Evaluation of the diagnostic reliability of the gill-based Ray's fluid thioglycollate medium assay for Perkinsus olseni infections in Manila clams (Ruditapes philippinarum) across Korean tidal flats.

IF 1.3 0 PARASITOLOGY
Parasites, hosts and diseases Pub Date : 2025-05-01 Epub Date: 2025-05-26 DOI:10.3347/PHD.25014
Young-Ghan Cho, Kajino Nobuhisa, Hee Jung Choi, Mun-Gyeong Kwon, Hyun-Sung Yang, Kwang-Sik Choi
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Abstract

The alveolate protozoan parasite Perkinsus olseni infects a range of marine bivalves inhabiting tidal flats and shallow subtidal zones, causing considerable damage to shellfish industries. Infection by P. olseni is typically assessed using Ray's fluid thioglycollate medium (RFTM) assay, with gill tissue often employed as a diagnostic proxy for whole-body infection. However, the diagnostic reliability of gill-based assays across diverse ecological settings-particularly under low-infection conditions-remains uncertain. In this study, we investigated tissue-specific distribution and the diagnostic performance of the RFTM assay in detecting P. olseni in Manila clams (Ruditapes philippinarum) collected from 6 tidal flats along Korea's west and south coast. The assay was applied to 6 different tissues, including gills and visceral mass. Infection prevalence reached 100% at most sites, except at Padori (90%). Whole-body infection intensity ranged from 0.1×104 to 3.7×106 cells per gram of tissue. The visceral mass consistently harbored the largest proportion of parasites (27.8%-49.0%), followed by the mantle (17.4%-30.6%) and gills (19.4%-25.2%). Gill infection levels correlated strongly with whole-body infection intensity (r²=0.6-0.95), supporting their diagnostic value in high-infection areas. However, at Padori-where infection levels were lowest-the efficacy of the gill assay dropped to 56%, resulting in a 44% false negative rate. These results underscore the limitations of relying solely on gill tissue in low-infection environments and highlight the need for a context-dependent diagnostic approach. A dual-tissue strategy incorporating both gill and whole-body samples is recommended to improve diagnostic accuracy in P. olseni surveillance of Manila clam populations.

以鳃为基础的Ray's液体巯基酸盐培养基检测韩国潮滩马尼拉蛤(Ruditapes philipparum)中奥氏珀金索菌感染的诊断可靠性评估。
奥尔塞尼泡形原生动物寄生虫感染了一系列居住在潮滩和浅潮下带的海洋双壳类,对贝类产业造成了相当大的损害。通常使用Ray的液体巯基酸盐培养基(RFTM)测定法评估奥氏假单胞菌感染,鳃组织常被用作全身感染的诊断指标。然而,在不同的生态环境中,特别是在低感染条件下,基于鳃的检测的诊断可靠性仍然不确定。在这项研究中,我们研究了在韩国西部和南部海岸的6个潮滩收集的马尼拉蛤(Ruditapes philipparum)中检测P. olseni的组织特异性分布和RFTM检测的诊断性能。该实验应用于6种不同的组织,包括鳃和内脏肿块。大多数地点的感染流行率达到100%,除了帕多利(90%)。全身感染强度范围从0.1×104到3.7×106细胞每克组织。寄生比例最大的是内脏(27.8% ~ 49.0%),其次是地幔(17.4% ~ 30.6%)和鳃(19.4% ~ 25.2%)。鳃感染水平与全身感染强度密切相关(r²=0.6-0.95),支持其在高感染地区的诊断价值。然而,在感染水平最低的帕多里,鳃试验的有效性降至56%,导致44%的假阴性率。这些结果强调了在低感染环境中仅依赖鳃组织的局限性,并强调了依赖于环境的诊断方法的必要性。建议采用双组织策略结合鳃和全身样本,以提高马尼拉蛤种群中P. olseni监测的诊断准确性。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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