Detergent prevented both multimerization and complex formation. Purified recombinant poliovirus polypeptide 3AB interacts with 3CDpro and 3Dpol as shown by coimmunoprecipitation with anti-3Dpol antibodies. A consequence of this interaction is an accelerated autoprocessing of 3CDpro to produce 3Cpro and 3Dpol. In contrast, 3CDpro-specific cleavage of the structural precursor P1 is inhibited by the addition of 3AB as shown by a decrease in the production of VP0 and VP3. Reynolds C Birnby D Chow M Folding and processing of the capsid protein precursor P1 is kinetically retarded in neutralization site 3B mutants of poliovirus.
All viable mutants display small-plaque phenotypes.
Characterization of these mutants indicates that capsid assembly is perturbed. Analyses of capsid assembly intermediates show a transient accumulation of the unprocessed capsid protein precursor, P1, indicating that cleavage of the mutant P1 by the 3CD protease is retarded. Thus, mutations at this residue are pleiotropic, altering the kinetics of capsid assembly and generating a virus that is more thermostable and more resistant to neutralization by the site 3B monoclonal antibodies.