Infectious Diseases and Immunology Division, Indian Institute of Chemical Biology, Kolkata, West Bengal, India.
Department of Botany, Serampore College, Hooghly, Serampore, West Bengal, India.
Parasit Vectors. 2020 May 30;13(1):272. doi: 10.1186/s13071-020-04138-7.
Visceral leishmaniasis (VL), is a parasitic disease that causes serious medical consequences if treatment is delayed. Despite a decline in the number of VL cases in the Indian subcontinent, the commencement of the disease in newer areas continues to be a major concern. Although serological diagnosis mainly by immunochromatographic tests has been found to be effective, a test of cure in different phases of treatment is still desired. Even though a good prophylactic response has been obtained in murine models by a number of vaccine candidates, few have been proposed for human use.
In this study, nine antigenic components (31, 34, 36, 45, 51, 63, 72, 91 and 97 kDa) of Leishmania promastigote membrane antigens (LAg), were electroeluted and evaluated through ELISA to diagnose and distinguish active VL from one month cured and six months post-treatment patients. Further, to investigate the immunogenicity of electroeluted proteins, human PBMCs of cured VL patients were stimulated with 31, 34, 51, 63, 72 and 91 kDa proteins.
We found that 34 and 51 kDa proteins show 100% sensitivity and specificity with healthy controls and other diseases. After six months post-treatment, antibodies to 72 and 91 kDa antigens show a significant decline to almost normal levels. This suggests that 34 and 51 kDa proteins are efficient in diagnosis, whereas 72 and 91 kDa proteins may be used to monitor treatment outcome. In another assay, 51 and 63 kDa proteins demonstrated maximum ability to upregulate IFN-γ and IL-12 with minimum induction of IL-10 and TGF-β. The results indicating that 51 and 63 kDa proteins could be strong candidates for human immunization against VL. In contrast, 34 and 91 kDa proteins demonstrated a reverse profile and may not be a good vaccine candidate.
The preliminary data obtained in this study proposes the potential of some of the antigens in Leishmania diagnosis and for test of cure. Additionally, some antigens demonstrated good immunoprophylactic cytokine production through T cell-mediated immune response, suggesting future vaccine candidates for VL. However, further studies are necessary to explore these antigens in diagnosis and to access the long-term immune response.
内脏利什曼病（VL）是一种寄生虫病，如果治疗不及时，会导致严重的医疗后果。尽管印度次大陆的 VL 病例数量有所下降，但新出现的疾病仍然是一个主要关注点。尽管免疫层析试验等血清学诊断已被证明是有效的，但仍需要在治疗的不同阶段进行治疗效果的检测。尽管许多疫苗候选物在小鼠模型中产生了良好的预防性反应，但很少有疫苗被提议用于人类。
在这项研究中，从利什曼原虫膜抗原（LAg）中电洗脱了 9 种抗原成分（31、34、36、45、51、63、72、91 和 97 kDa），并通过 ELISA 进行评估，以诊断和区分活动性 VL 与一个月治愈和六个月治疗后患者。此外，为了研究电洗脱蛋白的免疫原性，用 31、34、51、63、72 和 91 kDa 蛋白刺激治愈的 VL 患者的人 PBMC。
我们发现，34 和 51 kDa 蛋白与健康对照和其他疾病具有 100%的灵敏度和特异性。治疗后六个月，72 和 91 kDa 抗原的抗体显著下降至接近正常水平。这表明 34 和 51 kDa 蛋白在诊断中有效，而 72 和 91 kDa 蛋白可能用于监测治疗效果。在另一项检测中，51 和 63 kDa 蛋白表现出最大的能力来上调 IFN-γ和 IL-12，同时最小程度地诱导 IL-10 和 TGF-β。结果表明，51 和 63 kDa 蛋白可能是针对 VL 的人类免疫的有力候选物。相比之下，34 和 91 kDa 蛋白表现出相反的特征，可能不是一个好的疫苗候选物。
本研究初步数据提出了利什曼抗原在诊断和疗效检测方面的潜力。此外，一些抗原通过 T 细胞介导的免疫反应产生了良好的免疫预防细胞因子，这表明了 VL 的未来疫苗候选物。然而，需要进一步的研究来探索这些抗原在诊断中的应用，并评估其长期免疫反应。
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