Capsid destabilization is required for antibody-mediated disruption of poliovirus

Three out of 36 poliovirus type 1-specific monoclonal antibodies which, at 37 °C in a medium of normal ionic strength (µ = 0.16), caused only aggregative neutralization (reversible by immune complex dissociation at pH 2) shifted to cause disruptive, acid-irreversible neutralization when the temperature was raised to 39 °C or the ionic strength was lowered to 1/100 of normal. Under both conditions, the antigenic conversion was stoichiometric, but the efficiency was lower at 39 °C than at low ionic strength. Antigenic conversion and irreversible neutralization under both conditions were inhibited by WIN 51711, a capsid-stabilizing compound. Complete inhibition required filling of most of the virion's binding pockets by this compound.