Intrinsic D614G and P681R/H mutations in SARS-CoV-2 VoCs Alpha, Delta, Omicron and viruses with D614G plus key signature mutations in spike protein alters fusogenicity and infectivity.

"We sincerely thank Prof Pramod Kumar Garg, Executive Director, THSTI for full support and valuable inputs and guidance. We thank Prof. S Pöhlmann, Infection Biology Unit, Göttingen, Germany for providing ACE2-Fc plasmids as a kind gift. We thank Dr. B Graham (VRC/NIAID/NIH) for providing us with the spike construct (SARS-2-CoV S 2P). The following reagent was deposited by the Centers for Disease Control and Prevention and obtained through BEI Resources, NIAID, NIH: SARS Related Coronavirus 2, Isolate USA-WA1/2020, NR-52281,SARS-Related Coronavirus 2, Isolate hCoV-19/USA/PHC658/2021 (Lineage B.1.617.2; Delta Variant), NR-55611, contributed by Dr. Richard Webby and Dr. Anami Patel, SARS Related Coronavirus 2, Isolate Isolate hCoV-19/USA/MD-HP20874/2021 (Lineage B.1.1.529; Omicron Variant), NR-56461, contributed by Andrew S. Pekosz, HEK-HEK293T-hACE2 Cell Line, NR-52511, HEK293T-ACE2.TMPRSS2 (mCherry)-NR-55293. The TMPRSS2 plasmid was a gift from Roger Reeves (Addgene plasmid # 53887). The following reagent was contributed by David Veesler for distribution through BEI Resources, NIAID, NIH: Vector pcDNA3.1(-) Containing the SARS-Related Coronavirus 2, Wuhan-Hu-1 Spike Glycoprotein Receptor Binding Domain (RBD). The authors declare no competing interests. The following reagent was obtained through BEI Resources, NIAID, NIH: Homo sapiens Lung Adenocarcinoma Cells (Clone 2B4) with High Expression of Human Angiotensin-Converting Enzyme 2 [Calu-3 (Clone 2B4)-ACE2], NR-55340. We thank Dr. Deepak Rathore, Flowcytometry core facility, THSTI for helping in the analysis of FACS data. We would like to thank Department of Biotechnology (DBT), Government of India for continous support and encouragement to facilate COVID-19 research."

"Funding This work was supported by Global Immunology and Immune Sequencing for Epidemic Response (GIISER)-South Asia grant, Investment ID INV-030592 from Bill and Melinda Gates Foundation, Seattle, USA."