Standard membrane feeding assay (SMFA)

The functional activity of transmission-blocking vaccines was evaluated by SMFA²⁶. Purified IgG was diluted to desirable test concentrations in a mixture of approximately 0.3% P. falciparum (NF54) gametocytes, human red blood cells (50% hematocrit), and normal human sera. The antibody-parasite mixture was fed to 25-40, 4–6-day old An. stephensi mosquitoes (starved 6–8 h) using glass membrane feeders maintained at 37 °C for 15 min. Unfed mosquitoes were removed and blood-fed mosquitoes were maintained at 27–28 °C with 70–80% relative humidity for 7–8 days. Mosquito midguts were dissected, and oocysts were enumerated after staining with 0.5% mercurochrome for 15–20 min. Transmission reducing activity is defined as the percent reduction in mean oocysts between the test IgG-fed mosquitoes and the control IgG-fed mosquitoes. Transmission blocking activity is defined as the percent reduction in the proportion of infected mosquitoes between the test IgG fed and control IgG fed groups.