RT Journal Article SR Electronic(1) A1 Biddle, F.YR 1968 T1 The Action of Protease on Influenza A2 Virus JF Journal of General Virology, VO 2 IS 1 SP 19 OP 28 DO https://doi.org/10.1099/0022-1317-2-1-19 PB Microbiology Society, SN 1465-2099, AB SUMMARY The main effects of the proteolytic digestion of the Asian (A 2) strain of influenza virus were a loss of the characteristic surface morphology and a change in density. The untreated virus was found to have a density of 1·204 g./cm.3 on a sucrose gradient, but after protease action the density was 1·168 g./cm.3. The density change was correlated with a change in particle mass as indicated by a fall in sedimentation coefficient (S20 ) from the normal 788 Svedbergs to 562 Svedbergs. From the data obtained with the protease-treated and control virus preparations it was calculated that the changes observed could be accounted for by a loss of 35 to 40 % of the particle mass. The action of the protease appeared to be confined to the surface of the virus. Concomitantly with the destruction of the haemagglutinating activity there was a release of neuraminidase activity, and on a density gradient this could be separated from the residual virus and was located at the top of the gradient tube. In addition to the changes described, there appeared to be a destruction of the virus V antigen., UL https://www.microbiologyresearch.org/content/journal/jgv/10.1099/0022-1317-2-1-19