Structure and transcription of the Helicoverpa armigera densovirus (HaDV2) genome and its expression strategy in LD652 cells

Abstract

BackgroundDensoviruses (DVs) are highly pathogenic to their hosts. However, we previously reported a mutualistic DV (HaDV2). Very little was known about the characteristics of this virus, so herein we undertook a series of experiments to explore the molecular biology of HaDV2 further.ResultsPhylogenetic analysis showed that HaDV2 was similar to members of the genus Iteradensovirus. However, compared to current members of the genus Iteradensovirus, the sequence identity of HaDV2 is less than 44% at the nucleotide-level, and lower than 36, 28 and 19% at the amino-acid-level of VP, NS1 and NS2 proteins, respectively. Moreover, NS1 and NS2 proteins from HaDV2 were smaller than those from other iteradensoviruses due to their shorter N-terminal sequences. Two transcripts of about 2.2 kb coding for the NS proteins and the VP proteins were identified by Northern Blot and RACE analysis. Using specific anti-NS1 and anti-NS2 antibodies, Western Blot analysis revealed a 78 kDa and a 48 kDa protein, respectively. Finally, the localization of both NS1 and NS2 proteins within the cell nucleus was determined by using Green Fluorescent Protein (GFP) labelling.ConclusionThe genome organization, terminal hairpin structure, transcription and expression strategies as well as the mutualistic relationship with its host, suggested that HaDV2 was a novel member of the genus Iteradensovirus within the subfamily Densovirinae.Electronic supplementary materialThe online version of this article (doi:10.1186/s12985-017-0691-y) contains supplementary material, which is available to authorized users.

Gypsy moth genome provides insights into flight capability and virus–host interactions

“…Initial testing of potential bioinsecticides has greatly benefited from the development of gypsy moth cell lines, such as the ovarian tissue-derived LD652 cell line. Since the creation of the LD652 cell line 40 y ago (12), these cells have been used to investigate the life cycle of diverse DNA viruses, including baculoviruses (12), poxviruses (13)(14)(15)(16)(17), and densoviruses (18). More recently, we (19,20) and others (21) have reported RNA virus model systems in LD652 and LD652Y cells, the latter of which appears to be a derivative of LD652 cells that are persistently infected with a newly discovered iflavirus (21).…”

Rapid spread of a densovirus in a major crop pest following wide-scale adoption of Bt-cotton in China

“…Recently, we showed in laboratory trials that infection with a densovirus, Helicoverpa armigera densovirus-1 (HaDV2, named as HaDNV-1 previously, GenBank accession number: NC_015718), was associated with significantly enhanced tolerance of cotton bollworm, H. armigera , to a baculovirus ( H. armigera nucleopolyhedrovirus, HaNPV) ( Xu et al, 2014 ), and there was some suggestion that the densovirus also increased tolerance to Cry1Ac toxin in a Bt-susceptible strain of H. armigera ( Xu et al, 2014 ; Xu et al, 2017a ; Xu et al, 2017b ). HaDV2 was found to be widespread in wild populations of H. armigera adults (>67% prevalence between 2008 and 2012) ( Xu et al, 2014 ).…”

Rapid spread of a symbiotic virus in a major crop pest following wide-scale adoption of Bt-cotton in China

“…Recently, we showed in laboratory trials that infection with a densovirus, Helicoverpa armigera densovirus-1 (HaDNV-1 / HaDV2) was associated with significantly enhanced resistance of cotton bollworm, H. armigera , to a baculovirus ( H. armigera nucleopolyhedrovirus, HaNPV) ( Xu et al, 2014 ), and there was some suggestion that the densovirus also increased resistance to Cry1Ac toxin in a Bt-susceptible strain of H. armigera ( Xu et al, 2014, 2017a and 2017b ). HaDV2 was found to be widespread in wild populations of H. armigera adults (>67% prevalence between 2008 and 2012) ( Xu et al, 2014 ).…”