Carola SchäferNicholas DambrauskasLaura M. ReynoldsOlesya TrakhimetsAndrew RaappanaErika L. FlanneryWanlapa RoobsoongJetsumon SattabongkotSebastian A. MikolajczakStefan H.I. KappeD. Noah SatherFaculty of Tropical Medicine, Mahidol UniversityUniversity of WashingtonSeattle Biomedical Research Institute2022-08-042022-08-042021-05-12Cell Host and Microbe. Vol.29, No.5 (2021), 752-756.e419346069193131282-s2.0-85104930169https://repository.li.mahidol.ac.th/handle/20.500.14594/77287Latent forms of Plasmodium vivax, called hypnozoites, cause malaria relapses from the liver into the bloodstream and are a major obstacle to malaria eradication. To experimentally assess the impact of a partially protective pre-erythrocytic vaccine on reducing Plasmodium vivax relapses, we developed a liver-humanized mouse model that allows monitoring of relapses directly in the blood. We passively infused these mice with a suboptimal dose of an antibody that targets the circumsporozoite protein prior to challenge with P. vivax sporozoites. Although this regimen did not completely prevent primary infection, antibody-treated mice experienced 62% fewer relapses. The data constitute unprecedented direct experimental evidence that suboptimal efficacy of infection-blocking antibodies, while not completely preventing primary infection, has a pronounced benefit in reducing the number of relapses. These findings suggest that a partially efficacious pre-erythrocytic Plasmodium vivax vaccine can have a disproportionately high impact in positive public health outcomes.Mahidol UniversityImmunology and MicrobiologyArticleSCOPUS10.1016/j.chom.2021.03.011