SARS-CoV-2 spike-protein D614G mutation increases virion spike density and infectivity

Area of Science:

• Virology
• Molecular Biology
• Infectious Diseases

Background:

• The SARS-CoV-2 virus, responsible for the COVID-19 pandemic, has rapidly evolved.
• Spike (S)-protein mutations, particularly D614G, have become globally dominant.
• Understanding the functional impact of these mutations is crucial for controlling viral spread.

Purpose of the Study:

• To compare the biological properties of the mutated SARS-CoV-2 spike protein (S^G614) with the original (S^D614).
• To elucidate the mechanisms by which the D614G mutation influences viral infectivity and entry.

Main Methods:

• Generation and characterization of pseudoviruses and virus-like particles (VLPs) expressing different S-protein variants.
• Assessment of viral entry efficiency into ACE2-expressing cells.
• Analysis of S1-domain shedding and S-protein incorporation into virions.
• Evaluation of S-protein binding to ACE2 and neutralization sensitivity.

Main Results:

• Pseudoviruses with S^G614 demonstrated significantly more efficient entry into ACE2-expressing cells compared to those with S^D614.
• Increased entry correlated with reduced S1-domain shedding and enhanced S-protein incorporation into the virion.
• The D614G mutation did not alter S-protein binding affinity to ACE2 or the neutralization sensitivity of pseudoviruses.

Conclusions:

• The D614G mutation enhances SARS-CoV-2 infectivity by increasing the assembly of functional S protein into the virion.
• This mechanism contributes to the predominant circulation of D614G variants globally.
• Further research into S-protein dynamics is essential for developing effective antiviral strategies.