Center for Vector Biology & Zoonotic Diseases, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT 06511, USA.
Center for Vector Biology & Zoonotic Diseases, The Connecticut Agricultural Experiment Station, 123 Huntington Street, New Haven, CT 06511, USA.
J Invertebr Pathol. 2018 Jan;151:113-125. doi: 10.1016/j.jip.2017.11.007. Epub 2017 Nov 8.
A multi-year study was conducted to examine the natural ecology of the microsporidium Amblyospora khaliulini and more fully characterize parasite development and histopathology in all stages of its primary mosquito host, Aedes communis and intermediate copepod host, Acanthocyclops vernalis with redescription of the species. A. khaliulini exhibits polymorphic development, produces three morphologically and functionally distinct spores, and is both horizontally and vertically transmitted. Development in A. vernalis is restricted to females, occurs within the ovaries and results in death of the host. Development is haplophasic with division by binary and multiple fission producing rosette-shaped sporogonial plasmodia and conical uninucleate spores that are orally infectious to Ae. communis larvae. Both sexes are equally susceptible and infections are confined to testes in males and ovaries in females. Initial stages of development include uninucleate schizonts that undergo karyokinesis forming diplokaryotic meronts that divide repeatedly by binary fission. Sporogony occurs in both host sexes, but sporogenesis does not progress normally in adult males and elliptical, thin walled binucleate spores that function in vertical transmission of the microsporidium via infection of the ovaries and eggs are formed in adult females only. Development of vertically acquired infections in larval Ae. communis hosts occurs within fat body tissue, leads to the production of meiospores in male hosts only and results in death during the 4th larval stadium. Initial development is characterized by merogonial multiplication of diplokarya by synchronous binary division producing additional diplokarya. The cessation of merogony and the onset of sporogony are characterized by the simultaneous secretion of a sporophorous vesicle and meiotic division of diplokarya resulting in the formation of octonucleate sporonts that undergo cytokinesis and sporogenesis to form eight uninucleate, broadly ovoid meiospores enclosed within a sporophorous vesicle. The natural prevalence of patent vertically acquired fat body infections in field populations of Ae. communis ranged from 1.6% to 3.6%. Yearly infection rates in A. vernalis copepods ranged from 57.1% to 15.0%. Prevalence rates of horizontally acquired infections in emerging adult Ae. communis ranged from 69.0% to 11.9% in males and 50.0% to 16.4% in females.
一项为期多年的研究旨在研究微孢子虫 Amblyospora khaliulini 的自然生态，并更全面地描述其在主要蚊宿主 Aedes communis 和中间桡足类宿主 Acanthocyclops vernalis 的所有阶段的寄生虫发育和组织病理学，同时对该物种进行重新描述。A. khaliulini 表现出多态发育，产生三种形态和功能上明显不同的孢子，并通过水平和垂直传播进行传播。在 A. vernalis 中的发育仅限于雌性，发生在卵巢内，并导致宿主死亡。发育是单倍的，通过二分法和多次分裂产生玫瑰形孢子体原生质团和锥形单核孢子，这些孢子对 Ae. communis 幼虫具有口腔感染力。雌雄两性同样易感，感染局限于雄性的睾丸和雌性的卵巢。发育的初始阶段包括单核裂殖体，其经历核分裂形成二倍体 meronts，这些 meronts通过二分法多次分裂。在两种宿主中都发生孢子发生，但雄性成虫中的孢子发生不能正常进行，只有在雌性成虫中才形成功能上垂直传播微孢子虫的椭圆形、薄壁双核孢子，通过感染卵巢和卵子进行。幼虫 Ae. communis 宿主中垂直获得的感染的发育发生在脂肪组织中，仅导致雄性宿主中减数分裂孢子的产生，并在第 4 个幼虫阶段导致死亡。初始发育的特征是通过同步二分法使二倍体 merogony 倍增，产生额外的二倍体。merogony 的停止和孢子发生的开始的特征是同时分泌孢子囊和二倍体的减数分裂，导致形成八核孢子原，其经历细胞分裂和孢子发生，形成八个单核、宽卵形减数分裂孢子，被孢子囊包裹。在 Ae. communis 的野外种群中，垂直获得的脂肪体感染的自然流行率为 1.6%至 3.6%。桡足类 A. vernalis 每年的感染率从 57.1%到 15.0%不等。新兴成年 Ae. communis 中水平获得感染的流行率在雄性中从 69.0%到 11.9%不等，在雌性中从 50.0%到 16.4%不等。
