Eszterbauer Edit, Sipos Dóra, Kaján Győző L, Szegő Dóra, Fiala Ivan, Holzer Astrid S, Bartošová-Sojková Pavla
Institute for Veterinary Medical Research, Centre for Agricultural Research, 1143 Budapest, Hungary.
Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, 370 05 České Budějovice, Czech Republic.
Microorganisms. 2020 Sep 29;8(10):1502. doi: 10.3390/microorganisms8101502.
We studied the genetic variability of serine protease inhibitors (serpins) of Myxozoa, microscopic endoparasites of fish. Myxozoans affect the health of both farmed and wild fish populations, causing diseases and mortalities. Despite their global impact, no effective protection exists against these parasites. Serpins were reported as important factors for host invasion and immune evasion, and as promising targets for the development of antiparasitic therapies. For the first time, we identified and aligned serpin sequences from high throughput sequencing datasets of ten myxozoan species, and analyzed 146 serpins from this parasite group together with those of other taxa phylogenetically, to explore their relationship and origins. High intra- and interspecific variability was detected among the examined serpins. The average sequence identity was 25-30% only. The conserved domains (i.e., motif and signature) showed taxon-level differences. Serpins clustered according to taxonomy rather than to serpin types, and myxozoan serpins seemed to be highly divergent from that of other taxa. None of them clustered with their closest relative free-living cnidarians. The genetic distinction of myxozoan serpins further strengthens the idea of an independent origin of Myxozoa, and may indicate novel protein functions potentially related to parasitism in this animal group.
我们研究了粘孢子虫（鱼类的微观内寄生虫）的丝氨酸蛋白酶抑制剂（丝氨酸蛋白酶抑制剂）的遗传变异性。粘孢子虫影响养殖鱼类和野生鱼类种群的健康，导致疾病和死亡。尽管它们具有全球影响，但目前尚无针对这些寄生虫的有效保护措施。丝氨酸蛋白酶抑制剂被报道为宿主入侵和免疫逃避的重要因素，也是抗寄生虫疗法开发的有希望的靶点。我们首次从十个粘孢子虫物种的高通量测序数据集中鉴定并比对了丝氨酸蛋白酶抑制剂序列，并对该寄生虫群体的146种丝氨酸蛋白酶抑制剂与其他分类群的丝氨酸蛋白酶抑制剂进行了系统发育分析，以探索它们的关系和起源。在所检测的丝氨酸蛋白酶抑制剂中检测到高种内和种间变异性。平均序列同一性仅为25%-30%。保守结构域（即基序和特征）显示出分类群水平的差异。丝氨酸蛋白酶抑制剂根据分类学而非丝氨酸蛋白酶抑制剂类型聚类，并且粘孢子虫的丝氨酸蛋白酶抑制剂似乎与其他分类群的丝氨酸蛋白酶抑制剂高度不同。它们中没有一个与其最亲近的自由生活刺胞动物聚类。粘孢子虫丝氨酸蛋白酶抑制剂的遗传差异进一步强化了粘孢子虫独立起源的观点，并可能表明该动物群体中与寄生相关的新蛋白质功能。
