Detection of emergent strains of West Nile virus with a blood screening assay.

Abstract

West Nile virus (WNV) is a threat to transfusion safety. WNV Kunjin strain (WNVKUN ) is endemic across parts of Australia; however, human infection is believed to be infrequent and is often associated with relatively minor symptoms. A virulent strain, closely related to WNVKUN (termed WNVNSW2011 ) was recently identified as the etiologic agent of encephalitis in Australian horses. The aim of this project was to investigate whether a commercially available WNV blood screening assay can detect different strains of WNVKUN , including the virulent WNVNSW2011 , in human blood donor samples. Plasma samples were spiked with four different strains of WNVKUN , as well as a prototype WNV strain, at high, medium, and low viral loads. Spiking was confirmed with real-time reverse transcription-polymerase chain reaction (RT-PCR), before testing with the Procleix WNV transcription-mediated amplification (TMA) blood screening assay (Grifols). All WNV strains used were detectable by RT-PCR after being spiked into plasma. Additionally, all viral spiked samples were reactive by WNV TMA. We experimentally demonstrate that a commercially available WNV blood screening assay can detect different strains of WNVKUN . Given that WNV can be transfusion transmissible, it is essential to confirm that emergent strains are detectable by existing blood screening methods.