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, Instituto de Ciências Exatas e Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais, Brazil.
Cell Immunol. 2020 Oct;356:104194. doi: 10.1016/j.cellimm.2020.104194. Epub 2020 Aug 13.
Most studies evaluating vaccine candidates against visceral leishmaniasis (VL) have used parasite promastigote-expressed antigens; however, Leishmania proteins expressed in the amastigote forms should be considered, since few hours after infection this stage comes into contact with the host immune system and is responsible for the development of the disease. In this context, in the present study, a Leishmania amastigote-specific hypothetical protein, called LiHyJ, was evaluated as a recombinant protein plus saponin as an adjuvant or DNA vaccine to protect against VL. The vaccine effect was evaluated by means of the evaluation of immunological and parasitological analyses performed in BALB/c mice against Leishmania infantum infection. Results showed that rLiHyJ/saponin and DNA LiHyJ induced significantly higher levels of anti-protein and anti-parasite IFN-γ, IL-12, GM-CSF, and IgG2a isotype antibodies, which were associated with a low presence of IL-4 and IL-10. DNA vaccination induced higher IFN-γ production, mainly by CD8 T cells, while rLiHyJ/saponin stimulated the production of this cytokine, mainly by CD4 T cells. The parasite load evaluated in distinct organs showed that both immunization schedules significantly reduced organic parasitism, when compared to the controls. Similar results were found in the immunological and parasitological assays when using the recombinant protein or DNA, although the vaccination with rLiHyJ plus saponin induced a slightly higher Th1 response and lower parasite load, when compared to the use of DNA plasmid. The protein also proved to be immunogenic when peripheral blood mononuclear cells of treated VL patients and healthy subjects were in vitro stimulated, since higher IFN-γ and lower IL-4 and IL-10 levels were found in the culture supernatants. In conclusion, LiHyJ should be considered in future studies as a vaccine candidate to protect against VL.
大多数评估内脏利什曼病 (VL) 候选疫苗的研究都使用寄生虫前鞭毛体表达的抗原;然而,应该考虑利什曼原虫在无鞭毛体形式中表达的蛋白质,因为在感染后几个小时,这个阶段就会与宿主免疫系统接触,并负责疾病的发展。在这种情况下,在本研究中,一种利什曼无鞭毛体特异性假设蛋白,称为 LiHyJ,被评估为重组蛋白加皂苷作为佐剂或 DNA 疫苗来预防 VL。通过评估 BALB/c 小鼠对感染利什曼原虫婴儿的免疫和寄生虫分析来评估疫苗效果。结果表明,rLiHyJ/皂苷和 DNA LiHyJ 诱导了明显更高水平的抗蛋白和抗寄生虫 IFN-γ、IL-12、GM-CSF 和 IgG2a 同种型抗体,这与 IL-4 和 IL-10 的低水平相关。DNA 疫苗诱导了更高水平的 IFN-γ产生,主要由 CD8 T 细胞产生,而 rLiHyJ/皂苷刺激了这种细胞因子的产生,主要由 CD4 T 细胞产生。在不同器官中评估的寄生虫负荷表明,与对照组相比,两种免疫方案均显著降低了有机寄生虫感染。当使用重组蛋白或 DNA 时,在免疫和寄生虫检测中也发现了类似的结果,尽管 rLiHyJ 加皂苷疫苗接种诱导了稍高的 Th1 反应和较低的寄生虫负荷,与 DNA 质粒的使用相比。当用治疗 VL 患者和健康受试者的外周血单核细胞进行体外刺激时,该蛋白也被证明是免疫原性的,因为在培养上清液中发现了更高水平的 IFN-γ和更低水平的 IL-4 和 IL-10。总之,LiHyJ 应该在未来的研究中被视为预防 VL 的候选疫苗。