Genetic characteristics of human coronavirus HKU1 in mainland China during 2018.

Human coronavirus HKU1 (HCoV-HKU1) is a pathogen that causes acute respiratory tract infections in children and circulates worldwide. To investigate the molecular characteristics and genetic diversity of HCoV-HKU1 in China, a molecular epidemiological analysis based on complete genome sequences was performed. A total of 68 endemic-HCoV-positive samples were identified from 1358 enrolled patients during 2018, including four HCoV-229E, nine HCoV-OC43, 24 HCoV-NL63, and 31 HCoV-HKU1. The detection rate of endemic HCoVs was 5.01% during 2018, while for HCoV-HKU1, it was 2.28%. Eight complete genomic sequences of HCoV-HKU1 were obtained and compared to 41 reference genome sequences corresponding to genotypes A, B, and C, obtained from the GenBank databank. Of the eight HKU1 sequences, four belonged to genotype A and four belonged to genotype B. No genotype C strains were detected in this study. For genotype A, 18 variations in the S protein with respect to the reference sequence were present in more than 5% of the sequences, whereas for genotype B, this number was 25. Most of the amino acid changes occurred in the S1 subunit. No amino acid substitutions were found in the sites that are essential for interaction with neutralizing antibodies, while a 510T amino acid insertion was found in almost one third of genotype B sequences. About 82-83, 85-89, and 88-89 predicted N-glycosylation sites and 7-13, 6-8, and 9 predicted O-glycosylation sites were found among the sequences of genotype A, B, and C, respectively. Six conserved O-glycosylation sites were present in all of the genotype A sequences. Only genotype A and B strains were detected after 2005. The S protein exhibited relatively high diversity, with most of the amino acid changes occurring in the S1 subunit.

[Expression of a SARS-CoV-2 neutralizing nanobody in Trichoderma reesei].

Nanobodies derived from camelid single-chain antibodies have the advantages of being small, simple, highly soluble and stable. Nanobodies can be administered by inhalation and therefore is potentially valuable for the prevention and control of respiratory viruses. Trichoderma reesei is a food-grade protein expression host with a cellulase production capacity of up to 80 g/L, which can be employed for low-cost production of therapeutic proteins. In this study, a codon-optimized SARS-CoV-2 neutralizing nanobody Nb20 was expressed in T. reesei under a strong constitutive promoter Pcdna1. Nb20 protein was fused downstream of the N-terminal fragment of cellobiohydrolase Ⅰ, and the fusion protein can be intracellularly cleaved by the KEX2 protease to release Nb20. In a shake-flask fermentation using glucose medium, 47.4 mg/L Nb20 was detected in the culture after 48 h of cultivation. The expressed Nb20 showed the ability to interact with the receptor-binding domain of SARS-CoV-2 spike protein, suggesting that it can be used for the neutralization of SARS-CoV-2. The results indicate that T. reesei has the potential for recombinant production of nanobodies.

Epidemiological characteristics and clinical manifestations of pediatric patients with COVID-19 in China: A multicenter retrospective study.

Importance: The Coronavirus disease 2019 (COVID-19) global pandemic poses a considerable challenge for pediatricians. Objective: This study aimed to identify the epidemiological characteristics and clinical features of pediatric patients with COVID-19 in China. Methods: This multicenter retrospective study included pediatric patients from 46 hospitals in China, covering 12 provinces and two municipalities. Epidemiological, demographic, clinical, laboratory, treatment, and outcome data were analyzed. Results: In total, 211 pediatric patients with COVID-19 were included in this study. The median age was 7.0 years (range: 22 days to 18 years). Approximately 16.3% of the patients exhibited asymptomatic infections, 23.0% had upper respiratory tract infections, and 60.7% had pneumonia, including two with severe pneumonia and one with critical illness. Approximately 78.7% of the pediatric patients occurred in familial clusters. The most three common symptoms or signs at onset in children with COVID-19 were fever (54.5%), cough (49.3%), and pharyngeal congestion (20.8%). Only 17.6% of the patients presented with decreased lymphocyte count, whereas 13.6% had increased lymphocyte count. Among the patients with pneumonia who exhibited abnormal chest computed tomography findings, 18.2% (23/127) of the patients had no other symptoms. Generally, the chest radiographs showed abnormalities that affected both lungs (49.6%); ground-glass opacity (47.2%) was the most common manifestation. The cure and improvement rates were 86.7% (183/211) and 13.3% (28/211), respectively. Only one patient with an underlying condition received invasive mechanical ventilation; none of the patients died. Interpretation: Similar to adults, children of all age groups are susceptible to COVID-19. Fortunately, most pediatric patients have mild symptoms or remain asymptomatic, despite the high incidence of pneumonia. Decreased proportions of white blood cells and lymphocytes are less frequent in children than in adults.

