Characterization of Heliothis Virescens Ascovirus 3h orf21 that Encodes a Virion Protein

Abstract

Homologues of Heliothis virescens ascovirus 3h (HvAV-3h) orf21 are found in 9 completely sequenced members of the ascoviruses, but so far their functions are unknown. Here, orf21 (3h-21) was cloned in-frame into a pET-28a bacterial expression vector. The fusion protein produced by this construct was used for the preparation of a polyclonal antiserum. RT-PCR analysis showed a single transcript of 3h-21 of approximately 0.7kb was transcribed beginning at 24h post-infection in infected Helicoverpa armigera larvae. Western blot analysis of extracts from HvAv-3h-infected Helicoverpa armigera larvae detected a 25.6 kDa protein late in infection. This antiserum also reacted with a 25.6 kDa protein in purified virions of HvAv-3h. The protein was not extensively modified post-translation. Immunoelectron microscopy confirmed that the 3H-21 is associated with the structure of HvAV-3h virions.