HCoV-NL63 Research Articles

Prevalence of viral pathogens in a sample of hospitalized Egyptian children with acute lower respiratory tract infections: a two-year prospective study

BackgroundViral pneumonias are a major cause of childhood mortality. Proper management needs early and accurate diagnosis. This study objective is to investigate the viral etiologies of pneumonia in children.ResultsThis prospective study enrolled 158 and 101 patients in the first and second year, respectively, and their mean age was 4.72 ± 2.89. Nasopharyngeal swabs were collected and subjected to virus diagnosis by reverse transcription polymerase chain reaction (RT-PCR). Viral etiologies of pneumonia were evidenced in 59.5% of the samples in the first year, all of them were affirmative for influenza A, 2 samples were affirmative for Human coronavirus NL63, and one for Human coronavirus HKU1. In the second year, 87% of patients had a viral illness. The most prevalent agents are human metapneumovirus which was detected in 44 patients (43.6%) followed by human rhinovirus in 35 patients (34.7%) and then parainfluenza–3 viruses in 33 patients (32.7%), while 14 patients had a confirmed diagnosis for both Pan coronavirus and Flu-B virus.ConclusionsViral infection is prevalent in the childhood period; however, the real magnitude of viral pneumonia in children is underestimated. The reverse transcriptase polymerase chain reaction has to be a vital tool for epidemiological research and is able to clear the gaps in-between clinical pictures and final diagnoses.

RespiCoV: Simultaneous identification of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and 46 respiratory tract viruses and bacteria by amplicon-based Oxford-Nanopore MinION sequencing.

Since December 2019 the world has been facing the outbreak of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Identification of infected patients and discrimination from other respiratory infections have so far been accomplished by using highly specific real-time PCRs. Here we present a rapid multiplex approach (RespiCoV), combining highly multiplexed PCRs and MinION sequencing suitable for the simultaneous screening for 41 viral and five bacterial agents related to respiratory tract infections, including the human coronaviruses NL63, HKU1, OC43, 229E, Middle East respiratory syndrome coronavirus, SARS-CoV, and SARS-CoV-2. RespiCoV was applied to 150 patient samples with suspected SARS-CoV-2 infection and compared with specific real-time PCR. Additionally, several respiratory tract pathogens were identified in samples tested positive or negative for SARS-CoV-2. Finally, RespiCoV was experimentally compared to the commercial RespiFinder 2SMART multiplex screening assay (PathoFinder, The Netherlands).

Clinical Study of Human Coronavirus NL63, OC43, 229E, HKU1 Infentions in Hospitalized Children from 2015 to 2020.

ObjectiveThis study aims to analyze the clinical characteristics of hospitalized children infected with HCoV-NL63, OC43, 229E, HKU1 and provide the basis for disease diagnosis and treatment.MethodsA retrospective analysis was conducted on clinical manifestations, imaging data, and treatment measures of hospitalized children with positive HCoV-NL63, OC43, 229E, HKU1 from 2015 to 2020.ResultsA total of 1062 children aged 33 days to 12 years were analyzed, including 879 (82.77%) between 33 days to three years. Lower respiratory tract infections were the most common in 698 children positive for HCoVs (65.72%). The incidences of runny nose, cough, pharyngeal hyperemia, and fine crackles in the mild case group (n = 894, 84.18%) were significantly higher than in the severe case group, and the differences were statistically significant (P < 0.01). The incidences of gasp, stridor, and convulsions, the proportion of underlying diseases, such as congenital heart disease, laryngomalacia, and general developmental disorders, anemia, and abnormal liver function, and mixed infections in the severe group (n = 168, 15.82%) were significantly higher than in the mild group, and the differences were statistically significant (P < 0.01 or P < 0.05). Imaging manifestations differed. Pleural effusion and atelectasis occurred in the severe cases. After treatment, patients fully recovered or improved and were discharged from the hospital. There were no deaths.ConclusionHCoV-NL63, OC43, 229E, HKU1 infection is most common in children under three years old, and the infection site is mainly the lower respiratory tract. The main clinical manifestations include fever, cough, and runny nose. Inspiratory three concave signs, respiratory failure, and heart failure occurred in the severe cases, with pleural effusion and atelectasis possibly occurring at the same time. Severe cases should be identified early so that they may be given comprehensive treatment in time to improve the prognosis.

