Further Data on HBs Antigen Subtypes – Geographical Distribution

Abstract. 605 HB antigens from silent carriers of different geographic areas were subtyped. Guinea pigs and goats were immunized with selected HB antigens. Subtyping was performed by CIEP using monospecific or duospecific antisera, and by ID with unabsorbed antisera if the antigen was strong enough. Eight categories of HB antigens previously described were confirmed: a₁y(w), a₂Iy(w), a₂3y(w), a₃(w), ayr, a₂Id(w,) a₃d(w) and adr. The relations between the four categories of a subdeterminants and ‘w’ are analysed. All the antigens with ‘w’ determinant are either a₁ or a₂l or a₂3 or a₃. The ‘w’ determinant can be subdivided into the system of a subdeterminants which are mutually exclusive among themselves. r appears to be allelic with the group of the four a subdeterminants. It cannot yet be stated if r may be considered as a fifth subdeterminant of a or if it is independant of a subdeterminant. For the present time we use the following terminology a₁(w), a₂l(w₂), a₂3(w₃), a₃(w₄) and r. By combining a(w) subdeterminants, r, d and y determinants, it is possible to greatly increase our knowledge about the geographical distribution of HB antigen: ay subtype is predominant in Africa and in Mediterranean countries but three areas can be distinguished by means of a subdeterminants: a₃(w₄)y being mainly found in West and Central Africa (87%) and a₂1(w₂)y in Mediterranean countries (86%) except for Greece where a same ratio of a₂1(w₂)y and a₂3(w₃)y is encountered. This a₂3y subtype is the most frequent of ay subtypes in France and in Hungary. In these two countries, the subtypes ad(w) are predominant: 67% of a₂1(w₂)d and 1.3% of a₃(w₄)d in France. adr is widespread in Asia and especially in the Thai area (Thailand and Laos), but we have found a₁(w₁)y in Vietnam. Many examples are given which show that the subtype of HB antigen is related to the country of origin and does not seem to depend of the host. These findings illustrate the importance of HB antigen subtyping for epidemiology and for study of populations.