Peptide Binder with High-Affinity for the SARS-CoV-2 Spike Receptor-Binding Domain.

Rapid antigen detection tests are urgently needed for the early diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The discovery of a binder with high affinity and selectivity for the biomarkers presented by SARS-CoV-2 is crucial to the development of the rapid antigen detection method. We utilized the surface biopanning to identify a peptide binder R1 from a phage-displayed peptide library consisting of 109 independent phage recombinants. The R1 peptide exhibited high-affinity for specific binding with the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein with a dissociation constant KD of (7.5 ± 1.9) × 10-10 M, which maintained high binding affinity with the RBD derived from Gamma, Lambda, Delta, and Omicron variants. The composition and sequence dependence of binding characteristics in R1-RBD interactions was revealed by the binding affinity fluctuations between RBD and the scrambled sequences or single-site mutants of R1. The R1-functionalized gold nanoparticles possessed concentration-dependent response to RBD and selectivity over bovine serum albumin and human serum albumin. The peptide binder R1 shows the potential to be used for constructing a rapid detection method for the early-stage diagnostics for SARS-CoV-2.

Effect of Virus Inactivation by Heating on Routine Clinical Laboratory Indicators in Serum.

BACKGROUND: Highly infectious viruses such as SARS-CoV-2, MERS-CoV, and Ebola virus represent a threat to clinical laboratory workers. We aimed to investigate how virus inactivation by heating at 60°C for 1 hour affects routine clinical laboratory indicators. METHODS: Each collected serum sample was separated into two aliquots, and various indicators were measured in first aliquot after inactivation by heating at 60°C for 1 hour and in the second after room-temperature incubation for 1 hour. RESULTS: Serological test results for 36 indicators remained mostly unaffected by heat inactivation, with a mean estimated bias of < 10%. By contrast, the results for alanine transaminase, pseudocholinesterase, creatine kinase, lactate dehydrogenase, cardiac troponin I, and myoglobin were affected by heat inactivation, with the mean esti-mated bias here being > 20%, which was further increased in the case of the results for alkaline phosphatase, lipase, and creatine kinase isoenzyme MB. Immunological serological measurements showed good agreement according to Kappa consistency checks after heat inactivation of serum. The results for alanine transaminase, pseudocholinesterase, creatine kinase, lactate dehydrogenase, cardiac troponin I, and myoglobin were significantly correlated (r > 0.95) after heat inactivation, and after correction by using a regression equation, the results for the indicators still retained a clinical reference value. CONCLUSIONS: Inactivation by heating at 60°C for 1 hour exerts no marked effect on numerous routine biochemical and immunological indicators in serum, but the detection values for certain items are significantly decreased. Our method could serve as reference strategy for routine serological diagnostics in patients with suspected or confirmed infection with highly pathogenic viruses.