Graduate PhD Degree Program in Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
Department of Parasitology, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand.
Acta Trop. 2019 Nov;199:105157. doi: 10.1016/j.actatropica.2019.105157. Epub 2019 Sep 3.
Leishmania (Mundinia) orientalis is a newly described species causing human leishmaniasis in Thailand whose natural vector is unknown. L. orientalis infections in sand flies and/or biting midges under laboratory conditions have not been previously investigated. In this study, the development of L. orientalis in two experimental vectors, Lutzomyia longipalpis sand flies and Culicoides sonorensis biting midges was investigated for the first time using light microscopy, scanning electron microscopy, and histological examination. The results showed that L. orientalis was unable to establish infection in Lu. longipalpis. No parasites were found in the sand fly gut 4 days post-infected blood meal (PIBM). In contrast, the parasite successfully established infection in C. sonorensis. The parasites differentiated from amastigotes to procyclic promastigotes in the abdominal midgut (AMG) on day 1 PIBM. On day 2 PIBM, nectomonad promastigotes were observed in the AMG and migrated to the thoracic midgut (TMG). Leptomonad promastigotes appeared at the TMG on day 3 PIBM. Clusters of leptomonad promastigotes and metacyclic promastigotes colonized around the stomodeal valve with the accumulation of a promastigote secretory gel-like material from day 3 PIBM onwards. Haptomonad-like promastigotes were observed from day 5 PIBM, and the proportion of metacyclic promastigotes reached 23% on day 7 PIBM. The results suggest that biting midges or other sand fly genera or species might be vectors of L. orientalis.
东方曼氏利什曼原虫是一种新描述的种属，可引起泰国的人类利什曼病，但其天然媒介尚不清楚。以前没有研究过实验室条件下在沙蝇和/或吸血蠓中东方曼氏利什曼原虫的感染情况。在这项研究中，首次使用光学显微镜、扫描电子显微镜和组织学检查来研究两种实验性载体——长角血蝇和致倦库蚊中东方曼氏利什曼原虫的发育情况。结果表明，东方曼氏利什曼原虫无法在长角血蝇中建立感染。在感染后 4 天的吸血餐中，未在沙蝇肠道中发现寄生虫。相比之下，寄生虫在 C. sonorensis 中成功建立了感染。寄生虫在吸血后第 1 天从无鞭毛体分化为前鞭毛体，在腹部中肠（AMG）中分化。在吸血后第 2 天，在 AMG 中观察到唾腺前鞭毛体，并迁移到胸中肠（TMG）。在吸血后第 3 天，在 TMG 中出现了前鞭毛体。从吸血后第 3 天开始，围绕口器阀有唾腺前鞭毛体和循环前鞭毛体聚集，同时积累了一种前鞭毛体分泌的凝胶状物质。从吸血后第 5 天开始观察到类哈氏前鞭毛体，吸血后第 7 天循环前鞭毛体的比例达到 23%。结果表明，吸血蠓或其他沙蝇属或种可能是东方曼氏利什曼原虫的媒介。
