Department of Animal Biology, Institute of Biology, University of Campinas, 13083-970, Campinas, SP, Brazil.
Department of Ecology and Evolutionary Biology, Federal University of São Paulo (UNIFESP), Diadema, SP, 09972-270, Brazil.
Microb Pathog. 2023 Jun;179:106116. doi: 10.1016/j.micpath.2023.106116. Epub 2023 Apr 15.
The present study describes a new species of Henneguya infecting the ornamental fish Caquetaia spectabilis from the Brazilian Amazon. Fish specimens were collected where the Tapajós and Amazon rivers merge, municipality of Santarém in the State of Pará, Brazil. Infections were intense, with several plasmodia spread on the opercula, fins and eye. Phylogenetic characterization and host-parasite relationship studies of the new Henneguya species used a combination of small subunit ribosomal DNA (ssrDNA) and morphological (photonic and transmission electron microscopy) analyses. Plasmodia were white round to ellipsoidal measuring up to 1.8 mm. The myxospores body measured 20.5 ± 3.9 (15-27) in length, 7.9 μm (6.2-10.8) in width, 6.7 μm (6.0-7.6) in thickness, 20.5 μm (14.4-32.3) in caudal appendages length, and 40.6 μm (34.2-54.6) in total length. The two polar capsules were elongated and equal in size, measuring 4.3 μm (3.3-5.4) in length and 2.1 μm (1.3-2.8) in width. Histological analysis revealed the parasite development in connective tissues of the fins, eyes and opercula. The skin of the fins and opercula presented detachment of the epidermis, however, no inflamatory infiltrate was observed. In the eye were observed inflammatory infiltratate in the epithelium and stroma of the cornea. Ultrastructure analysis showed the connective tissue capsule composed by an inner cellular layer with fibroblasts and outer layer where collagen fibers arranged transversely yet interspersed by layers of fibers arranged longitudinally. Numerous invaginations and extensive pinocytotic channels were observed in the plasmodial membrane. A layer of microfilament-like microfilament-like material was observed in the ectoplasm area and along to the internal surface of the plasmodial membrane. Generative cells and early stages of sporogenesis were seen more internally. The ssrDNA based phylogeny showed the South American species grouped in two lineages and the new species arises in a well-sustained subclade as sister branch of the clade composed by Henneguya spp. parasites of cichlids fish.
本研究描述了一种新的亨尼鱼属寄生虫，感染了来自巴西亚马逊地区的观赏鱼卡奎塔亚spectabilis。鱼标本采集于塔帕若斯河和亚马逊河交汇处，巴西帕拉州圣塔伦市。感染非常严重，有多个疟原虫在鳃盖、鳍和眼睛上扩散。新的亨尼鱼属寄生虫的种系发生特征和宿主-寄生虫关系研究采用了小亚基核糖体 DNA (ssrDNA)和形态学（光子和透射电子显微镜）分析相结合的方法。疟原虫呈白色圆形至椭圆形，最长可达 1.8 毫米。粘孢子体的体长为 20.5 ± 3.9(15-27)微米，宽度为 7.9 微米(6.2-10.8)，厚度为 6.7 微米(6.0-7.6)，尾附属物长度为 20.5 微米(14.4-32.3)，总长度为 40.6 微米(34.2-54.6)。两个极囊细长且大小相等，长 4.3 微米(3.3-5.4)，宽 2.1 微米(1.3-2.8)。组织学分析显示寄生虫在鳍、眼和鳃盖的结缔组织中发育。鳍和鳃盖的皮肤出现表皮脱落，但未观察到炎症浸润。在眼睛中，观察到角膜上皮和基质的炎症浸润。超微结构分析显示，结缔组织囊由内层含有成纤维细胞的细胞层和外层组成，外层胶原纤维横向排列，而纤维层纵向排列。在疟原虫膜上观察到许多内陷和广泛的胞饮通道。在质膜外质区和质膜内表面观察到一层类似微丝的微丝样物质。在更内部的地方可以看到生殖细胞和孢子发生的早期阶段。基于 ssrDNA 的系统发育树显示，南美洲的物种分为两个谱系，而新物种在一个维持良好的亚分支中出现，是由慈鲷鱼类寄生虫组成的分支的姐妹分支。
