Department of Parasitology, College of Veterinary Medicine, Sichuan Agricultural University, Ya'an 625014, China.
Vet Res. 2013 Oct 3;44(1):90. doi: 10.1186/1297-9716-44-90.
The intestinal nematode Baylisascaris schroederi is an important cause of death for wild and captive giant pandas. Inorganic pyrophosphatases (PPases) are critical for development and molting in nematode parasites and represent potential targets for vaccination. Here, a new PPase homologue, Bsc-PYP-1, from B. schroederi was identified and characterized, and its potential as a vaccine candidate was evaluated in a mouse challenge model. Sequence alignment of PPases from nematode parasites and other organisms show that Bsc-PYP-1 is a nematode-specific member of the family I soluble PPases. Immunohistochemistry revealed strong localization of native Bsc-PYP-1 to the body wall, gut epithelium, ovary and uterus of adult female worms. Additionally, Bsc-PYP-1 homologues were found in roundworms infecting humans (Ascaris lumbricoides), swine (Ascaris suum) and dogs (Toxocara canis). In two vaccine trials, recombinant Bsc-PYP-1 (rBsc-PYP-1) formulated with Freund complete adjuvant induced significantly high antigen-specific immunoglobulin (Ig)G but no IgE or IgM responses. Analysis of IgG-subclass profiles revealed a greater increase of IgG1 than IgG2a. Splenocytes from rBsc-PYP-1/FCA-immunized mice secreted low levels of T helper (Th)1-type cytokines, interferon-γ and interleukin (IL)-2, while producing significantly high levels of IL-10 and significantly elevated levels of IL-4 (Th2 cytokines) after stimulation with rBsc-PYP-1 in vitro. Finally, vaccinated mice had 69.02-71.15% reductions (in 2 experiments) in larval recovery 7 days post-challenge (dpc) and 80% survival at 80 dpc. These results suggest that Th2-mediated immunity elicited by rBsc-PYP-1 provides protection against B. schroederi, and the findings should contribute to further development of Bsc-PYP-1 as a candidate vaccine against baylisascariasis.
肠道寄生线虫贝氏蛔虫是野生和圈养大熊猫死亡的重要原因。无机焦磷酸酶（PPases）对寄生虫的发育和蜕皮至关重要，是疫苗接种的潜在靶点。本研究鉴定并表征了来自贝氏蛔虫的新的 PPase 同源物 Bsc-PYP-1，并在小鼠攻毒模型中评估了其作为疫苗候选物的潜力。来自线虫寄生虫和其他生物的 PPase 序列比对表明，Bsc-PYP-1 是家族 I 可溶性 PPases 中具有线虫特异性的成员。免疫组织化学显示，天然 Bsc-PYP-1 强烈定位于成年雌性虫体的体壁、肠道上皮、卵巢和子宫。此外，还在感染人类（蛔虫）、猪（猪蛔虫）和狗（犬蛔虫）的圆线虫中发现了 Bsc-PYP-1 同源物。在两项疫苗试验中，与弗氏完全佐剂联合配制的重组 Bsc-PYP-1（rBsc-PYP-1）诱导了显著高水平的抗原特异性免疫球蛋白（Ig）G，但没有 IgE 或 IgM 反应。IgG 亚类谱分析显示 IgG1 的增加大于 IgG2a。rBsc-PYP-1/FCA 免疫小鼠的脾细胞分泌低水平的辅助性 T（Th）1 型细胞因子干扰素-γ和白细胞介素（IL）-2，但在体外刺激 rBsc-PYP-1 后产生显著高水平的 IL-10 和显著升高的 IL-4（Th2 细胞因子）。最后，在两次实验中，攻毒后 7 天（7 dpc）幼虫回收减少 69.02-71.15%，80 dpc 时 80%的小鼠存活。这些结果表明，rBsc-PYP-1 诱导的 Th2 介导免疫提供了对贝氏蛔虫的保护，研究结果应为进一步开发 Bsc-PYP-1 作为贝氏蛔虫病候选疫苗做出贡献。
