The PfSPZ vaccine is a candidate vaccine targeting the Plasmodium falciparum parasite, which is the cause of the most lethal type of human malaria. This study used de-identified blood samples collected from 316 infants aged 5 to 12 months (inclusive) enrolled in a Phase 2, randomized, placebo-controlled trial (<a href="https://clinicaltrials.gov/ct2/show/NCT02687373">NCT02687373</a>) of the PfSPZ malaria vaccine, conducted in a region of western Kenya where malaria transmission is high and perennial. The study began in July, 2016, after peak malaria transmission, and was completed in August, 2018. In this study, three doses of the PfSPZ Vaccine (4.5x105 PfSPZ, 9.0x105 PfSPZ, and 1.8x106 PfSPZ) were tested against a normal saline placebo comparator. In all four groups, doses were administered in 3 doses at 0, 8, and 16 weeks by direct venous inoculation. Vaccine efficacy was determined at 3, 6, and 12 months of follow-up after the third immunization. RNA was extracted from whole blood collected in PAXgene tubes before PfSPZ immunization, and two weeks after the third (final) dose, from 262 children for which sufficient material was available at both time points (82% of 316 enrolled children; 525 samples). RNA was depleted of globin and ribosome transcripts before library generation and sequencing on the Illumina NovaSeq platform. RNA-seq expression data was analyzed to determine blood transcriptional signatures, before and after PfSPZ vaccine immunization, that predicts sterile protection from naturally occurring P. falciparum infection or delayed parasitemia at 3 months post-immunization. Gene expression data will also be correlated to P. falciparum-specific IgG antibody and cellular responses to identify possible molecular correlates of vaccine-induced immunogenicity

Systems Analysis of the PfSPZ Vaccine in Kenyan Infants

Safety, immunogenicity and efficacy of PfSPZ Vaccine against malaria in infants in western Kenya: a double-blind, randomized, placebo-controlled phase 2 trial

Safety, tolerability, and immunogenicity of PfSPZ Vaccine administered by direct venous inoculation to infants and young children: findings from an age de-escalation, dose-escalation double-blinded randomized, controlled study in western Kenya.

Feasibility of direct venous inoculation of the radiation-attenuated Plasmodium falciparum whole sporozoite vaccine in children and infants in Siaya, western Kenya.