Authors

Discussion

The characterisation of parasite products secreted/excreted during the initial infection of Schistosoma mansoni is important for fully understanding the intricacies of long-term host/parasite interactions. To this end, we investigate a novel S. mansoni protein of unknown function, SmCSS-1, recently found in cercarial/schistosomula exosome-like extracellular vesicles. Utilising existing DNA microarray and RNAseq data, we find that SmCSS-1 is differentially expressed across the schistosome lifecycle with peak expression in mixed-sex cercariae larvae and male biased expression in the dioecious adult. Sequencing analysis of SmCSS-1 transcripts cloned fromdifferent parasite lifestages reveal multiple isoforms that differ in abundance. Comparative sequence analysis has revealed homologues in other schistosome species (S. haematobium, S. japonicum and S. magrebowei). No homologues were present in other related trematode genomes or transcriptomes analysed. Recombinant protein expression of CSS-1 has been successful in E. coli, enabling future research into the location of SmCSS-1 within the parasite, immune responses elicited by this protein and the role of different isoforms during parasite development.Collectively, these results point to SmCSS-1 being an abundant new class of schistosomesecreted protein.