Hidden fraction of Polish population immune to SARS-CoV-2 in May 2021.

Population immunity (herd immunity) to SARS-CoV-2 derives from two sources: vaccinations or cases of infection with the virus. Infections can be diagnosed as COVID-19 and registered, or they can be asymptomatic, oligosymptomatic, or even full-blown but undiagnosed and unregistered when patients recovered at home. Estimation of population immunity to SARS-CoV-2 is difficult and remains a subject of speculations. Here we present a population screening for SARS-CoV-2 specific IgG and IgA antibodies in Polish citizens (N = 501) who had never been positively diagnosed with or vaccinated against SARS-CoV-2. Serum samples were collected in Wrocław (Lower Silesia) on 15th and 22nd May 2021. Sera from hospitalized COVID-19 patients (N = 22) or from vaccinated citizens (N = 14) served as positive controls. Sera were tested with Microblot-Array COVID-19 IgG and IgA (quantitative) that contain specific SARS-CoV-2 antigens: NCP, RBD, Spike S2, E, ACE2, PLPro protein, and antigens for exclusion cross-reactivity with other coronaviruses: MERS-CoV, SARS-CoV, HCoV 229E Np, HCoV NL63 Np. Within the investigated population of healthy individuals who had never been positively diagnosed with or vaccinated against SARS-CoV-2, we found that 35.5% (178 out of 501) were positive for SARS-CoV-2-specific IgG and 52.3% (262 out of 501) were positive for SARS-CoV-2-specific IgA; 21.2% of the investigated population developed virus-specific IgG or IgA while being asymptomatic. Anti-RBD IgG, which represents virus-neutralizing potential, was found in 25.6% of individuals (128 out of 501). These patients, though positive for anti-SARS-CoV-2 antibodies, cannot be identified in the public health system as convalescents due to undiagnosed infections, and they are considered unaffected by SARS-CoV-2. Their contribution to population immunity against COVID-19 should however be considered in predictions and modeling of the COVID-19 pandemic. Of note, the majority of the investigated population still lacked anti-RBD IgG protection (74.4%); thus vaccination against COVID-19 is still of the most importance for controlling the pandemic.

Brilacidin, a COVID-19 drug candidate, demonstrates broad-spectrum antiviral activity against human coronaviruses OC43, 229E, and NL63 through targeting both the virus and the host cell.

Brilacidin, a mimetic of host defense peptides (HDPs), is currently in Phase 2 clinical trial as an antibiotic drug candidate. A recent study reported that brilacidin has antiviral activity against severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) by inactivating the virus. In this study, we discovered an additional mechanism of action of brilacidin by targeting heparan sulfate proteoglycans (HSPGs) on the host cell surface. Brilacidin, but not acetyl brilacidin, inhibits the entry of SARS‐CoV‐2 pseudovirus into multiple cell lines, and heparin, an HSPG mimetic, abolishes the inhibitory activity of brilacidin on SARS‐CoV‐2 pseudovirus cell entry. In addition, we found that brilacidin has broad‐spectrum antiviral activity against multiple human coronaviruses (HCoVs) including HCoV‐229E, HCoV‐OC43, and HCoV‐NL63. Mechanistic studies revealed that brilacidin has a dual antiviral mechanism of action including virucidal activity and binding to coronavirus attachment factor HSPGs on the host cell surface. Brilacidin partially loses its antiviral activity when heparin was included in the cell cultures, supporting the host‐targeting mechanism. Drug combination therapy showed that brilacidin has a strong synergistic effect with remdesivir against HCoV‐OC43 in cell culture. Taken together, this study provides appealing findings for the translational potential of brilacidin as a broad‐spectrum antiviral for coronaviruses including SARS‐CoV‐2.

