Qualification of working cell banks for the Vero cell line to produce licensed human vaccines

Since 1980, Merieux Institute has prepared on microcarriers four working cell banks from Vero Cells (137th p.) received from the ATCC in May 1979 (at 124th p.). The lots have been or are used for the production of rabies and inactivated poliomyelitis vaccines. Three lots were controlled according to WHO requirements described in the technical report 673, 1982. For the fourth lot, we have followed the WHO requirements corresponding to the technical report 745, 1987. All the tests required us to demonstrate: i) Safety and purity (tests in animals and eggs, sterility tests, cocultures with human cells and other electron microscopic observations). ii) The absence of tumorigenicity (tests in newborn rats treated with antihymocyte serum at the WBC level and on the cells propagated to at least 10 population doublings beyond the maximum passage level used for production. Assays of cell transformation with DNA from the Vero line in the standard 3T3 assay system). iii) Identity (isoenzyme technique). All were satisfactory.