Human immunodeficiency virus-like particles produced by a vaccinia virus expression vector

Area of Science:

• Virology
• Molecular Biology
• Immunology

Background:

• Retrovirus particles have a core of RNA and gag-pol proteins within a lipid envelope with env proteins.
• Understanding retrovirus assembly is crucial for developing antiviral strategies and vaccines.

Purpose of the Study:

• To investigate the assembly and maturation of human immunodeficiency virus (HIV)-like particles.
• To determine if HIV-like particles can be produced in the absence of infectious RNA or env proteins.

Main Methods:

• A recombinant vaccinia virus was engineered to express the full gag-pol precursor protein of HIV-1.
• Mammalian cells infected with the recombinant virus were analyzed for protein synthesis, processing, and particle formation.
• Electron microscopy was used to visualize retrovirus-like particles budding from cells and in the extracellular medium.
• Reverse transcriptase activity and gag polypeptide processing (p24, p17) were assessed in the produced particles.

Main Results:

• Synthesis and processing of HIV-1 gag proteins occurred in infected mammalian cells.
• Immature and mature HIV-like particles were observed budding from the plasma membrane and extracellularly.
• Functional reverse transcriptase and processed p24 and p17 gag polypeptides were detected in the mature HIV-like particles.
• Particle assembly and maturation proceeded without infectious RNA or env proteins.

Conclusions:

• HIV-like particles can assemble and mature in mammalian cells expressing only gag-pol proteins.
• This process occurs independently of infectious viral RNA and env proteins.
• The production of these noninfectious, virus-like particles offers a safe platform for biochemical studies and potential vaccine development.