Recombinant-expressed virus-like particle pseudotypes as an approach to vaccine development

Coinfection of a cell with two different types of enveloped virus can result in the generation of infectious virus particle pseudotypes having the internal proteins of one virus and the envelope proteins of the other virus. Vaccinia virus recombinants expressing either non-infectious virus-like particles of simian immunodeficiency virus (SIV) or the gD2 glycoprotein of herpes simplex virus were used to coinfect cells to determine if virus-like particle pseudotypes would be formed. Sucrose gradient sedimentation analysis and immunoprecipitation with a monoclonal antibody provided independent evidence of virus-like particle pseudotype formation. Preparations of such particles were immunogenic in mice. Recombinant-expressed virus-like particles thus represent a novel vaccine approach to presenting envelope glycoprotein antigens in a non-infectious state that mimics natural infection.