Comparative studies of wild-type and 'cold-mutant' (temperature sensitive) influenza viruses: geneology of the matrix (M) and non-structural (NS) proteins in recombinant cold-adapted H3N2 viruses

Abstract

The matrix (M) protein of the H2N2 virus A/Ann Arbor/6/60 may be distinguished from M protein of several H3N2 viruses and A/New Jersey/76 (HSWINI) by SDS acrylamide gel electrophoresis using a discontinuous buffer system. The smallest RNA (RNA 8) of the A/Ann Arbor/6/60 virus may be distinguished from RNA 8 of several H3N2 viruses by acrylamide gel electrophoresis in 3% or 3-6% gels in the absence of urea, if electrophoresis is done at 30 to 36 degrees C or 20 degrees C respectively. Ten clones of conditionally-lethal temperature-sensitive (ts) mutants were studied, which derived their cold-adaption and ts genes from mutant A/Ann Arbor/6/60, and their haemagglutinin from the H3N2 virus A/Scotland/840/74. Each clone was found to derive its M protein from A/Ann Arbor/6/60 mutant, and its RNA 8 from A/Scotland/840/74. The only assignment of genes 7 and 8 consistent with these findings for the recombinants is that in each parent virus (and in the recombinants) gene 7 codes for M protein, and gene 8 for NS protein. Furthermore, it may be concluded from the results that the biologically important ts lesions in the A/Ann Arbor/6/60 mutant parent are not present in the NS gene. In addition to the recombinants of A/Ann Arbor/6/60 and A/Scotland/840/74, five independent ts/cold-adapted recombinants of A/Ann Arbor/6/60 mutant with H3N2 and HSWINI wild-type viruses were examined, and all were found to contain the M protein of the A/Ann Arbor/6/60 mutant parent. This is suggestive that M protein may be at least partially responsible for the cold-adaptation and/or ts properties of the A/Ann Arbor/6/60 mutant and the recombinants.