An antiviral compound that blocks structural transitions of poliovirus prevents receptor binding at low temperatures

Abstract

Drugs such as WIN51711 that inhibit picornavirus replication are thought to block poliovirus infectivity by binding to the capsid and preventing structural transitions required for uncoating. We examined the activity of WIN51711 at temperatures where capsid flexibility is thought to be decreased. Below 37 degrees C, WIN51711 inhibits the binding of wild-type poliovirus to cells but does not affect the binding of a poliovirus mutant which is believed to undergo structural transitions more readily. These results suggest that the poliovirus capsid must undergo structural changes to bind to its cellular receptor.

FIG. 1

WIN51711 inhibits poliovirus binding at low temperatures. ³⁵S-methionine-labeled poliovirus (strain P1/Mahoney) was incubated for 0 or 1 h at different temperatures with WIN51711 at the indicated concentrations. Virus was added to HeLa cell suspensions (MOI = 10) in medium containing the same concentrations of WIN51711, the suspensions were agitated at the indicated temperatures overnight, and samples were taken in triplicate to determine the percentage of radioactive methionine bound to cells.

FIG. 2

Poliovirus capsid mutations can bypass binding inhibition by WIN51711. ³⁵S-methionine-labeled poliovirus mutants P1095S/V1160I (labeled 1095) and Q3178R/I2231M (labeled 3178) were added to cell suspensions (MOI = 5) in medium containing WIN51711 at the indicated concentrations, the suspensions were agitated at the indicated temperatures overnight, and samples were taken in triplicate to determine the percentage of radioactive methionine bound to cells.

FIG. 3

Thermostabilization of WT and mutant poliovirus P1/Mahoney by WIN51711. WT or mutant P1/Mahoney virus was incubated at 25°C in PBS with 0.2% bovine calf serum with or without 5 μg of WIN51711 per ml for 1 h and then transferred to a 45°C water bath. Samples were taken in triplicate at 0, 1, 5, 10, 30, and 60 min after the temperature shift, and the viral titer of each sample was determined by plaque assay.