Griffin Matt, Quiniou Sylvie, Ware Cynthia, Bogdanovic Lewis, Soto Esteban
Department of Pathology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Stoneville, Mississippi 38776.
J Parasitol. 2014 Feb;100(1):110-6. doi: 10.1645/12-142.1. Epub 2013 Aug 28.
Numerous myxozoan cysts (∼ 1 mm) were found in the musculature of blackfin tuna (Thunnus atlanticus) harvested off the Caribbean island of St. Kitts. Myxospores were consistent with quadrate members of the Kudoidae, measuring 8.8 (8.2-9.4) μm wide, 7.3 (6.6-8.3) μm thick, and 6.2 (5.8-6.9) μm long with 4 uniform drop-like polar capsules measuring 2.7 (2.2-3.2) μm long and 2.0 (1.7-2.2) μm wide. The 18S small-subunit (SSU) and 28S large-subunit (LSU) ribosomal DNA sequences did not result in direct matches to any published sequences. However, the SSU sequences (1,786 base pairs [bp]) obtained from 6 individual cysts were identical and demonstrated high homology to Kudoa thunni (99.0%) from albacore (Thunnus alalunga). Alternatively, 33 unique sequences were obtained for the LSU (∼ 800 bp), demonstrating 0.1 to 5.0% variability between them, although a majority of these sequences (60%) demonstrated high homology (>99%) to K. thunni. Morphologically, the case isolate was smaller than published descriptions of K. thunni; however, rDNA sequence homology, and phylogenetic placement based on concatenated SSU and LSU rDNA sequences suggests this case isolate and K. thunni are conspecific. To our knowledge this is the first report of K. thunni infection in blackfin tuna from the Caribbean.
在从加勒比海圣基茨岛捕获的黑鳍金枪鱼（Thunnus atlanticus）肌肉组织中发现了大量粘孢子虫囊肿（约1毫米）。粘孢子与 Kudoidae 的方形成员一致，宽8.8（8.2 - 9.4）μm，厚7.3（6.6 - 8.3）μm，长6.2（5.8 - 6.9）μm，有4个均匀的滴状极囊，长2.7（2.2 - 3.2）μm，宽2.0（1.7 - 2.2）μm。18S 小亚基（SSU）和 28S 大亚基（LSU）核糖体 DNA 序列与任何已发表的序列均无直接匹配。然而，从6个单个囊肿中获得的 SSU 序列（1786个碱基对[bp]）是相同的，并且与长鳍金枪鱼（Thunnus alalunga）的 Kudoa thunni 具有高度同源性（99.0%）。另外，LSU（约800 bp）获得了33个独特序列，它们之间的变异性为0.1%至5.0%，尽管这些序列中的大多数（60%）与 K. thunni 具有高度同源性（>99%）。形态学上，该病例分离株比已发表的 K. thunni 描述要小；然而，rDNA 序列同源性以及基于串联的 SSU 和 LSU rDNA 序列的系统发育定位表明，该病例分离株与 K. thunni 是同种的。据我们所知，这是加勒比海黑鳍金枪鱼中 K. thunni 感染的首次报告。
