RESUMO
BACKGROUND: HBV-infected patients are potential sources of intra-familial transmission. We studied HBV transmission and molecular characteristics within families of HBV-related chronic liver disease (CLD) patients. METHODS: Family members [index cases (ICs), spouses, and 1-18-year-old children] of HBV-related CLD patients were tested for HBsAg, anti-HBc, and anti-HBs. HBsAg-positive subjects were tested for HBeAg/anti-HBe. Anti-HBc-positive children together with their family members were further investigated for HBV DNA. Sequences of positive isolates were analyzed over surface, precore (PC) and basal core promoter (BCP) regions. RESULTS: Among 94 children of 46 ICs, the prevalence of HBsAg, anti-HBc, and anti-HBs was 10 (10.6 %), 19 (20.2 %), and 46 (48.9 %), respectively. Thirty-eight (40.4 %) children were seronegative, indicating susceptibility to HBV infection. HBV DNA was identified in all ICs, 4 spouses, and 16 children. Having both parents with HBsAg positive and at least two HBV carriers in the households were significant risk factors of intra-familial transmission. HBV genotype/subtype distributions were comparable between children and ICs/spouses, with predominance of genotype B. The majority of HBV DNA sequences found in children were identical to their corresponding ICs-particularly mothers-including mutation patterns in the surface, PC, and BCP regions. Recognized mutations associated with HBsAg detection and/or vaccination failure, T140I, T143S/M, G145R, and Y161F, were identified in 20 subjects; while mutations linked to HBeAg-defective variants, PC G1896A and BCP A1762T/G1764A, were found in 7 and 11 subjects, respectively. CONCLUSIONS: Children of HBV-related CLD patients were at increased risk of HBV infection through multi-modal transmission routes despite negative parental HBsAg and HBeAg status.