The infectivity and the haemagglutinin activity of A2/Aichi/2/68 influenza virus were unchanged during a 2-year storage in allantoic fluid at -80 °C. Over the temperature range from -20 to + 37 °C, exponential slopes could be drawn by means of the regression analysis, the velocity constants showing very low values. Conversely, at + 56 °C inactivation took place in a two-component fashion, each following first-order kinetics. Haemagglutinin and neuraminidase activities were not impaired by exposure to [60Co]-γ-rays (3 × 106 rad), which completely removed infectious particles. The specific rate constants for inactivation of haemagglutinin and neuraminidase activities of untreated and irradiated virus were overlapping when samples were stored for 2 years in the frozen state (- 80 and - 20 °C), whereas a significantly increasing rate of inactivation was recorded for γ-irradiated samples following storage at temperature above 4 °C. Nevertheless, the energy of activation required for thermal inactivation was very low and the entropy of activation showed negative values for both the untreated and the irradiated virus preparations.
CompansR. W.,
KlenkH. D.,
CaliguiriL. A.,
ChoppinP. W.1970; Influenza virus proteins. I. Analysis of polypeptides of the virion and identification of spike glycoproteins. Virology 42:880–889
WebsterR. G.,
LaverW. G.1967; Preparations and properties of antibody directed specifically against the neuraminidase of influenza virus. Journal of Immunology 99:49–55
WebsterR. G.1970; Estimation of the molecular weights of the polypeptide chains from the isolated hemagglutinin and neuraminidase subunits of influenza viruses. Virology 40:643–654