GENOTYPE-F PREVAILS IN HBV INFECTED PATIENTS OF HISPANIC ORIGIN IN CENTRAL-AMERICA AND MAY CARRY THE PRECORE STOP MUTANT

The distribution of HBV genotypes and the presence of the precore stop mutation were investigated in HBV strains from Central America. 333 H BsAg positive sera from chronic HBsAg carriers and acute hepatitis B c ases from five different countries (Costa Rica, Nicaragua, Honduras, E l Salvador and Guatemala) were tested for HBV DNA by nested PCR. Genot yping by limited sequencing within the S gene was performed on 90 stra ins, 66 from sera with a high level of HBV DNA, and another 24 from se ra positive for HBV DNA only after nested PCR. 23 of the samples were anti-HBe positive. Genotype F was found in 71 (79%), A in 13 (14%), D in 5 (6%) and C in one of the 90 sera. 18 patients with genotype F inf ection had anti-HBe and HBV DNA in serum. Since the three published pr ecore sequences of genotype F strains have a C-1858, which is known to prevent the precore stop mutation from G to A at position 1896, the p recore and part of the core genes were sequenced from 19 anti-HBe posi tive sera with HBV DNA, 17 with genotype F and 2 with genotype A. The A(1896) mutation was found in 11 of the 17 genotype F strains. All the se had a T-1858, which was also present in 5 of the 6 genotype F strai ns with G(1896). The precore region was therefore sequenced from genot ype F strains from 5 HBeAg positive sera from the five different Centr al American countries. These also had a T-1858, which thus is the wild type substitution in genotype F in Central America. A number of mutat ions were recorded between residues 57 and 68 in the core protein corr esponding to a unique clustering region of the genotype F strains. The predominance of genotype F in Central American populations of Hispani c origin was not anticipated since this genotype is regarded as indige nous to the Amerindian populations of the New World. (C) 1997 Wiley-Li ss, Inc.