Printed in Great Britain Replication of Two Influenza Virus Strains and a Recombinant in HEF and LEP Cells

The replication of influenza viruses A/NWS-D, A/WS-MK and their rl ~ recom-binant in human embryo fibroblast (HEF) and human diploid fibroblast (LEP) cell lines was studied. In HEF cells virus NWS-D and recombinant r12 induced synthesis of virus-specific macromolecules and produced infectious virions; virus WS-MK induced synthesis of virus complementary RNA (cRNA), virion RNA (vRNA), proteins, RNP and non-infectious virions, but haemagglutinin cleavage was impaired and the virions formed contained uncleaved haemagglutinin. I LEP cells, infectious virions were formed only by virus NWS-D; viruses WS-MK and r~2 induced synthesis of virus cRNA, vRNA, proteins and RNP; virus rlz had the haemagglutinin cleaved, whereas in virus WS-MK this process was impaired; neither virus WS-MK nor r~2 was capable of forming virions. Analysis of the recombinant rl ~ genome showed that it had only inherited a single gene from NWS-D, the one coding for neuraminidase, having inherited all others (P1, P2, P3, HA, NP, M, NS) from WS-MK. The data obtai~ied suggested that the inability of virus WS-MK to form infectious virions in HEF cells is due to the character of its neuraminidase, which is incapable of participating in haemagglutinin cleavage. The deficient reproduction of this virus in the other host-cell system (LEP) is apparently associated with some characteristics of another protein (other proteins) of this virus