Cell fusion studies identified multiple cellular factors involved in mouse hepatitis virus entry

Area of Science:

• Virology
• Cell Biology
• Infectious Diseases

Background:

• Murine cell lines resistant to mouse hepatitis virus (MHV) JHM strain infection despite expressing viral receptors.
• Previous studies indicated restriction occurs at the virus entry level.

Purpose of the Study:

• Investigate if JHM resistance in murine cells is due to a defective cellular factor or an inhibitor.
• Determine the specific stage of JHM virus entry that is restricted in resistant cell lines.

Main Methods:

• Polyethylene glycol (PEG)-mediated fusion of JHM-resistant BC10 cells (murine) with COS cells (simian).
• Assessing JHM replication in hybrid BC10-COS cells.
• Evaluating JHM virus binding, penetration, and internalization in BC10 cells.
• Complementary fusion experiments with other murine cell lines.

Main Results:

• JHM replicated in BC10-COS hybrid cells, indicating complementation of a defective cellular factor.
• JHM binding and penetration were normal in BC10 cells, but internalization did not lead to replication.
• Restriction was identified at the viral uncoating stage, which could be complemented by fusion with JHM-permissive murine cells.
• Fusion with COS cells did not overcome resistance in most other murine cell lines, suggesting varied defects.

Conclusions:

• JHM resistance in BC10 cells is due to a defective cellular factor required for viral uncoating, not an inhibitor.
• JHM viral entry requires multiple cellular factors beyond the viral receptor.
• Different murine cell lines may have distinct defects in JHM virus entry functions.