• Vaccine Name: P. falciparum Subunit SE36 Protein Vaccine
• Target Pathogen: Plasmodium spp.
• Target Disease: Malaria
• Vaccine Ontology ID: VO_0011415
• Type: Subunit vaccine
• Status: Clinical trial
• SERA-5 gene engineering:
  • Type: Recombinant protein preparation
  • Description:
  • Detailed Gene Information: Click Here.
• Adjuvant:
  • Adjuvant name:
  • VO adjuvant ID: VO_0000127
• Immunization Route: Intramuscular injection (i.m.)

Monkey Response

• Host Strain: squirrel monkey (Saimiri sciureus)
• Vaccination Protocol: The monkeys, weighing between 680 and 760 g at the beginning of the experiment, were divided into two groups. Group1 monkeys (R57, R59, and R61) received SE36/AHG and Group2 monkeys (R60 and R62) received PBS as a control by intra-muscular injection in their left thigh 5 and 3 weeks before challenge infection. Monkey R61 received a third injection on the 2 weeks before challenge infection. The dose used was 50 μg SE36 protein with 500 μg aluminum hydroxide gel (50/500) in 0.5 ml of PBS. Group2 monkeys (R60 and R62) received the same volume of PBS (Horii et al., 2010).
• Challenge Protocol: Two weeks after the last immunization, all monkeys were challenged with P. falciparum-infected red blood cells. Each of the five squirrel monkeys received 1 × 10^9 parasitized red blood cells. Parasitemia was monitored daily by counting 5000 RBCs in Giemsa-stained thin blood smears (Horii et al., 2010).
• Efficacy: Whereas two control monkeys developed 10–20% peak parasitemia, the parasitemia in the two immunized monkeys with higher antibody titers stayed at low values below 3% (Fig. 3B). One vaccinated monkey (Monkey R61), with the lowest antibody titer, developed 5% peak parasitemia but was able to control parasitemia by Day 7 onwards. Importantly, control monkeys did not raise anti-SE36 IgG titer even after the onset of parasitemia which parallels the less immunogenicity of SERA5 N-terminal domain observed in endemic areas. Thus, although the observed protection was not able to prevent infection, vaccinated monkeys had lower parasitemia and booster effects on antibody titers were observed after infection for all vaccinated monkeys (Horii et al., 2010).

Chimpanzee Response

• Vaccination Protocol: Three chimpanzees, named Satoru (7 years old male, 45 kg), Arare (10 years old female, 51 kg) and Mizuo (11 years old male, 60 kg) were born in Japan, and thus have no prior exposure to P. falciparum. Satoru, Arare and Mizuo received 10/100, 50/500 and 450/4500 SE36/AHG, respectively by subcutaneous injection on their backs after anesthetization with Ketamine hydrochloride (5 mg/kg) at Weeks 0, 4 and 8 (Horii et al., 2010).
• Immune Response: Chimpanzee immunization experiment, likewise, indicated the immunogenicity of SE36/AHG and a long duration of antibody production over 1-year with only a gradual decrease. Three chimpanzees were immunized with GMP-grade SE36/AHG of either 10/100, 50/500 or 450/4500 dose. Throughout the study, all blood biochemistry results were normal according to human standards and no signs of systemic aberrations were observed, except for the commonly observed swelling at the administration sites (Horii et al., 2010).