Isolation and purification of a granulosis virus from infected larvae of the Indian meal moth, Plodia interpunctella

Abstract

A procedure was developed for purification of a granulosis virus inclusion body produced in vivo in the Indian meal moth, Plodia interpunctella (Hübner). Purification was accomplished by differential centrifugation, treatment with sodium deoxycholate, and velocity sedimentation in sucrose gradients. The adequacy of the procedure was confirmed by mixing experiments in which uninfected, radioactively labeled larvae were mixed with infected, unlabeled larvae. After purification, the virus was shown to be free of host tissue, to retain its physical integrity, and to be highly infectious per os. Preparations of purified virus consisted of homogeneous populations of intact inclusion bodies (210 by 380 nm) whose buoyant density was 1.271 g/cm3 when centrifuged to equilibrium in sucrose gradients. Electron microscopy of thin-sectioned virus or of virus sequentially disrupted on electron microscope grids demonstrated three components: protein matrix, envelope, and nucleocapsid.