Year: 2021
Type: article
Abstract: BACKGROUND: RTS,S/AS01, the leading malaria vaccine has been recommended by the WHO for widespread immunization of children at risk. RTS,S/AS01-induced anti-CSP IgG antibodies are associated with the vaccine efficacy. Here, the long-term kinetics of RTS,S/AS01-induced antibodies was investigated. METHODS: 150 participants were randomly selected from the 447 children who participated in the RTS,S/AS01 phase IIb clinical trial in 2007 from Kilifi-Kenya. Cumulatively, the retrospective follow-up period was 93 months with annual plasma samples collection. The levels of anti-CSP IgM, total IgG, IgG1, IgG2, IgG3, and IgG4 antibodies were then determined using an enzyme-linked immunosorbent assay. RESULTS: RTS,S/AS01 induced high levels of anti-CSP IgG antibodies which exhibited a rapid waning over 6.5 months post-vaccination, followed by a slower decay over the subsequent years. RTS,S/AS01-induced anti-CSP IgG antibodies remained elevated above the control group levels throughout the 7 years follow-up period. The anti-CSP IgG antibodies were mostly IgG1, IgG3, IgG2, and to a lesser extent IgG4. IgG2 predominated in later timepoints. RTS,S/AS01 also induced high levels of anti-CSP IgM antibodies which increased above the control group levels by month 3. The controls exhibited increasing levels of the anti-CSP IgM antibodies which caught up with the RTS,S/AS01 vaccinees levels by month 21. In contrast, there were no measurable anti-CSP IgG antibodies among the controls. CONCLUSION: RTS,S/AS01-induced anti-CSP IgG antibodies kinetics are consistent with long-lived but waning vaccine efficacy. Natural exposure induces anti-CSP IgM antibodies in children, which increases with age, but does not induce substantial levels of anti-CSP IgG antibodies.
Source: Malaria Journal
Language: English
Topic: Malaria Research and Control
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $1,986
Funders: Wellcome Trust, Government of the United Kingdom, Freie Universität Berlin, New Partnership for Africa's Development, African Academy of Sciences, Medical Research Council, Alliance for Accelerating Excellence in Science in Africa, European and Developing Countries Clinical Trials Partnership
Awards: G1101575161, G3375908201, G3578294335, Clinical and immunological evaluation in East Africa of new malaria vaccines encoding the circumsporozoite protein., Initiative to Develop African Research Leaders (IDeAL), Mechanisms of naturally acquired immunity to P.falciparum malaria., An integrated programme on the immuno-epidemiology of human blood stage immunity to P falciparum malaria., F Ndungu, Pwani University, Determining Cellular Correlates of Immunity to Malaria in an Experimental Human Challenge Model of Exposed Adults, G8009821660, G8592383710, Determining Correlates of Naturally Acquired Pre-Erythrocytic Immunity to Plasmodium falciparum Malaria in an Experimental Human Challenge Model
OpenAlex ID: W3216005132