Zribi Lilia, El-Goulli Amel F, Ben-Abid Meriem, Gharbi Mohamed, Ben-Sghaier Ines, Boufaden Imed, Aoun Karim, Bouratbine Aïda
Department of Clinical Parasitology, Laboratoire de recherche LR 11-IPT-06 "Parasitologie Médicale, Biotechnologies et Biomolécules", Institut Pasteur de Tunis, Université Tunis El-Manar, 13 Place Pasteur, BP 74, 1002, Tunis, Tunisia; Faculté des Sciences de Bizerte, Université de Carthage, Bizerte, Tunisia.
Service de Pathologie médicale des équidés et des carnivores domestiques, Ecole Nationale de Médecine Vétérinaire de Sidi-Thabet, Université de la Manouba, 2020, Sidi-Thabet, Tunisia.
Vet Parasitol. 2017 Nov 15;246:88-92. doi: 10.1016/j.vetpar.2017.08.029. Epub 2017 Sep 1.
Interferon-Gamma (IFN-γ) Release Assays (IGRAs) are easy tests that allow rapid screening of primed memory T-cells immunity in response to antigen. The aim of this study was to use IGRA to assess IFN-γ release in response to Soluble Leishmania infantum antigen (SLA) in whole blood of dogs living in endemic area of visceral leishmaniasis and to interpret IGRA results according to clinical examination, specific anti-Leishmania humoral response and presence of L. infantum DNA in blood. The study was carried out on 56 dogs living in greater Tunis area. Physical examination, quantitative serology and PCR on blood were used to characterize dogs' status in relation to Leishmania infection and disease. IGRA consisted on testing by ELISA for IFN-γ-secretion in whole blood after a 20-h challenge with SLA. PBS and Phytohemagglutinin (PHA) stimulations were used as controls. Four groups of dogs were characterized: 31 were negative by both serology and PCR, two had doubtful serology, 10 presented no to mild clinical signs but low antibodies levels and 13 were affected by Canine Leishmaniasis (CanL). In seronegative dogs, IGRA was little contributory in 4 puppies (age <6months) and 5 old dogs (median age=72months, IQR: 45-84 months) that didn't respond to PHA stimulation, IGRA was negative in 19 and positive in three animals with lymph node enlargement. In dogs with doubtful serology, IGRA was positive in one dog and negative in the other. In infected dogs with no to mild clinical signs, one dog exhibited high level of IFN-γ in absence of antigenic stimulation and all the other were positive by IGRA. CanL dogs showed variable IGRA results. Negative IGRAs (n=4) were shown in animals with the highest parasitic burden whereas positive IGRAs (n=5) were shown in dogs with negative PCR or low parasitic load. The 4 remaining dogs either didn't respond to PHA (n=2) or showed non-specific secretion in PBS tube (n=2). The results of this study showed that IGRA is a useful new tool that can assess exposure to Leishmania in dogs with no to mild clinical signs in endemic area. Further comparative investigations using assays exploring cellular immunity are needed to determine its accuracy.
干扰素-γ（IFN-γ）释放试验（IGRAs）是一种简单的检测方法，可快速筛查引发的记忆T细胞对抗原的免疫反应。本研究的目的是使用IGRA评估生活在内脏利什曼病流行地区的犬全血中可溶性婴儿利什曼原虫抗原（SLA）刺激下的IFN-γ释放，并根据临床检查、特异性抗利什曼原虫体液反应和血液中婴儿利什曼原虫DNA的存在情况来解释IGRA结果。该研究在大突尼斯地区的56只犬上进行。通过体格检查、定量血清学和血液PCR来确定犬与利什曼原虫感染及疾病相关的状态。IGRA包括在用SLA刺激20小时后通过ELISA检测全血中的IFN-γ分泌。使用PBS和植物血凝素（PHA）刺激作为对照。将犬分为四组：31只血清学和PCR均为阴性，2只血清学结果可疑，10只无至轻度临床症状但抗体水平低，13只患有犬利什曼病（CanL）。在血清阴性的犬中，4只幼犬（年龄<6个月）和5只老龄犬（中位年龄=72个月，四分位间距：45-84个月）对PHA刺激无反应，IGRA对其诊断贡献不大，19只动物IGRA为阴性，3只淋巴结肿大的动物IGRA为阳性。在血清学结果可疑的犬中，一只犬IGRA为阳性，另一只为阴性。在无至轻度临床症状的感染犬中，一只犬在无抗原刺激时IFN-γ水平较高，其他所有犬IGRA均为阳性。CanL犬的IGRA结果各不相同。寄生虫负荷最高的动物IGRA为阴性（n=4），而PCR阴性或寄生虫负荷低的犬IGRA为阳性（n=5）。其余4只犬要么对PHA无反应（n=2），要么在PBS管中显示非特异性分泌（n=2）。本研究结果表明，IGRA是一种有用的新工具，可以评估流行地区无至轻度临床症状的犬对利什曼原虫的暴露情况。需要使用探索细胞免疫的检测方法进行进一步的比较研究以确定其准确性。
