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SUMMARYThe aim of this study was to assess the seroprevalence of the Toxoplasma gondii parasite in pork produced in France, and to determine infection risk factors. An innovative survey was designed based on annual numbers of slaughtered pigs from intensive and outdoor farms in France. A total of 1549 samples of cardiac fluids were collected from pig hearts to determine seroprevalence using a Modified Agglutination Test. Of those, 160 hearts were bio-assayed in mice to isolate live parasites. The overall seroprevalence among fattening pigs was 2·9%. The adjusted seroprevalence in pigs from intensive farms was 3·0%; the highest in sows (13·4%); 2·9% in fattening pigs and 2·6% in piglets. Adjusted seroprevalence in fattening animals from outdoor farms was 6·3%. Strains were isolated from 41 animals and all were genotyped by Restriction Fragment Length Polymorphism as type II. Risk-factor analysis showed that the risk of infection was more than three times higher for outdoor pigs, and that sows’ risk was almost five times higher than that of fattening animals. This study provides further evidence of extensive pork infection with T. gondii regardless of breeding systems, indicating that farm conditions are still insufficient to guarantee ‘Toxoplasma-free pork’.

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.

SUMMARYTrichinella spiralisis an intracellular parasitic nematode of mammalian skeletal muscle, causing a serious zoonotic disease in humans and showing a high economic impact mainly in pig breeding. Serine proteinases ofT. spiralisplay important roles in the host–parasite interactions mediating host invasion. In this study, we have focused on newborn larvae (NBL-1), the first identified serine proteinase from the NBL stage ofT. spiralis.Five monoclonal antibodies (mAbs) directed against the C-terminal part of NBL1, were produced. These mAbs were IgG1κisotype and specifically recognized as a common motif of 10 amino acids (PSSGSRPTYP). Selected mAbs were further characterized using antigens from various developmental stages ofT. spiralis.Western blot revealed that selected mAbs reacted with the native NBL1 at Mr50 kDa in the adult and NBL mixed antigens and NBL stage alone. Indirect immunofluorescence analysis revealed that selected mAbs intensely stained only the embryos within the gravid females and the NBL. Thus, the produced mAbs are useful tools for the characterization of NBL1 as a major antigen ofTrichinellainvolved in the invasion of the host but also for the development of new serological tests with an early detection ofT. spiralisinfection.