Identification of a mutation in Hepatitis B virus surface antigen capable of evading ELISA screening

Abstract

ABSTRACT. Hepatitis B virus (HBV) infection can cause HBVrelated cirrhosis, liver failure, and hepatocellular carcinoma. At present, a hepatitis B surface antigen (HBsAg) blood test is the primary clinical and diagnostic marker for the identification of a chronic HBV infection. In the current study, we isolated a novel HBV mutant from a chronic HBV patient, capable of causing a false negative test result for most (7 of 8) commercial HBsAg ELISA kits. DNA sequencing of the HBsAg region of this HBV mutant revealed two novel mutation sites that resulted in a Thr-to-Met substitution at amino acid (aa) position 118 and a Lys to Asn substitution at aa position 122 of HBsAg. Moreover, a mutagenesis assay showed that the aa118 (Thr to Met) mutation was the leading cause of the false negative results from the HBsAg ELISA tests. The false negative result was restored, in that the mutation was correctly detected, when the Thr at aa position 118 of this mutated HBsAg was reconstituted. In conclusion, our study revealed a novel aa118 Met mutation of HBsAg HBV that will benefit the future development of HBV diagnosis.

HBV S antigen evolution in the backdrop of HDV infection affects epitope processing and presentation

“…43 Substitutions and indels in HBsAg, principally in "a" determinant region of the major hydrophilic loop, may lead to defective antigenicity and detection of HBsAg, resulting in impaired or partial protection against HBV infection. 44 High genetic variability with an increased number of mutations, such as SG145R, SK122N, and ST118M, seen in the "a" determinant region located between amino acids 124-147, affects the antigenicity and secretion of HBsAg. 45 This "a" determinant region is rich in cysteine and is organized into two loops located between amino acids C124 and C137 and C139 and C147.…”

“…Moreover, HBsAg protein is present in the HBV vaccine, where the postvaccination immune response is mostly elicited against the “a” determinant region within HBsAg 43 . Substitutions and indels in HBsAg, principally in “a” determinant region of the major hydrophilic loop, may lead to defective antigenicity and detection of HBsAg, resulting in impaired or partial protection against HBV infection 44 . High genetic variability with an increased number of mutations, such as SG145R, SK122N, and ST118M, seen in the “a” determinant region located between amino acids 124–147, affects the antigenicity and secretion of HBsAg 45 .…”

Optimization and Application of Quantitative In-House ELISA for Diagnosis of HBsAg and its Correlation with Commercial ELISA and Molecular Kits

“…In conjunction with public vaccination, timely diagnosis of HBV infection is a vital measure to decrease complications and mortality (5). Serological biomarkers such as HBsAg, anti-HBs, and anti-HBc antibodies are useful for diagnosing HBV (6,7).…”