Malaria-related deaths in Africa have decreased by 44% since 2000, but advances in reducing the global malaria burden have been slow in recent years (WHO, 2020). This may be due to many factors, such as a shortfall in funding, the resistance of vectors to widely used insecticides, the resistance of parasites to antimalarial drugs, and health service disruption caused by the COVID-19 pandemic. Malaria prevention and control depend on, to a large extent, insecticide-treated nets, indoor spraying of insecticides, and effective antimalarial drugs (Challenger et al., 2021). Therefore, new technologies to eliminate malaria are urgently needed, and developing such technologies will benefit tremendously from a better understanding of parasite biology and disease transmission.

Sexual development is essential for the transmission of malaria parasites from humans to mosquitoes. Gametocytes are activated to produce gametes in the mosquito midgut when a female Anopheles mosquito ingests blood from an infected person. Within the blood bolus, the gametes are fertilized to form zygotes, which develop into motile ookinetes and then traverse the midgut epithelium. The ookinetes colonize the mosquito’s midgut and differentiate into oocysts, where hundreds of sporozoites develop. After being released, sporozoites enter the salivary glands, waiting to be transmitted to a new human host during subsequent blood-feeding.

Transmission-blocking vaccines (TBVs) have been designed to induce antibodies that interrupt malaria transmission (Keleta et al., 2021). Instead of providing direct protection against infections, they prevent or inhibit the transmission of malaria parasites between mosquitoes and humans. At present, TBV candidates include antigens expressed in sexual stages, such as the pre-fertilization antigens P48/45 and P230 (Kocken et al., 1993, Williamson et al., 1993, Arevalo-Herrera et al., 2015) and the post-fertilization antigens P25 and P28 (Kaslow et al., 1988, Hisaeda et al., 2000), as well as the mosquito midgut alanyl aminopeptidase N (Dinglasan et al., 2007). Although Plasmodium falciparum P25 (Pfs25) has been tested in malaria-endemic settings (Sagara et al., 2018), future efforts are demanded to discover additional TBV candidates and optimize the current design (Delves et al., 2018).

In the last decade, the vast ‘omics’ information has revolutionized biological research, especially in silico discovery of vaccine targets (Nanda Kumar et al., 2016, Pandey et al., 2018). Numerous antigens expressed in sexual-stage malaria parasites have been discovered (Hall et al., 2005, van Dijk et al., 2010, Wass et al., 2012, Richards et al., 2013, Swearingen et al., 2016), but their validation requires continuous effort. In this work, we mined the PlasmoDB database and reported identification of Pbs54 in the rodent malaria parasite Plasmodium berghei, a conserved membrane protein localized on the gametes and ookinetes. We investigated its function during P. berghei parasite development and found that pbs54 was involved in gamete fertilization. To probe its potential for TBV, antibodies were raised against recombinant Pbs54, which showed transmission-reducing activity (TRA) in mosquito feeding assays.