Increased levels of anti-PfCSP antibodies in post-pubertal females versus males immunized with PfSPZ Vaccine does not translate into increased protective efficacy.

Background

While prior research has shown differences in the risk of malaria infection and sickness between males and females, little is known about sex differences in vaccine-induced immunity to malaria. Identifying such differences could elucidate important aspects of malaria biology and facilitate development of improved approaches to malaria vaccination.

Methods

Using a standardized enzyme-linked immunosorbent assay, IgG antibodies to the major surface protein on

Results

Females ≥ 11 years of age made significantly higher levels of antibodies to PfCSP than did males in most trials, while there was no indication of such differences in infants or children. Although adult females had higher levels of antibodies, there was no evidence of improved protection compared to males. In 2 of the 7 trials with sufficient data, protected males had significantly higher levels of antibodies than unprotected males, and in 3 other trials protected females had higher levels of antibodies than did unprotected females.

Conclusion

Immunization with PfSPZ Vaccine induced higher levels of antibodies in post-pubertal females but showed equivalent protection in males and females. We conclude that the increased antibody levels in post-pubertal females did not contribute substantially to improved protection. We hypothesize that while antibodies to PfCSP (and PfSPZ) may potentially contribute directly to protection, they primarily correlate with other, potentially protective immune mechanisms, such as antibody dependent and antibody independent cellular responses in the liver.

Informations de copyright

Copyright © 2022 KC, Church, Riyahi, Chakravarty, Seder, Epstein, Lyke, Mordmüller, Kremsner, Sissoko, Healy, Duffy, Jongo, Nchama, Abdulla, Mpina, Sirima, Laurens, Steinhardt, Oneko, Li, Murshedkar, Billingsley, Sim, Richie and Hoffman.

Déclaration de conflit d'intérêts

NK, LC, PR, SC, TM, PB, BS, TR and SH are salaried employees of Sanaria Inc., the developer and owner of PfSPZ Vaccine and sponsor of the clinical trials. In addition, BS and SH have a financial interest in Sanaria Inc. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The authors declare this study received funding from Sanaria Inc. The funder had the following involvement in the study: proposal of the study hypothesis, conduct of the ELISAs and data analysis.