Mosquito-based transmission-blocking vaccine candidates for malaria: progress, challenges, and innovations

Over the last two decades, a significant reduction has been seen in malaria-attributable morbidity and mortality but still, it remains a major public health burden in many countries. The outbreak of malaria due to climate change in some countries emphasizes the critical need for improved strategies to treat, prevent, and control malaria. Although WHO has recommended RTS, S/AS01, and R-21/Matrix-M (R21), these vaccines have shown lesser efficacy. The low efficacy of the vaccines emphasizes the need for discovering a promising vaccine. Present vaccines are parasite-based and can only reduce the severity of the disease and risk of death. Transmission-blocking vaccines (TBVs) can prevent the risk of the spread of infectious malaria disease worldwide. Several studies revealed that mosquito-based TBVs can effectively target a wide variety of parasites, and significantly reduce the survival rate of the vector. In the present review, various mosquito-based studies involving antisera-raising methods for evaluating transmission-blocking efficacy are included. This review focuses on the efforts made to justify a specific protein as a TBV candidate, the status of mosquito-based TBV antigens, challenges in developing potential mosquito-based TBV, and promising approaches for improving the transmission-blocking efficacy of the TBVs. This review gives an insight into the benefits of using mosquito-based TBVs as a transmission-blocking strategy for malaria.