杆状病毒感染可以防止昆虫的化蛹。幼体激素(JH)在调节昆虫蜕皮和变态中起着至关重要的作用。然而,杆状病毒通过调控幼体激素(JH)途径阻止幼虫化蛹的分子机制尚不清楚。在这项研究中,我们发现,油菜多核多角体病毒(MbMNPV)感染延长了第四龄棉铃虫的幼虫期(H。棉铃虫)增加0.52d,并导致JH滴度增加。为了鉴定有助于棉铃虫-MbMNPV相互作用中JH增加的基因,我们分析了MbMNPV感染的棉铃虫脂肪体的mRNA表达谱。通过RNA-seq分析过滤出总共3637种差异表达的mRNA(DE-mRNA)。这些DE-mRNA主要富集在剪接体中,真核生物中的核糖体生物发生,氨酰tRNA生物合成,不匹配修复,和RNA降解信号通路,与病毒感染有关。使用实时PCR来验证RNA测序结果。为了找出哪些基因导致了JH滴度的增加,我们分析了转录组中的所有DE-mRNA,发现JHE和JHEH基因,与JH降解途径有关,被下调。通过RT-qPCR,与对照组相比,MbMNPV感染组幼虫中的JHE和JHEH基因显着下调。我们通过RNAi进一步证明了JH在棉铃虫幼虫中被JHE降解,ELISA,RT-qPCR和生物测定,而JHEH在棉铃虫幼虫中对JH的水解几乎可以忽略。敲除HaJHE促进了JH受体基因Met和下游基因Kr-h1的表达和MbMNPV的复制。这项研究阐明了JH在棉铃虫幼虫中主要被JHE降解。棉铃虫幼虫MbMNPV感染通过抑制JHE的表达导致JH滴度升高。JH滴度的增加促进了JH受体基因Met和下游基因Kr-h1的表达,从而阻止了棉铃虫的化蛹,并促进MbMNPV复制。本研究为棉铃虫和MbMNPV相互作用机制提供了新的见解。
Baculovirus infection can prevent the pupation of insects. Juvenile hormone (JH) plays a vital role in regulating insect molting and metamorphosis. However, the molecular mechanism of baculovirus preventing the pupation of larvae by regulating the Juvenile hormone (JH) pathway is still unclear. In this study, we found that the Mamestra brassicae multiple nucleopolyhedroviruses (MbMNPV) infection prolonged the larval stage of fourth instar Helicoverpa armigera (H. armigera) by 0.52 d and caused an increase in JH titer. To identify the genes that contribute to the JH increase in H. armigera-MbMNPV interaction, we analyzed mRNA expression profiles of the fat bodies of H. armigera infected by MbMNPV. A total of 3637 differentially expressed mRNAs (DE-mRNAs) were filtered out through RNA-seq analysis. These DE-mRNAs were mainly enriched in Spliceosome, Ribosome biogenesis in eukaryotes, Aminoacyl-tRNA biosynthesis, Mismatch repair, and RNA degradation signaling pathway, which are related to the virus infection. Real-time PCR was used to verify the RNA sequencing results. To find out which genes caused the increase in JH titer, we analyzed all the DE-mRNAs in the transcriptome and found that the
JHE and JHEH genes, which were related to JH degradation pathway, were down-regulated.
JHE and JHEH genes in the larvae of MbMNPV-infected group were significantly down-regulated compared with the control group by RT-qPCR. We further proved that the JH is degraded by
JHE in H. armigera larvae by RNAi, ELISA, RT-qPCR and bioassay, while the hydrolysis of JH by JHEH in H. armigera larvae can almost be ignored. Knocking down of HaJHE promoted the expression of the JH receptor gene Met and the downstream gene Kr-h1, and the replication of MbMNPV. This study clarified that JH is mainly degraded by
JHE in H. armigera larvae. The MbMNPV infection of H. armigera larvae leads to the increase of JH titer by inhibiting the expression of
JHE. The increase in JH titer promotes the expression of the JH receptor gene Met and the downstream gene Kr-h1, which prevents the pupation of H. armigera, and promotes MbMNPV replication. This study provides new insights into H. armigera and MbMNPV interaction mechanisms.