Porcine coronavirus SADS-CoV has been identified from suckling piglets with severe diarrhea in southern China in 2017. The SADS-CoV genome shares ~95% identity to that of bat α-coronavirus HKU2, suggesting that SADS-CoV may have emerged from a natural reservoir in bats. Here we report the cryo-EM structures of HKU2 and SADS-CoV spike (S) glycoprotein trimers at 2.38 Å and 2.83 Å resolution, respectively. We systematically compare the domains of HKU2 spike with those of α-, β-, γ-, and δ-coronavirus spikes, showing that the S1 subunit N- and C-terminal domains of HKU2/SADS-CoV are ancestral domains in the evolution of coronavirus spike proteins. The connecting region after the fusion peptide in the S2 subunit of HKU2/SADS-CoV adopts a unique conformation. These results structurally demonstrate a close evolutionary relationship between HKU2/SADS-CoV and β-coronavirus spikes and provide insights into the evolution and cross-species transmission of coronaviruses. Several coronaviruses infecting humans and animals have emerged in recent years. Here, the authors provide structures of the spike proteins of the porcine coronavirus SADS-CoV and closely related bat coronavirus HKU2, providing insights into evolution of coronavirus spike proteins.
【저자키워드】 viral evolution, Cryoelectron microscopy, Virus structures, 【초록키워드】 Structure, Evolution, Coronaviruses, coronavirus, spike, Human, Genome, diarrhea, China, glycoprotein, fusion peptide, bats, S2 subunit, C-terminal domain, Cross-species transmission, identity, spikes, domain, trimer, coronavirus spike proteins, β-coronavirus, infecting, cryo-EM structure, the S1 subunit, unique, the spike protein, α-coronavirus, 【제목키워드】 Structure, Evolution, coronavirus, spike glycoprotein,