ORF603 derived from AcMNPV plays entirely opposite roles in regulating BmNPV infection

Affiliations

• ¹ Jiangsu Key Laboratory of Sericultural and Animal Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, Jiangsu, China.
• ² Jiangsu Key Laboratory of Sericultural and Animal Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, Jiangsu, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang 212100, Jiangsu, China.
• ³ Jiangsu Key Laboratory of Sericultural and Animal Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, Jiangsu, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang 212100, Jiangsu, China. Electronic address: qinsheng@just.edu.cn.
• ⁴ Jiangsu Key Laboratory of Sericultural and Animal Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, Jiangsu, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang 212100, Jiangsu, China. Electronic address: xueyangwang@just.edu.cn.
• ⁵ Zhenjiang Hospital of Integrated Traditional Chinese and Western Medicine, Zhenjiang 212004, China. Electronic address: 13952882272@163.com.
• ⁶ Jiangsu Key Laboratory of Sericultural and Animal Biotechnology, School of Biotechnology, Jiangsu University of Science and Technology, Zhenjiang 212100, Jiangsu, China; Key Laboratory of Silkworm and Mulberry Genetic Improvement, Ministry of Agriculture and Rural Affairs, Sericultural Research Institute, Chinese Academy of Agricultural Science, Zhenjiang 212100, Jiangsu, China. Electronic address: mwli@just.edu.cn.

• Abstract

  Autographa californica multiple nucleopolyhedrovirus (AcMNPV) and Bombyx mori nucleopolyhedrovirus (BmNPV) exhibit high genomic similarity but display significant differences in host range. The identification of key genes associated with this difference is of great importance for expanding its application in pest biocontrol. Fifteen genes specific to AcMNPV were identified. Among the constructed recombinant BmNPV, only ORF603 altered the virulence of BmNPV. Interestingly, our findings reveal a biological phenomenon that contradicts the prevailing theoretical framework. Current theory posits a positive correlation between viral virulence and replication efficiency; however, we observed that the recombinant virus vBmNPV-ORF603 exhibited high virulence despite significantly inhibited viral DNA replication. Furthermore, ORF603 exhibits entirely opposing roles during infections by AcMNPV and BmNPV. The underlying mechanism was determined to involve ORF603-induced G2/M phase cell cycle arrest in BmN cells, which consequently suppressed viral DNA replication. Meanwhile, the significant upregulation of genes associated with ribosome biogenesis and autophagy enhanced the transcription and translation efficiency of viral genes, thereby facilitating viral proliferation and intensifying the infection. The results demonstrate that the ORF603 of AcMNPV mediates a trade-off between viral virulence and transmission capacity in BmNPV. This functional dichotomy offers novel insights into the regulation of infection strategies in baculoviruses and highlights potential targets for engineering enhanced viral biopesticides.

  Keywords: Autophagy; Baculoviruses; Cell cycle; Molecular mechanism; ORF603.