Distribution of HBsAg Subtypes in the World

Abstract

HB_sAg subtyping was performed in 5,337 sera from chronic carriers who originated from 54 different countries of the 5 continents. Nine subtypes were defined: ayw₁, ayw₂, ayw₃, ayw₄, ayr, adw₂, adw₄, adr q- and adr q+. The repartition of these subtypes, according to the country of origin of the carriers, enhances the previous results and supplies new data: ayw₁ is prevalent only in Vietnam (51%); ayw₂ in Mediterranean countries (73%); ayw₃ in Greece and Yugoslavia (54%) along with ayw₂ (41%); ayw₄ in West Africa (82%) and Central Africa (42%) along with ayw₂; ayr was only found in Vietnam (3.4%); adw₂ is prevalent in North and Central Europe (70%), East and South Africa (95%), India (55%), along with ayw₃ (35%) in northern South America (74%), and in the Antilles (82%); adw₄ is widespread in French Polynesia (45%) — with a 100% frequency in the Marquesas archipelago — as well as in Argentina (42%); adr q- was found only in Oceania: French Polynesia (34%) with a 69% frequency in the Australes, New Caledonia (3 out of 3 HB_sAg carriers); adr q+ is the prevalent subtype in South-East Asia if we exclude Vietnam (61%). These results show that a precise geographical distribution of HB_sAg subtypes needs more than ‘four main subtypes’ generally used. Enlarging from 4 subtypes to 9 is a requirement for valuable epidemiologic studies, as well as for the specification of anti-HB_s antibodies produced by hybrids or induced by synthetic peptide. The geographical distribution of these 9 HB_sAg subtypes and the serological relationship between some determinants suggest a genetic recombination of viral DNA.