Before revision:  The proposed lattice path method is implemented to characterize the topological features of the protein structures of corona viruses. This demonstrates new insights to building a coherent statistical inference procedure in persistent homology .
After revision:  The proposed lattice path method is implemented to characterize the topological features of the protein structures of COVID-19 viruse. We demonstrate that there are topological changes during the conformation change of spike proteins that are needed to initiate the infection of host cells .