Three of thirty-six monoclonal antibodies were found to cause irrevers
ible inactivation of type 1 poliovirus at 39-degrees-C but not at 37-d
egrees-C. Neutralization at 37-degrees-C depended on aggregation and w
as reversible by acid-induced deaggregation; at 39-degrees-C, the viri
ons (N antigenic, 160S) were disrupted to empty capsids (H antigenic,
100S), and neutralization was irreversible. The rate of antibody-depen
dent conversion of N to H antigen increased steeply between 37 and 39-
degrees-C.