Trichinellosis is an important zoonotic parasitic disease worldwide and is principally caused by ingesting animal meat containing Trichinella infective larvae. Aspartyl aminopeptidase is an intracytoplasmic metalloproteinase that specifically hydrolyzes the N-terminus of polypeptides free of acidic amino acids (aspartic acid and glutamate), and plays an important role in the metabolism, growth and development of organisms. In this study, a novel T. spiralis aspartyl aminopeptidase (TsAAP) was cloned and expressed, and its biological properties and roles in worm growth and development were investigated. The results revealed that TsAAP transcription and expression in diverse T. spiralis stages were detected by RT-PCR and Western blotting, and primarily localized at cuticle, stichosome and intrauterine embryos of this nematode by immunofluorescence test. rTsAAP has the enzymatic activity of native AAP to hydrolyze the substrate H-Glu-pNA. There was a specific binding between rTsAAP and murine erythrocyte, and the binding site was localized in erythrocyte membrane proteins. Silencing of TsAAP gene by specific dsRNA significantly reduced the TsAAP expression, enzymatic activity, intestinal worm burdens and female fecundity. The results demonstrated that TsAAP participates in the growth, development and fecundity of T. spiralis and it might be a potential target molecule for anti-Trichinella vaccines.

Cysticercus cellulosae, C. bovis, and C. taiwanensis are the three species of cysticercosis of human taeniid with their adults worms Taenia solium, T. saginata saginata and T. s. asiatica respectively. C. cellulosae is prevalent in America, Europe and Asia, C. bovis in Africa, America and Asia and C. taiwanensis in Asia. The natural infection source is pig for C. cellulosae, cattle for C. bovis and pig and wild boar for C. taiwanensis. The predilection sites are muscles for C. cellulosae and C. bovis and liver for C. taiwanensis. While the prepatent periods of these three species were 60-70 days, 60-75 days and 28 days respectively. Most C. cellulosae and a few for C. bovis and C. taiwanensis survive in pig, while most C. bovis and a few for C. taiwanensis survive in cattle. In rodent, all three species have a long life. C. cellulosae and C. bovis migrate through blood and lymph vessels to the small intestinal wall and then to the body muscles while C. taiwanensis migrate through blood vessels to the small intestinal wall and then to the liver. The minimal effective dosage of praziquantel against cysticercosis should be 100 mg/kg daily for three consecutive days.