Ultrasensitive detection of SARS-CoV-2 S protein with aptamers biosensor based on surface-enhanced Raman scattering.

A rapid and accurate diagnostic modality is essential to prevent the spread of SARS-CoV-2. In this study, we proposed a SARS-CoV-2 detection sensor based on surface-enhanced Raman scattering (SERS) to achieve rapid and ultrasensitive detection. The sensor utilized spike protein deoxyribonucleic acid aptamers with strong affinity as the recognition entity to achieve high specificity. The spherical cocktail aptamers-gold nanoparticles (SCAP) SERS substrate was used as the base and Au nanoparticles modified with the Raman reporter molecule that resonates with the excitation light and spike protein aptamers were used as the SERS nanoprobe. The SCAP substrate and SERS nanoprobes were used to target and capture the SARS-CoV-2 S protein to form a sandwich structure on the Au film substrate, which can generate ultra-strong "hot spots" to achieve ultrasensitive detection. Analysis of SARS-CoV-2 S protein was performed by monitoring changes in SERS peak intensity on a SCAP SERS substrate-based detection platform. This assay detects S protein with a LOD of less than 0.7 fg mL-1 and pseudovirus as low as 0.8 TU mL-1 in about 12 min. The results of the simulated oropharyngeal swab system in this study indicated the possibility of it being used for clinical detection, providing a potential option for rapid and accurate diagnosis and more effective control of SARS-CoV-2 transmission.

Aerosolized Ad5-nCoV booster vaccination elicited potent immune response against the SARS-CoV-2 Omicron variant after inactivated COVID-19 vaccine priming (preprint)

The SARS-CoV-2 Omicron variant has become the dominant SARS-CoV-2 variant around the world and exhibits immune escape to current COVID-19 vaccines to some extent due to its numerous spike mutations. Here, we evaluated the immune responses to booster vaccination with intramuscular adenovirus-vectored vaccine (Ad5-nCoV), aerosolized Ad5-nCoV, a recombinant protein subunit vaccine (ZF2001) or homologous inactivated vaccine (CoronaVac) in those who received two doses of inactivated COVID-19 vaccines 6 months prior. We found that the Ad5-nCoV booster induced potent neutralizing activity against the wild-type virus and Omicron variant, while aerosolized Ad5-nCoV generated the greatest neutralizing antibody responses against the Omicron variant at day 28 after booster vaccination, at 14.1-fold that of CoronaVac, 5.6-fold that of ZF2001 and 2.0-fold that of intramuscular Ad5-nCoV. Similarly, the aerosolized Ad5-nCoV booster produced the greatest IFNgamma T-cell response at day 14 after booster vaccination. The IFNgamma T-cell response to aerosolized Ad5-nCoV was 12.8-fold for CoronaVac, 16.5-fold for ZF2001, and 5.0-fold for intramuscular Ad5-nCoV. Aerosolized Ad5-nCoV booster also produced the greatest spike-specific B cell response. Our findings suggest that inactivated vaccine recipients should consider adenovirus-vectored vaccine boosters in China and that aerosolized Ad5-nCoV may provide a more efficient alternative in response to the spread of the Omicron variant.

The corticosteroid treatment and response of patients with COVID-19 in Hubei, China: a retrospective, cohort study (preprint)

Background Since December 2019, COVID-19 has emerged in Wuhan, China and spread globally. As of now, there is still no explicit therapeutic regimen and the use of corticosteroid is also controversial. We aimed to explore the effectiveness of corticosteroid and provide evidence for the rational use of corticosteroid in different patients with COVID-19.Methods In this multi-centered, retrospective study, we extracted the clinical data of 649 cases with COVID-19 with definite outcome (discharged or dead) from 14 hospitals in Hubei province, and evaluated the clinical characteristics, treatment regimens, and their association with outcomes.Results Ninety-five of 649 patients had died. Older male patients with comorbidities had an increased risk of death and more obvious abnormalities in clinical indicators. Corticosteroid, γ-globulin treatment and invasive ventilation were more frequently used in non-survivors. Survivors with corticosteroid treatment had a prolonged hospitalization. The median time duration for temperature restore for non-survivors after corticosteroid treatment was longer than that of both survivors. The lymphocyte count on admission was lower in the patients treated with corticosteroids compared to those without corticosteroid treatment. Lymphocyte count recovered significantly after corticosteroid treatment in survivors, but not in non-survivors.Conclusions The responses to corticosteroid treatment were different in COVID-19 patients with different outcomes. The surviving patients with relatively lower lymphocyte count were more likely to be given corticosteroids. For non-survivors, the lymphocyte count was too low and the effect of corticosteroids was poor. Survivors under corticosteroid treatment had a prolonged hospitalization, but had a recovery of lymphocytes. The recovery of lymphocyte count and temperature after corticosteroid treatment may be used as predictors of prognosis of patients with COVID-19.