Polycaryocyte formation mediated by Sindbis virus glycoproteins

Area of Science:

• Virology
• Cell Biology
• Membrane Protein Function

Background:

• Sindbis virus infection can induce cell fusion.
• Viral membrane proteins play a role in mediating this fusion process.

Purpose of the Study:

• To investigate the mechanism of Sindbis virus-mediated cell fusion.
• To identify the specific viral components and modifications required for fusion.

Main Methods:

• Infection of BHK-21 cells with Sindbis virus (wild-type and mutants).
• Treatment with acid pH to induce fusion.
• Analysis of viral glycoprotein synthesis, transport, and modification (proteolytic cleavage, glycosylation).
• Assessment of fusion function under various inhibition conditions (drug, protease).

Main Results:

• Cell fusion occurs after Sindbis virus infection and acid pH treatment when viral proteins are on the cell surface.
• Synthesis and cell surface transport of viral glycoproteins (PE2 and E1) are necessary for fusion.
• Glycosylation of viral membrane proteins is essential for fusion.
• Proteolytic conversion of PE2 to E2 is not required for fusion.
• Viral temperature-sensitive mutations do not impair the fusion ability of the virus.

Conclusions:

• Sindbis virus-mediated cell fusion is dependent on the presence and proper modification (glycosylation) of viral glycoproteins at the cell surface.
• Acid pH is a critical trigger for initiating fusion in infected cells.
• Specific viral proteins and their post-translational modifications are key determinants of cell-cell fusion mediated by enveloped viruses.