Safety and immunogenicity of a Plasmodium falciparum sporozoite vaccine: boosting of antibody response in a population with prior natural exposure to malaria.
Recombinant sporozoite vaccine or placebo were administered once to 25 volunteers from an area endemic for malaria. Antibody to R32tet32 rose in 9 of 15 receiving vaccine and remained elevated in 6 for 6 months. Mean absorbance increase was 0.43 +/- 0.40 with vaccine, 0.01 +/- 0.23 with placebo, and 0.72 +/- 0.19 in responders. Six non-responders had significantly lower pre-immunization levels (0.07 +/- 0.05) than responders (0.39 +/- 0.25). There was an association between an increase in immunofluorescence (n = 4) and an increase in absorbance (n = 9) among vaccine recipients (n = 15). Vaccine-induced increase in antibody to natural circumsporozoite antigen was indicated by increases in immunofluorescence and by increases in circumsporozoite precipitation score in 2 of the 5 responders with highest antibody increase measured by enzyme-linked immunosorbent assay. Response to subunit sporozoite vaccine paralleled response to prior natural sporozoite exposure and was significant and prolonged in a population with prior natural exposure to malaria.
Sherwood
J A
JA
US Army Medical Research Unit-Kenya.
Oster
C N
CN
Adoyo-Adoyo
M
M
Beier
J C
JC
Gachihi
G S
GS
Nyakundi
P M
PM
Ballou
W R
WR
Brandling-Bennett
A D
AD
Schwartz
I K
IK
Were
J B
JB
D000328:Adult; D000818:Animals; D000913:Antibodies, Protozoan / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D006801:Humans; D007113:Immunity, Innate; D007630:Kenya; D008288:Malaria / Q000276:immunology / Q000517:prevention & control*; D008297:Male; D010963:Plasmodium falciparum / Q000276:immunology*; D016052:Protozoan Vaccines / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology; D013997:Time Factors
D000913:Antibodies, Protozoan; D016052:Protozoan Vaccines; D011994:Recombinant Proteins