Detection and molecular characterisation of a diagnosis escape variant associated with occult hepatitis B virus in Brazil

Abstract

BACKGROUND Many studies have identified mutations in the hepatitis B surface antigen (HBsAg) as important factors limiting the ability of commercial serological assays to detect this viral antigen. However, an association between mutations in the HBsAg gene and the occurrence of occult HBV infection (OBI) in patients has not been established.OBJECTIVES To detect hepatitis B virus (HBV) DNA in patients with anti-HBc as a unique serological marker, a previously published, cost-effective TaqMan-based real-time polymerase chain reaction (PCR) test with minor groove binding probes was adapted for use in this study. The current study also aimed to investigate HBsAg mutations and genotypes of HBV in OBI at the Viral Hepatitis Ambulatory Clinic in Rio de Janeiro to determine any possible association.METHODS Intra-assay and inter-assay reproducibility were determined, and the mean coefficient of variation values obtained were 2.07 and 3.5, respectively. Probit analysis indicated that the 95% detection level was 25 IU/mL. The prevalence of OBI was investigated in 35 serum samples with an ‘anti-HBc alone’ profile from individuals who attended our clinic between 2011 and 2013.FINDINGS HBV DNA was detected in only one sample, resulting in an OBI rate of 2.9%. Nucleotide sequencing of the pre-S/S region was performed to genotype and analyse mutations within the HBsAg gene of this HBV DNA. The HBV in the OBI case was classified as sub-genotype A1, and a sequence analysis of the small S gene revealed 12 mutations in the major hydrophilic region compared to the consensus A1 sequence. Most of these mutations occurred in amino acid residues that have been reported as clinically relevant because they have been implicated in vaccine escape and/or inability to detect HBsAg by commercial serological assays.MAIN CONCLUSIONS Our study suggests the importance of specific HBsAg mutations, different from those in D, B, and C genotypes, in sub-genotype A1 HBV associated with OBI.

HBV DNA in the Plasma and Peripheral Blood Mononuclear Cells in Chronic HBV Infected Individuals Who Became HBsAg-Serocleared or Seroconverted

“…In another study, in spite of negative serological tests in some patients, viral DNA was detected in the plasma, which was attributed to viral DNA mutation (17). Similarly, in our study, DNA was found in peripheral lymphocytes, even in patients with high levels of antibodies.…”

Occult and active hepatitis B virus detection in donated blood in São Paulo, Brazil

“…In our study population, the frequency of OBI was 0.61% in blood samples that were HBcAb‐positive/HBsAg‐negative. Previously published data have reported an OBI prevalence of 0% to 4% in the HBcAb‐positive blood donor population in Brazil 24–27 . This rate varied by HBV prevalence in different regions and the detection limit of the applied assay.…”

Endemic hepatitis B virus (HBV) among hospital in-patients in Bangladesh, including evidence of occult infection

“…Given that no mutations linked to OBI were identified at the consensus level in sample 118, this suggests that all sequences must carry at least one of the mutations observed in the HBV surface gene, and reliance on short-read sequencing technology is limiting our current understanding of how these mutations interact to produce a particular phenotype. Many different mutations have been described in OBI, and the individual or combined influence of each of these is often not well defined; furthermore, relevant polymorphisms may differ between genotypes 65 .…”

“…17.20037085 doi: medRxiv preprint is limiting our current understanding of how these mutations interact to produce a particular phenotype. Many different mutations have been described in OBI, and the individual or combined influence of each of these is often not well defined; furthermore, relevant polymorphisms may differ between genotypes 65 .…”