Biochemical and molecular characterization of the tegument protein RT10 from Raillietina tetragona

Tegument antigens of tapeworm play an important role in modulation of host response and parasite survival. Characterizing appropriate antigens for parasite infection diagnosis and vaccination is rational and could have both economic and epidemiological significance in poultry industry. In the present study, a major protoscolex homologue (named RT10) of Echinococcus and Taenia spp. was amplified from Raillietina tetragona cestode. The RT10 cDNA was 1,877 bp long containing an open reading frame of 1,683 bp nucleotides, which encoded a deduced protein of 560 amino acids with an isoelectric point of 6.33. Secondary structure analysis demonstrated that RT10 was both hydrophilic and antigenic, and possessed N-terminal FERM domain and C-terminal ERM domain, respectively. With the same structural properties of previously reported antigens from Echinococcus and Taenia spp., RT10 tegument antigen had a more than 82% similarity in nucleotide level with initially reported antigens from Echinococcus and Taenia spp., and a more than 83% similarity in protein level, with the highest similarity of 85.2% to Taenia antigen H17g. In addition, phylogenetic analysis illustrated a high consistency between different genus antigens and evolutionary branching. Although the detailed function of RT10 is still unknown, the high sequence conservation and structural similarity to formerly identified tegument antigens from Echinococcus and Taenia spp. suggested that RT10 may play a similar role as the previous reported antigens between cestode and host. It is significant to clarify the antigenic and serodiagnostic characteristics in the subsequent work.