Intra-host variability of SARS-CoV-2: Patterns, causes and impact on COVID-19

Area of Science:

• Virology
• Genetics
• Epidemiology

Background:

• Intra-host viral variability influences pathogenicity, persistence, drug resistance, and clade emergence.
• Significant data on SARS-CoV-2 intra-host variability has been accumulated, with implications for COVID-19 and the emergence of variants of concern (VOCs).

Purpose of the Study:

• To review and synthesize current knowledge on SARS-CoV-2 intra-host variability.
• To address the implications of this variability in COVID-19 pathogenesis, drug resistance, and the evolution of VOCs and lineage-defining mutations.

Main Methods:

• Review of existing literature and data on SARS-CoV-2 intra-host variability.
• Analysis of polymorphism distribution, mutational signatures, and patterns of emergence/extinction.
• Examination of factors governing viral mutation abundance, frequency, and type (synonymous, nonsynonymous, indels, nonsense).

Main Results:

• Intra-host polymorphisms are distributed across the SARS-CoV-2 genome with specific mutational signatures.
• Viral mutations exhibit dynamic patterns of emergence and extinction during infection.
• Replication and mutation can occur in different anatomical compartments, suggesting a broader context beyond respiratory samples.

Conclusions:

• SARS-CoV-2 intra-host variability plays a critical role in viral evolution and COVID-19.
• Understanding these variations is key to predicting and managing future viral threats and therapeutic strategies.
• The compartmentalized replication of SARS-CoV-2 may lead to a more complex evolutionary landscape than currently understood from respiratory samples.