Isolation and Characterization of a Herpesvirus from Leukemic Guinea Pigs

A guinea pig herpesvirus (GPHV) has consistently been isolated from leukemic lymphoblasts of strain-2 guinea pigs. GPHV is serologically related to the guinea pig herpes-like virus isolated by Hsiung and Kaplow. The virions of GPHV consist of an icosahedral capsid containing a dense nucleoprotein core enclosed in a double-layered membrane. The average diameters of GPHV virion and capsid were 166 and 101 nm, respectively. Studies on the morphogenesis of GPHV revealed that, as in other herpesvirus infections, only the naked capsids with or without the nucleoprotein core were found in the infected cell nuclei; it was also learned that the virion acquired its envelope by budding from the nuclear membrane of the infected cells. However, GPHV-infected cell nuclei also contained dense fibrous rods, resembling nucleo-protein core outside the capsids, and tubules resembling viral core protein. The capsids were often embedded in dense granular antigen. GPHV deoxyribonucleic acid (DNA) has a density of 1.716 g/ml in cesium chloride compared to herpes simplex virus DNA (rho = 1.728 g/ml) and cellular DNA (rho = 1.700 g/ml).