The specific reduction of a and d antigenic determinants after periodate treatment of hepatitis B surface antigen (HBsAg).

HBsAg antigenicity was found to be sensitive to periodate treatment. Antigenic determinants a and d were especially sensitive, losing almost all of their activity, while determinants r and w were found to be quite stable. Also, it is now possible to prepare the monospecific antibodies, anti-r and anti-w, by the use of this new, simpler procedure.