Immunoelectron microscopic localization of herpes simplex virus glycoprotein gB in the nuclear envelope of infected cells.

Herpesvirus, such as herpes simplex type 1 (HSV-1) acquire their envelope by budding through a modified inner membrane of the nuclear envelope which forms thick and dense patches at the site of budding. This suggests that some of the viral envelope glycoproteins must be transported to the nuclear envelope in order to be incorporated into the virus. In an effort to establish the localization of the HSV-1 glycoprotein gB-1 in the nuclear envelope of HSV-1 infected cells directly, we have studied the distribution of the glycoprotein gB-1 by immunoelectron microscopy using a polyclonal anti gB-1 antibody. A specific accumulation of gB-1 in the nuclear envelope, which was five times more labeled than the plasma membrane was observed. The glycoprotein gB-1 was localized in both the outer and the inner membrane of the nuclear envelope. The labeling over the nuclear envelope was distributed evenly and no preferential concentration of gB-1 around or within the patches where the virus buds was detected. The nucleocapsids were found to be labeled only when they become associated with the nuclear envelope indicating that gB-1 is incorporated into the virus at this site.