An interesting case of isolated false-negative hepatitis B surface antigen in a blood donor.

Abstract

An important requirement for a hepatitis B surface antigen (HBsAg) screening assay is reliable detection of HBsAg mutant forms, especially in blood donation. Here we investigate and describe the case of an isolated false-negative result of commercial serology HBsAg screening assay of a blood donor. The current donation was routinely tested for HBsAg and hepatitis B virus (HBV) DNA in the mini-pool mode nucleic acid testing (MP-NAT of six samples), and further evaluated by individual donation ID-NAT. Finally, it was quantified and sequenced. All previous donations were found to have negative HBsAg and HBV DNA, as also the subsequent sample taken 3 months after the marked donation. The current donation of the 53-year-old unvaccinated female with 14 previous donations was initially HBsAg negative and HBV DNA (MP-NAT) positive. Further testing showed HBsAg positive using other HBV serological assays, antibodies to HBV core antigen immunoglobulin Mpositive and HBV DNA ID-NAT positive, and contained 200 IU/mL of HBV DNA. The implicated donation carried genotype D strains, subtype ayw2 (F83S, V96A, V190A, L193S, I195T, L213S, F220L). The mutations in three positions, namely amino acids T118A, P120T, and P127T, were proven subsequently. This unique mutation combination near the target epitope of one of the immunoassay monoclonals is a possible cause of the reduced analytical sensitivity of the serology assay.