Hepatitis B virus (HBV) genotype A has been divided recently into two subgroups, designated A-A' (genotype A excluding A') and A'. Isolates belonging to subgroup A' have been identified in Africa. A new genotyping method, based on PCR amplification of the pre-S/S genome region and subsequent restriction fragment length polymorphism (RFLP) analysis, was developed, that established a correlation between RFLP subtypes and subgroups within genotype A. To investigate the occurrence of subgroup A' in South America, 119 Brazilian HBV isolates were analyzed. Ninety-three (78%) of them belonged to genotype A, with three predominating RFLP subtypes: 44 (37%) isolates were classified as AI, 30 (25%) were AII, and 18 (15%) were AIII. Pre-S/S nucleotide sequences of 15 genotype A isolates were determined. Phylogenetic analysis performed with these 15 and an additional 41 sequences revealed that isolates AI and AII clustered in subgroup A', whereas isolates AIII were classified into subgroup A-A'. The correlation RFLP subtypes-subgroups was confirmed by the presence of amino acid residues specific for subgroup A' in the surface antigens and polymerase of isolates AI and AII. The high proportion (63%) of isolates from subgroup A' suggested an African origin for a large number of Brazilian HBVs.

The complete genome of a hepatitis B virus (HBV) from Brazil that expressed the subtype adw4 of HBV surface antigen (HBsAg) was cloned and sequenced. The genome, termed w4B, consists of 3215 bp. The overall genetic organization of typical hepadnaviruses with four open reading frames including the preC region was found to be conserved. When comparing the w4B sequence with 19 complete HBV genomes it was, however, found to be more divergent (15 %) than any other HBV sequence thus far reported. Until now, no more than 11% divergence has been reported. Distinct from the five known HBV genotypes A to E, w4B made up a new, sixth genotype. The importance of the conserved third start codon in the HBV X gene became apparent in isolate w4B. By mutation, this ATG was out of frame, and by what appears to have been a linked mutation, a new start site two codons downstream was re-established. The significance of several other mutations is discussed.

An hemodialysis population in Central Brazil was screened by polymerase chain reaction (PCR) and serological methods to assess the prevalence of hepatitis C virus (HCV) infection

Detection of hepatitis B virus (HBV) serological markers in dried blood spot (DBS) samples by enzyme immunoassay (ELISA) has not yet been fully optimized. In this study, the ability to detect three HBV markers (HBsAg, anti-HBc, and anti-HBs) was evaluated in DBS samples using a modified commercial ELISA. Matched serum and DBS samples were obtained from individuals with or without a past history of HBV infection. Sera samples were tested according to the manufacturer's instructions, but for DBS testing, paper diameters, elution buffer, volume of input sample, and cut-off values were evaluated to optimize the assay. Stability studies were done on DBS stored at for up to 180 days at different temperatures. The absorbance values that yielded the maximum sensitivity and specificity were determined based on the area under the ROC curve (AUROC) and chosen as the cut-off value. Using this parameter, sensitivity was 90.5%, 97.6%, and 78% for anti-HBc, HBsAg, anti-HBs assays, respectively. Specificity was 92.6%, 96.7%, and 97.3% for anti-HBc, HBsAg, and anti-HBs assays, respectively. HBV markers could be detected in DBS samples until 63 days after sample collection at most temperatures, but storage at -20°C yielded more consistent results. These results indicate that modified ELISA can be used to detect HBV markers in DBS samples, particularly if the samples are stored appropriately.

A retrospective study on the prevalence of hepatitis E virus (HEV)