In vitro potency assay for yellow fever vaccines: Comparison of three verocell lines sources

Quality control of Yellow Fever vaccines performed by Control Authorities p rior to marketing vaccines batches requires in vitro potency assays. The tw o currently available methods are the plaque formation assay and the cytopa thic effect assay based on the use of porcine kidney PS cells or monkey kid ney Vero cells. Among several sources of variation in virus titration, the cell systems are considered as important issues and Quality Assurance stron gly recommends working with cell banks from certified suppliers. The aim of our study was to compare the behaviour and the sensitivity of three Vero c ell sources obtained from ATCC, WHO and EP used at different passage levels in a plaque formation test. The conclusion of this work was that the yello w fever live attenuated virus titration, adapted in Vero cell lines appeare d as a reliable method applicable for routine in vitro potency assay. The c omparison of Vero cell lines, originated from three different sources, show ed that they could be equally used as substrates by laboratories having the basic facility of cell culture, without influence on the final viral titre .