• IMMUNE NETWORK
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• v.21 no.2
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• pp.12.1-12.17
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• 2021

Coronavirus disease 2019 (COVID-19) is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Since the emergence of SARS-CoV-2 in the human population in late 2019, it has spread on an unprecedented scale worldwide leading to the first coronavirus pandemic. SARS-CoV-2 infection results in a wide range of clinical manifestations from asymptomatic to fatal cases. Although intensive research has been undertaken to increase understanding of the complex biology of SARS-CoV-2 infection, the detailed mechanisms underpinning the severe pathogenesis and interactions between the virus and the host immune response are not well understood. Thus, the development of appropriate animal models that recapitulate human clinical manifestations and immune responses against SARS-CoV-2 is crucial. Although many animal models are currently available for the study of SARS-CoV-2 infection, each has distinct advantages and disadvantages, and some models show variable results between and within species. Thus, we aim to discuss the different animal models, including mice, hamsters, ferrets, and non-human primates, employed for SARS-CoV-2 infection studies and outline their individual strengths and limitations for use in studies aimed at increasing understanding of coronavirus pathogenesis. Moreover, a significant advantage of these animal models is that they can be tailored, providing unique options specific to the scientific goals of each researcher.

• Clinical and Experimental Pediatrics
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• v.64 no.12
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• pp.652-660
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• 2021

Background: Viral load and shedding duration are highly associated with the transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection. However, limited studies have reported on viral load or shedding in children and adolescents infected with sudden acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Purpose: This study aimed to investigate the natural course of viral load in asymptomatic or mild pediatric cases. Methods: Thirty-one children (<18 years) with confirmed SARS-CoV-2 infection were hospitalized and enrolled in this study. Viral loads were evaluated in nasopharyngeal swab samples using real-time reverse transcription polymerase chain reaction (E, RdRp, N genes). cycle threshold (Ct) values were measured when patients met the clinical criteria to be released from quarantine. Results: The mean age of the patients was 9.8 years, 18 (58%) had mild disease, and 13 (42%) were asymptomatic. Most children were infected by adult family members, most commonly by their mothers. The most common symptoms were fever and sputum (26%), followed by cough and runny nose. Nine patients (29%) had a high or intermediate viral load (Ct value≤30) when they had no clinical symptoms. Viral load showed no difference between symptomatic and asymptomatic patients. Viral rebounds were found in 15 cases (48%), which contributed to prolonged viral detection. The mean duration of viral detection was 25.6 days. Viral loads were significantly lower in patients with viral rebounds than in those with no rebound (E, P=0.003; RdRp, P=0.01; N, P=0.02). Conclusion: Our study showed that many pediatric patients with coronavirus disease 2019 (COVID-19) experienced viral rebound and showed viral detection for more than 3 weeks. Further studies are needed to investigate the relationship between viral rebound and infectiousness in COVID-19.

• International Journal of Advanced Culture Technology
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• v.10 no.4
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• pp.316-321
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• 2022

Since 2019, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has spread rapidly, infecting millions of people worldwide. On March 11, 2020, the World Health Organization declared coronavirus disease (COVID-19) a pandemic owing to the worldwide spread of SARS-CoV-2, which created an unprecedented burden on the global healthcare system. In this context, there are increasing concerns regarding co-infections with other respiratory viruses, such as the influenza virus. In this study, clinical data of patients infected with SARS-CoV-2 and other respiratory viruses were compared with patients infected with SARS-CoV-2 alone. The hematology and blood biochemistry results of 178 patients infected with SARS-CoV-2 , who were tested on admission, were retrospectively reviewed. In patients with SARS-CoV-2 and adenovirus co-infection, C-reactive protein levels were elevated on admission, whereas lactate dehydrogenase (LDH), prothrombin time, international normalized ratio, activated partial thromboplastin clotting time, and bilirubin values were all within the normal range. Moreover, patients with SARS-CoV-2 and human bocavirus co-infection had low LDH and high bilirubin levels on admission. These findings reveal the clinical features of respiratory virus and SARS-CoV-2 co-infections and support the development of appropriate approaches for treating patients with SARS-CoV-2 and other respiratory virus co-infections.

• IMMUNE NETWORK
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• v.21 no.1
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• pp.3.1-3.16
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• 2021

Coronavirus disease 2019 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been spreading worldwide since its outbreak in December 2019, and World Health Organization declared it as a pandemic on March 11, 2020. SARS-CoV-2 is highly contagious and is transmitted through airway epithelial cells as the first gateway. SARS-CoV-2 is detected by nasopharyngeal or oropharyngeal swab samples, and the viral load is significantly high in the upper respiratory tract. The host cellular receptors in airway epithelial cells, including angiotensin-converting enzyme 2 and transmembrane serine protease 2, have been identified by single-cell RNA sequencing or immunostaining. The expression levels of these molecules vary by type, function, and location of airway epithelial cells, such as ciliated cells, secretory cells, olfactory epithelial cells, and alveolar epithelial cells, as well as differ from host to host depending on age, sex, or comorbid diseases. Infected airway epithelial cells by SARS-CoV-2 in ex vivo experiments produce chemokines and cytokines to recruit inflammatory cells to target organs. Same as other viral infections, IFN signaling is a critical pathway for host defense. Various studies are underway to confirm the pathophysiological mechanisms of SARS-CoV-2 infection. Herein, we review cellular entry, host-viral interactions, immune responses to SARS-CoV-2 in airway epithelial cells. We also discuss therapeutic options related to epithelial immune reactions to SARS-CoV-2.

