Electron microscopic studies on the replication of ibaraki virus.

Abstract

Ibaraki virus is an agent of epizootic cattle disease resembling bluetongue. The virus was purified from infected BHK-21 cells and bovine kidney cells. The particle negatively stained was icosahedral and had a diameter of 45–50 μ. By electron microscopy, the virus was found in the cytoplasm of cells, assembling in lysosomal or matrix-like dense bodies. In early stages of infection, 2 to 7 hr, virus particles were located in vesicles, simulating a viropexis, whereas at 24 to 30 hr, after infection, a large number of cores of progeny virus were scattered in matrix-like bodies or packed and crystallized in lysosomal bodies bounded by a membrane. Sometimes peculiar tubular structures were found near the matrix-like bodies. The relationship between these structures and virus replication was not clear. The morphological features of the particles and virus development in cells resembled those of viruses of bluetongue, African horse-sickness, Colorado tick fever and reo.