Comparison of Clinical Characteristics Among COVID-19 and Non-COVID-19 Pediatric Pneumonias: A Multicenter Cross-Sectional Study.

Background: The pandemic of Coronavirus Disease 2019 (COVID-19) brings new challenges for pediatricians, especially in the differentiation with non-COVID-19 pneumonia in the peak season of pneumonia. We aimed to compare the clinical characteristics of pediatric patients with COVID-19 and other respiratory pathogens infected pneumonias. Methods: We conducted a multi-center, cross-sectional study of pediatric inpatients in China. Based on pathogenic test results, pediatric patients were divided into three groups, including COVID-19 pneumonia group, Non-COVID-19 viral (NCV) pneumonia group and Non-viral (NV) pneumonia group. Their clinical characteristics were compared by Kruskal-Wallis H test or chi-square test. Results: A total of 636 pediatric pneumonia inpatients, among which 87 in COVID-19 group, 194 in NCV group, and 355 in NV group, were included in analysis. Compared with NCV and NV patients, COVID-19 patients were older (median age 6.33, IQR 2.00-12.00 years), and relatively fewer COVID-19 patients presented fever (63.2%), cough (60.9%), shortness of breath (1.1%), and abnormal pulmonary auscultation (18.4%). The results were verified by the comparison of COVID-19, respiratory syncytial virus (RSV) and influenza A (IFA) pneumonia patients. Approximately 42.5%, 44.8%, and 12.6% of the COVID-19 patients presented simply ground-glass opacity (GGO), simply consolidation, and the both changes on computed tomography (CT) scans, respectively; the proportions were similar as those in NCV and NV group (p>0.05). Only 47.1% of COVID-19 patients had both lungs pneumonia, which was significantly lower than that proportion of nearly 80% in the other two groups. COVID-19 patients presented lower proportions of increased white blood cell count (16.5%) and abnormal procalcitonin (PCT) (10.7%), and a higher proportion of decreased lymphocyte count (44.0%) compared with the other two groups. Conclusion: Majority clinical characteristics of pediatric COVID-19 pneumonia patients were milder than non-COVID-19 patients. However, lymphocytopenia remained a prominent feature of COVID-19 pediatric pneumonia.

Updated diagnosis, treatment and prevention of COVID-19 in children: experts' consensus statement (condensed version of the second edition).

In the early February, 2020, we called up an experts' committee with more than 30 Chinese experts from 11 national medical academic organizations to formulate the first edition of consensus statement on diagnosis, treatment and prevention of coronavirus disease 2019 (COVID-19) in children, which has been published in this journal. With accumulated experiences in the diagnosis and treatment of COVID-19 in children, we have updated the consensus statement and released the second edition recently. The current version in English is a condensed version of the second edition of consensus statement on diagnosis, treatment and prevention of COVID-19 in children. In the current version, diagnosis and treatement criteria have been optimized, and early identification of severe and critical cases is highlighted. The early warning indicators for severe pediatric cases have been summarized which is utmost important for clinical practice. This version of experts consensus will be valuable for better prevention, diagnosis and treatment of COVID-19 in children worldwide.

Diagnosis, treatment, and prevention of 2019 novel coronavirus infection in children: experts' consensus statement.

Since the outbreak of 2019 novel coronavirus infection (2019-nCoV) in Wuhan City, China, by January 30, 2020, a total of 9692 confirmed cases and 15,238 suspected cases have been reported around 31 provinces or cities in China. Among the confirmed cases, 1527 were severe cases, 171 had recovered and been discharged at home, and 213 died. And among these cases, a total of 28 children aged from 1 month to 17 years have been reported in China. For standardizing prevention and management of 2019-nCoV infections in children, we called up an experts' committee to formulate this experts' consensus statement. This statement is based on the Novel Coronavirus Infection Pneumonia Diagnosis and Treatment Standards (the fourth edition) (National Health Committee) and other previous diagnosis and treatment strategies for pediatric virus infections. The present consensus statement summarizes current strategies on diagnosis, treatment, and prevention of 2019-nCoV infection in children.