Synergistic role of CSPBP and SGS1 in sporozoite entry into Aedes aegypti salivary glands

Vector-borne diseases, particularly malaria, continue to pose a major global health challenge, underscoring the urgent need for innovative and sustainable vector control strategies. Among emerging solutions, genetic control holds great promise for interrupting disease transmission at its source. Malaria transmission relies on the parasite’s ability to overcome multiple barriers within the mosquito and ultimately invade the salivary glands during the sporozoite stage. Using Plasmodium gallinaceum as a model parasite, this study investigates two Aedes aegypti proteins, the salivary gland surface protein 1 (SGS1) and the putative ortholog of circumsporozoite protein-binding protein (AaCSPBP), that are involved in this critical step. We identified AaCSPBP through in silico homology and structural analyses and achieved gene knockdown via RNA interference. Knockdown of AaCSPBP alone resulted in a ~ 62% reduction in salivary gland sporozoite numbers and increased accumulation in the hemolymph, indicating impaired salivary gland invasion. Dual knockdown of AaCSPBP and SGS1 resulted in a synergistic effect, reducing salivary gland sporozoites by ~ 94%, a reduction significantly greater than the sum of the individual effects. These findings suggest that AaCSPBP and SGS1 act cooperatively to mediate sporozoite invasion of mosquito salivary glands. Targeting this interaction offers a promising genetically based approach to disrupting malaria transmission.