What specific molecular mechanisms contribute to the increased transmissibility of flirt variants? 
- Mutations in the Spike Protein: The FLiRT variants (KP.2, KP.3, and KP.1.1) have specific mutations in the spike protein, including changes at amino acid positions 456 (F → L) and 346 (R → T). These mutations may enhance the virus’s ability to bind to and enter host cells, increasing its transmissibility.
- Evolutionary Optimization: The FLiRT variants have undergone evolutionary optimization, allowing them to adapt to the human host and exploit existing immunity. This optimization may have favored increased transmissibility over other traits, such as severity or virulence.
- Neutralization Escape: The FLiRT variants have developed mechanisms to evade neutralizing antibodies, which are proteins produced by the immune system to recognize and bind to viral proteins. By evading these antibodies, the FLiRT variants can infect cells more efficiently, contributing to their increased transmissibility.
- Enhanced Receptor Binding: The FLiRT variants may have improved binding to the human ACE2 receptor, which is the primary receptor used by SARS-CoV-2 for cell entry. Stronger binding to the receptor could enhance the virus’s ability to infect cells and spread between individuals.
- Increased Viral Load: The FLiRT variants may produce higher viral loads, leading to increased shedding of infectious particles and a greater likelihood of transmission.
Key Takeaways:
- The FLiRT variants’ increased transmissibility is likely attributed to a combination of molecular mechanisms, including mutations in the spike protein, evolutionary optimization, neutralization escape, enhanced receptor binding, and increased viral load.
- These mechanisms may have evolved to optimize the virus’s ability to spread efficiently within human populations, potentially leading to a higher transmission rate compared to previous SARS-CoV-2 strains.
