Apyrases are a recurrent feature of secretomes from numerous species of parasitic nematodes. Here we characterise the five apyrases secreted by Heligmosomoides polygyrus, a natural parasite of mice and a widely used laboratory model for intestinal nematode infection. All five enzymes are closely related to soluble calcium-activated nucleotidases described in a variety of organisms, and distinct from the CD39 family of ecto-nucleotidases. Expression is maximal in adult worms and restricted to adults and L4s. Recombinant apyrases were produced and purified from Pichia pastoris. The five enzymes showed very similar biochemical properties, with strict calcium dependence and a broad substrate specificity, catalysing the hydrolysis of all nucleoside tri- and diphosphates, with no activity against nucleoside monophosphates. Natural infection of mice provoked very low antibodies to any enzyme, but immunisation with an apyrase cocktail showed partial protection against reinfection, with reduced egg output and parasite recovery. The most likely role for nematode secreted apyrases is hydrolysis of extracellular ATP, which acts as an alarmin for cellular release of IL-33 and initiation of type 2 immunity.

腺苷三磷酸双磷酸酶是来自多种寄生线虫的分泌组的反复出现的特征。在这里，我们描述了 Heligmosomoides polygyrus 分泌的五种腺苷三磷酸双磷酸酶，这是一种小鼠的天然寄生虫，也是一种广泛使用的肠道线虫感染实验室模型。所有五种酶都与多种生物体中描述的可溶性钙激活核苷酸酶密切相关，并且与外核苷酸酶 CD39 家族不同。表达在成虫中最大，仅限于成虫和 L4。从毕赤酵母中生产和纯化重组腺苷三磷酸双磷酸酶. 这五种酶显示出非常相似的生化特性，具有严格的钙依赖性和广泛的底物特异性，催化所有核苷三磷酸和二磷酸的水解，对核苷单磷酸没有活性。小鼠的自然感染对任何酶都产生了非常低的抗体，但用 apyrase 鸡尾酒免疫显示出部分保护免受再感染，减少了产卵量和寄生虫恢复。线虫分泌的腺苷三磷酸双磷酸酶最可能的作用是细胞外 ATP 的水解，它作为细胞释放 IL-33 和启动 2 型免疫的警报。