稻纵卷叶螟颗粒体病毒的增殖与持续传播特征

Proliferation and persistent spread characteristics of baculovirus CnmeGV in Cnaphalocrocis medinalis

摘要:

【目的】分析稻纵卷叶螟颗粒体病毒(Cnaphalocrocis medinalis Guenée granulovirus, CnmeGV)在稻纵卷叶螟(Cnaphalocrocis medinalis)体内的增殖动态,明确其持续传播特征,丰富杆状病毒流行病学研究,为CnmeGV制剂的高效应用提供理论支撑。【方法】转录组测序分析幼虫感染CnmeGV 96 h后及羽化成虫中病毒基因的转录水平,建立基于CnmeGV特异基因Cmorf123的定量检测标记,分析CnmeGV在稻纵卷叶螟体内的增殖动态和持续传播特征。【结果】转录组测序分析表明,CnmeGV所有基因都在幼虫体内转录,其中转录水平最高的为乙酰基转移酶基因,但在成虫转录组中未发现病毒基因的转录。建立了CnmeGV定量检测体系,发现病毒在侵染48 h后,基因复制水平稳定;在侵染后的2 d与4 d病毒拷贝数显著增加,侵染4 d后,DNA含83个病毒拷贝/ng。稻纵卷叶螟幼虫感染CnmeGV后,在成虫和卵中未检测到病毒基因的转录,而在蛹中检测到少量的病毒转录本;86.7%以上的蛹和蛹蜕中均检测到病毒DNA,13.3%成虫中检测到病毒DNA,卵和感染后的第二代幼虫也均能检测到病毒DNA,但卵表经处理后未检测到病毒DNA。【结论】CnmeGV感染稻纵卷叶螟4 d内增殖水平逐渐增加并稳定。CnmeGV病毒粒子可以通过成虫经卵表跨代传播,羽化是稻纵卷叶螟清除CnmeGV的主要途径。

Abstract:

【Objective】 This study explored the proliferation dynamics and persistent spread characteristics of Cnaphalocrocis medinalis granulovirus (CnmeGV) in Cnaphalocrocis medinalis, aiming to enrich the epidemiological knowledge about baculovirus and provide theoretical support for the efficient application of CnmeGV formulations. 【Methods】 Transcriptome sequencing was employed to determine the transcriptional levels of viral genes in the larvae infected with CnmeGV for 96 h and in the emerged adults. A quantitative detection marker based on the specific gene Cmorf123 of CnmeGV was established to measure the proliferation dynamics and persistent spread characteristics of CnmeGV in C. medinalis. 【Results】 All the genes of CnmeGV were transcribed in the infected larvae, with the acetyltransferase gene showing the highest transcription level. However, no transcription of viral gene was detected in the transcriptome of adults. The measurement with the quantitative detection marker of CnmeGV showed that the replication level of viral gene remained stable within 48 h post infection. The copies of viral genes significantly increased 2 and 4 days post infection, and each nanogram of DNA contained 83 copies of viral genes 4 days post infection. After infection, no viral transcription was detected in the adults or eggs, while a few transcripts were detected in the pupae. Viral DNA was detected in more than 86.7% of pupa and pupal slough samples and while 13.3% of adults. Viral DNA was detected in both the eggs and the second-generation larvae after infection, while no viral DNA was detected on the egg after the surface treatment. 【Conclusion】 The proliferation level of CnmeGV in C. medinalis gradually increased and then remained stable within 4 days post infection. CnmeGV particles can be spread for two generations by the egg surface. The eclosion of C. medinalis is the main pathway for clearing CnmeGV.