Prolonged SARS-CoV-2 RNA shedding in a young man recovering from traumatic pneumothorax

We describe a case of prolonged SARS-CoV-2 RNA shedding in an HIV-negative 21-year-old man recovering from abdominal and thoracic trauma. Nasopharyngeal (NP) swabs collected at 12 time points over a 95-day span all tested positive for SARS-CoV-2 by reverse transcription polymerase chain reaction (RT-PCR). Genotyping revealed canonical beta-variant E484K and N501Y mutations at earlier time points. Human rhinovirus, coronavirus NL63 and respiratory syncytial virus B were detected at different time points by RT-PCR. Full blood analysis at time point 9 (day 82) showed leukopenia with lymphocytosis. The patient’s NP swab tested negative for SARS-CoV-2 by RT-PCR 101 days after the first positive test. The prolonged duration of SARS-CoV-2 RNA shedding in the context of trauma presented here is unique and has important implications for COVID-19 diagnosis, management and policy guidelines

Antiviral activity of galvanic microcells of zinc and copper contained within painted surfaces

This study presents research related to the antiviral activity of painted surfaces containing galvanic microcells of zinc and copper. The aim of this study was to investigate the virucidal activity of galvanic microcells of zinc and copper grains fixed with adequate homogeneity and degree of aggregation in water-based acrylic paint layers in reference to a non-treated reference control. This paper provides evidence that a paint coating with a total copper surface area of 4.4% displays antiviral activity against human coronavirus NL63 according to ISO 21702 and inactivates > 99% of virus after 4 h of contact relative to a non-treated reference control.

Detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its first variants in fourplex real-time quantitative reverse transcription-PCR assays.

The early diagnosis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections is required to identify and isolate contagious patients to prevent further transmission of SARS-CoV-2. In this study, we present a multitarget real-time TaqMan reverse transcription PCR (rRT-PCR) assay for the quantitative detection of SARS-CoV-2 and some of its circulating variants harboring mutations that give the virus a selective advantage. Seven different primer-probe sets that included probes containing locked nucleic acid (LNA) nucleotides were designed to amplify specific wild-type and mutant sequences in Orf1ab, Envelope (E), Spike (S), and Nucleocapsid (N) genes. Furthermore, a newly developed primer-probe set targeted human β2-microglobulin (B2M) as a highly sensitive internal control for RT efficacy. All singleplex and fourplex assays detected ≤ 14 copies/reaction of quantified synthetic RNA transcripts, with a linear amplification range of nine logarithmic orders. Primer-probe sets for detection of SARS-CoV-2 exhibited no false-positive amplifications with other common respiratory pathogens, including human coronaviruses NL63, 229E, OC43, and HKU-1. Fourplex assays were evaluated using 160 clinical samples positive for SARS-CoV-2. Results showed that SARS-CoV-2 viral RNA was detected in all samples, including viral strains harboring mutations in the Spike coding sequence that became dominant in the pandemic. Given the emergence of SARS-CoV-2 variants and their rapid spread in some populations, fourplex rRT-PCR assay containing four primer-probe sets represents a reliable approach to allow quicker detection of circulating relevant variants in a single reaction.

Structure-function relationships among selected human coronaviruses

Identifying the key proteins among different types of human disease-causing coronaviruses is essential for the molecular mechanism and thereby designing potential drug molecules. Eight selected proteins of seven types of disease-causing coronaviruses, viz.SARS-CoV-2 (severe acute respiratory syndrome coronavirus2), SARS-CoV (severe acute respiratory syndrome coronavirus), MERS-CoV (middle east respiratory syndrome coronavirus), Human coronavirus OC43, Human coronavirus HKU1, Human coronavirus 229E and Human coronavirus NL63, were chosen for the comparison. Further, an attempt has been made to explore the most important host-pathogen interactions with a special focus on spike (RBD) protein region as this region deemed to be functionally most important. Epitope region was also identified which helps in the design of epitope-based vaccines. The structural comparison carried out among the seven types of human coronaviruses has revealed the molecular level details on the similarity among this series. This study has facilitated the identification of the important residues in the studied proteins which control the key functions such as viral replication and transmission. Thus, exploring the protein space in the family of coronaviruses, provide valuable insights into the molecular basis associated with the role of proteins and viral infections, which is expected to trigger the identification of the drug targets for coronaviruses infections, in a rational way.

Cytopathic Effect Assay and Plaque Assay to Evaluate in vitro Activity of Antiviral Compounds Against Human Coronaviruses 229E, OC43, and NL63.

