Sequence analysis of full-length Hepatitis B virus genomes ascribed to genotype E isolated from two children in Argentina.

CUESTAS ML,; MATHET VL,; MINASSIAN ML,; RIVERO C,; TRINKS J,; DALEOSO G,; LEÓN LM,; SALA A,; LIVELLARA B,; CORACH D,; KURBANOV F,; LEZAMA C,; GALOPPO M,; GIACOVO G,; GALOPPO C,; AMEIGEIRAS BM,; OUBIÑA JR.

Buenos Aires

Congreso; 6th World Congress of the World Society for Pediatric Infectious Diseases.; 2009

World Society for Pediatric Infectious Diseases.

Background and aims: Long-term prognosis of Hepatitis B virus infection (HBV), its initial clinical picture and the host response to treatment may differ depending on HBV genotypes. Among all of them, genotype E holds the most divergent a determinant within the HBsAg. This feature appears to be an influencing factor for diagnostic assays testing HBsAg, and raises concerns about the efficacy of current vaccination in the African continent where this genotype is predominant. The aim of this study was to better characterize the genomic bases of an unprecedented detection of genotype E HBV isolates from two sisters in Argentina with chronic hepatitis B, whose respective S gene partial sequences have been previously reported. One of them, a 5 year-old girl received the full HBV vaccination schedule and showed co-circulation of HBsAg/anti-HBs antibodies, in the absence of S-escape mutants, while her unvaccinated 13-year-old sister surprisingly carried the HBsAg immune escape mutant D144A in the absence of co-circulating anti-HBs antibodies. Both of them had shown an L209V replacement within the HBsAg. Methods. Serum samples from 2 chronically infected HBV patients were the source of viral DNA. PCR-amplification and sequence analysis of complete genomes were carried out. Results. Sequence analysis of full-length genomes of two HBV isolates ascribed to genotype E revealed changes in the two regulatory elements of the basal core promoter (T1634 and T1659) and the rtL217R adefovir resistant variant in both sisters, and only the D144A S-escape mutant (together with a minor wt subpopulation), in the unvaccinated one. Conclusion. This study characterizes the genomic bases of an unprecedented detection of genotype E HBV isolates in Argentina as well as its exceptional circulation in the Americas.