Emerging microbes & infections
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Emerg Microbes Infect · Dec 2020
Defining the Syrian hamster as a highly susceptible preclinical model for SARS-CoV-2 infection.
Following emergence in late 2019, SARS-CoV-2 rapidly became pandemic and is presently responsible for millions of infections and hundreds of thousands of deaths worldwide. There is currently no approved vaccine to halt the spread of SARS-CoV-2 and only very few treatment options are available to manage COVID-19 patients. For development of preclinical countermeasures, reliable and well-characterized small animal disease models will be of paramount importance. ⋯ Neither hamster age nor sex had any impact on the severity of disease or course of infection. Finally, prolonged viral persistence in interleukin 2 receptor gamma chain knockout hamsters revealed susceptibility of SARS-CoV-2 to adaptive immune control. In conclusion, the Syrian hamster is highly susceptible to SARS-CoV-2 making it a very suitable infection model for COVID-19 countermeasure development.
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Emerg Microbes Infect · Dec 2020
Rapid Determination of SARS-CoV-2 antibodies using a bedside, point-of-Care, serological test.
Background: Several serological tests for SARS-CoV-2 have been developed or use, but most have only been validated on few samples, and none provide medical practitioners with an easy-to-use, self-contained, bedside test with high accuracy. Material and methods: Two-hundred fifty-six sera from 101 patients hospitalized with SARS-CoV-2 infection (positive RT-PCR) and 50 control sera were tested for IgM/IgG using the NG-Test IgM-IgG COVID all-in-one assay. The seroconversion dynamic was assessed by symptom onset and day of RT-PCR diagnosis. ⋯ No difference in seroconversion delay was observed regardless of whether patients received ventilation. Conclusions: The NG-test is a bedside serological assay that could serve as a complementary source of diagnostic information to RT-PCR and chest imaging. It may also be useful to monitor immunological status of medical and non-medical workers during the ongoing pandemic, and the general population after social distancing measures have eased.
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Emerg Microbes Infect · Dec 2020
Delayed specific IgM antibody responses observed among COVID-19 patients with severe progression.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly worldwide since it was confirmed as the causative agent of COVID-19. Molecular diagnosis of the disease is typically performed via nucleic acid-based detection of the virus from swabs, sputum or bronchoalveolar lavage fluid (BALF). However, the positive rate from the commonly used specimens (swabs or sputum) was less than 75%. ⋯ The GICA was found to be positive with the detected 82.2% (37/45) of RT-qPCR confirmed COVID-19 cases, as well as 32.0% (8/25) of clinically confirmed, RT-qPCR negative patients (4-14 days after symptom onset). Investigation of IgM-negative, RT-qPCR-positive COVID-19 patients showed that half of them developed severe disease. The GICA was found to be a useful test to complement existing PCR-based assays for confirmation of COVID-19, and a delayed specific IgM antibody response was observed among COVID-19 patients with severe progression.
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Emerg Microbes Infect · Dec 2020
LetterRetrospective detection of SARS-CoV-2 in hospitalized patients with influenza-like illness.
Since the first report of the coronavirus disease (COVID-19) in late December 2019, the pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has now widely spread to more than 187 countries and regions. However, it is unclear whether there has been cryptic transmission before these early officially confirmed cases, we therefore retrospectively screened for the SARS-CoV-2 RNA in 1271 nasopharyngeal swab samples, as well as the prevalence of IgM, IgG, and total antibodies against SARS-CoV-2 in 357 matched serum samples collected from hospitalized patients with influenza-like illness between 1 December 2018 and 31 March 2020 in Shanghai Ruijin Hospital. ⋯ Before this time point, the presence of SARS-CoV-2 was not observed, which limited the possibility that SARS-CoV-2 has already spread among the population before the large-scale outbreak. Additionally, among 6662 patients with influenza-like illness from 1 December 2017 to 31 March 2020, the overall number of patients positive for influenza and other respiratory viruses during the COVID-19 period decreased significantly when compared with that in the same period of the last two years, reflecting that public health interventions can effectively control the spread of common respiratory viruses.
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Emerg Microbes Infect · Dec 2020
LetterAnalytical comparisons of SARS-COV-2 detection by qRT-PCR and ddPCR with multiple primer/probe sets.
Different primers/probes sets have been developed all over the world for the nucleic acid detection of SARS-CoV-2 by quantitative real time polymerase chain reaction (qRT-PCR) as a standard method. In our recent study, we explored the feasibility of droplet digital PCR (ddPCR) for clinical SARS-CoV-2 nucleic acid detection compared with qRT-PCR using the same primer/probe sets issued by Chinese Center for Disease Control and Prevention (CDC) targeting viral ORF1ab or N gene, which showed that ddPCR could largely minimize the false negatives reports resulted by qRT-PCR [Suo T, Liu X, Feng J, et al. ddPCR: a more sensitive and accurate tool for SARS-CoV-2 detection in low viral load specimens. medRxiv [Internet]. 2020;2020.02.29.20029439. Available from: https://medrxiv.org/content/early/2020/03/06/2020.02.29.20029439.abstract]. ⋯ Moreover, false positive reports of qRT-PCR with UCDC-N1, N2 and CCDC-N primers/probes sets were observed. In contrast, ddPCR showed significantly better performance in general for low viral load samples compared to qRT-PCR. Remarkably, the background readouts of ddPCR are relatively lower, which could efficiently reduce the production of false positive reports.