Possible link between higher transmissibility of B.1.617 and B.1.1.7 variants of SARS-CoV-2 and increased structural stability of its spike protein and hACE2 affinity

The Severe Acute syndrome corona Virus 2 (SARS-CoV-2) outbreak in December 2019 has caused a global pandemic. The rapid mutation rate in the virus has caused alarming situations worldwide and is being attributed to the false negativity in RT-PCR tests, which also might lead to inefficacy of the available drugs. It has also increased the chances of reinfection and immune escape. We have performed Molecular Dynamic simulations of three different Spike-ACE2 complexes, namely Wildtype (WT), B.1.1.7 variant (N501Y Spike mutant) and B.1.617 variant (L452R, E484Q Spike mutant) and compared their dynamics, binding energy and molecular interactions. Our result shows that mutation has caused the increase in the binding energy between the Spike and hACE2. In the case of B.1.617 variant, the mutations at L452R and E484Q increased the stability and intra-chain interactions in the Spike protein, which may change the interaction ability of human antibodies to this Spike variant. Further, we found that the B.1.1.7 variant had increased hydrogen interaction with LYS353 of hACE2 and more binding affinity in comparison to WT. The current study provides the biophysical basis for understanding the molecular mechanism and rationale behind the increase in the transmissivity and infectivity of the mutants compared to wild-type SARS-CoV-2.