Antigenic N to H conversion of poliovirus by a monoclonal antibody at low ionic strength

Monoclonal antibody 35-1f4 at low ionic strength converted native virions (N antigen) to noninfectious H-antigenic, empty capsids. The reaction was stoichiometric, as the amount of N antigen that could be converted to H was limited to an average of 2 virions per molecule of antibody. The antibody remained associated with virus aggregates after antigenic conversion. Using antibody immobilized onto protein A-bearing staphylococci, it could be shown that the loss of antigen-converting power was concomitant with the loss of antigen-binding ability. Only a small amount of viral protein (equivalent to 0.02 empty capsid per molecule of antibody) remained attached to the antibody. Heating to 56 degrees caused most of this material to be released and restored the antibody's antigen-binding and antigen-converting abilities. Several possible explanations for the heat-reversible inactivation of the antibody are discussed.