SARS-CoV-2 Mutation Detail Information

Virus Mutation SARS-CoV-2 Mutation E166V


Basic Characteristics of Mutations
Mutation Site E166V
Mutation Site Sentence Here, we investigate the molecular basis of drug resistance conferred by E166A and E166V mutations against nirmatrelvir and the related PF-00835231, individually and in combination with the distal mutation L50F.
Mutation Level Amino acid level
Mutation Type Nonsynonymous substitution
Gene/Protein/Region Mpro
Standardized Encoding Gene ORF1a  
Genotype/Subtype -
Viral Reference -
Functional Impact and Mechanisms
Disease COVID-19    
Immune -
Target Gene -
Clinical and Epidemiological Correlations
Clinical Information -
Treatment nirmatrelvir
Location -
Literature Information
PMID 40183562
Title Molecular mechanisms of drug resistance and compensation in SARS-CoV-2 main protease: the interplay between E166 and L50
Author Zvornicanin SN,Shaqra AM,Flynn J,Carias Martinez H,Jia W,Moquin S,Dovala D,Bolon DN,Kurt Yilmaz N,Schiffer CA
Journal mBio
Journal Info 2025 May 14;16(5):e0406824
Abstract The SARS-CoV-2 main protease (M(pro)) is essential for viral replication and is a primary target for COVID-19 antivirals. Direct-acting antivirals such as nirmatrelvir, the active component of Paxlovid, target the M(pro) active site to block viral polyprotein cleavage and thus replication. However, drug resistance mutations at the active site residue Glu166 (E166) have emerged during in vitro selection studies, raising concerns about the durability of current antiviral strategies. Here, we investigate the molecular basis of drug resistance conferred by E166A and E166V mutations against nirmatrelvir and the related PF-00835231, individually and in combination with the distal mutation L50F. We found that E166 mutations reduce nirmatrelvir potency by up to 3,000-fold while preserving substrate cleavage, with catalytic efficiency reduced by only up to twofold. This loss of catalytic efficiency was compensated for by the addition of L50F in the double-mutant variants. We have determined three cocrystal structures of the E166 variants (E166A, E166V, and E166V/L50F) bound to PF-00835231. Comparison of these structures with wild-type enzyme demonstrated that E166 is crucial for dimerization and for shaping the substrate-binding S1 pocket. Our findings highlight the mutability of E166, a prime site for resistance for inhibitors that leverage direct interactions with this position, and the potential emergence of highly resistant and active variants in combination with the compensatory mutation L50F. These insights support the design of inhibitors that target conserved protease features and avoid E166 side-chain interactions to minimize susceptibility to resistance. IMPORTANCE: Drug resistance remains a great challenge to modern medicine. This study investigates SARS-CoV-2 main protease variants E166A and E166V which confer nirmatrelvir resistance. These variants can retain considerable enzymatic activity through combination with the compensatory mutation L50F. For single- and double-mutant variant enzymes, we assessed catalytic efficiency, measured loss in potency for nirmatrelvir and its analog PF-00835231, and cocrystallized with inhibitors to investigate drug resistance caused by these mutations. Our results contribute toward understanding of molecular mechanisms of resistance and combinations of mutations, which pushes toward resistance-thwarting inhibitor design. These principles also apply broadly to many quickly evolving drug targets in infectious diseases.
Sequence Data -
Mutation Information
Note
Basic Characteristics of Mutations
  • Mutation Site: The specific location in a gene or protein sequence where a change occurs.
  • Mutation Level: The level at which a mutation occurs, including the nucleotide or amino acid level.
  • Mutation Type: The nature of the mutation, such as missense mutation, nonsense mutation, synonymous mutation, etc.
  • Gene/Protein/Region: Refers to the specific region of the virus where the mutation occurs. Including viral genes, viral proteins, or a specific viral genome region. If the article does not specifically indicate the relationship between the mutation and its correspondence, the main
  • Gene/Protein/Region studied in the article is marked.
  • Genotype/Subtype: Refers to the viral genotype or subtype where the mutation occurs. If the article does not specifically indicate the relationship between the mutation and its correspondence, the main Genotype/Subtype studied in the article is marked.
  • Viral Reference: Refers to the standard virus strain used to compare and analyze viral sequences.
Functional Impact and Mechanisms
  • Disease: An abnormal physiological state with specific symptoms and signs caused by viral infection.
  • Immune: The article focuses on the study of mutations and immune.
  • Target Gene: Host genes that viral mutations may affect.
Clinical and Epidemiological Correlations
  • Clinical Information: The study is a clinical or epidemiological study and provides basic information about the population.
  • Treatment: The study mentioned a certain treatment method, such as drug resistance caused by mutations. If the study does not specifically indicate the relationship between mutations and their correspondence treatment, the main treatment studied in the article is marked.
  • Location: The source of the research data.
Literature Information
  • Sequence Data: The study provides the data accession number.