Baculovirus structural proteins

Department of Agricultural Chemistry, Oregon State University, Corvallis, Oregon 97331-6502, U.S.A. Introduction. Baculovirus biology. The Baculoviridae are a diverse family of virus pathogens which are infectious for arthropods, particularly insects of the order Lepidoptera. They have also been isolated from the insect orders Hymenoptera, Diptera and Trichoptera, as well as from the crustacean order Decapoda (shrimp) (Couch, 1974). Although baculoviruses infect over 600 species of insects (Martignoni & Iwai, 1986), individual isolates normally show a limited host range and infect only closely related species. Baculoviruses are characterized by large rod-shaped virions containing supercoiled dsDNA genomes ranging in size from 88 to over 160 kbp. A prominent feature is the occlusion of virions in a crystalline protein matrix, and two genera have been distinguished based on the gross structure of the occlusion body. One genus, the nuclear polyhedrosis viruses (NPVs), has polyhedron-shaped occlusion bodies 1 to 15 µm in diameter composed of a protein called polyhedrin which crystallizes around many enveloped nucleocapsids (see Fig. 1 and 2).