ABSTRACT
The receptor-binding domain (RBD) variants of SARS-CoV-2 could impair antibody-mediated neutralization of the virus by host immunity; thus, prospective surveillance for such antibody escape mutants is urgently needed. Here, we comprehensively profiled four antigenic sites of the RBD and mapped the binding hot spots for a panel of RBD-specific monoclonal antibodies isolated from COVID-19 convalescents, especially dominant VH3-53/3–66 antibodies, which are valuable indicators of antigenic changes in the RBD. We further demonstrated that several natural mutations, namely, K417N, F486L, N450K, L452R, E484K, F490S and R346S, significantly decreased the neutralizing activity of multiple human monoclonal antibodies and of human convalescent plasma obtained in the early stage of the COVID-19 pandemic. Of note, among the natural escape mutations, L452R enhanced ACE2 binding affinity, indicating that it potentially increased virulence. Overall, the in-depth maps may have far-reaching value for surveillance of SARS-CoV-2 immune escape variants and guidance of vaccine design.
Subject(s)
COVID-19ABSTRACT
Objective To analyze the clinical features of patients with coronavirus disease 2019 (COVID-19) in Shanghai and to investigate the risk factors for disease progression to severe cases. Methods The clinical data of 292 adult patients with COVID-19 hospitalized in Shanghai Public Health Clinical Center from January 20, 2020 to February 10, 2020 were retrospectively analyzed, including 21 severe patients and 271 mild patients. The demographic characteristics, epidemiological history, history of underlying diseases and laboratory examinations were compared between the two groups. Measurement data were compared using t test or Mann-Whitney U test. The count data were compared using hi-square test. The binary logistic regression equation was used to analyze the risk factors for the progression of patients to severe cases. Results Among the 292 patients, 21 were severe cases with the rate of 7.2% (21/292). One patient died, and the mortality rate was 4.8% in severe patients. The severe patients aged (65.0±15.7) years old, 19 (90.5%) were male, 11 (52.4%) had underlying diseases, 7 (33.3%) had close relatives diagnosed with COVID-19. The mild patients aged (48.7±15.7) years old, 135 (49.8%) were male, 74 (27.3%) had underlying diseases, 36 (13.3%) had close relatives diagnosed with COVID-19. The differences between two groups were all significant statistically ( t =-4.730, χ 2 =12.930, 5.938 and 4.744, respectively, all P <0.05). Compared with the mild patients, the levels of absolute numbers of neutrophils, alanine aminotransferase, aspartate aminotransferase, lactate dehydrogenase, creatinine, serum cystatin C, C reactive protein (CRP), procalcitonin , D -dimer, pro-B-type natriuretic peptide (proBNP), serum myoglobin, creatine kinase (CK), creatine kinase isoenzyme (CK-MB), serum troponin I (cTnI) in severe patients were all significantly higher ( U =2 091.5, 1 928.0, 1 215.5, 729.0, 1 580.5, 1 375.5, 917.5, 789.5, 1 209.0, 1 434.0, 638.0, 964.5, 1 258.0 and 1 747.5, respectively, all P <0.05), while the levels of lymphocyte count, albumin, transferrin, CD3 + T lymphocyte count, CD8 + T lymphocyte count and CD4 + T lymphocyte count in severe patients were all significantly lower ( U =1 263.5, t =4.716, U =1 214.0, 962.0, 1 167.5 and 988.0, respectively, all P <0.05). Further logistic regression analysis showed that the albumin (odds ratio ( OR )=0.806, 95% CI 0.675-0.961), CRP ( OR =1.016, 95% CI 1.000-1.032), serum myoglobin ( OR =1.010, 95% CI 1.004-1.016), CD3 + T lymphocyte count ( OR =0.996, 95% CI 0.991-1.000) and CD8 + T lymphocyte count ( OR =1.006, 95% CI 1.001-1.010) at admission were independent risk factors for the progression of COVID-19 patients to severe illness (all P <0.05). Conclusions Severe cases of patients with COVID-19 in Shanghai are predominantly elderly men with underlying diseases. Albumin, CRP, serum myoglobin, CD3 + T lymphocyte count and CD8 + T lymphocyte count could be used as early warning indicators for severe cases, which deserve more clinical attention.