Isolation and characterization of an arildone-resistant poliovirus 2 mutant with an altered capsid protein VP1

Arildone (4-[6-(2-chloro-4-methoxyphenoxy)hexyl] -3,5-heptanedione is a selective inhibitor of poliovirus uncoating. We have isolated an arildone-resistant poliovirus 2 variant and characterized it. In single cycle growth curve experiments the resistant virus was not influenced by 1 microgram/ml of arildone, which completely inhibited the replication of the sensitive virus. In neutralization experiments the rates of inactivation vs time of the parent and the resistant virus proved indistinguishable. The adsorption behavior of the mutant closely resembled that of the wild-type. Uncoating as measured with neutral red-sensitized arildone-resistant mutant virus was unaffected by arildone, in contrast to the uncoating of the sensitive parent virus. It has been previously shown that arildone stabilizes the poliovirus capsid from alkaline degradation. The arildone-resistant mutant, however, was not markedly stabilized by the drug under these conditions. No difference in thermostability between mutant and parent virus could be detected. In isoelectric focusing the sensitive virus exhibited 2 peaks, but in the presence of arildone only one peak was apparent. In contrast, the arildone-resistant virus remained unaffected by the presence of arildone. Analysis of the capsid proteins of the sensitive parent and the resistant virus in SDS-polyacrylamide gels revealed no difference in the patterns; however, peptide mapping showed clear differences in VP1.