ABSTRACT
INTRODUCTION Virus-like particles (VLPs) are nonreplicating virus capsids made using recombinant DNA technology. They are generally formed when viral structural protein(s) are synthesized in eukaryotic or prokaryotic expression systems, and the proteins self-assemble to form particles mimicking the structure of native virions. VLPs are not infectious because they lack the viral genome. They can be formed simply by expression of one viral capsid protein (papillomavirus, parvovirus, calicivirus, hepatitis B core protein, or Qb bacteriophage coat protein) or by coexpression of multiple proteins, which formmore complex capsid structures (orbivirus, Ebola and Marburg virus, herpesvirus, and rotavirus). VLPs can be produced for both nonenveloped and enveloped RNA and DNA viruses. They are being investigated as vaccines for a number of diseases and as vaccine or DNA delivery vectors to carry protein/peptide antigens or nucleic acid. VLPs are especially useful in situations where native virions cannot be readily isolated or produced (e.g., papillomavirus, Ebola virus, or human norovirus), where traditional vaccine approaches are not possible (1-6).
