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.

本研究旨在分离并进行分子和表型表征 弓形虫感染伊比利亚猪的品系在半自由条件下繁殖，供人类食用。在屠宰场收集了来自伊比利亚猪生产主要地区的10种不同畜群的361只育肥猪的血液和心脏组织样本；对血清进行了抗血清检测弓形虫使用市售的间接ELISA试剂盒检测抗体的抗体，并使用来自各个地理位置的血清阳性个体代表的心肌进行小鼠生物测定。361只动物中有79只（21.9％）的抗弓形虫抗体根据血清学测试。对15个心肌组织样品进行生物测定，并获得5个分离株（TgPigSp1至TgPigSp5）。通过使用11种PCR-RFLP遗传标记对分离株进行表征。三个分离株具有ToxoDB＃3基因型（3/5），两个分离株具有ToxoDB＃2基因型（2/5）。选择TgPigSp1和TgPigSp4分离株以鉴定小鼠中的毒力，作为发现的每种不同RFLP基因型的实例。TgPigSp1分离株（＃2基因型）在小鼠中具有高毒力，具有明显的累积死亡率（87.5％）和发病率（100％）；TgPigSp4（＃3）无毒，在42.1％的血清反应阳性小鼠中触发了轻度的临床体征。分析了两个分离株的感染动力学和器官分布。数据显示出显着差异，p<0.05）。此外，检测到的组织病理学损伤的严重程度似乎与更高的寄生虫负担有关。考虑到与克隆基因型III相关的出乎意料的高死亡率和寄生虫负荷，传统上认为该基因型在小鼠中是无毒的，因此需要进一步研究和鉴定弓形虫 强调了在欧洲任何宿主中传播的菌株。