Plant–derived vaccine protects target animals against a viral disease

The successful expression of animal or human virus epitopes on the surface of plant viruses has recently been demonstrated. These chimeric virus particles (CVPs) could represent a cost-effective and safe alternative to conventional animal cell-based vaccines. We report the insertion of oligonucleotides coding for a short linear epitope from the VP2 capsid protein of mink enteritis virus (MEV) into an infectious cDNA clone of cowpea mosaic virus and the successful expression of the epitope on the surface of CVPs when propagated in the black-eyed bean, Vigna unguiculata. The efficacy of the CVPs was established by the demonstration that one subcutaneous injection of 1 mg of the CVPs in mink conferred protection against clinical disease and virtually abolished shedding of virus after challenge with virulent MEV, demonstrating the potential utility of plant CVPs as the basis for vaccine development. The epitope used occurs in three different virus species—MEV, canine parvovirus, and feline panleukopenia virus—and thus the same vaccine could be used in three economically important viral hosts—mink, dogs, and cats, respectively.