Drug-resistant and immune-escape hepatitis B virus mutants, occult hepatitis B infection and coinfections in public hospital patients from Argentina.

Argentina exhibits low serological prevalence for Hepatitis B virus (HBV); however, occult hepatitis B infection (OBI) has been reported in blood donors, Amerindians and individuals coinfected with hepatitis C virus (HCV), and/or human immunodeficiency virus (HIV). The aim of this study was to analyze the genetic diversity of HBV and to evaluate serological marker associations and coinfections with HCV and HIV in patients attending and treated in a public hospital in the province of Buenos Aires, Argentina. A total of 189 HBV reactive samples (HBsAg and/or anti-HBc) were analyzed for HBV DNA characterization. All reactive samples were tested for anti-HCV and HIV-antigen/antibody using CMIA assays. Thirty-six samples exhibited detectable HBV DNA, 7 of which were OBI. HBV sequences were classified as subgenotypes A1, A2, B2, D3, F1b, F3 and F4. Mutations related to the ability to escape the host's immune response, resistance to antiviral therapy and progression to disease were found in patients, partly due to the variable sensitivity of HBsAg, the reverse transcriptase, the basal core promoter and the preCore. HCV and HIV prevalence was 10% and most of the genotypes found in the sequences were genotype 1 and B/F recombinant subtype, respectively. Of the total samples analyzed, 7 exhibited coinfections. This study shows the frequency of OBI, subgenotype distribution, HBV mutations and coinfections, which may have important clinical implications in public hospital patients. Planned prevention, detection and treatment adherence are needed to reduce transmission and morbidity in vulnerable populations.