Hepatitis B virus genotype E surface antigen detection with different immunoassays and diagnostic impact of mutations in the preS/S gene

Abstract

The major neutralizing epitope, the "a" determinant of the hepatitis B virus (HBV) genotype E surface antigen (HBsAg) is most divergent from that of genotype A, which is used for preparing monoclonal antibodies used in commercially available HBV reagents. To evaluate the performance of the latest generation of HBsAg detection assays with respect to genotype E HBsAg. Three commercial assays were evaluated using sera from 200 Nigerian patients compared to the preS/S sequence of DNA positive samples. Out of 200 samples, 61 and 103 gave concordant positive and negative results between the three HBsAg assays. Of 36 samples with discordant results, 35 were confirmed negative by neutralisation. One of the three assays showed significantly high rate of false positives (29 of 35). DNA positive samples with no detectable HBsAg or reduced HBsAg detection signals (<75% of mean signal obtained with HBsAg positive samples) revealed several mutations (V14A, F46S, N48T, L49R, I49T, D51G, A53V, P54L, Q82P, F83C, L127P, A184V, T189I, S204N, V224A), mostly outside the a-determinant. Several of these mutations are found as wild type nucleotides normally in genotype A and only exceptionally in genotype E. All three assays showed comparable sensitivities for genotype E HBsAg detection (98.4-100%) but differed considerably in specificity (84-99%). Failure to detect HBsAg antigen and differences in signal intensity were mainly associated with mutations in the preS/S gene outside the "a" determinant.

Occult hepatitis B virus infection among Egyptian blood donors

“…In Egypt, HBV screening in blood banks relies only on detection of HBsAg; however, introducing NAT in some major blood banks is under implementation. Discrepancies in analytical sensitivity and specificity have been recorded among commonly used EIAs for the detection of HBsAg from viruses of different genotypes [22,23] . Failure to detect HBsAg antigen and differences in signal…”

“…February 27, 2013|Volume 5|Issue 2| WJH|www.wjgnet.com Said intensity were mainly associated with mutations in the preS/S gene outside the "a" determinant [23] . In this study, the overall prevalence of total anti-HBc antibodies among HBsAg negative blood donors was 14.2% (451/3167).…”

Detection of Highly Prevalent Hepatitis B Virus Coinfection among HIV-Seropositive Persons in Ghana

“…Genotype E shows approximately 8% amino acid divergence from genotype A, which is commonly used as the reference virus type for the development of HBsAg diagnostic assays (35). Previous studies indicated overall good performance of commercial assays with genotype E samples (31,32,43) but also suggested that amino acid changes within and outside the "a" determinant may affect HBsAg recognition (37). The performance of the three reference assays in this study was overall consistent with that reported by previous studies using European or reference samples (27,32,43).…”

Transfusion-transmitted hepatitis B virus infection

“…Differences in analytical sensitivity and specificity in detection of HBsAg from viruses of different genotypes have been reported among commonly used EIAs [11,12]. Mutations associated with conformational and hydrophobic changes within and outside the immunogenic major hydrophilic region (MHR) of the S antigen (the main target for capture antibodies used in diagnostic tests) and with reduced synthesis or secretion of HBsAg may account solely or in conjunction for the failure or a significant decrease in detecting HBsAg by immunoassays [13].…”