Tydén E, Engström A, Morrison D A, Höglund J
Department of Biomedical Sciences and Veterinary Public Health, Section for Parasitology, Swedish University of Agricultural Sciences, S-750 07 Uppsala, Sweden.
Mol Biochem Parasitol. 2013 Jul;190(1):38-43. doi: 10.1016/j.molbiopara.2013.05.003. Epub 2013 May 16.
Benzimidazoles (BZ) are used to control infections of the equine roundworm Parascaris equorum and the poultry roundworm Ascaridia galli. There are still no reports of anthelmintic resistance (AR) to BZ in these two nematodes, although AR to BZ is widespread in several other veterinary parasites. Several single nucleotide polymorphisms (SNP) in the β-tubulin genes have been associated with BZ-resistance. In the present study we have sequenced β-tubulin genes: isotype 1 and isotype 2 of P. equorum and isotype 1 of A. galli. Phylogenetic analysis of all currently known isotypes showed that the Nematoda has more diversity among the β-tubulin genes than the Vertebrata. In addition, this diversity is arranged in a more complex pattern of isotypes. Phylogenetically, the A. galli sequence and one of the P. equorum sequences clustered with the known Ascaridoidea isotype 1 sequences, while the other P. equorum sequence did not cluster with any other β-tubulin sequences. We therefore conclude that this is a previously unreported isotype 2. The β-tubulin gene sequences were used to develop a PCR for genotyping SNP in codons 167, 198 and 200. No SNP was observed despite sequencing 95 and 100 individual adult worms of P. equorum and A. galli, respectively. Given the diversity of isotype patterns among nematodes, it is likely that associations of genetic data with BZ-resistance cannot be generalised from one taxonomic group to another.
苯并咪唑类药物（BZ）用于控制马蛔虫（Parascaris equorum）和家禽蛔虫（Ascaridia galli）的感染。尽管BZ耐药性在其他几种兽医寄生虫中广泛存在，但目前仍没有关于这两种线虫对BZ产生抗驱虫药抗性（AR）的报道。β-微管蛋白基因中的几个单核苷酸多态性（SNP）与BZ耐药性有关。在本研究中，我们对β-微管蛋白基因进行了测序：马蛔虫的同种型1和同种型2以及家禽蛔虫的同种型1。对所有目前已知的同种型进行系统发育分析表明，线虫的β-微管蛋白基因多样性比脊椎动物更多。此外，这种多样性以更复杂的同种型模式排列。在系统发育上，家禽蛔虫序列和其中一个马蛔虫序列与已知的蛔虫总科同种型1序列聚类，而另一个马蛔虫序列未与任何其他β-微管蛋白序列聚类。因此，我们得出结论，这是一种先前未报道的同种型2。利用β-微管蛋白基因序列开发了一种PCR方法，用于对密码子167、198和200中的SNP进行基因分型。尽管分别对95条和100条马蛔虫和家禽蛔虫的成虫进行了测序，但未观察到SNP。鉴于线虫同种型模式的多样性，遗传数据与BZ耐药性之间的关联可能无法从一个分类群推广到另一个分类群。
