title: Trichinella spiralis Paramyosin Binds Human Complement C1q and Inhibits Classical Complement Activation.
abstract: 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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Capital Medical University, Beijing, PR China.
authors.forename: Ran
authors.initials: R
authors.lastname: Sun
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Capital Medical University, Beijing, PR China.
authors.forename: Xi
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Capital Medical University, Beijing, PR China.
authors.forename: Zixia
authors.initials: Z
authors.lastname: Wang
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Capital Medical University, Beijing, PR China.
authors.forename: Jing
authors.initials: J
authors.lastname: Yang
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Capital Medical University, Beijing, PR China.
authors.forename: Limei
authors.initials: L
authors.lastname: Zhao
authors.affiliation: Department of Pediatrics, National School of Tropical Medicine, Baylor College of Medicine, Houston, Texas, United States of America.
authors.forename: Bin
authors.initials: B
authors.lastname: Zhan
authors.affiliation: Department of Parasitology, School of Basic Medical Sciences, Capital Medical University, Beijing, PR China.
authors.forename: Xinping
authors.initials: X
authors.lastname: Zhu
mesh_terms: D000818:Animals; D015922:Complement C1q / Q000276:immunology* / Q000378:metabolism; D003185:Complement C8 / Q000037:antagonists & inhibitors / Q000276:immunology; D003186:Complement C9 / Q000037:antagonists & inhibitors / Q000276:immunology; D003171:Complement Pathway, Classical / Q000187:drug effects*; D004912:Erythrocytes / Q000187:drug effects; D005260:Female; D006461:Hemolysis; D006801:Humans; D057131:Immune Evasion / Q000187:drug effects*; D007155:Immunologic Factors / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology; D008807:Mice, Inbred BALB C; D008813:Mice, Inbred ICR; D011994:Recombinant Proteins; D017160:Trichinella spiralis / Q000276:immunology*; D014235:Trichinellosis / Q000276:immunology*; D014335:Tropomyosin / Q000276:immunology / Q000378:metabolism / Q000494:pharmacology*
chemical_list: D003185:Complement C8; D003186:Complement C9; D007155:Immunologic Factors; D011994:Recombinant Proteins; D014335:Tropomyosin; D015922:Complement C1q