Identification ofTrichinella spiralisearly antigens at the pre-adult and adult stages

SUMMARYThree expression cDNA libraries fromTrichinella spiralisworms 14 h, 20 h and 48 h post-infection (p.i.) were screened with serum from pigs experimentally infected with 20 000T. spiralismuscle larvae. Twenty-nine positive clones were isolated from the 14 h p.i. cDNA library, corresponding to 8 different genes. A putative excretory-secretory protein similar to that ofT. pseudospiraliswas identified. Three clones corresponded to aT. spiralisserine proteinase inhibitor known to be involved in diverse functions such as blood coagulation and modulation of inflammation. Screening of the 20 h p.i. cDNA library selected 167 positive clones representing 12 different sequences. The clone with the highest redundancy encoded a small polypeptide having no sequence identity with any known proteins fromTrichinellaor other organisms. Fourteen clones displayed sequence identity with the heat shock protein (HSP) 70. HSPs are produced as an adaptive response of the parasite to the hostile environment encountered in the host intestine but their mechanism of action is not yet well defined. From the 48 h p.i.T. spiraliscDNA library, 91 positive clones were identified representing 7 distinct sequences. Most of the positive clones showed high similarity with a member of a putativeT. spiralisserine protease family. This result is consistent with a possible major role for serine proteases during invasive stages ofTrichinellainfection and host-parasite interactions.