ABSTRACT
Viruslike particles (VLPs) are nonreplicating, virus capsids made using recombinant DNA technology that mimic the structure of native virions [1,2]. They generally are formed when viral structural protein(s) are synthesized in eukaryotic or prokaryotic expression systems and the proteins self-assemble to form particles. VLPs are not infectious because they lack the viral genome. VLPs can be simple and formed by expression of one viral capsid protein (papillomavirus, parvovirus, calicivirus, hepatitis B core protein) or by coexpression of multiple proteins that form more complex capsid structures (orbivirus, Ebola virus, herpesvirus, and rotavirus). VLPs can be produced for both nonenveloped and enveloped RNA and DNA viruses. VLPs mimic the immunogenicity of native virions because they display authentic or near-authentic conformational epitopes. VLPs are being investigated in many viral systems as subunit vaccines and as vectors to carry other proteins, peptides, or nucleic acids for gene transfer, gene therapy, or DNA vaccines (Table 1). VLPs provide vaccine approaches in systems where native virions cannot be readily isolated or produced (e.g., papillomavirus, Ebola virus, or Norwalk virus) and traditional vaccine approaches are not possible [3-5]. VLPs are also useful reagents in these same systems to produce diagnostic reagents or to evaluate immune responses in vaccine trials [5-9].
