Quantitation of Antisporozoite Immunoglobulins in the Hemolymph of Anopheles Stephensi after Bloodfeeding

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  • Department of Microbiology and Immunology, University of Maryland School of Medicine, Department of Entomology, Walter Reed Army Institute of Research, Biomedical Research Institute, Baltimore, Maryland

Passage of rat antibodies induced by Plasmodium falciparum circumsporozoite protein (anti-CS IgG) from the bloodmeal into the hemocoel of uninfected Anopheles stephensi mosquitoes was quantified using enzyme-linked immunosorbent assay (ELISA) techniques. Anti-CS IgG were present in hemolymph immediately upon cessation of mosquito feeding. Titers peaked at 3 hr post-ingestion then declined steadily, becoming negligible at 18 hr. Substantial titers were present in the bloodmeal at 24 hr post-ingestion. By 48 hr, anti-CS IgG in both mosquito hemolymph and bloodmeal were virtually absent. Estimated quantitites of anti-CS IgG in the hemolymph at 3 hr post-ingestion were 905–958 ng/ml, representing ∼0.5 % of that present in the host serum. Rat IgG subclasses 1, 2a, and 2b passed into hemolymph more readily than did IgM and possibly IgG2c. Hemolymph volume of unengorged mosquitoes (0.53 µl) increased after a bloodmeal (0.73 µl at 3 hr post-ingestion), suggesting that anti-CS IgG may move into the hemocoel in an aqueous solution.

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