Exploring factors favoring transmission of SARS-CoV-2 Delta sublineage AY.4.2 over the Delta variant

In the present study, researchers isolated an infectious AY.4.2 strain of COVID-19 from the nasopharyngeal swab of a symptomatic individual from the Paris region. Then, they introduced the AY.4.2 signature mutations – T95I, Y145H, and A222V – in an expression plasmid coding the Delta protein to study the function of the AY.4.2 S protein.