Electron microscopic autoradiography in the development of herpesvirus of turkey

Summary

Quail fibroblast cultures inoculated with herpesvirus of turkey (Strain FC126) were incubated in the presence of³H-thymidine for various periods of time and examined by electron microscopy and electron microscopic autoradiography. The small nuclear particles did not become labeled with³H-thymidine, but those incorporated into the capsids (cross-shaped capsids) did. It was observed rarely that small enveloped particles (ca. 140–170 nm) in the perinuclear space were unenveloped in passing through the outer nuclear membrane into the cytoplasm. After exposure to³H-thymidine for 1 hour, virus particles in the nuclei became labeled, but most of them in the cytoplasm did not. However, the virus particles in the cytoplasm became labeled after chasing with unlabeled thymidine. The capsids in the cytoplasm were wrapped by electron opaque materials in adjoining what we called “flattened sacks.” Subsequently it was suggested that the capsids acquired the envelope and also peripheral spikes by passing through the membrane of the flattened sacks and thus became large enveloped particles (ca. 190–370 nm). Large enveloped particles in the cytoplasmic inclusions became labeled earlier than those in the extracellular space after chasing.