HearSNPV orf83 encodes a late, nonstructural protein with an active chitin-binding domain

The ORF83 (ha83) of Helicoverpa armigera nucleopolyhedrovirus (HearSNPV) was characterized during the present study. Sequence analysis and chitin-binding assay revealed that Ha83 contained an active chitin-binding domain. Northern blot and Western blot analyses demonstrated that ha83 was expressed as a late gene and encoded a nonstructural protein of HearSNPV. Ha83 gene was transcribed beginning at 12 h post-infection in infected Helicoverpa zea cells (HzAM1). Western blot analysis using a rabbit derived polyclonal antibody showed the product of ha83 in infected cells was a 20 kDa protein, in tune with the theoretical size of 18.8 kDa. The protein was first detected in the cytoplasm of infected HzAM1 cells at 12 h p.i., and was transported later into the nucleus during infection.