Inhibition of simian virus 40 replication by kanamycin derivative.

Recently, the antiviral activity of kanamycin derivatives against influenza and herpes simplex virus has been reported1~3). The mechanism of antiviral action of these agents is not well understood. In this report, the mechanism of antiviral effect of 1-N-eicosanoyl-3"-N-(trifluoroacetyl)kanamycin (ETK), one of these agents, was studied. We have tried to test the effect of ETK on simian virus 40 (SV40), a DNA virus. When the permissive monkey cells are infected with SV40, the following phenomena occur; expression of early genes, production of T antigen, replication of SV40 DNA, expression of late genes, production of late proteins, and finally the maturation of virus particles'). ETK inhibits the multiplication of SV40. The agent inhibits the production of T antigen coded by SV40 early gene, followed by inhibition of SV40 DNA replication. However, the transcription of early gene was stimulated. The complicated results may come from release of autoregulation of T antigen production by inhibition of T antigen synthesis by ETK. The monkey cell line, GC75) was infected with SV40 at a multiplicity of infection of 50 PFU per cell. At 40 hours after infection, the production of late proteins was examined by indirect immunofluorescence technique using anti-SV40 V antigen rabbit serum (Table 1). The intensity of fluorescence was normalized as follows: The strong fluorescence was scored +2 and weak fluorescence was scored +1. The results are shown as the sum of these two figures per plate. It is clear that production of viral late proteins were suppressed in a concentration dependent manner by ETK. The 10-4 M of ETK inhibited approximately 70% of production. We next checked the effect of ETK on SV40 DNA replication. At 16 hours after infection, the infected GC7 cells were labeled with 100,uCi of [3H]thymidine per ml for 60 minutes. The low molecular weight DNA containing SV40 DNA was extracted from GC7 cells by HIRT procedure6), separated on 1 % agarose gel conTable 1. Effect of ETK on SV40 multiplication.