Jennes Malgorzata, De Craeye Stéphane, Devriendt Bert, Dierick Katelijne, Dorny Pierre, Cox Eric
Laboratory for Immunology, Faculty of Veterinary Medicine, Ghent UniversityMerelbeke, Belgium.
National Reference Laboratory for Toxoplasmosis, Operational Direction Communicable and Infectious Diseases, Scientific Institute of Public Health, Security of Food Chain and EnvironmentBrussels, Belgium.
Front Cell Infect Microbiol. 2017 Jun 8;7:232. doi: 10.3389/fcimb.2017.00232. eCollection 2017.
is a worldwide prevalent parasite of humans and animals. The global infection burden exceeds yearly one million disability-adjusted life years (DALY's) in infected individuals. Therefore, effective preventive measures should be taken to decrease the risk of infection in humans. Although human toxoplasmosis is predominantly foodborne by ingestion of tissue cysts in meat from domestic animals such as pigs, the incidence risk is difficult to estimate due to the lack of screening of animals for infection and insights in location and persistence of the parasite in the tissues. Hence, experimental infections in pigs can provide more information on the risk for zoonosis based on the parasite burden in meat products intended for human consumption and on the immune responses induced by infection. In the present study, homo- and heterologous infection experiments with two distinct strains (IPB-LR and IPB-Gangji) were performed. The humoral and cellular immune responses, the presence of viable parasites and the parasite load in edible meat samples were evaluated. In homologous infection experiments the parasite persistence was clearly strain-dependent and inversely correlated with the infection dose. The results strongly indicate a change in the amount of parasite DNA and viable cysts in porcine tissues over time. Heterologous challenge infections demonstrated that IPB-G strain could considerably reduce the parasite burden in the subsequent IPB-LR infection. A strong, however, not protective humoral response was observed against GRA7 and TLA antigens upon inoculation with both strains. The IFN-γ production by TLA-stimulated PBMCs was correlated with the infection dose and predominantly brought about by CD3CD4CD8α T-lymphocytes. The described adaptive cellular and humoral immune responses in pigs are in line with the induced or natural infections in mice and humans. Previous studies underscored the heterogeneity of strains and the corresponding virulence factors. These findings suggest the potential of the IPB-G strain to elicit a partially protective immune response and to reduce the parasite burden upon a challenge infection. The IPB-G strain could be used as a promising tool in limiting the number of viable parasites in edible tissues and, hence, in lowering the risk for human toxoplasmosis.
是一种在全球范围内流行的人类和动物寄生虫。全球感染负担每年超过100万感染个体的伤残调整生命年（DALY）。因此，应采取有效的预防措施来降低人类感染风险。虽然人类弓形虫病主要通过摄入来自猪等家畜肉类中的组织包囊经食物传播，但由于缺乏对动物感染的筛查以及对寄生虫在组织中的位置和存活情况的了解，发病风险难以估计。因此，猪的实验性感染可以根据供人类食用的肉类产品中的寄生虫负荷以及感染诱导的免疫反应，提供更多关于人畜共患病风险的信息。在本研究中，进行了两种不同菌株（IPB-LR和IPB-Gangji）的同源和异源感染实验。评估了体液和细胞免疫反应、可存活寄生虫的存在以及可食用肉类样本中的寄生虫负荷。在同源感染实验中，寄生虫的持续存在明显依赖于菌株，并且与感染剂量呈负相关。结果强烈表明猪组织中寄生虫DNA和活包囊的数量随时间变化。异源攻击感染表明，IPB-G菌株可以显著降低随后IPB-LR感染中的寄生虫负荷。接种两种菌株后，针对GRA7和TLA抗原观察到强烈但无保护性的体液反应。TLA刺激的外周血单核细胞产生的IFN-γ与感染剂量相关，并且主要由CD3CD4CD8α T淋巴细胞引起。猪中描述的适应性细胞和体液免疫反应与小鼠和人类中的诱导感染或自然感染一致。先前的研究强调了菌株的异质性和相应的毒力因子。这些发现表明IPB-G菌株具有引发部分保护性免疫反应并在攻击感染时降低寄生虫负荷的潜力。IPB-G菌株可作为一种有前景的工具，用于限制可食用组织中活寄生虫的数量，从而降低人类弓形虫病的风险。
