Characterization of a novel member of genus Iflavirus in Helicoverpa armigera

He, Yu; Xu, Pengjun; Yang, Xinming; Graham, Robert I.; Wilson, Kenneth; Wu, Kongming

doi:10.1016/j.jip.2017.01.011

Cited by 19 publications

(23 citation statements)

References 54 publications

(62 reference statements)

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“…However, recent studies on an iflavirus of Helicoverpa armigera revealed the presence of up to 10 6 iflavirus genomes/μg of larval feces [47]. This was sufficient to assure the horizontal transmission of the iflavirus to conspecific larvae.…”

Section: Discussionmentioning

confidence: 99%

Co-infection with iflaviruses influences the insecticidal properties of Spodoptera exigua multiple nucleopolyhedrovirus occlusion bodies: Implications for the production and biosecurity of baculovirus insecticides

et al. 2017

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Biological insecticides based on Spodoptera exigua multiple nucleopolyhedrovirus (SeMNPV) can efficiently control S. exigua larvae on field and greenhouse crops in many parts of the world. Spanish wild populations and laboratory colonies of S. exigua are infected by two iflaviruses (SeIV-1 and SeIV-2). Here we evaluated the effect of iflavirus co-infection on the insecticidal characteristics of SeMNPV occlusion bodies (OBs). Overall, iflavirus co-inoculation consistently reduced median lethal concentrations (LC50) for SeMNPV OBs compared to larvae infected with SeMNPV alone. However, the speed of kill of SeMNPV was similar in the presence or absence of the iflaviruses. A reduction of the weight gain (27%) associated with iflavirus infection resulted in a 30% reduction in total OB production per larva. Adult survivors of SeMNPV OB inoculation were examined for covert infection. SeMNPV DNA was found to be present at a high prevalence in all SeIV-1 and SeIV-2 co-infection treatments. Interestingly, co-inoculation of SeMNPV with SeIV-2 alone or in mixtures with SeIV-1 resulted in a significant increase in the SeMNPV load of sublethally infected adults, suggesting a role for SeIV-2 in vertical transmission or reactivation of sublethal SeMNPV infections. In conclusion, iflaviruses are not desirable in insect colonies used for large scale baculovirus production, as they may result in diminished larval growth, reduced OB production and, depending on their host-range, potential risks to non-target Lepidoptera.

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Section: Discussionmentioning

confidence: 99%

Co-infection with iflaviruses influences the insecticidal properties of Spodoptera exigua multiple nucleopolyhedrovirus occlusion bodies: Implications for the production and biosecurity of baculovirus insecticides

et al. 2017

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“…Iflavirus in cotton bollworm (HaIV, around 28%) (Yuan et al, 2017) and Drosophila Nora virus (around ##%) (Habayeb et al, 2009). In addition, the HaNV titre of sodium hypochlorite-treated eggs was significantly lower than for non-treated eggs (t = 2.840, df = 4, P = 0.047; Fig 4), suggesting that the vertical transmission is mainly due to transovum transmission (i.e.…”

Section: Hanv Transmission Strategiesmentioning

confidence: 98%

“…An N-strain (Non-infected) laboratory culture of H. armigera, uninfected with known viruses Helicoverpa armigera densovirus-2 (HaDV2), Helicoverpa armigera iflavirus (HaIV), HaNPV, HaNV and known bacterium Wolbachia, was established as described previously (Xu et al, 2014;Yuan et al, 2017;Zhou et al 1998).…”

Section: Uninfected Colony Construction and Pcr Protocolsmentioning

confidence: 99%

“…Viruses show great diversity in their transmission strategies and efficiencies (Chen et al, 2006;Zhou et al, 2005). For example, HaDV2 could be efficiently vertically transmitted (around 100%) and horizontally transmitted via contaminated food (Xu et al, 2014); whereas the picorna virus Drosophila Nora virus, HaIV and baculovirus pathogen HaNPV can be efficiently horizontally transmitted by ingestion of virus-contaminated food (Fuxa, 2004;Habayeb et al, 2009;Yuan et al, 2017). For HaNV, the N-strain larvae were allowed to develop through to pupation and newly-eclosed adults were tested for the presence of HaNV.…”

