Development of a quantitative flow cytometry-based assay to assess infection by Plasmodium falciparum sporozoites

The human malaria parasite Plasmodium falciparum causes the most deadly parasitic disease worldwide, necessitating the development of interventions that block infection. Yet, preclinical assays to measure inhibition of infection date from the 1980s and are based on microscopy. Here, we describe the development of a simple flow cytometric assay that can be used to quantitatively assess P. falciparum sporozoite infection in vitro in low and medium throughput. We demonstrate the utility of this assay for assessing both drug inhibition of infection and measuring efficacy of antibodies in blocking parasite infection. This methodology will aid in assessing functional antibody responses to vaccination and novel drugs that prevent mosquito-to-man transmission of malaria.

In order to monitor infection, hepatocytes were infected with Plasmodium falciparum sporozoites, stained with a parasite-specific antibody, and analyzed by flow cytometry.131Highlights► We describe a simple flow cytometric assay that can be used to quantitatively assess Plasmodium falciparum sporozoite infection in vitro. ► Assay can be used for evaluation of invasion-blocking drugs. ► Assay quantitatively assesses neutralizing ability of invasion-blocking antibodies.