ABSTRACT
The recent outbreaks of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its rapid international spread pose a global health emergency. The trimeric spike (S) glycoprotein interacts with its receptor human ACE2 to mediate viral entry into host-cells. Here we present cryo-EM structures of an uncharacterized tightly closed SARS-CoV-2 S-trimer and the ACE2-bound-S-trimer at 2.7-Å and 3.8-Å-resolution, respectively. The tightly closed S-trimer with inactivated fusion peptide may represent the ground prefusion state. ACE2 binding to the up receptor-binding domain (RBD) within S-trimer triggers continuous swing-motions of ACE2-RBD, resulting in conformational dynamics of S1 subunits. Noteworthy, SARS-CoV-2 S-trimer appears much more sensitive to ACE2-receptor than SARS-CoV S-trimer in terms of receptor-triggered transformation from the closed prefusion state to the fusion-prone open state, potentially contributing to the superior infectivity of SARS-CoV-2. We defined the RBD T470-T478 loop and residue Y505 as viral determinants for specific recognition of SARS-CoV-2 RBD by ACE2, and provided structural basis of the spike D614G-mutation induced enhanced infectivity. Our findings offer a thorough picture on the mechanism of ACE2-induced conformational transitions of S-trimer from ground prefusion state towards postfusion state, thereby providing important information for development of vaccines and therapeutics aimed to block receptor binding.Competing Interest StatementThe authors have declared no competing interest.View Full Text
ABSTRACT
Objective To investigate the attention bias characteristics of first-episode depressive patients.Methods Forty two patients in our hospital from June 2011 to May 2014 with first-episode depressive and 42 healthy people for physical examination were selected.The reaction time and error number were recorded.Results The reaction time in observation group was significantly longer than control group.Difference between negative and neutral words of observation group was showed (P ＜ 0.01).Conclusions First-episode depressive patients have obviously attention bias in negative related stimulation.
ABSTRACT
100 cases of gastritis verrucosa were classified into acute stage and chronic active stage according to the morpnological and histological characteristics.The CP positive rates in the above two stages were 97% and 68.7%,respectively,while that of the erosion area and the surrounding intact mucosa ' were 83.0% and 45.0%,respectively.The amount of CP was directly related to the degree of inflammatory cell infiltration and erosion.So VG was closely related to CP infection.In the chronic active stage,the detection rates of the Ig coated CP in the tissue section,serum IgA,IgG,and gastric juice IgA were all higher than those in the acute stage (P
