Vudriko Patrick, Umemiya-Shirafuji Rika, Tayebwa Dickson Stuart, Byaruhanga Joseph, Byamukama Benedicto, Tumwebaze Maria, Xuan Xuenan, Suzuki Hiroshi
Research Center for Tropical Diseases and Vector Control, Department of Veterinary Pharmacy, Clinics and Comparative Medicine, School of Veterinary Medicine and Animal Resources, College of Veterinary Medicine, Animal Resources and Biosecurity, Makerere University, Kampala P.O. Box 7062, Uganda.
National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-Cho, Obihiro 080-8555, Japan.
Microorganisms. 2022 Nov 30;10(12):2384. doi: 10.3390/microorganisms10122384.
We previously reported the emergence of amitraz-resistant () ticks in the western region of Uganda. This study characterized the octopamine/tyramine receptor gene (OCT/Tyr) of amitraz-resistant and -susceptible (.) ticks from four regions of Uganda. The OCT/Tyr gene was amplified from genomic DNA of 17 (.) larval populations of known susceptibility to amitraz. The amplicons were purified, cloned and sequenced to determine mutations in the partial coding region of the OCT/Tyr gene. The amplified (.) OCT/Tyr gene was 91-100% identical to the (.) OCT/Tyr gene. Up to 24 single nucleotide polymorphisms (SNPs) were found in the OCT/Tyr gene from ticks obtained from high acaricide pressure areas, compared to 8 from the low acaricide pressure areas. A total of eight amino acid mutations were recorded in the partial OCT/Tyr gene from ticks from the western region, and four of them were associated with amitraz-resistant tick populations. The amino acid mutations M1G, L16F, D41G and V72A were associated with phenotypic resistance to amitraz with no specific pattern. Phylogenetic analysis revealed that the OCT/Tyr gene sequence from this study clustered into two distinct groups that separated the genotype from high acaricide pressure areas from the susceptible populations. In conclusion, this study is the first to characterize the () OCT/Tyr receptor gene and reports four novel amino acid mutations associated with phenotypic amitraz resistance in Uganda. However, lack of mutations in the ORF of the OCT/Tyr gene fragment for some of the amitraz-resistant (.) ticks could suggest that other mechanisms of resistance may be responsible for amitraz resistance, hence the need for further investigation.
我们之前报道过在乌干达西部地区出现了对双甲脒耐药的蜱虫。本研究对来自乌干达四个地区的双甲脒耐药和敏感蜱虫的章鱼胺/酪胺受体基因（OCT/Tyr）进行了表征。从17个已知对双甲脒敏感的幼虫群体的基因组DNA中扩增出OCT/Tyr基因。对扩增产物进行纯化、克隆和测序，以确定OCT/Tyr基因部分编码区的突变。扩增得到的OCT/Tyr基因与[具体基因名称]的OCT/Tyr基因有91%-100%的同一性。与来自低杀螨剂压力地区的蜱虫相比，在来自高杀螨剂压力地区的蜱虫的OCT/Tyr基因中发现了多达24个单核苷酸多态性（SNP），而低杀螨剂压力地区的蜱虫中发现了8个。在来自西部地区的蜱虫的部分OCT/Tyr基因中总共记录到8个氨基酸突变，其中4个与双甲脒耐药蜱虫群体有关。氨基酸突变M1G、L16F、D41G和V72A与对双甲脒的表型抗性相关，且无特定模式。系统发育分析表明，本研究中的OCT/Tyr基因序列聚为两个不同的组，将来自高杀螨剂压力地区的基因型与敏感群体区分开来。总之，本研究首次对[具体蜱虫种类]的OCT/Tyr受体基因进行了表征，并报道了与乌干达双甲脒表型抗性相关的四个新的氨基酸突变。然而，一些对双甲脒耐药的蜱虫的OCT/Tyr基因片段的开放阅读框中缺乏突变，这可能表明其他抗性机制可能导致了双甲脒抗性，因此需要进一步研究。
