Morphological components of herpesvirus. III. Localization of herpes simplex virus type 1 nucleocapsid polypeptides by immune electron microscopy.

Herpes simplex virus type 1 (HSV-1) nucleocapsids were observed in the electron microscope after their reaction with IgG's purified from the sera of rabbits immunized with the individual nucleocapsid polypeptides. The combining sites of NC1, the major capsid protein (mol. wt. 154K), were distributed over the entire capsid surface. This result provides further evidence that NC1 represents the major hexamer constituent. NC2 (mol. wt. 50K) was less widely distributed and appeared to be located at capsid vertices; that antigen may be a constituent of the pentamers or of peripentameric hexamers. One or both of NC3 and NC4 (mol. wt. 40K and 38K) were also located all over the capsid, possibly at positions interior to those of NC1. One or both may represent the intercapsomeric fibrils, hexamer-associated protein or material associated with the pericore. The locations of the other nucleocapsid polypeptides could not be determined.