Identification of disease resistance loci against bacterial disease (Streptococcus iniae)in rainbow trout(Oncorhynchus mykiss)

由新链球菌引起的链球菌病是虹鱼(Oncorhynchus Mykis)的一种严重细菌性疾病。开发抗链球菌病彩虹鲑鱼将减少这种疾病的暴发数量，并减少对药物和疫苗的需求。遗传连锁分析是鉴定与抗病相关的数量性状基因座的有效方法。本研究利用遗传连锁图谱中筛选出的微卫星标记，对虹鳟鱼及其BC_1代的抗病和感病亲本杂交后代进行了抗病QTL的检测。同一连锁群上的免疫相关基因与显著的抗病QTL相关。特别是一些研究报道，QTL与MHC I、II类或Toll样受体区域位于同一连锁群上。QTL区域上的连锁群是这些研究的特别目标，因为它们携带经典的MHC I类和II类基因，这些基因以前与病毒、细菌和寄生虫病的易感性差异有关。在RT-3、RT-16、RT-2、RT-29、RT-27、RT-31、RT-17和RT-22连锁群中发现了一些与抗病相关的基因座。这些QTL区域是抗链球菌感染的候选基因。

Streptococcal disease (streptococcosis) caused by Streptococcus iniae is a serious bacterial disease in rainbow trout (Oncorhynchus mykiss). Developing streptococcosis-resistant rainbow trout will reduce the number of outbreaks of this disease as well as reduce the need for medicines and vaccines. Genetic linkage analysis is an effective method for identifying quantitative trait loci (QTL) associated with resistance to a disease. In this study, microsatellite markers selected from genetic linkage maps of rainbow trout and BC_1 progeny from crosses between disease-resistant and disease-susceptible parents were used for detection of QTL associated with resistance to this disease. The immune-related genes on the same linkage group are correlated with significant QTL about disease resistance. Especially some studies have reported that QTLs are located on the same linkage group with the MHC class I, II or toll-like receptor regions. Linkage groups on QTL region were specifically targeted in these studies because they carry the classical MHC class I and II genes previously linked to differences in susceptibility to viral, bacterial, and parasitic diseases. Some loci associated with disease resistance were found in the RT-3、RT-16、RT-2、RT-29、RT-27、RT-31、RT-17and RT-22 linkage groups. These QTL regions are candidates for disease resistance against streptococcal infection.