Time and temperature dependence of influenza virus membrane fusion at neutral pH.

The time course and temperature requirements for fusion of influenza virus membranes with liposomes at pH 7.5 were found to be consistent with the requirements for cell entry. At 37 degrees C, fusion was most rapid during the first 5 min and then continued more slowly up to at least 1 h. The amount of fusion increased semilogarithmically with increasing temperature up to 50 degrees C.