piperidines and Poliomyelitis

A novel small molecule, H1PVAT, was identified as a potent and selective inhibitor of the in vitro replication of all three poliovirus serotypes, whereas no activity was observed against other enteroviruses. Time-of-drug-addition studies revealed that the compound interfered with an early stage of virus replication. Four independently-selected H1PVAT-resistant virus variants uniformly carried the single amino acid substitution I194F in the VP1 capsid protein. Poliovirus type 1 strain Sabin, reverse-engineered to contain this substitution, proved to be completely insensitive to the antiviral effect of H1PVAT and was cross-resistant to the capsid-binding inhibitors V-073 and pirodavir. The VP1 I194F mutant had a smaller plaque phenotype than wild-type virus, and the amino acid substitution rendered the virus more susceptible to heat inactivation. Both for the wild-type and VP1 I194F mutant virus, the presence of H1PVAT increased the temperature at which the virus was inactivated, providing evidence that the compound interacts with the viral capsid, and that capsid stabilization and antiviral activity are not necessarily correlated. Molecular modeling suggested that H1PVAT binds with high affinity in the pocket underneath the floor of the canyon that is involved in receptor binding. Introduction of the I194F substitution in the model of VP1 induced a slight concerted rearrangement of the core β-barrel in this pocket, which disfavors binding of the compound. Taken together, the compound scaffold, to which H1PVAT belongs, may represent another promising class of poliovirus capsid-binding inhibitors next to V-073 and pirodavir. Potent antivirals against poliovirus will be essential in the poliovirus eradication end-game.

Topics: Amino Acid Substitution; Animals; Antiviral Agents; Base Sequence; Binding Sites; Capsid; Capsid Proteins; Cell Line, Tumor; Chlorocebus aethiops; Drug Resistance, Viral; HeLa Cells; Humans; Models, Molecular; Piperidines; Poliomyelitis; Poliovirus; Pyrazoles; Pyridazines; Pyrimidines; RNA, Viral; Sequence Analysis, RNA; Virus Replication

Poliovirus type 1 (Mahoney) was treated with the capsid-binding pyridazinamine R 78206, followed by dialysis to remove free compound. Upon infection of HeLa cells by R 78206-pretreated virus, the formation of intra- and extracellular modified particles was completely inhibited, except for a small amount of empty capsids. The synthesis of viral proteins and first cycle progeny virus was delayed by 1 h. The results suggest that poliovirus infection does not require intracellular accumulation of 135 S eclipse particles.

Topics: Antiviral Agents; Capsid; HeLa Cells; Humans; Piperidines; Poliomyelitis; Poliovirus; Pyridazines; Viral Proteins; Virion; Virus Replication