Trichinella spiralis Paramyosin Binds Human Complement C1q and Inhibits Classical Complement Activation

Background: trichinella spiralis expresses paramyosin (ts-pmy) as a defense mechanism. ts-pmy is a functional protein with binding activity to human complement c8 and c9 and thus plays a role in evading the attack of the host’s immune system. in the present study,the binding activity of ts-pmy to human complement c1q and its ability to inhibit classical complement activation were investigated. methods and findings: the binding of recombinant and natural ts-pmy to human c1q were determined by elisa,far western blotting and immunoprecipitation,respectively. binding of recombinant ts-pmy (rts-pmy) to c1q inhibited c1q binding to igm and consequently inhibited c3 deposition. the lysis of antibody-sensitized erythrocytes (eas) elicited by the classical complement pathway was also inhibited in the presence of rts-pmy. in addition to inhibiting classical complement activation,rts-pmy also suppressed c1q binding to thp-1-derived macrophages,thereby reducing c1q-induced macrophages migration. conclusion: our results suggest that t. spiralis paramyosin plays an important role in immune evasion by interfering with complement activation through binding to c1q in addition to c8 and c9. © 2015 sun et al.