A simple method for increased recovery of purified paramyxovirus virions

A simple method involving vigorous agitation of infected cell monolayers prior to collection of culture medium is described to greatly increase the recovery of purified virions of measles virus, respiratory syncytial virus and human parainfluenza virus. Vigorous agitation of the flasks containing monolayers of infected cells increased the recovery of purified virions by at least 3- to 10-fold as judged by the intensity of [35S]methionine labeled viral proteins on sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). These protein profiles also indicated that these virions were as clean as those purified from gently collected medium. Analysis of titers of infectious virus recovered from medium of agitated and non-agitated flasks showed similar increases. These results suggest that the cell associated nature of these viruses may be at least partly due to either partially budded virions or mature virions sticking to the cell membrane, since these both might be expected to be freed from the cell by mechanical shearing.