Ascencio Mariano E, Florin-Christensen Monica, Mamoun Choukri B, Weir William, Shiels Brian, Schnittger Leonhard
Instituto de Patobiología, Centro de Investigaciones en Ciencias Veterinarias y Agronómicas (CICVyA), INTA-Castelar, Los Reseros y Nicolas Repetto s/n, Hurlingham 1686, Argentina.
National Council of Scientific and Technological Research (CONICET), Ciudad Autónoma de Buenos Aires C1033AAJ, Argentina.
Vet Sci. 2018 Apr 17;5(2):41. doi: 10.3390/vetsci5020041.
Piroplasmid parasites comprising of , , and are transmitted by ticks to farm and pet animals and have a significant impact on livestock industries and animal health in tropical and subtropical regions worldwide. In addition, diverse spp. infect humans as opportunistic hosts. Molecular phylogeny has demonstrated at least six piroplasmid lineages exemplified by , , , , sensu stricto (, , and ) and sensu stricto (, , and ). C1A cysteine-proteinases (C1A-Cp) are papain-like enzymes implicated in pathogenic and vital steps of the parasite life cycle such as nutrition and host cell egress. An expansion of C1A-Cp of and with respect to and was previously described. In the present work, C1A-Cp paralogs were identified in available genomes of species pertaining to each piroplasmid lineage. Phylogenetic analysis revealed eight C1A-Cp groups. The profile of C1A-Cp paralogs across these groups corroborates and defines the existence of six piroplasmid lineages. , and s.s. each showed characteristic expansions into extensive families of C1A-Cp paralogs in two of the eight groups. Underlying gene duplications have occurred as independent unique evolutionary events that allow distinguishing these three piroplasmid lineages. We hypothesize that C1A-Cp paralog families may be associated with the advent of the schizont stage. Differences in the invertebrate tick host specificity and/or mode of transmission in piroplasmid lineages might also be associated with the observed C1A-Cp paralog profiles.
由巴贝斯虫属、泰勒虫属和无形体属组成的梨形虫寄生虫通过蜱传播给农场动物和宠物，对全球热带和亚热带地区的畜牧业和动物健康产生重大影响。此外，多种无形体属物种感染人类作为机会性宿主。分子系统发育已证明至少有六个梨形虫谱系，以狭义的巴贝斯虫属、泰勒虫属、无形体属、嗜吞噬细胞无形体、反刍动物无形体和狭义的无形体属（嗜吞噬细胞无形体、反刍动物无形体和绵羊无形体）为代表。C1A半胱氨酸蛋白酶（C1A-Cp）是木瓜蛋白酶样酶，参与寄生虫生命周期的致病和关键步骤，如营养摄取和宿主细胞逸出。先前已描述了巴贝斯虫属和泰勒虫属相对于嗜吞噬细胞无形体和反刍动物无形体的C1A-Cp的扩增情况。在本研究中，在属于每个梨形虫谱系的物种的可用基因组中鉴定出C1A-Cp旁系同源物。系统发育分析揭示了八个C1A-Cp组。这些组中C1A-Cp旁系同源物的概况证实并确定了六个梨形虫谱系的存在。狭义的巴贝斯虫属、泰勒虫属和无形体属在八个组中的两个组中各自显示出向广泛的C1A-Cp旁系同源物家族的特征性扩增。潜在的基因复制作为独立的独特进化事件发生，这使得能够区分这三个梨形虫谱系。我们假设C1A-Cp旁系同源物家族可能与裂殖体阶段的出现有关。梨形虫谱系中无脊椎蜱宿主特异性和/或传播方式的差异也可能与观察到的C1A-Cp旁系同源物概况有关。
