2020 has shown the residues Leu455, Phe486, Gln493, Ser495, Asn501 of RBD of SARS CoV2, and Met82, Lys31, Glu35, Asp38, and Lys353 of ACE2 as important for the interaction of this virus with the human host doxycycline and sun exposure Robertson DM, Cahir N, Burger HG, Mamers P, McCloud PI, Pettersson K, McGuckin M 1999 Combined inhibin and CA125 assays in the detection of ovarian cancer