Expression of Heat shock protein 70 (Hsp70-1) in Plasmodium berghei ookinetes and its participation in midgut mosquito infection

•Several Hspt proteins are present in Plasmodium berghei sexual stages, but only PbHsp70-1 is expressed in ookinetes.•PbHsp70-1 was localized in micronemes and on the surface of ookinetes.•PbHsp70-1 participates in Plasmodium berghei sexual stages development and in the midgut infection of Anopheles albimanus. The heat shock protein family 70 (Hsp70) comprises chaperone proteins that play major multiple roles in Plasmodium asexual and sexual development. In this study, we analyzed the expression of Hsp70-1 in gametocytes, gametes, zygotes, and its participation in ookinete formation and their transition into oocysts. A monoclonal antibody against recombinant Hsp70-1 revealed its presence in zygotes and micronemes of ookinetes. Compared to wild type parasites, Hsp70-1 knockout ookinetes produced fewer oocysts in Plasmodium-susceptible Anopheles albimanus mosquitoes. This may indicate a defective transformation of ookinetes into oocysts in the absence of Hsp70-1. The presence of this protein in micronemes suggests its participation in mosquito infection, probably aiding to the adequate structural conformation of proteins in charge of motility, recognition and invasion of the insect midgut epithelium.