title: Evaluation of the VecTest Malaria Antigen Panel assay for the detection of Plasmodium falciparum and P. vivax circumsporozoite protein in anopheline mosquitoes in Thailand.
abstract: We evaluated the performance of the VecTest Malaria Antigen Panel (V-MAP) assay for the detection of Plasmodium falciparum and P. vivax (variants 210 and 247) circumsporozoite protein in anopheline mosquitoes in Thailand. The V-MAP assay is a rapid, one-step procedure using a 'dipstick' wicking test strip. The circumsporozoite (CS) ELISA was used as the reference standard. Mosquitoes evaluated in the study included field-collected specimens (n = 930) and laboratory-reared specimens that had been fed on blood collected from patients with and without Plasmodium gametocytes (n = 4,110) or on cultured P. falciparum gametocytes (n = 262). Field-collected mosquitoes were triturated individually or in pools of 2-5 and tested using 613 V-MAP assays. Laboratory-reared specimens were tested individually using 4,372 V-MAP assays. Assay performance depended on the species of Plasmodium and the number of sporozoites used as the cut-off. For P. falciparum, optimal performance was achieved using a cut-off of 150 sporozoites (sensitivity = 100%, specificity = 99.2%, and accuracy = 0.99). For P. vivax variant 210, optimal performance was also achieved using a cut-off of 150 sporozoites (sensitivity = 94.8%, specificity = 94.5%, and accuracy = 0.95). We were unable to develop a standard-curve for the CS-ELISA using P. vivax variant 247 because of a lack of sporozoites; however, using a cut-off of 30 pg P. vivax 247 antigen (mosquitoes with less than this amount of antigen were considered negative), assay performance (sensitivity = 94.3%, specificity = 99.2%, and accuracy = 0.99) was comparable to that achieved for P. falciparum and P. vivax 210. These results clearly demonstrate that the V-MAP assay performs at an acceptable level and offers practical advantages for field workers needing to make rapid surveys of malaria vectors.
authors.affiliation: Department of Entomology, U.S. Army Medical Component, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
authors.forename: Jetsumon
authors.initials: J
authors.lastname: Sattabongkot
authors.forename: Chukree
authors.initials: C
authors.lastname: Kiattibut
authors.forename: Chalermporn
authors.initials: C
authors.lastname: Kumpitak
authors.forename: Alongkot
authors.initials: A
authors.lastname: Ponlawat
authors.forename: Jeffrey R
authors.initials: JR
authors.lastname: Ryan
authors.forename: Adeline S T
authors.initials: AS
authors.lastname: Chan
authors.forename: Kirti
authors.initials: K
authors.lastname: Davé
authors.forename: Robert A
authors.initials: RA
authors.lastname: Wirtz
authors.forename: Russell E
authors.initials: RE
authors.lastname: Coleman
mesh_terms: D000818:Animals; D009033:Culicidae / Q000469:parasitology*; D010963:Plasmodium falciparum / Q000302:isolation & purification*; D010966:Plasmodium vivax / Q000302:isolation & purification*; D015800:Protozoan Proteins / Q000032:analysis*; D011934:Reagent Strips; D013785:Thailand
chemical_list: D015800:Protozoan Proteins; D011934:Reagent Strips; C041595:circumsporozoite protein, Protozoan