• Pediatric Infection and Vaccine
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• v.29 no.3
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• pp.155-160
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• 2022

Children and adolescents with coronavirus disease 2019 (COVID-19) generally have mild symptoms. Severe infection due to severe acute respiratory syndrome coronavirus 2 (SARSCoV-2) involving multiorgan dysfunction is rare in this population. Herein, we present an unusual case of severe SARS-CoV-2 infection with multiorgan involvement followed by multisystem inflammatory syndrome in children (MIS-C) in a vaccinated 16-year-old boy. The patient was unconscious on initial presentation, and had severe paralytic ileus. On laboratory examination, there was severe metabolic acidosis, lymphocytopenia, thrombocytopenia, elevated inflammatory markers, elevated liver enzymes, and evidence of acute kidney injury with proteinuria and hematuria. His symptoms improved with the administration of remdesivir and dexamethasone. The patient briefly experienced MIS-C 2 weeks after the diagnosis of COVID-19, but the patient was discharged without any complications.

• Journal of Microbiology and Biotechnology
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• v.25 no.12
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• pp.2007-2010
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• 2015

A new chemical inhibitor against severe acute respiratory syndrome (SARS) coronavirus helicase, 7-ethyl-8-mercapto-3-methyl-3,7-dihydro-1H-purine-2,6-dione, was identified. We investigated the inhibitory effect of the compound by conducting colorimetry-based ATP hydrolysis assay and fluorescence resonance energy transfer-based double-stranded DNA unwinding assay. The compound suppressed both ATP hydrolysis and double-stranded DNA unwinding activities of helicase with IC₅₀ values of 8.66 ± 0.26 μM and 41.6 ± 2.3 μM, respectively. Moreover, we observed that the compound did not show cytotoxicity up to 80 μM concentration. Our results suggest that the compound might serve as a SARS coronavirus inhibitor.

• Journal of Veterinary Science
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• v.22 no.6
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• pp.70.1-70.12
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• 2021

Bats are an important reservoir of several zoonotic diseases. However, the circulation of bat coronaviruses (BatCoV) in live animal markets in Indonesia has not been reported. Genetic characterization of BatCoV was performed by sequencing partial RdRp genes. Real-time polymerase chain reaction based on nucleocapsid protein (N) gene and Enzyme-linked immunosorbent assay against the N protein were conducted to detect the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral RNA and antibody, respectively. We identified the presence of BatCoV on Cynopterus brachyotis, Macroglossus minimus, and Rousettus amplexicaudatus. The results showed that the BatCoV included in this study are from an unclassified coronavirus group. Notably, SARS-CoV-2 viral RNA and antibodies were not detected in the sampled bats.

• Clinical and Experimental Pediatrics
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• v.64 no.7
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• pp.328-338
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• 2021

Humanity has been suffering from the global severe acute respiratory syndrome coronavirus 2 pandemic that began late in 2019. In 2020, for the first time in history, new vaccine platforms-including mRNA vaccines and viral vector-based DNA vaccines-have been given emergency use authorization, leading to mass vaccinations. The purpose of this article is to review the currently most widely used coronavirus disease 2019 vaccines, investigate their immunogenicity and efficacy data, and analyze the vaccine safety profiles that have been published, to date.

• Molecules and Cells
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• v.44 no.6
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• pp.377-383
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• 2021

Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) is a novel virus that causes coronavirus disease 2019 (COVID-19). To understand the identity, functional characteristics and therapeutic targets of the virus and the diseases, appropriate infection models that recapitulate the in vivo pathophysiology of the viral infection are necessary. This article reviews the various infection models, including Vero cells, human cell lines, organoids, and animal models, and discusses their advantages and disadvantages. This knowledge will be helpful for establishing an efficient system for defense against emerging infectious diseases.

• Clinical and Experimental Pediatrics
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• v.65 no.4
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• pp.167-171
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• 2022

In the era of the coronavirus disease 2019 (COVID-19) pandemic, countries worldwide have implemented several nonpharmaceutical interventions (NPIs) to contain its spread before vaccines and treatments were developed. NPIs included social distancing, mask wearing, intensive contact tracing and isolation, and sanitization. In addition to their effectiveness at preventing the rapid spread of COVID-19, NPIs have caused secondary changes in the epidemiology of other infectious diseases. In Korea, various NPI stages have been implemented since the first confirmed case of COVID-19 on January 20, 2020. This review, based on a PubMed database search, shows the impact of NPIs on several infectious diseases other than severe acute respiratory syndrome coronavirus 2 in the COVID-19 pandemic era in Korea.