title: Molecular epidemiology of hepatitis B virus in an isolated Afro-Brazilian community.
abstract: This study was conducted in an Afro-Brazilian, slave-descendant community with high (42.4%) hepatitis B virus (HBV) prevalence. Twenty (8.4%) out of the 239 subjects under study were HBsAg-positive, and HBV-DNA was detected in 59 (25%) individuals. A high rate (18.3%) of occult infection was therefore observed that was associated to low HBV loads (mean, 1.8 x 10(4) copies/ml) and to a specific amino acid substitution (C100Y) in the small surface antigen. Genotyping of 50 isolates showed that 43 (86%) were of subgenotype A1, one (2%) from subgenotype A2, and five (10%) from subgenotype D. Mixed genotypes A1 and E were observed in one (2%) sample. The genetic distance (0.8 +/- 0.3%) among the HBV/A1 isolates from the community was smaller than the intragroup divergence among A1 isolates from Brazil as a whole, but it was similar to that found between A2 isolates from different countries, suggesting that HBV/A1 was introduced in the community through different sources. The substitution W501R (polymerase), previously reported only in Gambia, was observed in 46% of the HBV/A1 isolates. The precore/core promoter region of HBsAg-positive isolates showed several substitutions that could explain the anti-HBe phenotype found in 18 of 20 (90%) of the HBsAg-positive subjects.
authors.affiliation: Departamento de Farmácia-Bioquímica, Laboratório de Imunologia Cínica, Universidade Federal de Mato Grosso do Sul, Campo Grande, Brazil. arcm.castro@hotmail.com
authors.forename: A R C
authors.initials: AR
authors.lastname: Motta-Castro
authors.forename: R M B
authors.initials: RM
authors.lastname: Martins
authors.forename: N M
authors.initials: NM
authors.lastname: Araujo
authors.forename: C
authors.initials: C
authors.lastname: Niel
authors.forename: G B
authors.initials: GB
authors.lastname: Facholi
authors.forename: B V
authors.initials: BV
authors.lastname: Lago
authors.forename: F C A
authors.initials: FC
authors.lastname: Mello
authors.forename: S A
authors.initials: SA
authors.lastname: Gomes
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D001938:Brazil / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000453:epidemiology* / Q000276:immunology / Q000821:virology; D006514:Hepatitis B Surface Antigens / Q000235:genetics / Q000276:immunology; D006515:Hepatitis B virus / Q000145:classification* / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008875:Middle Aged; D017720:Molecular Epidemiology; D008969:Molecular Sequence Data; D010802:Phylogeny; D015995:Prevalence; D055815:Young Adult
chemical_list: D006514:Hepatitis B Surface Antigens