Properties of Nucleocapsid Species Isolated from an In Vivo Herpesvirus Infection

Abstract

Capsid types present in hepatocyte nuclei of Syrian hamsters infected with the animal strain of equine herpesvirus type 1 (EHV-1H) were studied and characterized. Three capsid species were isolated: L capsids (.rho. [density] = 1.23 g/ml) which are devoid of a core structure and appear to be empty shells, I capsids (.rho. = 1.24 g/ml) which contain an electron-lucent, cross-shaped, immature core and H capsids (.rho. = 1.25 g/ml) which contain an electron-dense, mature core structure. All 3 capsids first appeared at .apprx. 6 h post inoculation and were present in a ratio of .apprx. 10:87:3 (L:I:H) at all times during infection. Analysis of the polypeptide and amino acid compositions of certain species indicated that these capsids are identical to L, I and H capsids isolated from cell cultures infected with the culture tissue strain of EHV-1. These findings support the model that I capsids are a major precursor of mature capsids and play a major role in the maturation of this herpesvirus.