Effect of D-penicillamine on poliovirus replication in HeLa cells

A series of mercaptan compounds were studied with respect to their ability to inhibit the growth of poliovirus in cultured cells. Of the compounds tested only d-penicillamine possessed antiviral activity. There was no direct effect on the virus itself, nor were the processes of adsorption, penetration and uncoating, or virus-induced "shut-off" of host cell protein synthesis inhibited. At concentrations where there was no effect on host cell RNA or protein synthesis, d-penicillamine caused a marked inhibition of virus-specific RNA and protein synthesis. Although much reduced, the relative concentrations of single-stranded and double-stranded viral RNA synthesized in the presence of d-penicillamine was unchanged. Similarly, all apparent precursor and cleavage product proteins could be synthesized in the presence of the drug. The inhibitory effect was reversible, after a lag of 1.5 to 2 h after removal of the drug, and normal yields of virus could be obtained. The structural and functional properties of d-penicillamine are discussed in relation to requirements for anti-polioviral activity.