MDBK CELLS WHICH SURVIVED INFECTION WITH A MUTANT OF INFLUENZA VIRUS-A WSN AND SUBSEQUENTLY RECEIVED MANY PASSAGES CONTAINED VIRAL-M AND VIRAL-NS GENES IN FULL-LENGTH IN THE ABSENCE OF VIRUS PRODUCTION/

From a variant of MDBK cell line carrying the nucleotide sequences spe cific to a mutant of influenza virus A/WSN, we obtained cDNA clones re presenting viral M and NS genes in full length by polymerase chain rea ction (PCR). The sequence analysis of five cDNA clones each for the re spective genes revealed 4 to 10 base changes with M and 2 to 6 with NS compared with the corresponding genes of the original virus, although it was possible that at least some of them were ascribed to the artif acts during reverse transcription or Taq polymerase reaction.