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.

The influence of hepatitis B virus (HBV) genotypes in the natural history of the disease and its response to antiviral treatment have been addressed in many studies. In Brazil, studies on HBV genotype circulation have been restricted to specific population groups and states. Here, we have conducted a nationwide multicentre study with an unprecedented sample size representing all Brazilian regions in an effort to better understand the viral variants of HBV circulating among chronic carriers. Seven HBV genotypes were found circulating in Brazil. Overall, HBV/A was the most prevalent, identified in 589 (58.7 %) samples, followed by HBV/D (23.4 %) and HBV/F (11.3 %). Genotypes E, G, C and B were found in a minor proportion. The distribution of the genotypes differed markedly from the north to the south of the country. While HBV/A was the most prevalent in the North (71.6 %) and Northeast (65.0 %) regions, HBV/D was found in 78.9 % of the specimens analysed in the South region. HBV/F was the second most prevalent genotype in the Northeast region (23.5 %). It was detected in low proportions (7 to 10 %) in the North, Central-West and Southeast regions, and in only one sample in the South region. HBV/E was detected in all regions except in the South, while monoinfection with HBV/G was found countrywide, with the exception of Central-West states. Our sampling covered 24 of the 26 Brazilian states and the Federal District and is the first report of genotype distribution in seven states. This nationwide study provides the most complete overview of HBV genotype distribution in Brazil to date and reflects the origin and plurality of the Brazilian population.

Hepatitis A virus (HAV) isolates from around the world have been classified into seven genotypes (I-VII). Most human strains belong to genotype I, which has been divided into two subgenotypes, A and B. South America has provided a small number of strains studied at the genome level. In the present study, IgM anti-HAV antibodies were detected in 116 out of 250 (46%) serum samples collected from consecutive patients with acute hepatitis referred to the Brazilian Reference Center for Viral Hepatitis, Rio de Janeiro. Viral RNA were extracted from all 250 samples and submitted to a reverse transcription-polymerase chain reaction (RT-PCR) assay designed to amplify a genome segment in the VP1/2A junction region. HAV RNA was detected in 54/116 (47%) and 17/134 (13%) IgM anti-HAV-positive and -negative sera, respectively. In addition, HAV RNA was detected in 17/35 (49%) IgM anti-HAV-positive sera that had been collected at a day care center where cases of acute hepatitis were being observed for 3 months. Nucleotide sequences (168 bp) of PCR products were determined for 30 HAV isolates. Phylogenetic analysis showed that 21 belonged to subgenotype IB, while 9 were of subgenotype IA. Interestingly, a concomitant circulation of isolates from subgenotypes IA and IB was observed in the day care center.

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DBS samples can be used for the detection of HCV AgAb by EIA as they present comparable performance characteristics and excellent stability among various storage conditions.