AFRICAN-GREEN MONKEY KIDNEY (VERO) CELLS PROVIDE AN ALTERNATIVE HOST-CELL SYSTEM FOR INFLUENZA-A AND INFLUENZA-B VIRUSES

The preparation of live, attenuated human influenza virus vaccines and of large quantities of inactivated vaccines after the emergence or re emergence of a pandemic influenza virus will require an alternative ho st cell system, because embryonated chicken eggs will likely be insuff icient and suboptimal. Preliminary studies indicated that an African g reen monkey kidney cell line (Vero) is a suitable system for the prima ry isolation and cultivation of influenza A viruses (E. A. Govorkova, N. V. Kaverin, L. V. Gubareva, B. Meignier, and R. G. Webster, J. Infe ct. Dis. 172:250-253, 1995). We now demonstrate for the first time tha t Vero cells are suitable for isolation and productive replication of influenza B viruses and determine the biological and genetic propertie s of both influenza A and B viruses in Vero cells; additionally, we ch aracterize the receptors on Vero cells compared,vith those on Madin-Da rby canine kidney (MDCK) cells. Sequence analysis indicated that the h emagglutinin of Vero cell-derived influenza B viruses was identical to that of MDCK-grown counterparts but differed from that of egg-grown v iruses at amino acid positions 196 to 198. Fluorescence-activated cell sorting analysis showed that although Vero cells possess predominantl y alpha 2,3 galactose-linked sialic acid, they are fully susceptible t o infection with either human influenza A or B viruses. Moreover, all virus-specific polypeptides were synthesized in the same proportions i n Vero cells as in MDCK cells. Electron microscopic and immunofluoresc ence studies confirmed that infected Vero cells undergo the same morph ological changes as do other polarized epithelial cells. Taken togethe r, these results indicate that Vero cell lines could serve as an alter native host system for the cultivation of influenza A and B viruses, p roviding adequate quantities of either virus to meet the vaccine requi rements imposed by an emerging pandemic.