Heterogeneity of hepatitis B virus surface antigen in sera of patients with acute hepatitis B infection in relative content of the antigenic determinants a and preS2.

Using five ELISA variants we have analyzed the ratios of the antigenic determinants 'a' (a-D), preS2 (preS2-D) and the polymerized human serum albumin binding domains (PHSA-BD) in the hepatitis B virus surface antigen (HBsAg) particles contained in sera of three patients with acute viral hepatitis B. Quantitative relations between the a-D, preS2-D and PHSA-BD were shown to differ in these sera. Population of the HBsAg particles in each of the sera appeared heterogeneous in respect to the PHSA-BD activity. The HBsAg particles with high affinity PHSA-BD prevailed in one serum. An additional class of particles with low affinity to PHSA or complete lack of the PHSA-BD was present in the remaining sera. The HBsAg particles carrying the high affinity PHSA-BD were characterized by an elevated (and almost constant for the three sera) surface density of the preS2-D. The results have led us to the conclusion that the existence of the preS2-D on the surface of the HBsAg particles is necessary but insufficient for the high affinity binding of the HBsAg to PHSA. A model for the interaction between the preS2-D carrying HBsAg particles and PHSA is presented.