Specific for HBsAg. Reacts with the following HBsAg subtypes: ayw1, ayw2, ayw3, ayw4, ayr, adw2, adw4, adrq+, adrq-, ayw3 (Fer). Can be used for detection of HBsAg in two-site enzyme immunoassay. Recommended pairs for sandwich immunoassay (coating - conjugate): HB13 - HB6