Coronaviruses are important human pathogens, among which the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent for the COVID-19 pandemic. To combat the SARS-CoV-2 pandemic, there is a pressing need for antivirals, especially broad-spectrum antivirals that are active against all seven human coronaviruses (HCoVs). For this reason, we are interested in developing antiviral assays to expedite the drug discovery process. Here, we provide the detailed protocol for the cytopathic effect (CPE) assay and the plaque assay for human coronaviruses 229E (HCoV-229E), HCoV-OC43, and HCoV-NL63, to identify novel antivirals against HCoVs. Neutral red was used in the CPE assay, as it is relatively inexpensive and more sensitive than other reagents. Multiple parameters including multiplicity of infection, incubation time and temperature, and staining conditions have been optimized for CPE and plaque assays for HCoV-229E in MRC-5, Huh-7, and RD cell lines; HCoV-OC43 in RD, MRC-5, and BSC-1 cell lines, and HCoV-NL63 in Vero E6, Huh-7, MRC-5, and RD cell lines. Both CPE and plaque assays have been calibrated with the positive control compounds remdesivir and GC-376. Both CPE and plaque assays have high sensitivity, excellent reproducibility, and are cost-effective. The protocols described herein can be used as surrogate assays in the biosafety level 2 facility to identify entry inhibitors and protease inhibitors for SARS-CoV-2, as HCoV-NL63 also uses ACE2 as the receptor for cell entry, and the main proteases of HCoV-OC43 and SARS-CoV-2 are highly conserved. In addition, these assays can also be used as secondary assays to profile the broad-spectrum antiviral activity of existing SARS-CoV-2 drug candidates.

Comparative assessment of favipiravir and remdesivir against human coronavirus NL63 in molecular docking and cell culture models

Human coronavirus NL63 (HCoV-NL63) mainly affects young children and immunocompromised patients, causing morbidity and mortality in a subset of patients. Since no specific treatment is available, this study aims to explore the anti-SARS-CoV-2 agents including favipiravir and remdesivir for treating HCoV-NL63 infection. We first successfully modelled the 3D structure of HCoV-NL63 RNA-dependent RNA polymerase (RdRp) based on the experimentally solved SARS-CoV-2 RdRp structure. Molecular docking indicated that favipiravir has similar binding affinities to SARS-CoV-2 and HCoV-NL63 RdRp with LibDock scores of 75 and 74, respectively. The LibDock scores of remdesivir to SARS-CoV-2 and HCoV-NL63 were 135 and 151, suggesting that remdesivir may have a higher affinity to HCoV-NL63 compared to SARS-CoV-2 RdRp. In cell culture models infected with HCoV-NL63, both favipiravir and remdesivir significantly inhibited viral replication and production of infectious viruses. Overall, remdesivir compared to favipiravir is more potent in inhibiting HCoV-NL63 in cell culture. Importantly, there is no evidence of resistance development upon long-term exposure to remdesivir. Furthermore, combining favipiravir or remdesivir with the clinically used antiviral cytokine interferon-alpha resulted in synergistic effects. These findings provided a proof-of-concept that anti-SARS-CoV-2 drugs, in particular remdesivir, have the potential to be repurposed for treating HCoV-NL63 infection.

SARS-CoV-2 mRNA Vaccines Induce Broad CD4+ T cell Responses that Recognize SARS-CoV-2 Variants and HCoV-NL63

