Role of LEF5 Nuclear Localization Signaling in the Production of Helicoverpa armigera Nucleopolyhedrovirus Progeny

Abstract

Late Expression Factor 5 (LEF-5) of Helicoverpa armigera nucleopolyhedrovirus (HaNPV) functions as an initiation factor and plays an important role in the production of infectious viral progeny. Previous study revealed that LEF-5 was localized to the nuclear in infection cells. Bioinformatic analysis identified two putative nuclear localization signals (NLSs), i.e., NLS145-176 and NLS241-271, in the LEF5 amino acid sequence from 145 to 176 and from 241 to 271. However, it was still elusive what were the roles of the two putative NLSs in HaNPV DNA replication and its late expression. In this work, we used GFP as gene reporter to examine the roles of the two LEF5 NLSs in the production of viral progeny. Several HaNPV mutants were constructed in which two NLSs were either truncated or deleted. We found that the deletion of NLS145-176 and NLS241-271 would not prevent the HaNPV LEF-5 from the localization into the nucleus while the HaNPV LEF-5 simultaneously presented in cytoplasm. The lef-5 knockout would not affect the early gene expression and DNA replication. However, the expression of typical late transcripts was dramatically reduced. The mutations in the LEF5 NLS motifs resulted in reduced levels of infectious virus production. (This work was supported by the National Natural Science Foundation of China, Grants No. 31500132).