Herpes simplex virus 1 envelopment follows two diverse pathways

Area of Science:

• Virology
• Cell Biology
• Microscopy

Background:

• Herpesvirus envelopment traditionally follows a complex, multi-step pathway.
• This pathway includes inner nuclear membrane envelopment, de-envelopment at the outer nuclear membrane, and re-envelopment at the trans-Golgi network.
• Previous hypotheses suggested de-envelopment via fusion with the outer nuclear membrane.

Purpose of the Study:

• To elucidate the diverse pathways of herpes simplex virus 1 (HSV-1) envelopment.
• To investigate the mechanism of virion transport from the perinuclear space to the rough endoplasmic reticulum (RER).
• To characterize the morphological events during cytoplasmic envelopment.

Main Methods:

• High-resolution microscopy was employed to visualize HSV-1 envelopment.
• Detailed ultrastructural analysis of virion pathways within cellular compartments.

Main Results:

• HSV-1 envelopment proceeds via two distinct pathways: nuclear and cytoplasmic.
• Nuclear envelopment involves budding at the inner nuclear membrane, acquisition of a dense envelope, and transport via RER to Golgi cisternae.
• Cytoplasmic envelopment occurs through direct nuclear pore exit, followed by budding at various cellular membranes including the outer nuclear membrane, RER, Golgi, and vacuoles.

Conclusions:

• The study reveals a more complex and diverse mechanism for HSV-1 envelopment than previously understood.
• Nuclear envelopment facilitates intraluminal transport of virions through the RER and Golgi.
• Cytoplasmic envelopment offers alternative routes for virion maturation and release.