Zhu X Q, Jacobs D E, Chilton N B, Sani R A, Cheng N A, Gasser R B
Department of Veterinary Science, University of Melbourne, Victoria, Australia.
Parasitology. 1998 Aug;117 ( Pt 2):155-64. doi: 10.1017/s0031182098002856.
The ascaridoid nematode of cats from Kuala Lumpur, Malaysia, previously identified morphologically as Toxocara canis, was characterized using a molecular approach. The nuclear ribosomal DNA (rDNA) region spanning the first internal transcribed spacer (ITS-1), the 5.8S gene and the second internal transcribed spacer (ITS-2) was amplified and sequenced. The sequences for the parasite from Malaysian cats were compared with those for T. canis and T. cati. The sequence data showed that this taxon was genetically more similar to T. cati than to T. canis in the ITS-1, 5.8S and ITS-2. Differences in the ITS-1 and ITS-2 sequences between the taxa (9.4-26.1%) were markedly higher than variation between samples within T. canis and T. cati (0-2.9%). The sequence data demonstrate that the parasite from Malaysian cats is neither T. canis nor T. cati and indicate that it is a distinct species. Based on these data, PCR-linked restriction fragment length polymorphism (RFLP) and single-strand conformation polymorphism (SSCP) methods were employed for the unequivocal differentiation of the Toxocara variant from T. canis and T. cati. These methods should provide valuable tools for studying the life-cycle, transmission pattern(s) and zoonotic potential of this parasite.
对来自马来西亚吉隆坡的猫身上的蛔虫类线虫进行了分子特征分析，该线虫之前在形态学上被鉴定为犬弓首蛔虫。扩增并测序了跨越第一个内部转录间隔区（ITS-1）、5.8S基因和第二个内部转录间隔区（ITS-2）的核糖体DNA（rDNA）区域。将来自马来西亚猫的寄生虫序列与犬弓首蛔虫和猫弓首蛔虫的序列进行了比较。序列数据表明，在ITS-1、5.8S和ITS-2区域，该分类群在基因上与猫弓首蛔虫的相似性高于犬弓首蛔虫。不同分类群之间ITS-1和ITS-2序列的差异（9.4 - 26.1%）明显高于犬弓首蛔虫和猫弓首蛔虫样本内部的差异（0 - 2.9%）。序列数据表明，来自马来西亚猫的寄生虫既不是犬弓首蛔虫也不是猫弓首蛔虫，而是一个独特的物种。基于这些数据，采用聚合酶链反应相关的限制性片段长度多态性（RFLP）和单链构象多态性（SSCP）方法来明确区分该弓首蛔虫变种与犬弓首蛔虫和猫弓首蛔虫。这些方法应为研究这种寄生虫的生命周期、传播模式和人畜共患病潜力提供有价值的工具。
