Numbers of virus foci in the MDCK cells infected with adamantane sensitive and resistant viruses. Figure 4A show results of experiment 1 which the viruses were added directly to the MDCK cell monolayer and the infected cells were cultured in the medium containing HuScFv, PAb to M2, rimantadine or medium alone for 15 h. No foci of the rimantadine sensitive virus were found in the infected cells cultured with HuScFv of clones no. 19 and 23 and rimantadine while only few foci were seen in cells exposed to HuScFv of clones no. 2 and 27 and PAb. The numbers of amantadine-resistant virus foci in infected cells cultured in HuScFv, PAb to M2 and rimantadine supplemented medium were markedly reduced compared with the infected cell control. Figure 4B shows results of experiment 2 which the viruses had been exposed to M2 specific-HuScFv, PAb to M2, rimatadine or medium before adding to the cell monolayer and the infected cells were cultured in the respective inhibitors or medium alone, the adamantane sensitive virus foci were not found in the cells exposed to all inhibitors. Numbers of foci of the amantadine resistant virus treated with the HuScFv, PAb to M2 and rimantadine were markedly reduced compared with the infected cell control.