Influenza virus vaccines, process for preparing them, process for propagating influenza viruses and cell culture inoculated with influenza virus

摘要

1. Method of preparing an influenza virus vaccine in which cells are infected with an influenza virus and the virus multiplies in the cells, whereupon the virus is isolated and a vaccine is prepared from the isolated virus, characterized in that some of the cells of a liquid cell culture are infected with an influenza virus and the infected culture is incubated in the presence of a proteolytic enzyme the concentration of which is sufficiently high to cause growth in a multiple number of cycles without causing any detachment of cells when confluent monolayers are used as the cell culture.