ABSTRACT

The iridescent viruses have many unique features with regard to their genomic structure, molecular biology, and ecological interactions. The Iridoviridae are large, icosahedral, nonoccluded dsDNA viruses that infect both vertebrates and invertebrates and are the largest group of nonoccluded insect viruses. The major common feature of all iridescent viruses is the iridescent, or opalescent, blue-green coloration of heavily infected larvae or purified pellets of the virus. This coloration is caused by closely packed paracrystalline arrays of virus particles within heavily infected tissues causing Bragg reflections of light with the color of the iridescence being determined by the interparticle spacing. Protein complexes extend through the single unit membrane, attaching the core polypeptides to the capsid polypeptides; this may be an explanation for the high stability of these viruses. Iridescent viruses have not been seriously considered as candidates for development as biological control agents.