Schistosomiasis, caused mainly by three major pathogenic schistosome species, Schistosoma japonicum, S. mansoni and S. haematobium, is one of most prevalent serious parasitic diseases worldwide, with an estimated 200 million people in 76 countries.

Schistosomes have a complex life cycle. The larvae termed cercariae in free water can directly penetrate skin to infect humans and then shed their tails and transform their trilaminate tegument into the heptalaminate form. After several days, the developing male and female worms depart the lungs and move into the hepatic portal system to pair up for mature, and subsequently migrate upstream to the mesenteric venules of the intestines. Eggs deposited by the adult female schistosomes embolize in the liver, intestines, and other sites and represent the key contributor to the pathology and morbidity associated with schistosomiasis. Evasion strategies that underpin avoidance of the host immune system, allowing schistosomes to survive for years despite strong host immunological responses, have long confounded and intrigued investigators intent on controlling these parasites through development of an effective vaccine.

We have performed high-throughput genomic and proteomic analyses to characterize the majority of the expressed genes and proteins of S. japonicum. More than 84,000 expression sequence tags (ESTs), 14,000 EST clusters and 8,400 putative protein-coding genes were isolated or identified from adult worms (males, females and mixed-sex adults), eggs and miracidia of S. japonicum. Furthermore, throught the comprehensive proteomic studies, we verified the expression of more than 3200 genes of S. japonicum from various life stagies including cercaria, schistosomula, adult worms (male, female and mixed-sex adult), eggs and miracidia, together with tegument preparations (including schistosomula, male, female and mixed-sex adult worms) and eggshell extracts.

All of these genes and protein information were phrased into this S. japonicum Transcriptome and Proteome Database (SjTPdb), and the sequences and information in SjTPdb are accessible via text search, stage search, integrated search, BLAST similarity search, and Download site.

The Life Stages of Schistosome