title: An Opsonic Phagocytosis Assay for Plasmodium falciparum Sporozoites.
abstract: Plasmodium falciparum malaria remains the deadliest parasitic disease worldwide. Vaccines targeting the preerythrocytic sporozoite and liver stages have the potential to entirely prevent blood-stage infection and disease, as well as onward transmission. Sporozoite surface and secreted proteins are leading candidates for inclusion in a preerythrocytic stage-specific, antibody-based vaccine. Preclinical functional assays to identify humoral correlates of protection in vitro and to validate novel sporozoite protein targets for inclusion in multisubunit vaccines currently do not consider the interaction of sporozoite-targeting antibodies with other components of the immune system. Here, we describe the development of a simple flow cytometric assay to quantitatively assess the ability of antibodies directed against P. falciparum sporozoites to facilitate their phagocytosis. We demonstrate that this sporozoite opsonic phagocytosis assay (SOPA) is compatible with both monoclonal antibodies and human immune serum and can be performed using cryopreserved P. falciparum sporozoites. This simple, accessible assay will aid with the assessment of antibody responses to vaccination with Plasmodium antigens and their interaction with phagocytic cells of the immune system.
authors.affiliation: Center for Infectious Disease Research, Seattle, Washington, USA.
authors.forename: Ryan W J
authors.identifier: http://orcid.org/0000-0002-4802-2896
authors.initials: RW
authors.lastname: Steel
authors.affiliation: Center for Infectious Disease Research, Seattle, Washington, USA.
authors.forename: Brandon K
authors.initials: BK
authors.lastname: Sack
authors.affiliation: HIV and Malaria Vaccine Program, Aaron Diamond AIDS Research Center, New York, New York, USA.
authors.forename: Moriya
authors.initials: M
authors.lastname: Tsuji
authors.affiliation: Center for Infectious Disease Research, Seattle, Washington, USA.
authors.forename: Mary Jane L
authors.initials: MJ
authors.lastname: Navarro
authors.affiliation: Center for Infectious Disease Research, Seattle, Washington, USA.
authors.forename: Will
authors.initials: W
authors.lastname: Betz
authors.affiliation: Center for Infectious Disease Research, Seattle, Washington, USA.
authors.forename: Matt E
authors.initials: ME
authors.lastname: Fishbaugher
authors.affiliation: Center for Infectious Disease Research, Seattle, Washington, USA.
authors.forename: Erika L
authors.initials: EL
authors.lastname: Flannery
authors.affiliation: Center for Infectious Disease Research, Seattle, Washington, USA Stefan.Kappe@cidresearch.org.|Department of Global Health, University of Washington, Seattle, Washington, USA.
authors.forename: Stefan H I
authors.initials: SH
authors.lastname: Kappe
mesh_terms: D000913:Antibodies, Protozoan / Q000097:blood*; D005434:Flow Cytometry / Q000379:methods; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D009895:Opsonin Proteins / Q000097:blood*; D010587:Phagocytosis; D010963:Plasmodium falciparum / Q000276:immunology*; D034101:Sporozoites / Q000276:immunology*
chemical_list: D000913:Antibodies, Protozoan; D009895:Opsonin Proteins
keywords: Plasmodium falciparum; antibodies; assay development; malaria; opsonization; phagocytosis; sporozoite; vaccines