A novel S2-derived peptide-based ELISA for broad detection of antibody against infectious bronchitis virus.

Avian infectious bronchitis (IB) is a highly contagious disease caused by infectious bronchitis virus (IBV). Vaccination is an effective approach for controlling IBV. Therefore, reliable immune monitoring for IB is critical for poultry. In this study, a novel peptide derived from S2 protein was used to develop an enzyme-linked immunosorbent assay (ELISA) for the detection of broadly cross-reactive antibodies against IBV. The peptide-based ELISA (pELISA) showed good specificity and sensitivity in detecting IBV antibodies against different serotypes. A semilogarithmic regression method for determining IBV antibody titers was also established. Antibody titers detected by pELISA and calculated with this equation were statistically similar to those evaluated by indirect fluorescence assay (IFA). Moreover, the comparison analysis showed a 96.07% compatibility between the pELISA and IDEXX ELISA. All these data demonstrate that the pELISA generated here can be as a rapid and reliable serological surveillance tool for monitoring IBV infection or vaccination.

A novel mAb broadly neutralizes SARS-CoV-2 VOCs in vitro and in vivo, including the Omicron variants.

Novel immune escape variants have emerged as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to spread worldwide. Many of the variants cause breakthrough infections in vaccinated populations, posing great challenges to current antiviral strategies targeting the immunodominance of the receptor-binding domain within the spike protein. Here, we found that a novel broadly neutralizing monoclonal antibody (mAb), G5, provided efficient protection against SARS-CoV-2 variants of concern (VOCs) in vitro and in vivo. A single dose of mAb G5 could significantly inhibit the viral burden in mice challenged with the mouse-adapted SARS-CoV-2 or SARS-CoV-2 Omicron BA.1 variant, as well as the body weight loss and cytokine release induced by mouse-adapted SARS-CoV-2. The refined epitope recognized by mAb G5 was identified as 1148 FKEELDKYF1156 in the stem helix of subunit S2. In addition, a human-mouse chimeric mAb was generated based on the variable region of heavy chain and VL genes of mAb G5. Our study provides a broad antibody drug candidate against SARS-CoV-2 VOCs and reveals a novel target for developing pan-SARS-CoV-2 vaccines.

'Dynamic zero-COVID' policy and viral clearance during an omicron wave in Tianjin, China: a city-wide retrospective observational study.

OBJECTIVE: To report how the Chinese mainland battled its first omicron wave, which happened in Tianjin, a metropolis with 14 million residents. We also sought to better understand how clinical features affected the timing of viral clearance. DESIGN: A retrospective study of the omicron wave in Tianjin between 8 January 2022 and 3 March 2022. SETTING: Except for the first cases on 8 January, all the omicron cases were identified through PCR mass testing in the residential communities. Residential quarantine and serial PCR mass testing were dynamically adjusted according to the trends of new cases. PARTICIPANTS: All the 417 consecutive PCR-positive cases identified through mass screening of the entire city's 14 million residents. 45.3% of the cases were male, and the median age was 37 (range 0.3-90). 389 (93%) cases had complete data for analysing the correlation between clinical features and the timing of viral clearance. MAIN OUTCOME AND MEASURE: Time to viral clearance. RESULTS: Tianjin initiated the 'dynamic zero-COVID' policy very early, that is, when daily new case number was ≈0.4 cases per 1 000 000 residents. Daily new cases dropped to <5 after 3 February, and the number of affected residential subdivisions dropped to ≤2 after 13 February. 64% (267/417) of the cases had no or mild symptoms. The median interval from hospital admission to viral clearance was 10 days (range 3-28). An exploratory analysis identified a feature cluster associated with earlier viral clearance, with HRs of 3.56 (95% CI 1.66 to 7.63) and 3.15 (95% CI 1.68 to 5.91) in the training and validation sets, respectively. CONCLUSIONS: The 'dynamic zero-COVID' policy can suppress an omicron wave within a month. It might be possible to predict in advance which cases will require shorter periods of isolation based on their clinical features.

Analysis of clinical characteristics of patients with COVID-19 in Tianjin

Objective: To explore the epidemiological, clinical and imaging characteristics of patients with novel coronavirus disease 2019 (COVID-19) in Tianjin.