BACKGROUND: There have been no comparisons of the relative sensitivity of the two Food and Drug Administration–licensed multiplex (MPX) nucleic acid test (NAT) systems (Procleix Ultrio [Gen-Probe], TIGRIS platform [Novartis]; and cobas TaqScreen MPX [Roche Molecular Systems], cobas s 201 platform [Roche Instrument Center]) for detecting hepatitis B virus (HBV)-infected donors in minipool sizes (MP) used in the United States.
STUDY DESIGN AND METHODS: Routine blood samples from Thailand were obtained from plasma units from 129 hepatitis B surface antigen (HBsAg)-negative, HBV NAT–yield donations. Blinded US testing included antibody to hepatitis B core antigen (anti-HBc), NAT using both manufacturers' systems (undiluted-individual donation [ID], in singlet and diluted 1:6 and 1:16 in triplicate), quantitative antibody to hepatitis B surface antigen, HBV DNA viral loads, and HBV genotyping. HBV yields in the United States were estimated using the incidence/window period (WP) model and compared to the calculated assay sensitivities.
RESULTS: Eighty samples were classified as occult HBV (anti-HBc reactive) and 49 as WP (anti-HBc nonreactive). For US pool sizes, MPX detected significantly more samples than Ultrio (MPX MP6 vs. Ultrio MP16; p < 0.0001 for occult and WP). Ultrio MP16 results were not statistically different from Ultrio MP6 (p = 0.68 for occult; p = 0.42 for WP). There was no difference between platforms for MP sizes used in most of the world (MPX MP6 vs. Ultrio ID; p = 0.70 for occult and p = 0.34 for WP). Viral loads were higher in WP samples. Modeled yield estimates were consistent with measured assay sensitivity on the Thai donor samples.
CONCLUSIONS: As used in the United States, MPX MP6 is more sensitive than Ultrio MP16, but the impact of this difference is mitigated by low numbers of HBV WP infections.