Section: Hanv Transmission Strategiesmentioning

confidence: 99%

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Discovery and characterization of a novel picorna-like RNA virus in the cotton bollworm Helicoverpa armigera

Yang

et al. 2019

Journal of Invertebrate Pathology

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We characterize a novel picorna-like virus, named Helicoverpa armigera Nora virus (HaNV), with a genome length of 11,200 nts, the sequence of which was isolated from the lepidopteran host cotton bollworm Helicoverpa armigera, using RNA-Seq. Phylogenetic analysis, using the putative amino acid sequence of the conserved RNA-dependent RNA polymerase (RdRp) domain, indicated that HaNV clustered with Spodoptera exigua Nora virus, Drosophila Nora virus and Nasonia vitripennis virus-3 with a high bootstrap value (100%), which might indicate a new viral family within the order Picornavirales. HaNV was efficiently horizontally transmitted between hosts via contaminated food, and transmission was found to be dose-dependent (up to 100% efficiency with 10 9 viral copy number/µl). HaNV was also found to be transmitted vertically from parent to offspring, mainly through transovum transmission (virus contamination on the surface of the eggs), but having a lower transmission efficiency (around 43%). Infection distribution within the host was also investigated, with HaNV mainly found in only the gut of both adult moths and larvae (>90%). Moreover, our results showed that HaNV appears not to be an overtly pathogenic virus to its host.

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“…Iflaviruses are diverse in their sequence identities and host taxa. For example, the polyprotein sequence of Helicoverpa armigera iflavirus shows a relatively higher similarity (61.0%) with the protein of the Lymantria dispar Iflavirus 1 [15]. However, the two mulberry silkworm infecting iflaviruses, Bombyx mori iflavirus and infectious flacherie virus, show only a relatively lower identity (23%) [16].…”

Section: Introductionmentioning

confidence: 99%

Codon Usage in the Iflaviridae Family Is Not Diverse Though the Family Members Are Isolated from Diverse Host Taxa

Sheng

Xia

2019

Viruses

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All iflavirus members belong to the unique genus, Iflavirus, of the family, Iflaviridae. The host taxa and sequence identities of these viruses are diverse. A codon usage bias, maintained by a balance between selection, mutation, and genetic drift, exists in a wide variety of organisms. We characterized the codon usage patterns of 44 iflavirus genomes that were isolated from the classes, Insecta, Arachnida, Mammalia, and Malacostraca. Iflaviruses lack a strong codon usage bias when they are evaluated using an effective number of codons. The odds ratios of the majority of dinucleotides are within the normal range. However, the dinucleotides at the 1st–2nd codon positions are more biased than those at the 2nd–3rd codon positions. Plots of effective numbers of codons, relative neutrality analysis, and PR2 bias analysis all indicate that selection pressure dominates mutations in shaping codon usage patterns in the family, Iflaviridae. When these viruses were grouped into their host taxa, we found that the indices, including the nucleotide composition, effective number of codons, relative synonymous codon usage, and the influencing factors behind the codon usage patterns, all show that there are non-significant differences between the six host-taxa-groups. Our results disagree with our assumption that diverse viruses should possess diverse codon usage patterns, suggesting that the nucleotide composition and codon usage in the family, Iflaviridae, are not host taxa-specific signatures.

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Characterization of a novel member of genus Iflavirus in Helicoverpa armigera

Cited by 19 publications

References 54 publications

Co-infection with iflaviruses influences the insecticidal properties of Spodoptera exigua multiple nucleopolyhedrovirus occlusion bodies: Implications for the production and biosecurity of baculovirus insecticides

Co-infection with iflaviruses influences the insecticidal properties of Spodoptera exigua multiple nucleopolyhedrovirus occlusion bodies: Implications for the production and biosecurity of baculovirus insecticides

Discovery and characterization of a novel picorna-like RNA virus in the cotton bollworm Helicoverpa armigera

Codon Usage in the Iflaviridae Family Is Not Diverse Though the Family Members Are Isolated from Diverse Host Taxa

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