(P-TS-42) Development of Novel Next Generation Blood Screening Assays That Support NAT Testing Sensitivity at the Speed of Serological Testing

Background/Case Studies: Rapid and effective screening of whole blood (WB) and plasma for transfusion-transmissible infections is essential to ensure the safety of blood transfusions and plasma for use in further manufacturing. Since the introduction of molecular testing in blood screening, it has been synonymous with a slow, yet sensitive method. The objective was to establish a new NAT methodology capable of achieving the sensitivity expected from molecular methods but with the speed of serological testing.

Study

Design/Methods: Pivotal to the discovery of this new NAT methodology was establishing the foundational technologies. For nucleic acid capture, Copper Titanium (CuTi) microparticles were selected. CuTi microparticles capture both RNA and DNA, support rapid automated sample extraction, and they are compatible with serum, plasma, and WB sample types. For amplification, an isothermal method called Recombinase Polymerase Amplification (RPA) was selected. RPA was chosen because of its sensitivity, automation compatibility, and speed, together with the capability for quantification and multiplexing. Detection is achieved through fluorescently labeled probes that bind to amplified product, allowing for target discrimination. With these foundational technologies in hand, the assay process was optimized for speed while ensuring assay performance meets or exceeds current standards. Prototype RPA assays have been developed with this new methodology against all current blood screening markers.

Results/Findings: The assay process takes 35 minutes from sample aspiration to the generation of the result. Eight prototype assays have been developed: a multiplex assay for the detection of HIV-1/2, HBV, and HCV; a duplex assay for the quantification of Parvovirus B19 and the qualitative detection of HAV; WNV; Zika; HEV; a duplex assay for the detection of Chikungunya and Dengue; as well as assays utilizing WB for the detection of Babesia and Malaria parasites. RPA technology has been optimized for quantitative purposes of Parvovirus B19 across a 6-log range. The 35-minute NAT methodology supports limit of detection sensitivities in the range of 3-25 IU/ml across the qualitative serum/plasma markers and as low as 2 iRBC/ml for the WB markers. These assays have demonstrated robustness to a wide range of genetic diversity and specificities of 100% with limited sample sizes up to approximately 1000 donor samples.

Conclusions: Compared to existing technologies, this new methodology can reduce the time to first result by 83%, from 3.5 hours to approximately 35 minutes. With expected NAT performance, there are opportunities for significant efficiencies in areas of staffing and blood screening workflows.