PRODUCTION OF THE M2-PROTEIN OF INFLUENZA-A VIRUS IN INSECT CELLS IS ENHANCED IN THE PRESENCE OF AMANTADINE

Recombinant baculoviruses that express the M2 protein from the genes o f either the amantadine-sensitive, influenza A/Ann Arbor/6/60 virus or a laboratory-derived, amantadine-resistant mutant of this virus were constructed. Addition of amantadine or rimantadine at 2 mug/ml to cult ures of Sf9 cells infected with the recombinant baculoviruses increase d the yield of the M2 protein from the amantadine-sensitive virus appr oximately 10-fold, but did not increase the yield of the M2 protein fr om the amantadine-resistant virus. Flow cytometry demonstrated that th e increased production of M2 in the presence of amantadine resulted in increased cell surface expression of the M2 protein. Pulse-chase expe riments indicated that whereas the rate of synthesis of the M2 protein increased in the presence of amantadine, the M2 protein was stable in both the presence and absence of amantadine. Addition of amantadine t o Sf9 cells as late as 72 h after infection with the recombinant virus increased the production of M2 protein. These data suggest that the M 2 protein exerts some biological activity in Sf9 cells.