RESUMO
Interventions that can block the transmission of malaria-causing Plasmodium falciparum (Pf) between the human host and Anopheles vector have the potential to reduce the incidence of malaria. Pfs48/45 is a gametocyte surface protein critical for parasite development and transmission, and its targeting by monoclonal antibody (mAb) 85RF45.1 leads to the potent reduction of parasite transmission. Here, we reveal how the Pfs48/45 6C domain adopts a (SAG1)-related-sequence (SRS) fold. We structurally delineate potent epitope I and show how mAb 85RF45.1 recognizes an electronegative surface with nanomolar affinity. Analysis of Pfs48/45 sequences reveals that polymorphisms are rare for residues involved at the binding interface. Humanization of rat-derived mAb 85RF45.1 conserved the mode of recognition and activity of the parental antibody, while also improving its thermostability. Our work has implications for the development of transmission-blocking interventions, both through improving vaccine designs and the testing of passive delivery of mAbs in humans.
Assuntos
Antígenos de Protozoários/química , Epitopos/química , Malária Falciparum/transmissão , Glicoproteínas de Membrana/química , Plasmodium falciparum/imunologia , Proteínas de Protozoários/química , Sequência de Aminoácidos , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais Humanizados/química , Anticorpos Monoclonais Humanizados/imunologia , Anticorpos Antiprotozoários/química , Anticorpos Antiprotozoários/imunologia , Reações Antígeno-Anticorpo , Antígenos de Protozoários/genética , Antígenos de Protozoários/imunologia , Epitopos/imunologia , Humanos , Vacinas Antimaláricas , Malária Falciparum/imunologia , Malária Falciparum/prevenção & controle , Glicoproteínas de Membrana/genética , Glicoproteínas de Membrana/imunologia , Modelos Moleculares , Domínios Proteicos , Dobramento de Proteína , Proteínas de Protozoários/genética , Proteínas de Protozoários/imunologia , RatosAssuntos
Adjuvantes Imunológicos , Vacinas , Animais , Ensaios Clínicos como Assunto , Emulsões , França , Saúde Global , Humanos , Minerais , Tensoativos , Organização Mundial da SaúdeRESUMO
Endothelial CD39 metabolizes ADP released from activated platelets. Recombinant soluble human CD39 (solCD39) potently inhibited ex vivo platelet aggregation in response to ADP and reduced cerebral infarct volumes in mice following transient middle cerebral artery occlusion, even when given 3 hours after stroke. Postischemic platelet and fibrin deposition were decreased and perfusion increased without increasing intracerebral hemorrhage. In contrast, aspirin did not increase postischemic blood flow or reduce infarction volume, but did increase intracerebral hemorrhage. Mice lacking the enzymatically active extracellular portion of the CD39 molecule were generated by replacement of exons 4-6 (apyrase-conserved regions 2-4) with a PGKneo cassette. Although CD39 mRNA 3' of the neomycin cassette insertion site was detected, brains from these mice lacked both apyrase activity and CD39 immunoreactivity. Although their baseline phenotype, hematological profiles, and bleeding times were normal, cd39(-/-) mice exhibited increased cerebral infarct volumes and reduced postischemic perfusion. solCD39 reconstituted these mice, restoring postischemic cerebral perfusion and rescuing them from cerebral injury. These data demonstrate that CD39 exerts a protective thromboregulatory function in stroke.