Specific primer sets used to amplify by PCR the hepatitis B virus overlapping S/Pol region select different viral variants

PCR detection of viral genomes has provided new insights into viral diagnosis. Nowadays, it is the most frequently used nucleic acid testing (qualitative and quantitative) technique. The aim of this study was to analyse the major circulating hepatitis B virus (HBV) variants PCR-amplified by three sets of primers in a patient infected with genotype E. The HBV S/Pol overlapping genomic region was amplified from the serum of an infected child using three primer sets previously described. Sequence analysis corresponding to the HBV S/Pol region revealed the presence of different viral populations depending on the set of primers used. D144A S-escape mutant was detected with two of the primer sets, while the rtL217R mutant within the Pol - conferring resistance to Adefovir - could be picked up with a different pair of primer sets. This study undoubtedly implies that the description of viral polymorphisms should be stated together with the sequence of the primers used for PCR amplification when studies of escape and/or antiviral-resistant HBV mutants are carried out.

Two simultaneous hepatitis B virus epidemics among injecting drug users and men who have sex with men in Buenos Aires, Argentina: characterization of the first D/A recombinant from the American continent

Previous studies have revealed that hepatitis B virus (HBV)/D and HBV/F predominate among blood donors from Buenos Aires, Argentina. In the present study, blood samples from two high-risk groups were analysed: 160 corresponding to street- and hospital-recruited injecting drug users [81.2% showing the 'anti-hepatitis B core antigen (anti-HBc) only' serological pattern] and 20 to hepatitis B surface antigen (HBsAg)(+)/anti-HBc(+) men who have sex with men. HBV genotypes were assigned by polymerase chain reaction amplification followed by restriction fragment length polymorphism and confirmed by nucleotide sequencing of two different coding regions. HBV DNA was detected in 27 injecting drug users (16.9%, occult infection prevalence: 7.7%), and 14 men who have sex with men (70%). HBV/A prevailed among injecting drug users (81.8%) while HBV/F was predominant among men who have sex with men (57.1%). The high predominance of HBV/A among injecting drug users is in sharp contrast to its low prevalence among blood donors (P = 0.0006) and men who have sex with men (P = 0.0137). Interestingly, all HBV/A S gene sequences obtained from street-recruited injecting drug users encoded the rare serotype ayw1 and failed to cluster within any of the known A subgenotypes. Moreover, one of the HBV strains from a hospital-recruited injecting drug user was fully sequenced and found to be the first completely characterized D/A recombinant genome from the American continent. Data suggest that two simultaneous and independent HBV epidemics took place in Buenos Aires: one spreading among injecting drug users and another one sexually transmitted among the homosexual and heterosexual population.