Schistosomiasis is a neglected tropical disease caused by the parasitic flatworm Schistosoma mansoni. It affects millions of people worldwide, particularly in regions where access to clean water and proper sanitation is limited. The parasite has a complex life cycle that depends on both humans and freshwater snails such as Biomphalaria glabrata. One important area of research focuses on understanding why some strains of B. glabrata are naturally resistant to S. mansoni while others are susceptible. Snail immune cells called hemocytes play a major role in this defense by recognizing, encapsulating, and destroying S. mansoni larvae before they can establish infection. Hemocytes express a variety of immune-related proteins, including thioester-containing proteins (TEPs). Previous studies suggest that TEPs are involved in the snail's capacity to recognize and bind S. mansoni parasites. This project investigates the expression of TEP genes in two strains of B. glabrata: BS90 (resistant) and BB02 (susceptible). RNAscope, an in situ hybridization technique that visualizes specific RNA molecules within cells is being used to identify and compare the expression of TEP genes between resistant and susceptible snails. In addition, snail hemocytes will be exposed to S. mansoni larval transformation products (LTPs) to test the modulation of TEPs in each of these snail strains. We hypothesize that the hemocytes of resistant BS90 snails will exhibit higher expression of TEPs upon exposure to parasite LTPs than the susceptible BB02 snail hemocytes. Identifying TEPs expression patterns will improve understanding of resistance mechanisms and may support future strategies to reduce schistosomiasis transmission.