arbor/6/60 has a different mobility from RNA I of wild-type (wt) A/Ann Arbor/6/60 when subjected to electrophoresis through acrylamide/agarose gels in the absence of denaturing agents. Detection of this lesion in RNA I of the mutant virus was dependent on the temperature of the gel during electrophoresis. Because RNA I is believed to code for a protein involved in virus-specific RNA synthesis we compared phenotypes of virion transcriptases in the wt and mutant viruses. The enzyme of the mutant virus was found to be about 40% less active at 40°C than the enzyme of the wt virus when related to their activities at 31°C. Two cold-adapted ts recombinants which derive their RNA I from the mutant A/Ann Arbor/6/60 have virion transcriptases with a phenotype similar to that of their mutant parent. Three different cold-adapted ts recombinants, however, which also derive their RNA I from the mutant A/Ann Arbor/6/60, have virion transcriptases with a phenotype similar to that of wt virus. We conclude, therefore, that the conditional-lethal ts property of A/A mn Arbor/6/60 mutant and its recombinants is independent of the phenotypic marker observed for the A/Ann Arbor/6/60 mutant virion transcriptase, and that the lesion in RNA I of the mutant may also be unrelated to the observed difference between virion transcriptases of the mutant and wt A/Ann Arbor/6/60 viruses. The phenotypes of the virion transcriptases in recombinants did, however, correlate with the derivation of their RNA 2. This suggests that the increased temperature-sensitivity of virion transcriptase of the A/Ann Arbor/6/60 mutant is caused by either (1) a lesion (not necessarily conditionally lethal) that occurred in its RNA 2 during the course of cold-adaptation, or (2) a lesion in another gene whose product is a component of the virion transcriptase complex, but which lesion is only expressed phenotypically when there is a synergistic interaction in the transcriptase complex with the product of A/Annm Arbor/6/60 RNA 2.