Abstract
The present study aimed to isolate and perform molecular and phenotypic characterization of Toxoplasma gondii strains infecting Iberian pigs bred under semi-free conditions and destined for human consumption. Blood and heart tissue samples from 361 fattening pigs from 10 various herds selected in the main areas of Iberian pig production were collected at a slaughterhouse; the sera were tested for anti-T. gondii antibodies using a commercial indirect ELISA kit, and a mouse bioassay was carried out using heart muscle of seropositive individual representatives from each geographical location. Seventy-nine (21.9%) of the 361 animals tested positive for anti-T. gondii antibodies according to the serology test. Fifteen samples of myocardial tissue were subjected to bioassay and 5 isolates (TgPigSp1 to TgPigSp5) were obtained. The isolates were characterized by using 11 PCR-RFLP genetic markers; three isolates had a ToxoDB #3 genotype (3/5) and two isolates had a ToxoDB #2 genotype (2/5). The TgPigSp1 and TgPigSp4 isolates were selected for virulence in mice characterization as instances of each different RFLP-genotype found. The TgPigSp1 isolate (#2 genotype) was virulent in mice with notable cumulative mortality (87.5%) and morbidity rates (100%); the TgPigSp4 (#3) was nonvirulent and triggered mild clinical signs in 42.1% of seropositive mice. Infection dynamics and organ distribution of both isolates were analyzed; the data revealed significant differences, including substantially higher parasite load in the lung during the acute phase of infection, in mice infected with TgPigSp1 than in the case of TgPigSp4 (median parasite load 7.6 vs. 0 zoites/mg, respectively; p < 0.05). Furthermore, degrees of severity of detected histopathological lesions appeared to be related to higher parasite burdens. Taking into account the unexpectedly high mortality rate and parasite load associated with the clonal genotype III, which is traditionally considered nonvirulent in mice, the need for further investigation and characterization of the T. gondii strains circulating in any host in Europe is emphasized.
Highlights
The eukaryotic parasite Toxoplasma gondii (Apicomplexa) can infect virtually all warm-blooded animals and constitutes a specific risk for food safety in the European Union [1,2,3]; it is considered the second causal agent of foodborne illness in the USA [4]
Toxoplasma gondii-specific IgG antibodies were detected in 21.9% (79/361) of serum samples collected from pigs raised in 10 various locations (Table 1); 15 myocardial tissues of representative animals of various origins with the highest ELISA PP values were subjected to bioassay; subsequently, five isolates (TgPigSp1 to TgPigSp5) were obtained (Table 2)
The CS3 marker was previously reported to have a high predictive value on virulence in mice [16], and was present in type II alleles in all isolates with the ToxoDB #3 genotype; type III alleles were detected in all isolates with the ToxoDB #2 genotype (Table 2)
Summary
The eukaryotic parasite Toxoplasma gondii (Apicomplexa) can infect virtually all warm-blooded animals and constitutes a specific risk for food safety in the European Union [1,2,3]; it is considered the second causal agent of foodborne illness in the USA [4]. Human infections are mainly acquired after ingestion of raw or undercooked meat containing viable T. gondii tissue cysts [5]. Black Iberian pigs (Sus scrofa) constitute a traditional and well-adapted pig breed whose production is linked to highly valuable meat products, especially cured ham and sausages. These animals are usually reared in extensive systems in southwestern areas of the Iberian Peninsula (covering Portugal and Spain), within a favorable ecosystem, called Dehesa, composed mostly of acorn Mediterranean forest with a high natural biodiversity, which is ideal for swine breeding [8] in sympatry with ruminant livestock and a number of other wild animals, such as Cervidae and wild boar
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
