Henneguya ictaluri is the etiologic agent of proliferative gill disease (PGD) in farm-raised Channel Catfish Ictalurus punctatus and hybrid catfish in the southeastern United States, and significant annual losses are attributed to this disease. Research suggests that H. ictaluri infection dynamics in Blue Catfish I. furcatus and hybrid catfish (Channel Catfish × Blue Catfish) differ from those in Channel Catfish. Two separate infectivity trials were conducted to investigate H. ictaluri development in Channel Catfish, Blue Catfish, and their hybrids. On two separate occasions with two different year-classes, fish were exposed to pond water containing H. ictaluri actinospores and sampled weekly for 12 weeks (trial 1) or 14 weeks (trial 2). In trial 1, the presence of H. ictaluri was evaluated histologically and by quantitative PCR of fish tissues, including gills, blood, anterior kidney, brain, heart, liver, posterior kidney, spleen, and stomach. Henneguya ictaluri DNA was detected in significantly higher concentrations throughout multiple organ systems in the Channel Catfish compared to the hybrid catfish and Blue Catfish, with the gills having higher quantities. Myxospores were observed in Channel Catfish gill tissue at 8 weeks postexposure. No myxospores were observed in Blue Catfish or hybrid catfish. The second trial focused on gills only and yielded similar results, with Channel Catfish having significantly greater H. ictaluri DNA quantities than hybrids or Blue Catfish across all time points. Myxospores were observed in Channel Catfish beginning at 6 weeks postexposure and were found in 36% (58/162) of Channel Catfish sampled for molecular and histological analysis during weeks 6-14. Myxospores in hybrid catfish were sparse, with single pseudocysts observed in two hybrid catfish (1.2%) at 14 weeks postexposure. These results imply arrested development of H. ictaluri in hybrid catfish. As such, culture of hybrid catfish may be an effective management strategy to minimize the burden of PGD.

中文翻译：

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Henneguya ictaluri Pote, Hanson, and Shivaji, 2000 (Cnidaria: Myxobolidae) 在 ♀ 通道鲶鱼 Ictalurus punctatus (Rafinesque, 1818) × ♂ 蓝鲶鱼 Ictalurus furcatus (Valenciennes, 杂交 1840) 中的发育受阻

Henneguya ictaluri 是美国东南部养殖的沟鲶 Ictalurus punctatus 和杂交鲶鱼增殖性鳃病 (PGD) 的病原体，这种疾病每年造成大量损失。研究表明，蓝鲶 I. furcatus 和杂交鲶鱼（沟鲶 × 蓝鲶）中的 H. ictaluri 感染动态与沟鲶不同。进行了两个独立的感染性试验，以研究鲶鱼、蓝鲶及其杂交种中的 H. ictaluri 发育。在两个不同年份的两个不同场合，将鱼暴露于含有 H. ictaluri 放线孢子的池塘水中，每周取样 12 周（试验 1）或 14 周（试验 2）。在试验 1 中，通过组织学和鱼类组织的定量 PCR 评估了鲎的存在，包括鳃、血、前肾、脑、心、肝、后肾、脾、胃。与杂交鲶鱼和蓝鲶鱼相比，海峡鲶鱼的多个器官系统中检测到的 Henneguya ictaluri DNA 浓度明显更高，鳃具有更高的数量。在暴露后 8 周，在沟鲶的鳃组织中观察到粘孢子。在蓝鲶鱼或杂交鲶鱼中未观察到粘孢子。第二项试验仅关注鳃并产生了类似的结果，在所有时间点，沟鲶的 DNA 量均显着高于杂交或蓝鲶鱼。在暴露后 6 周开始在沟鲶中观察到粘孢子，并且在第 6-14 周期间取样用于分子和组织学分析的沟鲶中发现了 36% (58/162) 的粘孢子。杂交鲶鱼中的粘孢子很少，在暴露后 14 周时在两条杂交鲶鱼 (1.2%) 中观察到单个假囊肿。这些结果意味着在杂交鲶鱼中抑制了 H. ictaluri 的发育。因此，杂交鲶鱼的养殖可能是减少 PGD 负担的有效管理策略。