Mapping of the complement C9 binding domain on Trichinella spiralis paramyosin

Abstract

BackgroundTrichinellosis is an important foodborne zoonosis that is distributed worldwide. Trichinella spiralis may evade host complement-mediated attack by expressing complement inhibitory proteins, such as paramyosin (Pmy). Previous studies have shown that Trichinella spiralis paramyosin (Ts-Pmy) is able to bind to the human complement component C9 to inhibit the complement activation and protect the parasite from complement-mediated attack. Further determination of the complement-binding domain on Ts-pmy will enable us to better understand the Ts-Pmy’s biofunction in the immune evasion and provide feasible approach to develop epitope-based subunit vaccine against trichinellosis.MethodsThe complement C9 binding region on Ts-Pmy was determined by expression of overlapped fragments of Ts-Pmy and their binding activities to C9. The exact binding site was further narrowed-down to a 14-amino acid peptide at C-terminus using synthesized peptides with different size of amino acid sequence. The C9 complement-binding of the 14-amino acid peptide and its interference in the C9 polymerization and the complement-mediated lysis of rabbit erythrocytes was investigated.ResultsThe protein interaction between human C9 and native Ts-Pmy was further confirmed by immunoprecipitation with T. spiralis lysates. The fragmental expression and C9 binding assays identified that the binding region of Ts-Pmy to C9 is located within 831–885 of Ts-Pmy C-terminus. The exact binding site on Ts-Pmy to C9 was narrowed down to 14 amino acid residues (866Val-879Met) by using different sizes of synthesized peptides. In the presence of the synthesized 14-amino acid peptide, human C9 polymerization and the hemolytic activity of the human complement was inhibited.ConclusionsOur results revealed the precise molecular basis for T. spiralis to produce Ts-Pmy as an immunomodulator to evade the attack of the host complement system as a survival mechanism.

Molecular identification of Trichinella spiralis nudix hydrolase and its induced protective immunity against trichinellosis in BALB/c mice

“…Trichinellosis is not only a public health hazard but also an economic problem in porcine animal production and food safety [ 7 ]. Thus, the development of vaccines capable of preventing swine from becoming infected is a promising approach for control of trichinellosis [ 8 - 10 ].…”

Identification of the complement 9‐binding protein in Setaria equina excretory‐secretory products

“…In H contortus and B malayi , the C3‐ and C1q‐binding proteins were identified as glyceraldehyde‐3‐phosphate dehydrogenase and calreticulin, respectively. Nevertheless, paramyosin which is located on the outer surface of Trichinella spiralis was found as C1q‐ and C9‐binding proteins . Generally, secretory products of parasitic helminthes had been known as anti‐inflammatory products .…”

“…Among the complement‐evasion strategies to escape the host immune attack, the capture of host complement components by the parasite proteins and then inactivating their functions is an evasion mechanism that is frequently adopted by many parasites during the establishment of parasitism . Paramyosin was found previously in Trichinella spiralis to bind C1q and C9 and inhibit the formation of membrane attack complex (MAC) . Furthermore, Brugia malayi calreticulin had been found to prevent classical complement pathway activation via its interaction with the first component C1q of the human host …”

Vaccines againstTrichinella spiralis: Progress, challenges and future prospects

“…The protein plays a crucial role in immunomodulatory during the helminth infection and has been identified as a potential candidate in development of vaccines against Schistosoma mansoni (Flanigan, King, Lett, Nanduri, & Mahmoud, ), Taenia solium (Vazquez‐Talavera, Solis, Terrazas, & Laclette, ), Brugia malayi (Li, Chandrashekar, & Weil, ) and some other parasitic helminths. T. spiralis paramyosin (TsPmy) can inhibit the classical complement pathway and reduce the C1q‐dependent migration of macrophages (Sun et al., ; Zhang et al., ; Zhao, Hao, Yang, Gu, & Zhu, ). The immunodominant epitopes of TsPmy protein have been characterized (Gu et al., ), which revealed a promising protective efficacy in reduction in T. spiralis muscle larvae (Gu et al., ; Wei et al., ).…”