Characterization of a human monoclonal antibody obtained after immunization with plasma vaccine and a booster with recombinant-DNA hepatitis B vaccine.

A human monoclonal antibody type IgG4, designated 1Ff4, was obtained by Epstein Barr virus transformation of peripheral blood lymphocytes from a hepatitis B vaccinee (HB-VAX: plasma-derived vaccine) after one boost of yeast recombinant DNA derived vaccine (Engerix-B). 1Ff4 binds preferentially to HBsAg/adw(2) and HBsAg/ayw(1). In binding experiments, it competes with antibodies induced by vaccination with HB-VAX-DNA (yeast recombinant) and HB-VAX (plasma-derived vaccine). 1Ff4 competes in part with a monoclonal antibody for the w/r region. Partial inhibition of binding of HBsAg/adw(2) to solid phase anti-HBs was detected, resembling inhibition obtained using other human monoclonal specific for the "a"-loop. 1Ff4 does not bind to linear peptides covering the two "a"-loops or to an adw(2)/G145R mutant, its binding to wild type HBsAg strongly depends on the presence of disulphide bonds. In a large series of HBsAg-positive samples from an endemic area, 1Ff4 antibodies were successfully used to discriminate between an adw(2) and an adrq+ strain. The characterisation of 1Ff4 and other human monoclonal anti-HBs antibodies may help to understand the fine specificity of protective antibodies elicited by immunization.