Herpes simplex virus types 1 and 2 in clinical infections: differences observed by electron microscopy.

Microtubule-like structures have been observed ultrastructurally in BHK-21/4 cells infected with herpes simplex virus type 2 (HSV-2) but not in cells infected with herpes simplex virus type 1 (HSV-1). BHK-21/4 cells were infected with two known strains of HSV-2 and one known strain of HSV-1, as well as with vesicular fluid from 50 clinical isolates (47 perioral, two penile, and one from the leg) in an examination of the accuracy of electron microscopy for differentiation between clinical isolates of HSV-1 and HSV-2. Cells infected with the known strains of HSV-2 or with material from the genital or leg lesions demonstrated microtubule-like structures. Cells infected by a known strain of HSV-1 or by material from perioral lesions did not show evidence of microtubule-like structures. Typing by indirect hemagglutination of these same 50 clinical isolates gave identical results.