Proliferation and persistent spread characteristics of baculovirus CnmeGV in Cnaphalocrocis medinalis

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.

Key words:baculovirus;persistent spread;cross-generational spread;latent infection;Cnaphalocrocis medinalis