Higher SARS-CoV-2 shedding in exhaled aerosol probably contributed to the enhanced transmissibility of Omicron BA.5 subvariant.

The global pandemic of the BA.5 subvariant had moved from prediction to reality. In this study, we compared SARS-CoV-2 aerosol emissions from patients with BA.2 or BA.5 subvariant infection. First, patients with BA.2 subvariant infection had higher upper respiratory viral loads than patients with BA.5 subvariant infection. However, the average breath emission rate (BER) of patients with BA.5 subvariant infection, which represented the concentration of exhaled SARS-CoV-2 aerosols, was nearly 40 times higher than that of patients with BA.2 subvariant. Second, aerosols exhaled by patients with BA.5 subvariant infection exhibited SARS-CoV-2 RNA detection positive rate than patients with BA.1 or BA.2 subvariant infection. Meanwhile, for BA.5 subvariant infection, patients that exhaled infectious SARS-CoV-2 aerosols accounted for 14.8% of all patients. Third, since the onset of COVID-19, the SARS-CoV-2 RNA detection signals of throat swabs showed a gradual decline trend, although the decline process was accompanied by fluctuations. Overall, the monitoring of infectious SARS-CoV-2 aerosols may provide the data support for the transmissibility evaluation of the Omicron BA.5 subvariant. This article is protected by copyright. All rights reserved.

TET2 is required for Type I IFN-mediated inhibition of bat-origin swine acute diarrhea syndrome coronavirus.

Swine acute diarrhea syndrome coronavirus (SADS-CoV) is a newly discovered bat-origin coronavirus with fatal pathogenicity for neonatal piglets. There is no vaccine to prevent SADS-CoV infection or clinically approved drugs targeting SADS-CoV. Therefore, unraveling cellular factors that regulate SADS-CoV for cell entry is critical to understanding the viral transmission mechanism and provides a potential therapeutic target for SADS-CoV cure. Here, we showed that Type I interferon (IFN-I) pretreatment potently blocks SADS-CoV entry into cells using lentiviral pseudo-virions as targets whose entry is driven by the SADS-CoV Spike glycoprotein. IFN-I-mediated inhibition of SADS-CoV entry and replication was dramatically impaired in the absence of TET2. These results suggest TET2 is found to serve as a checkpoint of IFN-I-meditated inhibition on the cell entry of SADS-CoV, and our discovery might constitute a novel treatment option to combat against SADS-CoV.

High performance of a novel antigen detection test on nasopharyngeal specimens for diagnosing SARS-CoV-2 infection.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic has become a major public health issue worldwide. Developing and evaluating rapid and easy-to-perform diagnostic tests is a high priority. The current study was designed to assess the diagnostic performance of an antigen-based rapid detection test (COVID-VIRO®) in a real-life setting. Two nasopharyngeal specimens of symptomatic or asymptomatic adult patients hospitalized in the Infectious Diseases Department or voluntarily accessing the COVID-19 Screening Department of the Regional Hospital of Orléans, France, were concurrently collected. The diagnostic specificity and sensitivity of COVID VIRO® results were compared to those of real-time reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR) results. A subset of patients underwent an additional oropharyngeal and/or saliva swab for rapid testing. A total of 121 patients confirmed to be infected and 127 patients having no evidence of recent or ongoing infection were enrolled for a total of 248 nasopharyngeal swab specimens. Overall, the COVID-VIRO® sensitivity was 96.7% (CI, 93.5%-99.9%). In asymptomatic patients, symptomatic patients having symptoms for more than 4 days and those with an RT-qPCR cycle threshold value ≥ 32, the sensitivities were 100%, 95.8%, and 91.9%, respectively. The concordance between RT-qPCR and COVID VIRO® rapid test results was 100% for the 127 patients with no SARS-CoV-2 infection. The COVID-VIRO® test had 100% specificity and sensitivity greater than 95%, which are better than the recommendations set forth by the WHO (specificity ≥ 97%-100%, sensitivity ≥ 80%). These rapid tests may be particularly useful for large-scale screening in emergency departments, low-resource settings, and airports.

Does SARS-CoV-2 has a longer incubation period than SARS and MERS?

The outbreak of a novel coronavirus (SARS-CoV-2) since December 2019 in Wuhan, the major transportation hub in central China, became an emergency of major international concern. While several etiological studies have begun to reveal the specific biological features of this virus, the epidemic characteristics need to be elucidated. Notably, a long incubation time was reported to be associated with SARS-CoV-2 infection, leading to adjustments in screening and control policies. To avoid the risk of virus spread, all potentially exposed subjects are required to be isolated for 14 days, which is the longest predicted incubation time. However, based on our analysis of a larger dataset available so far, we find there is no observable difference between the incubation time for SARS-CoV-2, severe acute respiratory syndrome coronavirus (SARS-CoV), and middle east respiratory syndrome coronavirus (MERS-CoV), highlighting the need for larger and well-annotated datasets.