ISOLATION AND CHEMICAL COMPOSITION OF THE MEMBRANES OF AN INSECT VIRUS AND THEIR RELATION TO THE VIRUS AND POLYHEDRAL BODIES

Abstract

Membranes which surround the Bombyx mori virus particles were separated from the latter by ultracentrifugation and demonstrated in the electron microscope. Both the spherical developmental membranes and the tubular intimate membranes have a rigid structure. They dissolve in a weak alkali and upon drying form monolayers of irregular shape. Repeated washing with water causes disintegration into thread-like structures. The membranes do not dissolve in acids. The membranes consist of about 80% protein, 1.3% lipids, and about 20% unidentified material, but contain no desexyribonucleic acid. The virus particles consist of about 77% protein, 8% desoxyribo-nucleic acid, 0.2% lipids, and about 15% unidentified material. The lipids in the virus prepn. may be contributed from the membranes which still surround the virus particles. Amino acid analyses of polyhedral protein, virus, and membranes showed that each is significantly different from the other. The virus and membranes are more similar to one another than either is to the polyhedral protein. This suggests that the polyhedral protein is not a building stone of the virus particles, but rather a metabolic by-product of the host induced by the virus infection. The chemical complexity provides evidence of the organismal nature of insect viruses which was proposed before on morph. grounds.