Herpes simplex virus types 1 and 2 infect the mouse pituitary gland and induce apoptotic cell death

Herpes simplex virus (HSV) infected the anterior lobe of the pituitary gland resulting in cytopathic changes following intravenous (i.v.) inoculation of male mice. Both HSV type 1 (HSV-1) and type 2 (HSV-2) were isolated from pituitary gland following i.v. infection, but not after intraperitoneal inoculation. HSV-infected pituitary cells were microscopically visible beginning at 24 h or 48 h following i.v. inoculation and were localized in the anterior pituitary. In both HSV-1 and -2 infections the pituitary lesions were apoptotic, as determined by light and electron microscopy, TUNEL, and DNA gel electrophoresis. However, the pituitary infection does not appear to be life-threatening since pituitary lesions were also observed following i.v. infection with HSV-1 strain -GC which possesses low virulence. These results suggest that the pituitary gland is one of the target organs of HSV infection.