Programa de Pós-Graduação em Ciências da Saúde: Infectologia e Medicina Tropical, Faculdade de Medicina, Universidade Federal de Minas Gerais, Belo Horizonte, Minas Gerais, Brazil.
Laboratório de Imunopatologia, Núcleo de Pesquisas em Ciências Biológicas/NUPEB, Departamento de Ciências Biológicas, Insituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil.
Cytokine. 2020 May;129:155031. doi: 10.1016/j.cyto.2020.155031. Epub 2020 Feb 12.
The control measures against visceral leishmaniasis (VL) include a precise diagnosis of disease, the treatment of human cases, and reservoir and vector controls. However, these are insufficient to avoid the spread of the disease in specific countries worldwide. As a consequence, prophylactic vaccination could be interesting, although no effective candidate against human disease is available. In the present study, the Leishmania infantum amastin protein was evaluated regarding its immunogenicity and protective efficacy against experimental VL. BALB/c mice immunized with subcutaneous injections of the recombinant protein with or without liposome/saponin (Lip/Sap) as an adjuvant. After immunization, half of the animals per group were euthanized and immunological evaluations were performed, while the others were challenged with L. infantum promastigotes. Forty-five days after infection, the animals were euthanized and parasitological and immunological evaluations were performed. Results showed the development of a Th1-type immune response in rAmastin-Lip and rAmastin-Sap/vaccinated mice, before and after infection, which was based on the production of protein and parasite-specific IFN-γ, IL-12, GM-CSF, and nitrite, as well as the IgG2a isotype antibody. CD4 T cells were mainly responsible for IFN-γ production in vaccinated mice, which also presented significant reductions in parasitism in their liver, spleen, draining lymph nodes, and bone marrow. In addition, PBMC cultures of treated VL patients and healthy subjects stimulated with rAmastin showed lymphoproliferation and higher IFN-γ production. In conclusion, the present study shows the first case of an L. infantum amastin protein associated with distinct delivery systems inducing protection against L. infantum infection and demonstrates an immunogenic effect of this protein in human cells.
内脏利什曼病（VL）的控制措施包括对疾病的精确诊断、对人类病例的治疗以及对储存宿主和传播媒介的控制。然而，这些措施不足以避免全球特定国家疾病的传播。因此，预防性疫苗接种可能是有意义的，尽管目前还没有针对人类疾病的有效候选疫苗。在本研究中，评估了利什曼原虫 amastin 蛋白的免疫原性和对实验性内脏利什曼病的保护效力。BALB/c 小鼠经皮下注射重组蛋白并用或不用脂质体/皂苷（Lip/Sap）作为佐剂进行免疫。免疫后，每组一半的动物被安乐死并进行免疫学评估，而其余动物则用利什曼原虫前鞭毛体进行攻毒。感染后 45 天，处死动物并进行寄生虫学和免疫学评估。结果显示，在感染前后，rAmastin-Lip 和 rAmastin-Sap/vaccinated 小鼠产生了 Th1 型免疫反应，这是基于蛋白和寄生虫特异性 IFN-γ、IL-12、GM-CSF 和亚硝酸盐以及 IgG2a 同种型抗体的产生。在接种疫苗的小鼠中，CD4 T 细胞主要负责 IFN-γ的产生，这些小鼠的肝脏、脾脏、引流淋巴结和骨髓中的寄生虫载量也显著降低。此外，用 rAmastin 刺激治疗的内脏利什曼病患者和健康受试者的 PBMC 培养物显示出淋巴细胞增殖和更高的 IFN-γ产生。总之，本研究首次报道了一种与不同传递系统相关的利什曼原虫 amastin 蛋白，该蛋白能诱导对利什曼原虫感染的保护作用，并证明了该蛋白在人类细胞中的免疫原性效应。
