Canadian Forest Service Publications
Polyhedrosis and granulosis viruses causing single and double infections in the spruce budworm, choristoneura fumiferana Clemens. 1959. Bird, F.T. Journal of Insect Pathology 1:406-430.
Issued by: Great Lakes Forestry Centre
Catalog ID: 34316
Availability: PDF (request by e-mail)
Spruce budworm larvae are susceptible to a polyhedrosis virus which multiplies in the nuclei of tracheal matrix, fat, hypodermal, and blood cells, and to a less virulent granulosis virus which multiplies in the cytoplasm of the same cells. Prior infection by one virus interferes with infection by the second. In general, it appears that a cell will accept either virus but not both. Adjacent cells are frequently infected with different viruses but usually blocks of cells are infected with the same virus. To produce double infection, an advantage must be given the granulosis virus either in time or infectious units. A cycle of development for polyhedrosis viruses based on an electron microscope study of thin sections of cells in various stages of virus development is proposed.