In this study, researchers analyzed the CD4+ T-cell responses to spike peptides from severe acute respiratory syndrome coronavirus 2 SARS-CoV-2 and 3 common cold coronaviruses (CCCs) before and after vaccination with Pfizer or Moderna messenger RNA (mRNA) coronavirus disease 2019 (COVID-19) vaccines to determine if the vaccine may be able to confer a T-cell response to SARS-CoV-2 variants and some endemic CCCs.Study participants included 30 healthy individuals who had not tested positive for COVID-19. They were vaccinated with either the Pfizer-BioNTech (BN162b2) or Moderna (MrNA-1273) mRNA COVID-19 vaccines. Some experiments were performed on smaller numbers of subjects for whom sufficient numbers of cells were available.Blood samples were studied to compare and quantify the frequency of virus-specific T cells before and after vaccination. Virus-specific T-cell responses to 3 CCCs (human coronavirus 229E, human coronavirus NL63 (HCoV-NL63), and human coronavirus OC43) were compared before and after vaccination. In the study, the researchers also compared antigen-specific T-cell responses of spike peptides from HCoV-NL63 and SARS-CoV-2. Finally, individual spike peptides targeted by CD4+ T cells were mapped and assayed so that distinct target peptides could be identified. The authors then determined if these spike peptide motifs were present in various coronaviruses, including 2 known COVID-19 variants: UK (B.1.1.7) and South African (B.1.351).The vaccines elicited a strong T-cell response against SARS-CoV-2, with a 74-fold increase in spot-forming units after vaccination. There was also an observed increase in T-cell response to HCoV-NL63, with a 3-fold increase in spot-forming units after vaccination. The results were similar when comparing the T-cell response to specific spike peptides of SARS-CoV-2 and HCoV-NL63 after vaccination: a 15-fold and 6.75-fold increase, respectively, in T cells coexpressing interferon γ and tumor necrosis factor α. Finally, the authors mapped 23 distinct peptides targeted by CD4+ T cells, one of which was conserved in many coronaviruses, including the ancestral COVID-19 virus and the B.1.1.7 and B.1.351 variants.The Pfizer-BioNTech (BN162b2) and Moderna (MrNA-1273) mRNA COVID-19 vaccines elicit strong T-cell responses to SARS-CoV-2. The vaccines elicited a significant increase in the response to HCoV-NL63, a common cold coronavirus, as well. The data, overall, suggest that the mRNA vaccines may provide protection against SARS-CoV-2 as well as some other common cold coronaviruses. The data also suggest that vaccine-elicited CD4+ T cells should recognize some of the widely circulating COVID-19 variants.With this study, the authors offer insight into the protection offered by the Pfizer and Moderna COVID-19 mRNA vaccines against COVID-19, its variants, and possibly common cold coronaviruses. This is important for the general pediatrician to understand as more children become eligible for vaccination against COVID-19. Therefore, it may be reasonable to educate parents on the positive implications of vaccination against COVID-19 and how vaccination may confer crossprotection against some COVID-19 variants and some common cold viruses.

Antiviral Activities of Halogenated Emodin Derivatives against Human Coronavirus NL63.

The current COVID-19 outbreak has highlighted the need for the development of new vaccines and drugs to combat Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2). Recently, various drugs have been proposed as potentially effective against COVID-19, such as remdesivir, infliximab and imatinib. Natural plants have been used as an alternative source of drugs for thousands of years, and some of them are effective for the treatment of various viral diseases. Emodin (1,3,8-trihydroxy-6-methylanthracene-9,10-dione) is a biologically active anthraquinone with antiviral activity that is found in various plants. We studied the selectivity of electrophilic aromatic substitution reactions on an emodin core (halogenation, nitration and sulfonation), which resulted in a library of emodin derivatives. The main aim of this work was to carry out an initial evaluation of the potential to improve the activity of emodin against human coronavirus NL63 (HCoV-NL63) and also to generate a set of initial SAR guidelines. We have prepared emodin derivatives which displayed significant anti-HCoV-NL63 activity. We observed that halogenation of emodin can improve its antiviral activity. The most active compound in this study was the iodinated emodin analogue E_3I, whose anti-HCoV-NL63 activity was comparable to that of remdesivir. Evaluation of the emodin analogues also revealed some unwanted toxicity to Vero cells. Since new synthetic routes are now available that allow modification of the emodin structure, it is reasonable to expect that analogues with significantly improved anti-HCoV-NL63 activity and lowered toxicity may thus be generated.

Research progress of human coronaviruses and associated eye diseases

Coronaviruses are RNA viruses. We should be alerted from the outbreak of the severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003, the discovery of the human coronavirus NL63 (HCoV-NL63) in 2004 and the pneumonia outbreak caused by the novel coronavirus in 2019 (2019-nCoV). Coronaviruses can adhere to mucous membranes of the eye, nose, mouth, respiratory tract and digestive tract through various media, which leads to inflammatory reaction, pulmonary fibrosis, kidney failure and death in severe cases. As an exposed organ, the eye can also be infected. With the progress of molecular technology and the in-depth research of coronaviruses, there have been seven known coronaviruses that can infect humans, among which HCoV-NL63, SARS-CoV and 2019-nCoV can cause eye diseases. This article summarizes and analyzes the latest research results at home and abroad concerning the structural characteristics, transmission routes, ocular pathogenic characteristics and treatment of HCoV-NL63, SARS-CoV and 2019-nCoV, in order to provide reference for clinical diagnosis and treatment. (Chin J Ophthalmol, 2021, 57: 871-875).

