The aim of this study was to evaluate the efficacy of selenium nanoparticle (an immune booster) and naloxone (an opioid receptor antagonist) as a new adjuvant in increasing immune responses against killed whole-cell Vibrio cholerae in a mouse cholera model. The Se NPs were synthesized and characterized by UV-visible, DLS, and zeta potential analysis. The SEM image confirmed the uniformity of spherical morphology of nanoparticle shape with 34 nm in size. The concentration of the Se NPs was calculated as 0.654 μg/ml in the ICP method. The cytotoxic activity of Se NPs on Caco-2 cells was assessed by the MTT assay and revealed 82.05% viability of cells after 24 h exposure with 100 μg/ml of Se NPs. Female BALB/C mice were orally immunized three times on days 0, 14, and 28, and challenge experiments were performed on immunized neonates with toxigenic V. cholerae. Administration of Se NP diet led to significant increase in V. cholerae-specific IgG and IgA responses in serum and saliva and caused protective immunity and 83.3% survival in challenge experiment against 1 LD50 V. cholerae in a group receiving diet of Se NPs compared with other groups including Dukoral vaccine. The IL-4 and IL-5 were significantly increased in response to WC+daily diet of Se NPs with or without naloxone. Naloxone proved no effect on IL-4 and IL-5 increase and is proposed as null in the cytokine and antibody production process. These results reveal that daily diet of Se NPs could efficiently induce immune cell effectors in both humoral and mucosal levels.

中文翻译：

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硒纳米颗粒在小鼠模型中诱导针对霍乱弧菌 WC 疫苗的有效保护性免疫反应

本研究的目的是评估硒纳米颗粒（一种免疫增强剂）和纳洛酮（一种阿片受体拮抗剂）作为一种新佐剂在小鼠霍乱模型中增加对被杀死的全细胞霍乱弧菌的免疫反应的功效。通过紫外-可见光、DLS 和 zeta 电位分析合成并表征了 Se NP。SEM 图像证实了尺寸为 34 nm 的纳米颗粒形状的球形形态的均匀性。在 ICP 方法中，Se NPs 的浓度计算为 0.654  μg /ml。通过 MTT 测定评估 Se NPs 对 Caco-2 细胞的细胞毒活性，并显示在 100 μ暴露 24 小时后细胞的存活率为 82.05% g/ml Se NPs。在第 0、14 和 28 天对雌性 BALB/C 小鼠进行 3 次口服免疫，并对具有产毒霍乱弧菌的免疫新生儿进行攻击实验。Se NP 饮食的施用导致血清和唾液中霍乱弧菌特异性 IgG 和 IgA 反应的显着增加，并在针对 1 LD50霍乱弧菌的攻击实验中引起保护性免疫和 83.3% 的存活率与包括 Dukoral 疫苗在内的其他组相比，接受 Se NPs 饮食的组中。IL-4 和 IL-5 显着增加，以响应 WC+每日饮食中含有或不含纳洛酮的硒 NP。纳洛酮证明对 IL-4 和 IL-5 的增加没有影响，并且在细胞因子和抗体生产过程中被认为是无效的。这些结果表明，Se NPs 的日常饮食可以有效地诱导体液和粘膜水平的免疫细胞效应物。