Expression of recombinant proteins in plants by using baculovirus vectors

Baculovirus has been widely used for the production of numerous recombinant proteins in insect cells. Baculovirus vectors have several advantages, including proper post-translational modification, biosafety, and multiple large gene expression ability. Most insect cell-produced proteins have been expressed by using the baculovirus expression vector system (BEVS) under the control of strong polyhedrin (Polh) or p10 promoters. There has been no report on the expression of recombinant proteins by baculovirus in plant cells. In this study, we used the baculovirus vector to express recombinant green fluorescent protein (GFP) in plants. To investigate the expression of GFP protein by baculovirus in plants, we cloned the gfp gene under the control of Polh promoter or Cauliflower Mosaic Virus (CaMV) 35S promoter to yield the Polh-GFP and 35S- GFP bacmids carrying the GFP expression cassettes, respectively. The presence of Polh-GFP and 35S-GFP expression cassettes in the bacmids was confirmed by polymerase chain reaction (PCR). Subsequently, both the GFP bacmids and GFP baculovirus vectors generated from the bacmid-transfected Sf9 insect cells were inoculated into Nicotiana benthamiana leaves. Confocal microscopy revealed that the gfp gene expression was high in plant leaves at 48 and 72 h after bacmid and baculovirus inoculation. Reverse transcription-PCR (RT-PCR) and fluorescence microscopy confirmed that the gfp genes under the control of Polh or CaMV35S promoters were highly expressed in plant leaves inoculated with 40 L of baculovirus solution. These results suggested that the baculovirus vector can be used to express recombinant proteins in plants. The baculovirus vector- mediated gene delivery and expression system could be used in plant biotechnology for fast and efficient production of recombinant proteins and for molecular virology studies in plants.