The optimization of an ultra-sensitive single molecule assay for the multiplexed detection of SARS-CoV-2 antigens

Abstract Introduction/Objective SARS-CoV-2 antigens, including the nucleocapsid (N) protein, spike protein, and its S1 subunit have served as key biomarkers for research and diagnostic purposes. We previously developed quantitative single molecule array (Simoa) assays to measure the concentration of spike, S1 subunit and N protein in plasma samples with femtomolar limits of detection. We aimed to test antibodies that were not available early in the pandemic, reduce assay cross-reactivity, develop a multiplexed assay for spike, S1, and N protein in order to minimize the sample volume needed. Methods/Case Report Using the Simoa platform, a bead-based digital enzyme-linked immunosorbent assay, we cross-tested 17 S1 subunit and spike antibodies for a total of 130 antibody-pair combinations, we performed dilution linearity experiments to determine the ideal dilution factor, spike and recovery experiments, tested the assay using S1 subunit from other human coronavirus HKV1, NL63, and 229E, pre-pandemic plasma samples from patients that were sick with viral or bacterial respiratory infections. We then used the best antibody pairs to measure S1 and spike in plasma samples collected from patients with severe SARS-CoV-2. Lastly, we conjugated the best-performing capture antibodies for spike, S1 and N to beads labeled with different fluorophores to test if the assay for all three antigens could be multiplexed. Results (if a Case Study enter NA) We observed no cross-reactivity with S1 from other coronavirus strains, no detection of S1 or spike in a cohort of 30 pre-pandemic samples and successfully developed a multiplexed assay for the detection of spike, S1, and N protein, enabling us to use 50% less sample volume. Conclusion Reduction of necessary sample volume is important for studies involving multisystem inflammatory syndrome in children (MIS-C), and possible adverse effects of SARS-CoV-2 vaccinations on children and young adults. An improved assay with minimal cross-reactivity will also be useful to study individuals with post-acute sequelae of SARS-CoV-2 infection (PASC).

Structural Insights on the SARS-CoV-2 Variants of Concern Spike Glycoprotein: A Computational Study With Possible Clinical Implications

Coronavirus disease 2019 (COVID-19) pandemic has been attributed to SARS-CoV-2 (SARS2) and, consequently, SARS2 has evolved into multiple SARS2 variants driving subsequent waves of infections. In particular, variants of concern (VOC) were identified to have both increased transmissibility and virulence ascribable to mutational changes occurring within the spike protein resulting to modifications in the protein structural orientation which in-turn may affect viral pathogenesis. However, this was never fully elucidated. Here, we generated spike models of endemic HCoVs (HCoV 229E, HCoV OC43, HCoV NL63, HCoV HKU1, SARS CoV, MERS CoV), original SARS2, and VOC (alpha, beta, gamma, delta). Model quality check, structural superimposition, and structural comparison based on RMSD values, TM scores, and contact mapping were all performed. We found that: 1) structural comparison between the original SARS2 and VOC whole spike protein model have minor structural differences (TM > 0.98); 2) the whole VOC spike models putatively have higher structural similarity (TM > 0.70) to spike models from endemic HCoVs coming from the same phylogenetic cluster; 3) original SARS2 S1-CTD and S1-NTD models are structurally comparable to VOC S1-CTD (TM = 1.0) and S1-NTD (TM > 0.96); and 4) endemic HCoV S1-CTD and S1-NTD models are structurally comparable to VOC S1-CTD (TM > 0.70) and S1-NTD (TM > 0.70) models belonging to the same phylogenetic cluster. Overall, we propose that structural similarities (possibly ascribable to similar conformational epitopes) may help determine immune cross-reactivity, whereas, structural differences (possibly associated with varying conformational epitopes) may lead to viral infection (either reinfection or breakthrough infection).

A proof of concept study for the differentiation of SARS-CoV-2, hCoV-NL63, and IAV-H1N1 in vitro cultures using ion mobility spectrometry

