Nature Research Centre, Akademijos 2, 08412 Vilnius, Lithuania.
Institute of Pathology, Department for Pathobiology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210 Vienna, Austria.
Int J Parasitol. 2023 Sep;53(10):531-543. doi: 10.1016/j.ijpara.2023.02.009. Epub 2023 May 30.
Avian haemosporidians are widespread parasites categorized into four families of the order Haemosporida (Apicomplexa). Species of the subgenus Parahaemoproteus (genus Haemoproteus) belong to the Haemoproteidae and are transmitted by Culicoides biting midges. Reports of death due to tissue damage during haemoproteosis in non-adapted birds have raised concerns about these pathogens, especially as their exo-erythrocytic development is known for only a few Haemoproteus spp. More research is needed to better understand the patterns of the parasites' development in tissues and their impact on avian hosts. Yellowhammers Emberiza citrinella (Emberizidae) and common house martins Delichon urbicum (Hirundinidae) were screened for Haemoproteus parasites by microscopic examination of blood films and PCR-based testing. Individuals with single infection were selected for histological investigations. H & E-stained sections were screened for detection and characterization of the exo-erythrocytic stages, while chromogenic in situ hybridization (CISH) and phylogenetic analysis were performed to confirm the Haemoproteus origin and their phylogenetic relationships. Haemoproteus dumbbellus n. sp. was discovered in Emberiza citrinella single-infected with the lineage hEMCIR01. Meronts of H. dumbbellus n. sp. developed in various organs of five of six tested individuals, a pattern which was reported in other Haemoproteus species clustering in the same clade, suggesting this could be a phylogenetic trait. By contrast, in Delichon urbicum infected with the Haemoproteus lineage hDELURB2, which was linked to the more distantly related parasite Haemoproteus hirundinis, only megalomeronts were found in the pectoral muscles of two of six infected individuals. All exo-erythrocytic stages were confirmed to be Haemoproteus parasites by CISH using a Haemoproteus genus-specific probe. While the development of meronts seems to be typical for species of the clade containing H. dumbbellus, further investigations and data from more species are needed to explore whether a phylogenetic pattern occurs in meront or megalomeront formation.
禽类血孢子虫广泛寄生，属于血孢子虫目（孢子虫纲）的四个科。亚属疟原虫（疟原虫属）的物种属于血孢子科，由库蠓属吸血蠓传播。在非适应鸟类中，由于血孢子虫病导致组织损伤而死亡的报告引起了人们对这些病原体的关注，尤其是因为只有少数疟原虫属物种的外红细胞发育是已知的。需要更多的研究来更好地了解寄生虫在组织中的发育模式及其对鸟类宿主的影响。通过血液涂片的显微镜检查和基于 PCR 的检测，对黄雀 Emberiza citrinella（雀科）和普通家燕 Delichon urbicum（燕科）进行了疟原虫寄生虫筛查。选择单一感染个体进行组织学研究。对 H&E 染色切片进行筛选，以检测和描述外红细胞期，同时进行显色原位杂交（CISH）和系统发育分析，以确认疟原虫的起源及其系统发育关系。在单一感染 hEMCIR01 谱系的黄雀 Emberiza citrinella 中发现了疟原虫哑铃属新种。疟原虫哑铃属新种的裂殖体在 6 个测试个体中的 5 个个体的各种器官中发育，这种模式在聚类在同一进化枝中的其他疟原虫物种中也有报道，这表明这可能是一种系统发育特征。相比之下，在感染 hDELURB2 谱系的 Delichon urbicum 中，该谱系与亲缘关系较远的寄生虫 Haemoproteus hirundinis 相关，仅在 6 个感染个体中的 2 个个体的胸肌中发现了大裂殖体。所有的外红细胞期都通过使用疟原虫属特异性探针的 CISH 被确认为疟原虫寄生虫。虽然裂殖体的发育似乎是包含疟原虫哑铃属的进化枝中的物种的典型特征，但需要进一步的调查和更多物种的数据来探索是否在外红细胞或大裂殖体形成中存在系统发育模式。
