A comparative study of the new Access^® HBs Ag assay and the HBs Ag confirmatory assay from Beckman Coulter

Abstract number: 1733_675

Duburcq X., Pouzet A., Marant L., Clément A., Duhamel D., Leirens Y., Margotteau F., Falcou-Briatte R., Bouniort F., Taskar S., Flecheux O.

Background: Hepatitis B virus infection is a worldwide problem of clinical significance. The virus is transmitted via parenteral contact, through the exchange of blood and blood products, by sexual contact, and by perinatal spread from mother to child. In this study, we compared the relative sensitivity and specificity performances of the new Access HBs Ag assay currently in development and the Abbott AxSYM§ HBsAg V2.

Methods: Analytical sensitivity was compared by testing the BBI PHA 106 panel composed of 15 points with low HBs Ag titer within 0.05 and 0.6 IU/mL. Clinical sensitivity was investigated using commercialised panels for subtypes and genotypes or in-house panel for variants, 30 commercialised seroconversion panels (including 177 samples), and 100 positive samples from recent, acute or chronic phase infected patients. Negative sample repartition was compared with 577 negative samples collected in a hospital in France.

Results: All low titer panel members up to 0.05 IU/mL were recognized by the Access HBs Ag assay, whereas AxSYM HBs Ag failed to recognize 2 of them up to 0.1 IU/mL. All subtypes, genotypes and variants tested were recognized by both methods. The Access HBs Ag assay showed equivalent results to AxSYM HBs Ag for 18 panels among the 30 tested. The Access HBs Ag assay was more sensitive with 10 panels and less sensitive with 2 panels. Among the 100 positive samples, all were found positive, displaying 100% of agreement between the Access HBs Ag and AxSYM assays. The specific margin (SM), defined as the number of SD between the negative sample mean and the cut-off, was determined equal to 21 for the Access HBsAg assay and 5.5 for AxSYM HBs Ag.

Conclusion: The performance of the Access HBsAg and the Access HBsAg Confirmatory assays are at least equivalent to that of the AxSYM HBsAg V2. The Access HBsAg and the Access HBsAg Confirmatory assays can be used either with the Access Immunoassay System or with the high-throughput UniCel^® DxI 800 Immunoassay System offering rapid and accurate results whatever the throughput requirement of the lab.

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