Rapid, high-throughput diagnostic tests are essential to decelerate the spread of the novel coronavirus disease 2019 (COVID-19) pandemic. While RT-PCR tests performed in centralized laboratories remain the gold standard, rapid point-of-care antigen tests might provide faster results. However, they are associated with markedly reduced sensitivity. Bedside breath gas analysis of volatile organic compounds detected by ion mobility spectrometry (IMS) may enable a quick and sensitive point-of-care testing alternative. In this proof-of-concept study, we investigated whether gas analysis by IMS can discriminate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from other respiratory viruses in an experimental set-up. Repeated gas analyses of air samples collected from the headspace of virus-infected in vitro cultures were performed for 5 days. A three-step decision tree using the intensities of four spectrometry peaks correlating to unidentified volatile organic compounds allowed the correct classification of SARS-CoV-2, human coronavirus-NL63, and influenza A virus H1N1 without misassignment when the calculation was performed with data 3 days post infection. The forward selection assignment model allowed the identification of SARS-CoV-2 with high sensitivity and specificity, with only one of 231 measurements (0.43%) being misclassified. Thus, volatile organic compound analysis by IMS allows highly accurate differentiation of SARS-CoV-2 from other respiratory viruses in an experimental set-up, supporting further research and evaluation in clinical studies.

Efficiency of coronavirus inactivation on environmental surfaces: A comparison study of two available disinfectants

Background: There are many coronaviruses of significant medical and veterinary concern, all of which are the result of spillover from another species. Disinfection of healthcare and veterinary environments is an important factor in limiting the transmission of coronaviruses. Disinfection agents for coronaviruses use bleach, quaternary compounds, hydrogen peroxide, and sodium hydroxide. Product labels list contact times that range from 10-30 minutes for total inactivation. Decon7 is a combination disinfectant that is currently used in the food and agriculture, medical facilities, and other industries. While Decon7 has been shown to inactivate a variety of pathogens and disrupt biofilms, its effectiveness and rate of coronavirus inactivation has not been evaluated.Objective: This project sought to evaluate Decon7’s effectiveness and rate of coronavirus inactivation.Methods: This study evaluated the disinfection efficacy of Decon7 (diluted at 1:4) and bleach (diluted at 1:10) after 3 coronaviruses (SARS-CoV-2, HCoV OC43, and HCoV NL63) were inoculated onto up to sixteen environmental surface materials.Results: A 1:4 dilution of Decon7 inactivated all coronaviruses on all surfaces with 1 minute contact time. A 1:10 dilution of bleach was not effective in inactivating coronaviruses with a contact time of 1 minute on all surfaces.Conclusions: New technologies and chemistries may offer more efficient inactivation of pathogens on environmental surfaces. These disinfection methods and materials, which require less than 10 minutes contact time, may improve the efficacy of cleaning and disinfecting surfaces in the built environment.

Changes in influenza and other respiratory virus activity during the COVID-19 pandemic—United States, 2020–2021

The COVID-19 pandemic and subsequent implementation of nonpharmaceutical interventions (e.g., cessation of global travel, mask use, physical distancing, and staying home) reduced the transmission of some viral respiratory pathogens.1 In the United States, influenza activity decreased in March 2020, was historically low through the summer of 2020,2 and remained low during October 2020–May 2021 (<0.4% of respiratory specimens with positive test results for each week of the season). Circulation of other respiratory pathogens, including respiratory syncytial virus (RSV), common human coronaviruses (HCoVs) types OC43, NL63, 229E, and HKU1, and parainfluenza viruses (PIVs) types 1–4 also decreased in early 2020 and did not increase until spring 2021.

Crystal structures of human coronavirus NL63 main protease at different pH values.

Human coronavirus NL63 (HCoV-NL63), which belongs to the genus Alphacoronavirus, mainly infects children and the immunocompromized and is responsible for a series of clinical manifestations, including cough, fever, rhinorrhoea, bronchiolitis and croup. HCoV-NL63, which was first isolated from a seven-month-old child in 2004, has led to infections worldwide and accounts for 10% of all respiratory illnesses caused by etiological agents. However, effective antivirals against HCoV-NL63 infection are currently unavailable. The HCoV-NL63 main protease (Mpro), also called 3C-like protease (3CLpro), plays a vital role in mediating viral replication and transcription by catalyzing the cleavage of replicase polyproteins (pp1a and pp1ab) into functional subunits. Moreover, Mpro is highly conserved among all coronaviruses, thus making it a prominent drug target for antiviral therapy. Here, four crystal structures of HCoV-NL63 Mpro in the apo form at different pH values are reported at resolutions of up to 1.78 Å. Comparison with Mpro from other human betacoronaviruses such as SARS-CoV-2 and SARS-CoV reveals common and distinct structural features in different genera and extends knowledge of the diversity, function and evolution of coronaviruses.