Ross University School of Veterinary Medicine, Saint Kitts, West Indies.
The University of Tennessee College of Veterinary, Knoxville, TN, USA.
Vet Pathol. 2023 Sep;60(5):640-651. doi: 10.1177/03009858231173355. Epub 2023 May 23.
Aspergillosis of gorgonian sea fans is a Caribbean-wide disease characterized by focal, annular purple pigmentation with central tissue loss. We applied a holistic diagnostic approach including histopathology and a combination of culture and direct molecular identification of fungi to evaluate these lesions with the goal of determining the diversity of associated micro-organisms and pathology. Biopsies were collected from 14 sea fans without gross lesions and 44 sea fans with lesions grossly consistent with aspergillosis in shallow fringing reefs of St. Kitts. Histologically, the tissue loss margin had exposure of the axis and amoebocyte encapsulation with abundant mixed micro-organisms. Polyp loss, gastrodermal necrosis, and coenenchymal amoebocytosis were at the lesion interface (purpled area transitioning to grossly normal tissue) with algae ( = 21), fungus-like hyphae ( = 20), ciliate protists ( = 16), cyanobacteria ( = 15), labyrinthulomycetes ( = 5), or no micro-organisms ( = 8). Slender, septate hyaline hyphae predominated over other morphological categories, but were confined to the axis with little host response other than periaxial melanization. Hyphae were absent in 6 lesioned sea fans and present in 5 control biopsies, questioning their pathogenicity and necessary role in lesion causation. From cultivation, different fungi were isolated and identified by sequencing of the nuclear ribosomal internal transcribed spacer region. In addition, 2 primer pairs were used in a nested format to increase the sensitivity for direct amplification and identification of fungi from lesions, thereby circumventing cultivation. Results suggest mixed and opportunistic infections in sea fans with these lesions, requiring longitudinal or experimental studies to better determine the pathogenesis.
柳珊瑚曲霉病是一种在加勒比地区广泛发生的疾病，其特征为局灶性、环形紫色色素沉着，伴有中心组织缺失。我们采用了一种整体诊断方法，包括组织病理学以及真菌的培养和直接分子鉴定相结合，以评估这些病变，目的是确定相关微生物和病理学的多样性。在圣基茨的浅缘礁中，从 14 个无明显病变的柳珊瑚和 44 个病变明显符合曲霉病的柳珊瑚中采集了活检样本。组织学上，组织缺失边缘暴露轴组织并被阿米巴细胞包裹，伴有大量混合微生物。息肉缺失、胃皮层坏死和基质阿米巴细胞增生位于病变界面（从紫色区域过渡到大体正常组织），其中有藻类（ = 21）、真菌样菌丝（ = 20）、纤毛虫原生动物（ = 16）、蓝藻（ = 15）、Labyrinthulomycetes（ = 5）或无微生物（ = 8）。纤细、有隔透明菌丝比其他形态类别更为常见，但仅限于轴组织，除了轴周黑色素沉着外，宿主反应很少。在 6 个病变的柳珊瑚中没有发现菌丝，而在 5 个对照活检中发现了菌丝，这使得它们的致病性和在病变发病机制中的必要作用受到质疑。通过培养，不同的真菌被分离并通过核核糖体内部转录间隔区的测序进行鉴定。此外，还使用了 2 对引物进行嵌套格式，以提高直接从病变中扩增和鉴定真菌的灵敏度，从而避免了培养。结果表明，这些病变的柳珊瑚存在混合和机会性感染，需要进行纵向或实验研究以更好地确定发病机制。
