SARS-CoV-2 egress from Vero cells: a morphological approach

Area of Science:

• Cell Biology
• Virology
• Microscopy

Background:

• Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remains a global health concern.
• Understanding the SARS-CoV-2 lifecycle, especially viral egress, is crucial for developing effective treatments.

Purpose of the Study:

• To elucidate the morphological characteristics of SARS-CoV-2 egress from host cells.
• To identify the primary route of nascent virion release into the extracellular environment.

Main Methods:

• Transmission and high-resolution scanning electron microscopy were employed.
• Serial electron tomography was utilized to visualize viral pathways.
• Infected and non-infected Vero cells were examined.

Main Results:

• SARS-CoV-2 egress predominantly occurs through individual vesicles.
• Virus accumulation was observed on curved cell surface areas, not from collective release.
• Long membrane projections, previously linked to viral transport, were found in non-infected cells, indicating they are constitutive.

Conclusions:

• SARS-CoV-2 utilizes individual vesicles for egress, challenging previous assumptions of collective release.
• The observed membrane projections are a normal cellular feature in Vero cells, not solely induced by SARS-CoV-2 infection.
• This study provides critical morphological insights into the SARS-CoV-2 replication cycle.