Objective To clone a stage-specific novel cDNA from 5 day-old adult worm (ADS) of Trichinella spiralis. Methods The cDNA library of AD5 was screened by an AD5 stage-specific cDNA probe labeled with digoxigenin (DIG). The positive clones were sequenced and analysed. Results The positive clone contained a cDNA insert of 1 132 bp in length with a full length open reading frame (ORF) of 1 032 bp. The cDNA encoded a polypeptide of 343 amino acid residues(aa) with a molecular weight of 35.1 kDa and an isoelectric point (IP) of 4.8. InterProScan analysis showed that the 117 - 120 aa (SGYG) was a glycosaminoglycan attachment site, 27- 86 aa was nematode cuticle collagen N-terminal domain and 153-228 aa was collagen repeat (G-x-y) domain. Signal PV2.0 analysis indicated that the region of 1-43 aa was a singal peptide. Blastn homology analysis in Genbank revealed that the cDNA had no obvious homology to any other known gene sequence. Blastp analysis revealed high homology to cuticle collagen with identities more than 40 % . Conclusion A novel ADS stage-specific cDNA encoding a full length ORF was cloned and sequence analysis showed this gene encoded cuticle collagen of Trichinella spiralis.

Objective To study the specificity, sensitivity of diagnostic antigen for Trichinella spiralis(T. s). Methods T668 recombinant protein from highly efficient expression of newborn larvae stage-specific gene of T. s in E. coli as diagnostic antigen. By using negative and positive sera from rabbit, pig, human as the first antibody, and goat-anti-rabbit IgG, goat-anti-pig IgG, goat-anti-human IgG labeled with HRP as the secondary antibody, indirect ELISA method was established for detecting anti-T.s antibody, while excretory-secretory (ES) antigen of T.s muscle larvae was used as control. Results Sera from rabbit, pig and human were detected by T668 recombinant protein as antigen, which showed a positive rate of 100% with 0.016 ?g/well. There was no difference on the results between the T668 recombinant antigen and the ES antigen for diagnosing T. s-infection. Conclusion The T668 recombinant antigen is promising in substituting ES antigen in the detection of anti-T. s antibody.

Serine proteases form one of the most important families of enzymes and perform significant functions in a broad range of biological processes, such as intra- and extracellular protein metabolism, digestion, blood coagulation, regulation of development, and fertilization. A number of serine proteases have been identified in parasitic helminths that have putative roles in parasite development and nutrition, host tissues and cell invasion, anticoagulation, and immune evasion. In this review, we described the serine proteases that have been identified in parasitic helminths, including nematodes (Trichinella spiralis, T. pseudospiralis, Trichuris muris, Anisakis simplex, Ascaris suum, Onchocerca volvulus, O. lienalis, Brugia malayi, Ancylostoma caninum, and Steinernema carpocapsae), cestodes (Spirometra mansoni, Echinococcus granulosus, and Schistocephalus solidus), and trematodes (Fasciola hepatica, F. gigantica, and Schistosoma mansoni). Moreover, the possible biological functions of these serine proteases in the endogenous biological phenomena of these parasites and in the host-parasite interaction were also discussed.
Animals ; Cestoda/classification/*enzymology/growth & development/physiology ; Host-Parasite Interactions ; Life Cycle Stages ; Nematoda/classification/*enzymology/growth & development/physiology ; Serine Proteases/genetics/*metabolism ; Trematoda/classification/*enzymology/growth & development/physiology