Two small virus-specific polypeptides are produced during infection with Sindbis virus

Area of Science:

• Virology
• Molecular Biology
• Cellular Biology

Background:

• Sindbis virus is an alphavirus that infects cells and produces specific viral proteins.
• Understanding viral protein processing is crucial for comprehending viral replication and assembly.

Purpose of the Study:

• To identify and characterize novel virus-specific polypeptides produced during Sindbis virus infection.
• To elucidate the origin and potential function of these newly identified viral polypeptides.

Main Methods:

• Infection of cells with Sindbis virus.
• Characterization of viral polypeptides using molecular weight determination and glycoprotein analysis.
• Analysis of polypeptide location (medium, virion, intracellular).

Main Results:

• Two virus-specific polypeptides were identified: a 9,800-dalton glycoprotein and a 4,200-dalton polypeptide.
• The 9,800-dalton glycoprotein is derived from the PE2 precursor during proteolytic conversion to E2 and is secreted into the medium, analogous to Semliki Forest virus E3 but not incorporated into the virion.
• The 4,200-dalton polypeptide is not a glycoprotein, not incorporated into the virion, and not released into the medium; its gene is located within the 26S mRNA encoding viral glycoproteins.

Conclusions:

• Sindbis virus produces a secreted glycoprotein analogous to E3 but distinct in virion incorporation.
• The 4,200-dalton polypeptide may function as a signal peptide in viral membrane glycoprotein synthesis.