Changes in the neuropeptide content of Biomphalaria ganglia nervous system following Schistosoma infection.

Background: Molluscs, including snails, are prone to parasite infection, which can lead to massive physiological and behavioural changes, yet many of the molecular components involved remain unresolved. Central to this point is the neural system that in snails consists of several ganglia that regulate the animals' physiology and behaviour patterns. The availability of a genomic resource for the freshwater snail Biomphalaria glabrata provides a mean towards the high throughput analysis of changes in the central nervous system (CNS) following infection with Schistosoma miracidia.

Results: In this study, we performed a proteomic analysis of the B. glabrata CNS at pre-patent infection, providing a list of proteins that were further used within a protein-protein interaction (PPI) framework against S. mansoni proteins. A hub with most connections for both non-infected and infected Biomphalaria includes leucine aminopeptidase 2 (LAP2), which interacts with numerous miracidia proteins that together belong to the immunoglobulin family of cell adhesion related molecules. We additionally reveal the presence of at least 165 neuropeptides derived from the precursors of buccalin, enterin, FMRF, FVRI, pedal peptide 1, 2, 3 and 4, RYamide, RFamide, pleurin and others. Many of these were present at significantly reduced levels in the snail's CNS post-infection, such as the egg laying hormone, a neuropeptide required to initiate egg laying in gastropod molluscs.

Conclusions: Our analysis demonstrates that LAP2 may be a key component that regulates parasite infection physiology, as well as establishing that parasite-induced reproductive castration may be facilitated by significant reductions in reproduction-associated neuropeptides. This work helps in our understanding of molluscan neuropeptides and further stimulates advances in parasite-host interactions.