West Nile Virus (WNV) NAT
The Procleix WNV Assay is a qualitative in vitro nucleic acid assay system for the detection of West Nile Virus (WNV) RNA in plasma specimens from individual human donors, including volunteer donors of whole blood and blood components, and other living donors.is also intended for use in testing plasma specimens to screen organ donors when specimens are obtained while the donor's heart is still beating. It is not intended for use on cord blood specimens. This assay is not intended for use as an aid in the diagnosis of West Nile Virus infection.
About West Nile Virus
WNV is a mosquito-borne flavivirus that is associated with human disease ranging from mild flu-like symptoms to severe neurological disease.1,2 Most WNV infections are asymptomatic and approximately 20% lead to a mild illness known as West Nile virus fever. Less than 1% of infections are estimated to cause serious neurological disease, with advanced age being the most significant risk factor.3
In most human infections, WNV multiplies to a relatively low level producing a transient viremia that can be detected in whole blood, plasma, and serum. Current diagnostic methods for WNV include Immunoglobulin M (IgM) enzyme immunoassays, Plaque Reduction Neutralization assays, and nucleic acid testing (NAT) methods. IgM antibody can be detected in serum or cerebrospinal fluid (CSF) collected within eight days of illness onset but NAT methods are capable of detecting infection prior to the presence of antibodies during the viremic phase. Because serologically based assays detect host immune response after this primary viremic phase and IgM can remain in the body for long periods of time, these tests may not be appropriate for blood screening.3,7
Screening of whole blood donations with NAT has been in place in the United States since early 1999 and licenses were granted for HIV-1 and HCV screening in 2002.16 The Procleix WNV Assay uses the same technology as the Procleix HIV-1/HCV Assay to detect WNV RNA and has been utilized in the United States for prospective blood screening since June 19, 2003 and was licensed in 2005.
The Procleix WNV Assay involves three main steps, which take place in a single tube: sample preparation; WNV RNA target amplification by Transcription-Mediated Amplification (TMA)26; and detection of the amplification products (amplicon) by the Hybridization Protection Assay (HPA)18. Test performed by VRL Eurofins, 6933 S. Revere Parkway, Centennial, CO 80112. This test has been cleared or approved for diagnostic use by the U.S. Food and Drug Administration. See package insert for more information.