LIVE-CELL FLUORESCENCE MICROSCOPY OF HSV-1 CELLULAR EGRESS BY EXOCYTOSIS

Area of Science:

• Virology
• Cell Biology
• Microscopy

Background:

• Herpes Simplex Virus 1 (HSV-1) establishes lifelong infections globally.
• HSV-1 assembly and egress mechanisms require further molecular and spatiotemporal elucidation.

Approach:

• Engineered a recombinant HSV-1 strain expressing the pH-sensitive reporter gM-pHluorin.
• Utilized advanced fluorescent microscopy to track individual virus particles during intracellular transport and exocytosis.
• Investigated the role of viral proteins (gE, gI, US9) and compared HSV-1 egress with pseudorabies virus in various cell types.

Key Points:

• HSV-1 particles are released individually from epithelial cells, unlike bulk release observed in other viruses.
• Virus particles accumulate at the cell periphery and cell-cell contacts, indicating preferential exocytosis sites.
• These egress sites facilitate cell-cell spread, and the accumulation is independent of specific viral proteins (gE, gI, US9) in non-neuronal cells.

Conclusions:

• Preferential HSV-1 exocytosis and clustering are cell-type dependent, not virus-dependent.
• The microtubule cytoskeleton arrangement influences preferential egress and clustering.
• Virus particles co-accumulate with kinesin motor proteins at cell protrusions, suggesting cytoskeletal involvement in egress.