Monoclonal antibody targeting complement C9 binding domain of Trichinella spiralis paramyosin impairs the viability of Trichinella infective larvae in the presence of complement

Abstract

Abstract Background Trichinella spiralis expresses paramyosin (Ts-Pmy) not only as a structural protein but also as an immunomodulator that inhibits host complement as a survival strategy. Previous studies demonstrated that Ts-Pmy bound to complement components C8 and C9 and inhibited the polymerization of C9 during the formation of the membrane attack complex (MAC). The C9 binding domain of Ts-Pmy was identified within 14 amino acid residues at the C-terminus of Ts-Pmy. The production of a monoclonal antibody that specifically targets the C9 binding site is necessary for further studies of Ts-Pmy function and may be used as a therapeutic agent for T. spiralis infection. Methods In this study, a monoclonal antibody against the complement C9 binding domain of Ts-Pmy (mAb 9G3) was produced using hybridoma technology. The binding activity of the mAb produced for recombinant or native Ts-Pmy and the blockade of Ts-Pmy binding to C9 by the mAb were assessed by Western blot analysis. The effect of the mAb on the viability of T. spiralis was observed by co-incubation of T. spiralis with mAb 9G3 in the presence of complement in vitro and by passive transfer of the mAb into naive mice following T. spiralis larval challenge. Results mAb 9G3 was successfully produced against the C9 binding domain of Ts-Pmy and bound specifically not only to recombinant Ts-Pmy but also to native Ts-Pmy expressed in different stages of T. spiralis, including adult worms, newborn larvae and muscle larvae. The binding of mAb 9G3 to Ts-Pmy efficiently blocked the binding of Ts-Pmy to human complement C9, resulting in a significant increase in the complement-mediated killing of newborn larvae in vitro and reduced infectivity of T. spiralis larvae in mice passively transferred with the mAb. Conclusions mAb 9G3 is a specific antibody that binds to the C9 binding domain of Ts-Pmy and interferes with Ts-Pmy’s complement-binding activity. Therefore, this mAb is a protective antibody that has potential as a preventive and therapeutic agent for T. spiralis infection.

Keywords

• Trichinella spiralis
• Immune evasion
• Paramyosin
• Monoclonal antibody