Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus ORF51 is a ChaB homologous gene involved in budded virus production and DNA replication
The baculovirus ChaB proteins are conserved in all completely sequenced Lepidopteran NPVs and are annotated as putative DNA binding proteins. Here we investigated Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearNPV) ORF51 ( ha51), one of the ChaB homologues in HearNPV. 5′-RACE rev...
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Veröffentlicht in: | Virus research 2011, Vol.155 (1), p.203-212 |
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Zusammenfassung: | The baculovirus ChaB proteins are conserved in all completely sequenced Lepidopteran NPVs and are annotated as putative DNA binding proteins. Here we investigated
Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus (HearNPV) ORF51 (
ha51), one of the ChaB homologues in HearNPV. 5′-RACE revealed that
Ha51 is transcribed from a conventional early promoter transcriptional initiator motif (CATT) located at 159nt upstream of ATG. RT-PCR confirmed that
ha51 is an early transcribed gene. To study the function of
Ha51 in the life cycle of HearNPV,
Ha51 knockout and repair bacmids were generated by homologous recombination in
Escherichia coli. Growth curve and DNA replication analyses showed that the levels of budded virus (BV) production and viral DNA accumulation were significantly higher in cells infected with
Ha51 null virus than those infected with wild-type bacmid derived virus. Electron microscopy revealed that polyhedra formation was not affected by the deletion of
Ha51. Bioassay demonstrated that the
Ha51-deleted virus had similar oral infectivity as the wild-type and rescued virus. Western blot analyses suggested that HA51 is a component of the nucleocapsid of BV and occlusion-derived virus as well as the envelope of BV. Immunofluorescence microscopy showed that HA51 protein is mainly localized in the cytoplasm of infected cells. Taken together, our results indicate that, unlike previously characterized baculovirual ChaB genes,
Ha51 is involved in viral DNA replication and BV production and is transcribed in the early stage of infection. |
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ISSN: | 0168-1702 1872-7492 |
DOI: | 10.1016/j.virusres.2010.10.006 |