Department of Parasitology, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, China.
Parasit Vectors. 2023 Jul 28;16(1):254. doi: 10.1186/s13071-023-05886-y.
Baylisascaris schroederi is the most common and harmful intestinal parasitic nematode of giant pandas, causing ascariasis. Although drug deworming is the main measure to control ascariasis in captive giant pandas, prolonged and repeated use of deworming drugs might induce resistance in nematodes and drug residues in giant pandas. Therefore, developing a safe and effective vaccine might provide a novel strategy to prevent ascariasis in captive giant pandas.
Four highly expressed secretome genes encoding excretory and secretory proteins of B. schroederi, including transthyretin-like protein 46 (BsTLP), uncharacterized protein (BsUP), hypothetical protein 1 (BsHP1), and hypothetical protein 2 (BsHP2) and four functional genes [(encoding Galectin (BsGAL), glutathione S-transferase (BsGST), fatty acid-binding protein (BsFABP), and thioredoxin peroxidase (BsTPX)] were identified based on genome and transcriptome databases of B. schroederi and used to construct recombinant proteins via prokaryotic expression. Kunming mice were vaccinated subcutaneously twice with the recombinant proteins (50 μg/mouse) mixed with Quil A adjuvant with a 2-week interval and then orally challenged with 3000 infective eggs. The immunoprotective effects of the eight recombinant proteins on mice were assessed comprehensively using surface lesion histology scores of the mouse liver and lung, larval worm reduction, serum antibody levels (IgG, IgE, IgA, IgG1, and IgG2a), and cytokine production [interferon gamma (IFN-γ), interleukin (IL)-2, IL-4, IL-5, and IL-10].
Mice vaccinated with recombinant (r)BsUP (76.5%), rBsGAL (74.7%), and rBsHP2 (71.5%) showed a significant (P < 0.001) reduction in the larval worm rate compared with that in the adjuvant control. Besides, the surface lesions in the liver and lung of the vaccinated mice were alleviated. Serum levels of total IgG, IgE, IgA, IgG1, IgG2a, and cytokines, including IL-10, IL-5, and IFN-γ, were significantly higher (P < 0.001) than those in the control group.
The results showed that candidate three vaccines (rBsUP, rBsGAL, and rBsHP2) could provide effective protection against egg infection in mice associated with a mixed Th1/2-type immune response.
比氏蛔虫是大熊猫最常见和危害最大的肠道寄生线虫，可引起蛔虫病。虽然药物驱虫是控制圈养大熊猫蛔虫病的主要措施，但长期和反复使用驱虫药物可能会导致线虫产生抗药性和药物残留。因此，开发一种安全有效的疫苗可能为预防圈养大熊猫蛔虫病提供一种新策略。
根据比氏蛔虫基因组和转录组数据库，鉴定了四个高度表达的分泌蛋白基因，包括转甲状腺素蛋白样蛋白 46（BsTLP）、未知蛋白（BsUP）、假设蛋白 1（BsHP1）和假设蛋白 2（BsHP2），以及四个功能基因[（编码半乳糖凝集素（BsGAL）、谷胱甘肽 S-转移酶（BsGST）、脂肪酸结合蛋白（BsFABP）和硫氧还蛋白过氧化物酶（BsTPX）]，并通过原核表达构建重组蛋白。昆明小鼠用重组蛋白（50μg/只）与 Quil A 佐剂混合皮下接种两次，间隔 2 周，然后口服 3000 个感染性虫卵进行攻毒。用小鼠肝、肺表面病变组织学评分、幼虫减少率、血清抗体水平（IgG、IgE、IgA、IgG1 和 IgG2a）和细胞因子产生[干扰素γ（IFN-γ）、白细胞介素（IL）-2、IL-4、IL-5 和 IL-10]综合评估八种重组蛋白对小鼠的免疫保护作用。
与佐剂对照组相比，重组（r）BsUP（76.5%）、rBsGAL（74.7%）和 rBsHP2（71.5%）疫苗接种小鼠的幼虫减少率显著（P<0.001）。此外，疫苗接种小鼠的肝、肺表面病变得到缓解。血清总 IgG、IgE、IgA、IgG1、IgG2a 和细胞因子，包括 IL-10、IL-5 和 IFN-γ 的水平明显高于对照组（P<0.001）。
结果表明，候选三种疫苗（rBsUP、rBsGAL 和 rBsHP2）可在混合 Th1/2 型免疫应答的情况下为小鼠提供有效的抗卵感染保护。
