Improving Baculovirus Infectivity by Efficiently Embedding Enhancing Factors into Occlusion Bodies

Area of Science:

• Molecular Biology
• Virology
• Biotechnology

Background:

• Baculoviruses are used as bioinsecticides but suffer from low host infectivity, limiting large-scale applications.
• Previous attempts to improve baculovirus infectivity by packaging enhancing factors into occlusion bodies (OBs) had low efficiency.

Purpose of the Study:

• To develop a novel strategy for efficient embedding of foreign proteins into Autographa californica multiple nucleopolyhedrovirus (AcMNPV) occlusion bodies (OBs).
• To enhance stable foreign protein expression and improve baculovirus infectivity using this novel embedding technique.

Main Methods:

• Constructed a recombinant AcMNPV bacmid using dimidiate polyhedrin fragments (N-terminal 150 aa and C-terminal 95 aa) under p10 and polyhedrin promoters, respectively.
• Fused enhanced green fluorescent protein (eGFP) to the polyhedrin C-terminus for visualization and stable passage.
• Fused truncated enhancin or GP37 (granulovirus proteins) to the polyhedrin C-terminus to assess infectivity enhancement.

Main Results:

• Recombinant AcMNPV formed normal OBs, with eGFP fusion resulting in fluorescent OBs stably passaged in vitro and in vivo.
• AcMNPV recombinants carrying enhancin or GP37 formed normal OBs.
• Bioassays showed a 3- to 5-fold reduction in median lethal concentrations for AcMNPV recombinants with embedded enhancing factors compared to control virus.

Conclusions:

• The novel strategy enables efficient and stable embedding of foreign proteins, including viral enhancing factors, into baculovirus OBs.
• Embedding enhancing factors like enhancin or GP37 significantly improves baculovirus infectivity.
• This technique holds potential for developing efficient protein expression systems and highly effective baculovirus-based insecticides.