Comparison of the complete genome sequence between C1 and G4 isolates of the Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus

The complete nucleotide sequence of Helicoverpa armigera single nucleocapsid nucleopolyhedrovirus isolate C1 (HearSNPV-C1) was determined and analyzed by comparing with the genome of HearSNPV-G4 isolate. C1 and G4 isolates occurred in the same host species and geographic location but showed different virulence. The HearSNPV-C1 genome consisted of 130,759 bp and 137 putative open reading frames larger than 150 nucleotides were identified. The two genomes shared 98.1% nucleotide sequence identity, with a total number of 555 bp substitutions, 1354 bp deletions, and 710 bp insertions in HearSNPV-C1. Comparison of ORFs and homologous repeat (hr) regions of the two genomes showed that there were four highly variable regions hr1, hr4, hr5, and bro-b, all in repeat regions. These results suggest that baculovirus strain heterogeneity may be often caused by SNPs and changes in the hrs and bro genes.