Cydiapomonella颗粒病毒(CpGV)的各种分离株被用作针对蛾的害虫防治剂(CM,CydiapomonellaL.),苹果园中的主要害虫。最近已鉴定出CM幼虫对CpGV的主要遗传场抗性的三种不同类型(I-III)。在这项研究中,在感染不同CpGV分离株的II型抗性CM幼虫的中肠细胞中病毒基因的转录,即,CpGV-M和CpGV-S(均倾向于II型抗性)以及CpGV-E2(破坏II型抗性)在早期感染阶段(感染后72小时)通过链特异性RNA测序(RNA-Seq)确定。基于读取计数的主成分分析和RNA-Seq数据中单核苷酸多态性(SNP)的定量分布,开发了生物信息学分析管道,用于后验鉴定感染因子。我们报告说(i)确定感染因子至关重要,特别是在体内感染实验中,当隐蔽病毒感染的激活是可能的,(ii)尽管抗性机制不同,但在II型抗性CM幼虫中发现CpGV-M和CpGV-S转录之间没有实质性差异,(iii)CpGV-M和CpGV-S的转录水平远低于CpGV-E2,(iv)orf59(sod),orf89(pif-6),orf92(p18),和orf137(lef-10)被鉴定为抗性易感分离株CpGV-M和CpGV-S中显著下调的基因。对于CM幼虫的II型抗性,我们得出结论,CpGV-M和CpGV-S都能够进入中肠细胞,但与抗性破坏分离株CpGV-E2相比,病毒转录在感染早期明显受损。
目的:CpGV是一种高毒力毒蛾病原,它已经发展成为世界上最成功的商业杆状病毒生物防治剂之一。对商业CpGV产品的蛾的田间抗性的出现是对CpGV的可持续使用的威胁。近年来,确定了不同类型的耐药性(I-III型)。对于II型电阻,对感染过程知之甚少。通过研究不同CpGV分离株在II型抗性蛾幼虫腹部的病毒基因表达模式,我们发现II型耐药机制很可能是基于细胞内因子而不是受体成分.通过应用RNA-Seq数据的SNP作图,我们进一步强调,在不能排除隐蔽感染的激活时,在体内实验中鉴定感染因子的重要性.
Various isolates of the Cydia pomonella granulovirus (CpGV) are used as insect pest control agents against codling moth (CM, Cydia pomonella L.), a predominant pest in apple orchards. Three different types (I-III) of dominantly inherited field
resistance of CM larvae to CpGV have been recently identified. In this study, transcription of virus genes in midgut cells of type II-resistant CM larvae infected with different CpGV isolates, i.e., CpGV-M and CpGV-S (both prone to type II resistance) as well as CpGV-E2 (breaking type II
resistance) was determined by strand-specific RNA sequencing (RNA-Seq) at an early infection stage (72 h post infection). Based on principal component analysis of read counts and the quantitative distribution of single nucleotide polymorphisms (SNPs) in the RNA-Seq data, a bioinformatics analysis pipeline was developed for an a posteriori identification of the infective agents. We report that (i) identification of infective agent is crucial, especially in in vivo infection experiments, when activation of covert virus infections is a possibility, (ii) no substantial difference between CpGV-M and CpGV-S transcription was found in type II-resistant CM larvae despite a different resistance mechanism, (iii) the transcription level of CpGV-M and CpGV-S was much lower than that of CpGV-E2, and (iv) orf59 (sod), orf89 (pif-6), orf92 (p18), and orf137 (lef-10) were identified as significantly downregulated genes in resistance-prone isolates CpGV-M and CpGV-S. For type II
resistance of CM larvae, we conclude that CpGV-M and CpGV-S are both able to enter midgut cells, but viral transcription is significantly impaired at an early stage of infection compared to the resistance-breaking isolate CpGV-E2.
OBJECTIVE: CpGV is a highly virulent pathogen of codling moth, and it has been developed into one of the most successful commercial baculovirus biocontrol agents for pome fruit production worldwide. The emergence of field resistance in codling moth to commercial CpGV products is a threat toward the sustainable use of CpGV. In recent years, different types of
resistance (type I-III) were identified. For type II
resistance, very little is known regarding the infection process. By studying the virus gene expression patterns of different CpGV isolates in midguts of type II-resistant codling moth larvae, we found that the type II resistance mechanism is most likely based on intracellular factors rather than a receptor component. By applying SNP mapping of the RNA-Seq data, we further emphasize the importance of identifying the infective agents in in vivo experiments when activation of a covert infection cannot be excluded.