Immunodetection of Plasmodium falciparum zygotes and ookinetes in Anopheles blood meals.
An indirect fluorescent antibody assay (IFA) using monoclonal antibodies to the 25-kDa Plasmodium falciparum ookinete surface antigen was developed to detect and quantify preoocyst stages of P. falciparum in mosquito blood meals. This IFA is suitable for the detection and quantitation of zygotes/macrogametes, retorts (immature ookinetes), and ookinetes. Time-course evaluations showed that zygotes represented > 52% of the parasites detected between 6 and 24 h. From 24 to 36 h similar densities of all 3 stages were observed. By 42 h. 56% of the detectable parasites were ookinetes. Compared to the hemocytometer the IFA provided a better estimate of stage-specific infection rates and densities. The assay is a useful new tool for evaluating preoocyst stages in laboratory-infected mosquitoes and has the potential for detecting natural infections in vector populations.
Chege
G M
GM
Department of Immunology and Infectious Diseases, School of Hygiene and Public Health, Johns Hopkins University, Baltimore, MD 21205.
Beier
J C
JC
D000818:Animals; D000852:Anopheles / Q000469:parasitology*; D001769:Blood / Q000469:parasitology; D005455:Fluorescent Antibody Technique; D006801:Humans; D008856:Microscopy, Fluorescence; D008858:Microscopy, Phase-Contrast; D010063:Ovum; D010963:Plasmodium falciparum / Q000254:growth & development / Q000302:isolation & purification*; D015053:Zygote