Establishment of a real-time recombinase-aided isothermal amplification (RT-RAA) assay for the rapid detection of bovine respiratory syncytial virus (preprint)

Background Bovine respiratory syncytial virus (BRSV) is a major cause of bovine respiratory disease, resulting in significant losses to the cattle industry. For rapid detection of BRSV, reverse transcription recombinase polymerase amplification assays targeting the F gene were developed by integrating the fluorescence detection platform (RT-RAA).Results The developed RT-RAA assays allowed the exponential amplification of the target fragment in 20 min at a constant temperature of 39°C. The RT-RAA assays also showed good specificity for BRSV, with no cross-reactions with Infectious Bovine Rhinotracheitis Virus (IBRV), Bovine Parainfluenza Virus Type 3 (BPIV3), Bovine Viral Diarrhea Virus (BVDV) and Bovine Coronavirus (BCoV). With the standard RNA of BRSV serving as a template, the limit of detection for RT-RAA was 5 × 102 copies per reaction. Forty clinical samples collected from cattle with respiratory disease were tested, and the positive rate was 7.5% (3/40), consistent with results using the conventional PCR method reported previously.Conclusion An RT-RAA assay for BRSV detection was established in this study. The method is specific and sensitive and can be completed within 20 min at 39℃. These results ascertain that the developed RT-RAA assays are effective diagnostic tools for rapidly detecting BRSV in resource-limited settings, which may be applied for clinical detection of BRSV.

Air concern and air pollution concentration under COVID-19 both increase people’s gym sports behavior in Beijing, China (preprint)

Air pollution may change people’s gym sports behavior. To test this claim, firstly we designed a questionnaire of Beijing, China and used regression models to evaluate the association between air risk perceptions and sports mode choice, results showed that people had a high possibility of switching from outdoor sports to gym sports when air concern rose. Second, using big data crawler technology and negative binomial regression model, we provided consistent evidence that a one standard deviation increased in PM2.5 concentration (fine particulate matter with diameters equal or smaller than 2.5 μm) derived from land use regression model (LUR) was positively associated with a 0.0305 and a 0.0622 standard deviation increased in gym visits without or with consideration of the COVID-19 epidemic in 2019-2020. Finally, subgroups analysis showed that urban people and males had a higher tendency to travelling to gyms under COVID-19, which needed extra additional precautions on polluted days. All in all, subjective air concern and the actual PM2.5 concentrations under COVID-19 both increased sport people’s gym sports behavior.

The SARS-CoV-2 RNA with mild pulmonary consolidation lasts longer in non-severe COVID-19 patients: an observational study (preprint)

Background: Since December 2019, COVID-19 has rapidly swept the world. It is particularly important to understand the dynamic changes of the whole disease course of non-severe patients from the onset to the follow-up after discharge.Methods: On February 1, 2020, 18 cases of non-severe COVID-19 appeared in a hospital in Beijing. All patients were SARS-CoV-2 RNA positive by RT-PCR for pharyngeal swabs. We recorded the clinical information and viral dynamics of these patients from the onset of the disease to 2 months after discharge. According to the severity of lung consolidation, 18 patients were divided into two groups (mild pulmonary consolidation group [imaging score ≤10]; severe pulmonary consolidation group [imaging score >10]).Results: Eighteen patients (median age 43) were included, including 14 females. Fever (11/18) and cough (8/18) were the most common symptoms. The duration of SARS-CoV-2 RNA positive in mild pulmonary consolidation group was significantly longer than severe pulmonary consolidation group (the median time was 30 days and 13 days, respectively, P= 0.0031). Two months after discharge, almost all patients were followed up for IgM antibody disappearance and IgG antibody production.Conclusion: In non-severe COVID-19 patients, the positive duration of the SARS-CoV-2 RNA in patients with mild pulmonary consolidation was longer than the severe pulmonary consolidation. However, it is necessary for a large sample to verify our conclusions.