Comparative genomic sequence analysis of novel Helicoverpa armigera nucleopolyhedrovirus (NPV) isolated from Kenya and three other previously sequenced Helicoverpa spp. NPVs

Abstract

A newly cloned Helicoverpa armigera nucleopolyhedrovirus (HearNPV) from Kenya, HearNPV-NNg1, has a higher insecticidal activity than HearNPV-G4, which also exhibits lower insecticidal activity than HearNPV-C1. In the search for genes and/or nucleotide sequences that might be involved in the observed virulence differences among Helicoverpa spp. NPVs, the entire genome of NNg1 was sequenced and compared with previously sequenced genomes of G4, C1 and Helicoverpa zea single-nucleocapsid NPV (Hz). The NNg1 genome was 132,425 bp in length, with a total of 143 putative open reading frames (ORFs), and shared high levels of overall amino acid and nucleotide sequence identities with G4, C1 and Hz. Three NNg1 ORFs, ORF5, ORF100 and ORF124, which were shared with C1, were absent in G4 and Hz, while NNg1 and C1 were missing a homologue of G4/Hz ORF5. Another three ORFs, ORF60 (bro-b), ORF119 and ORF120, and one direct repeat sequence (dr) were unique to NNg1. Relative to the overall nucleotide sequence identity, lower sequence identities were observed between NNg1 hrs and the homologous hrs in the other three Helicoverpa spp. NPVs, despite containing the same number of hrs located at essentially the same positions on the genomes. Differences were also observed between NNg1 and each of the other three Helicoverpa spp. NPVs in the diversity of bro genes encoded on the genomes. These results indicate several putative genes and nucleotide sequences that may be responsible for the virulence differences observed among Helicoverpa spp., yet the specific genes and/or nucleotide sequences responsible have not been identified.

Genetic variation and virulence of nucleopolyhedroviruses isolated worldwide from the heliothine pests Helicoverpa armigera, Helicoverpa zea, and Heliothis virescens

“…Fig. 1D contains the lef-8/lef-9/polh phylogenetic sub-tree of HzSNPV and HearSNPV isolates, including sequences from HzSNPV F16 (Chen et al, 2002), HearSNPV-C1 (Zhang et al, 2005), HearSNPV-G4 (Chen et al, 2001), HearNPV-NNg1 (Ogembo et al, 2009), and Busseola fusca NPV (BufuNPV A2-4; Jehle et al, 2006b). Three groups of isolates (HzSNPV Group, India Group, and China Group) are indicated, as is an indication of whether the HzSNPV bro gene orf42 was present (+) or absent (À) in an isolate, or if the isolate consisted of a mixture of both orf42 (+) and orf42 (À) genotypes (M).…”

“…According to these criteria, three strains of Hz/HearSNPV whose genomes have been fully sequenced (HzSNPV-F16, Chen et al, 2002;HearSNPV-C1, Zhang et al, 2005; and HearSNPV-G4, Chen et al, 2001) are part of the same species along with an NPV isolated from the maize stalk borer, Busseola fusca (Jehle et al, 2006b). An additional strain of Hz/HearSNPV, HearNPV-NNg1, also is a member of this species group (Ogembo et al, 2009).…”

Characterization of Helicoverpa Zea Single Nucleopolyhedrovirus Isolated in Brazil During the First Old World Bollworm (Noctuidae: Helicoverpa Armigera) Nationwide Outbreak

“…The viral DNA (1-2 µg) was individually cleaved with the restriction enzymes XhoI, BglII, PstI, or BamHI (Promega) according to manufacturer's instructions. Importantly, HzSNPV is found naturally infecting the genus Helicoverpa during its larval stage (Chen et al 2002;Ogembo et al 2009;Rowley et al 2011). Based on the comparison of both the viral DNA restriction enzyme profiles (FIG.…”

A Novel Binary Mixture of Helicoverpa armigera Single Nucleopolyhedrovirus Genotypic Variants Has Improved Insecticidal Characteristics for Control of Cotton Bollworms

“…H. armigera single NPV (HearSNPV) (genus Alphabaculovirus) has been shown to be an effective agent for the control of H. armigera (26)(27)(28)(29)(30)(31). Several isolates of HearSNPV have been characterized at the molecular and phenotypic levels (32)(33)(34)(35), including some isolates from the Iberian Peninsula (27, 36; M. Arrizubieta, O. Simón, T. Williams, and P. Caballero, submitted for publication). Genotypic diversity within field isolates of HearSNPV has been demonstrated by cloning the genotypic variants in vivo (37), in vitro (34), or by using bacterial artificial chromosome (BAC) technology (38).…”