Gomaa Ahmed M, El-Tantawy Nora L, Elsawey Aliaa M, Abdelsalam Ramy A, Azab Manar S
Department of Medical Parasitology, Faculty of Medicine, Mansoura University, Mansoura, Egypt.
Department of Medical Parasitology, Faculty of Medicine, Mansoura University, Mansoura, Egypt.
Exp Parasitol. 2019 Oct;205:107733. doi: 10.1016/j.exppara.2019.107733. Epub 2019 Aug 10.
Toxoplasma gondii is a ubiquitous protozoan of major medical and veterinary importance. Its treatment is difficult since the available drugs have severe side effects and reactivation may occur anytime. Vaccination with irradiated parasites exhibits ideal characteristics for vaccine development. In our experimental mice model, the protection against challenge with the virulent RH strain was assessed, using 255Gy irradiated tachyzoites. Eighty mice were allocated into 3 groups: naive control group, challenged with virulent RH tachyzoites group and a third group which is challenged with 1 × 10 irradiated tachyzoites, administered as two biweekly doses intraperitoneally. Protection was tested by challenging vaccinated mice with the virulent type RH tachyzoites 30 days after the 2nd vaccination dose. The assessment was built on qualitative clinical, quantitative parasitological, histopathological parameters and measurement of serum Nitric Oxide (NO). The results showed prolonged survival rate, absence of tachyzoites in the peritoneal aspirate by counting, absence of tachyzoites in all examined organs by impression smears, amelioration of histopathological changes in the liver, spleen, brain and lung specimens and increase of the serum NO level in the vaccinated group. Therefore, we propose that irradiated Toxoplasma tachyzoites confer protection for challenged mice and could be an alternative immunization schedule for vaccine development especially for who are at risk of severe immunosuppression.
刚地弓形虫是一种广泛存在的原生动物，具有重大的医学和兽医学意义。由于现有药物有严重的副作用且随时可能复发，其治疗很困难。用辐照过的寄生虫进行疫苗接种展现出了疫苗开发的理想特性。在我们的实验小鼠模型中，使用255Gy辐照速殖子评估了对强毒株RH攻击的保护作用。80只小鼠被分为3组：未感染对照组、用强毒株RH速殖子攻击组和第三组，第三组用1×10个辐照速殖子进行攻击，每两周腹腔注射一次。在第二次接种疫苗剂量30天后，用强毒株RH速殖子攻击接种过疫苗的小鼠来测试保护作用。评估基于定性临床、定量寄生虫学、组织病理学参数以及血清一氧化氮（NO）的测量。结果显示接种组的存活率延长、腹腔吸出物中通过计数未发现速殖子、所有检查器官的印片未发现速殖子、肝脏、脾脏、大脑和肺标本的组织病理学变化有所改善以及血清NO水平升高。因此，我们提出辐照过的刚地弓形虫速殖子能为受攻击的小鼠提供保护，并且可能是疫苗开发的一种替代免疫方案，特别是对于有严重免疫抑制风险的人群。
