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.

Potency test of killed polio vaccines. Statistical analysis of test on chicken and preliminary results in combination with ELISA D-antigen determinations.

The authors resume a several years' experience of potency testing inactivated polio vaccines with an in vivo-vitro assay based on inoculation of 3 week-old chicken and measure of neutralizing antibodies at 5 days on Hep 2 cells in a microplate system. Critical points, specificity and reproducibility are successively outlined. Preliminary combining results with determination of D-antigen by ELISA method and human immunization are submitted in view of a future standardization.

Direct enzyme linked immunosorbent assay (ELISA) for quantification of poliomyelitis virus D-antigen.

The proposed micro-ELISA assay by means of the double antibody method involves three steps: adsorption of type specific antiserum on micro-wells; simultaneous incubation of antigen and Horse Radish Peroxydase (HRPO) conjugated antiserum; substrate incubation followed by photometric measurement of absorbance at 403 nm. Preliminary results seem generally in good agreement with those obtained by other tests such as gel diffusion and indirect ELISA.