Cross-reaction of sera from COVID-19 patients with SARS-CoV assays.

Wei Yee Wan; Siew Hoon Lim; Eng Hong Seng

The similarities between these two viruses were described comprehensively in a recent published 28 article by Xu et al. 2 For structural proteins, including the nucleocapsid (N), matrix (M), and 29 envelope (E), high within-group conservation was maintained, with more modest similarity seen 30 across the entire CoV family. In contrast, the accessory proteins that distinguish CoV infections 31 from each other with high variability across the family, allow viruses to adopt to current and 32 novel hosts. 3 In a study which described the difference in amino acid substitutions of different 33 proteins for SARS-CoV-2 compared to SARS-CoV, it was found that there were no substitutions 34 that occurred in nonstructural protein 7 (nsp7), nsp13, envelop, matrix and accessory proteins p6 35 and 8b. 4 The N protein for SARS-CoV-2 has ~90% similar amino acid identity to the SAR-CoV 36 N protein and hence the SARS-CoV-2 antibodies against the N protein would likely recognize 37 and bind the SARS-CoV N protein as well. 5 Furthermore, a study by Zhou et al, showed that the 38 . CC-BY-NC-ND 4.0 International license It is made available under a author/funder, who has granted medRxiv a license to display the preprint in perpetuity.