Expressed sequence tag analysis of Sarcoptes scabiei

Sarcoptes scabiei is an important parasitic mite in both man and animals. Little is known about the molecular interactions between this pathogen and its host. This is in part explained by the paucity of mite-derived material, including antigens. To extend the knowledge of the molecular repertoire in S. scabiei, we have performed a gene survey by an expressed sequence tag (EST) analysis. A total of 1020 ESTs were generated from an S. scabiei cDNA library. The average sequence read was 510 bp after editing and the overall sequencing success was 89%. Clustering of the sequences resulted in 76 clusters, comprising 36% of the ESTs. Sequence similarity searches showed that almost half of the S. scabiei ESTs could be assigned a putative identity. Many of these transcripts shared similarity with genes involved in basic metabolism and cellular organization. In the data set we also identified several proteases and other types of potential allergens implicated in various disease mechanisms. A relatively large fraction of the ESTs coded for different proteins carrying protease inhibitor-like domains. The clones with no similarity to previously identified genes constituted 11% of our transcripts. The EST data generated in this stud), will be a valuable resource in further studies of the biology of S. scabiei and in the identification of genes that can serve as potential targets in the control of the parasite.