Structural proteins of Herpesvirus saimiri

Area of Science:

• Virology
• Molecular Biology
• Biochemistry

Background:

• Herpesvirus saimiri (H. saimiri) is a widely studied oncogenic herpesvirus.
• Understanding the structural components of H. saimiri virions is crucial for comprehending its biology and pathogenesis.

Purpose of the Study:

• To characterize the polypeptide composition of purified Herpesvirus saimiri particles.
• To identify and differentiate viral proteins, including glycoproteins, phosphoproteins, and other polypeptides.
• To compare the protein architecture across different H. saimiri strains and assess its utility as a taxonomic criterion.

Main Methods:

• Purification of Herpesvirus saimiri particles from infected owl monkey kidney cell cultures.
• Analysis of virion polypeptides using polyacrylamide gel electrophoresis (PAGE).
• Identification of proteins via Coomassie blue staining and [35S]methionine labeling followed by autoradiography.
• Precipitation of viral proteins using immune sera to confirm virion association.
• Analysis of protein profiles from different H. saimiri strains.

Main Results:

• A total of 21 predominant polypeptides were identified in H. saimiri virions, ranging from 12,000 to 160,000 daltons.
• Four glycoproteins (gp 155/160, gp 128, gp 84/90, gp 55) and three non-glycosylated polypeptides (p71, p35, p28) were localized to the envelope or matrix.
• The nucleocapsid fraction contained at least four phosphoproteins (pp132, pp118, pp55, pp13) and ten unmodified polypeptides.
• Most viral proteins, including all glycoproteins, showed conserved migration patterns across different H. saimiri strains.
• Strain-specific size variations were observed in three of the four phosphoproteins.
• Overall protein architecture similarity contrasts with biological variability, such as oncogenic potential.

Conclusions:

• The study provides a detailed characterization of the Herpesvirus saimiri virion proteome.
• Protein composition is largely conserved among H. saimiri strains, limiting its use for taxonomic distinction.
• DNA sequence divergence is a more reliable criterion for differentiating H. saimiri strains than virion protein analysis.