[Identification and functional study of the Schistosoma japonicum epidermal growth factor receptor gene].

Objective: To characterize the epidermal growth factor receptor ( EGFR ) gene in Schistosoma japonicum ( SjEGFR gene) and investigate the role of the EGFR gene in regulating the growth, reproductive system, maturation and fecundity of S. japonicum .
Methods: Rapid amplification of cDNA ends (RACE) was performed to obtain the full length of the SjEGFR gene, and the SjEGFR gene expression was quantified in different developmental stages of S. japonicum using a quantitative real-time PCR (qPCR) assay. The tissue localization of the SjEGFR gene was detected in 22-day parasite using whole-mount in situ hybridization (WISH). Following RNA interference (RNAi)-induced knockdown of the SjEGFR gene, the worm length, pairing rate and worm burden of S . japonicum were measured, and the worm morphology was observed using optical microscopy and confocal microscopy.
Results: The SjEGFR gene was identified with a conserved tyrosine-kinase active site, and the SjEGFR gene expression was detected at various developmental stages in male and female parasites. WISH showed that the transcript of the SjEGFR gene was localized on the tegument and in the digestive organs of S. japonicum . RNAi-induced SjEGFR knockdown resulted in marked suppression of the worm growth, smaller size of male testicles that contained more immature spermatocytes, and apparent impairment of ovary and vitelline gland development. In addition, no eggs were found in the uterus of SjEGFR knocked-down female parasites, indicating the interruption of egg production.
Conclusions: Inhibition of SjEGFR expression may remarkably suppress the growth and maturation of S. japonicum , and interrupt the egg production.