Evaluation Of The Malaria Transmission-Reducing Activity Of Pfs25-Imx313/Matrix-M Vaccine And Naturally Acquired Antibodies In Tanzanian Volunteers
| dc.contributor.author | Mulamba, Charles | |
| dc.date.accessioned | 2025-10-21T11:36:29Z | |
| dc.date.issued | 2025-07 | |
| dc.description | SDG-1: No Poverty SDG-3: Good Health and Well-being SDG-4: Quality Education SDG-5: Gender Equality SDG-6: Clean Water and Sanitation SDG-9: Industry, Innovation, and Infrastructure SDG-10: Reduced Inequalities | |
| dc.description.abstract | Malaria is still a public health challenge in Tanzania, control relies on the use of artemisinin-based combination therapies and insecticide-treated materials. The effectiveness of these interventions is threatened by drug and insecticide resistance in parasites and vectors respectively. Transmission-blocking interventions are therefore needed to supplement the current interventions. This study evaluated the ability of vaccine-induced Pfs25 antibodies, to block malaria parasite development in mosquitoes, following a Phase1 vaccine trial in Bagamoyo, Tanzania, between 2021 and 2023. The transmission reducing activity (TRA) was evaluated via Standard Membrane Feeding Assays (SMFAs), where laboratory mosquitoes were fed with a mixture of test or control antibodies and cultured Plasmodium falciparum gametocytes. The TRA was determined as the reduction in the number of oocysts by test antibodies compared to a negative control lacking blocking antibodies. In addition, a survey was conducted to determine the seroprevalence of natural antibodies to malaria antigens; Pfs25, Pfs230D1M, and Pfs48/45, as well as the malaria prevalence in 467 participants from five villages in Bagamoyo district. The malaria and natural antibody survey were conducted as a baseline for phase1 evaluation of Pfs25-IMX313/Matrix-M vaccine candidate. Trial results indicated that the Pfs25-IMX313/Matrix-M vaccine induced long-lasting antibodies, which promoted significant TRA in 18 of the 20 vaccinated participants. Survey findings showed that 23.5% (110/467) of the participants tested positive for malaria, and 24% of the malaria-positive participants had the sexual form of malaria (gametocytes) responsible for transmission. Regression analysis showed that gametocytes were more likely to be present among male participants than female participants [ORa: 2.79 (95% CI: 1.19 – 6.59) p=0.019]. The survey results further indicated that the seroprevalence of Pfs230D1M IgG was 56% (157/281), whereas that of Pfs48/45 IgG was 49% (141/291). Seroprevalence for anti-Pfs230 and anti-Pfs48/45 IgG increased significantly with participants’ age, with adults more likely to have antibodies than children; for Pfs230 [adjusted OR 3.18, (95% CI: 1.85 - 5.57), p=<0.0001], and Pfs45/48 [OR 3.11, (95% CI: 1.83 - 5.29), p = <0.0001]. When Pfs48/45 and Pfs230 seropositive serum was tested in the SMFAs, only two (2) of the 10 participants demonstrated significant TRA. We conclude that a transmission-blocking vaccine will be a great addition to the current malaria interventions, and children as well as adults should be targeted, if malaria elimination to be achieved. The Pfs25-IMX313/Matrix-M vaccine in this study should be further developed in combination with another transmission-blocking target such as Pfs230D1M or Pfs48/45. | |
| dc.identifier.uri | https://dspace.nm-aist.ac.tz/handle/123456789/3398 | |
| dc.language.iso | en | |
| dc.publisher | NM-AIST | |
| dc.title | Evaluation Of The Malaria Transmission-Reducing Activity Of Pfs25-Imx313/Matrix-M Vaccine And Naturally Acquired Antibodies In Tanzanian Volunteers | |
| dc.type | Thesis |