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IMRAS

IMRAS-Immunization with radiation-attenuated Plasmodium falciparum sporozoites by mosquito bite: Cellular immunity to sporozoites, CSP, AMA1, TRAP and CelTOS

August 25, 2021 - 16:20 -- Open Access
Author(s): 
Sedegah M, Hollingdale MR, Villasante E, et al.
Reference: 
PLoS One. 2021 Aug 20;16(8):e0256396

Immunization with radiation-attenuated sporozoites (RAS) by mosquito bites provides >90% sterile protection against Plasmodium falciparum malaria in humans. We conducted a clinical trial based on data from previous RAS clinical trials that suggested that 800–1200 infected bites should induce ~50% protective vaccine efficacy (VE) against controlled human malaria infection (CHMI) administered three weeks after the final immunization. Two cohorts were immunized separately. VE was 55% in Cohort 1 but 90% in Cohort 2, the cohort that received a higher first dose and a reduced (fractional) fifth dose. Immune responses were better boosted by the fractional fifth dose in Cohort 2 and suggested the importance of the fractional fifth dose for increased protection in Cohort 2 responses. Three protected subjects were later boosted and were protected suggesting that protection could be extended to at least 67 weeks.

Early whole blood transcriptional responses to radiation-attenuated Plasmodium falciparum sporozoite vaccination in malaria naïve and malaria pre-exposed adult volunteers

July 14, 2021 - 11:01 -- Open Access
Author(s): 
Fergal J. Duffy, Ying Du, Jason Carnes, Judith E. Epstein, Stephen L. Hoffman, Salim Abdulla, Said Jongo, Maxmillian Mpina, Claudia Daubenberger, John D. Aitchison and Ken Stuart
Reference: 
Malaria Journal 2021 20:308, 9 July 2021

Vaccination with radiation-attenuated Plasmodium falciparum sporozoites is known to induce protective immunity. However, the mechanisms underlying this protection remain unclear. In this work, two recent radiation-attenuated sporozoite vaccination studies were used to identify potential transcriptional correlates of vaccination-induced protection.

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