Rubella virus contains one capsid protein and three envelope glycoproteins, E1, E2a, and E2b

Area of Science:

• Virology
• Molecular Biology
• Structural Biology

Background:

• Rubella virus is an important human pathogen.
• Understanding rubella virus protein structure is crucial for developing antiviral strategies.

Purpose of the Study:

• To elucidate the structure and post-translational modifications of rubella virus structural proteins.
• To differentiate the rubella virus structural proteins and their locations within the virion.

Main Methods:

• Metabolic labeling with radioactive isotopes ([35S]methionine, [3H]mannose, [3H]glucosamine).
• External labeling with [3H]borohydride after galactose oxidase treatment.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE).
• Tryptic peptide mapping.
• Immunoprecipitation and tunicamycin treatment.

Main Results:

• Four structural proteins identified: E1 (58 kDa), E2a (47 kDa), E2b (42 kDa), and C (33 kDa).
• E1, E2a, and E2b are external envelope glycoproteins; C is an internal nucleocapsid protein.
• E1 and E2b are efficiently mannosylated, suggesting differential glycosylation between E2a and E2b.
• Tunicamycin treatment confirmed E1 and E2 as glycoproteins with reduced molecular weights.

Conclusions:

• Rubella virus possesses distinct structural proteins with specific cellular localizations.
• Differential glycosylation plays a role in the heterogeneity of rubella virus envelope proteins.
• The findings provide insights into rubella virus assembly and pathogenesis.