SUMMARY: The aim of this study was to assess the seroprevalence of theToxoplasma gondiiparasite 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 withT. gondiiregardless of breeding systems, indicating that farm conditions are still insufficient to guarantee ‘Toxoplasma-free pork’.

Infection by Toxoplasma gondii postnatally can occur after ingestion of contaminated meat or water (tissue cysts/oocysts). In Europe, percentage of meat borne infections is estimated between 30 and 63 %, out of which pork makes the most important source. The aim of this study was to (i) investigate the seroprevalence of T. gondii in intensive pig farms from western France; and (ii) identify the risk factors associated with seropositivity. Data were collected between November 2006 and February 2008 in 60 intensive farrow-to-finish farms, where sera were taken from 3595 fattening pigs, weaned and suckling piglets. Information about three classes of potential seropositivity risk factors were obtained through a questionnaire concerning: (i) breeding characteristics; (ii) farm management; and (iii) husbandry and hygiene. The modified agglutination test (MAT) was used for detection of specific anti T. gondii antibodies in pig sera, starting from 1/6 dilution. The overall proportion of seropositive animals was 6.9 %, but the proportion of herds with at least one positive pig was 100 %. Multivariate logistic mixed model showed an increased seropositivity risk in weaned compared to suckling piglets, and a decreasing risk for mid-sized and large farms. The presence of a Danish entry facility, that clearly separates clean and dirty areas, had a protective effect on T. gondii seropositivity as well. The observed proportion of herds with at least one T. gondii seropositive animal provides further evidence that even in confined conditions of pig breeding, infection occurs, and is common. The highest risk for acquiring T. gondii is at the end of weaning period. Smaller confined pig farms demonstrate higher T. gondii seropositivity levels. This study also showed that Danish entry on farm buildings provides effective protection against T. gondii.

Syphilis affects approximately 11 million people each year globally, and is the third most prevalent sexually transmitted bacterial infection in the United States. Inability to independently culture and genetically manipulate Treponema pallidum subsp. pallidum, the causative agent of this disease, has hindered our understanding of the molecular mechanisms of syphilis pathogenesis. Here, we used the non-infectious and poorly adherent B314 strain of the Lyme disease-causing spirochete, Borrelia burgdorferi, to express two variants of a known fibronectin-binding adhesin, Tp0136, from T. pallidum SS14 and Nichols strains. Using this surrogate system, we investigated the ability of Tp0136 in facilitating differential binding to mammalian cell lines offering insight into the possible role of this virulence factor in colonization of specific tissues by T. pallidum during infection. Expression of Tp0136 could be detected on the surface of B. burgdorferi by indirect immunofluorescence assay using sera from a secondary syphilis patient that does not react with intact B314 spirochetes transformed with the empty vector. Increase in Tp0136-mediated adherence of B314 strain to human epithelial HEK293 cells was observed with comparable levels of binding exhibited by both Tp0136 alleles. Adherence of Tp0136-expressing B314 was highest to epithelial HEK293 and C6 glioma cells. Gain in binding of B314 strain expressing Tp0136 to purified fibronectin and poor binding of these spirochetes to the fibronectin-deficient cell line (HEp-2) indicated that Tp0136 interaction with this host receptor plays an important role in spirochetal attachment to mammalian cells. Furthermore, preincubation of these cell lines with fibronectin-binding peptide from Staphylococcus aureus FnbA-2 protein significantly inhibited binding of B314 expressing Tp0136. Our results show that Tp0136 facilitates differential level of binding to cell lines representing various host tissues, which highlights the importance of this protein in colonization of human organs by T. pallidum and resulting syphilis pathogenesis. Syphilis is one of the most prevalent sexually transmitted infections that affect millions of people around the world. The causative bacterium, Treponema pallidum subsp. pallidum, can be transmitted from mother to fetus during maternal infection, resulting in adverse pregnancy outcomes. Although timely treatment of syphilis is highly effective, untreated infection causes late syphilis that affects virtually every organ and leads to serious clinical manifestations. Therefore, syphilis remains a serious healthcare problem. T. pallidum cannot be grown in laboratory using traditional methods, which has slowed the progress in understanding this pathogen biology and pathogenesis. We employed a novel approach of using a related bacterium, Borrelia burgdorferi, to express Tp0136 protein from two different T. pallidum isolates to study the function of this protein. This strategy enabled us to demonstrate the ability of this protein to bind to fibronectin and laminin receptors present on the surface of various host cells. We showed that Tp0136 facilitates binding to only those host cells that produce fibronectin. In addition, we found that Tp0136-mediated binding is not equivalent in all host cell types, suggesting that the protein could help in colonization of specific human organs and tissues during infection by T. pallidum.

Toll‐like receptors (TLRs) are a class of membrane‐spanning proteins of host cells. TLR2 and TLR4 are displayed on the surface of macrophages, neutrophils and dendritic cells and recognize structurally conserved microbial signatures defined as Pathogen associated molecular patterns (PAMPs). C3H mice are susceptible to tick‐borne pathogens; Lyme disease causing Borrelia burgdorferi that manifests arthritis and carditis and Apicomplexan protozoan, Babesia microti (Bm) that causes significant parasitemia associated with erythrocytopenia and haemoglobinuria. B. burgdorferi lacks typical TLR4 ligand lipopolysaccharides (LPS) and Bm TLR ligand(s) remain unknown. Only Borrelia lipoproteins that signal through TLR2 are established as PAMPs of these pathogens for TLR2/TLR4. Infection of C3H mice with each pathogen individually resulted in increase in the percentage of splenic B, T, and FcR+ cells while their co‐infection significantly diminished levels of these cells and caused increased B. burgdorferi burden in the specific organs. The most pronounced inflammatory arthritis was observed in co‐infected C3H/HeJ mice. Parasitemia levels and kinetics of resolution of Bm in both mice strains were not significantly different. Transfected HEK293 cells showed pronounced signaling by B. burgdorferi through TLR2 and to some extent by TLR4 while Bm and infected erythrocytes did not show any response confirming our results in mice.