title: Methods for detection of West Nile virus antibodies in mosquito blood meals.
abstract: We describe and compare 2 qualitative serologic techniques for detecting West Nile virus (WNV)-specific antibodies in mosquito blood meals. The techniques are the biotin microsphere immunoassay (b-MIA) and the inhibition platform of the VectorTest™ WNV antigen assay (VecTest-inhibition). To demonstrate the ability of these tests to detect WNV-neutralizing antibodies, we experimentally exposed feeding mosquitoes to blood containing 5 concentrations of 6B6C-1, a flavivirus-neutralizing monoclonal antibody. Antibody concentrations were quantified using the 90% plaque-reduction neutralization test (PRNT90). After 24 h of blood-meal digestion at 22.5°C, the threshold PRNT90 titer of detection was ≤18 for b-MIA and ≤50 for VecTest-inhibition. Both tests reliably detected antibodies in 3 of 3 blood meals that had been digested for up to 30 h, or were about 25% digested. The b-MIA was also applied to mosquitoes that had engorged on avian blood in Arizona following a WNV epidemic in 2010. There was no significant difference in the WNV antibody prevalence determined by b-MIA (52% of 71 avian blood meals) compared to the WNV-neutralizing antibody prevalence in birds determined by direct sampling (49% of 234 birds). VecTest-inhibition requires fewer resources and may be used in the field without a laboratory, but consumes the entire blood meal and relies on subjective interpretation of results. The b-MIA requires a laboratory and sophisticated equipment and reagents. Results for b-MIA are analyzed objectively and can be applied to mosquito blood meals with greater confidence than the VecTest-inhibition method and thus can contribute substantially to research and surveillance programs that would benefit from the detection of specific WNV antibodies in mosquito blood meals.
authors.affiliation: Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, 3156 Rampart Road, Fort Collins, CO 80521.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Komar
authors.forename: Nicholas A
authors.initials: NA
authors.lastname: Panella
authors.forename: Ginger R
authors.initials: GR
authors.lastname: Young
authors.forename: Alison J
authors.initials: AJ
authors.lastname: Basile
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D000956:Antigens, Viral / Q000097:blood*; D001130:Arizona; D001710:Biotin / Q000737:chemistry; D009033:Culicidae / Q000821:virology*; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D014902:West Nile virus / Q000276:immunology* / Q000302:isolation & purification*
chemical_list: D000914:Antibodies, Viral; D000956:Antigens, Viral; D001710:Biotin
keywords: Mosquito; West Nile virus; antibody; blood meal; surveillance
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