Middle East respiratory syndrome

Nuclear shuttling of CDC4 mediated broad-spectrum antiviral activity against diverse coronaviruses

Pandemics of coronavirus (CoV)-related infection have been a major issue since the outbreaks of SARS, MERS and COVID-2019 in the past decades, leading a substantial threat to public health. Porcine deltacoronavirus (PDCoV), a new swine coronavirus, causes enteropathogenic disease characterized by acute diarrhea, vomiting and dehydration in suckling piglets and poses potential risks of cross-species transmission. Here we reveal a novel function of CDC4 protein in restricting PDCoV infection. Ectopic expression of CDC4 suppresses PDCoV replication, whereas knockdown of CDC4 expression enhances PDCoV infection. Importantly, it was revealed that PDCoV encoded nucleocapsid (N) was involved in CDC4 nuclear-cytoplasmic shuttling, which was critical for CDC4 to exert the antiviral activity against PDCoV replication. Mechanistically, PDCoV N protein was detected to specifically interact with RIG-I to antagonize RIG-I-like receptor (RLR)-mediated IFN-β production, leading to disruptions of host innate immune defense. Meanwhile, CDC4 was proved to interact with PDCoV N protein and disrupted the interaction between PDCoV N and RIG-I, resulting in alleviated antagonism of IFN-β production mediated by PDCoV N. Similarly, a broad-spectrum inhibitory effects of CDC4 on N mediated antagonism were confirmed by the shared mechanisms among the different coronaviruses from Coronaviridae family, such as transmissible gastroenteritis virus (TGEV) from Alphacoronavirus (α-CoV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) from Betacoronavirus (β-CoV). Therefore, a novel antiviral role of CDC4 was elucidated that CDC4 competes binding with CoVs N proteins to suppress CoVs N mediated antagonism of RLR associated signaling pathway in the context of diverse coronavirus infections.

Outcomes of Home Isolation Care Among COVID-19 Patients During the 2021 Epidemic Crisis in the Bangkok Metropolitan Region, Thailand

Objectives. To determine the overall mortality and risk factors of COVID-19 patients who were admitted to the Home Isolation (HI) program in Bangkok, Thailand, during the epidemic crisis in 2021. Methods. We conducted a retrospective cohort study using the data from a government telehealth application from July to December 2021. The vital status was verified from the government database on September 20, 2022. We used survival analysis to analyze the 28-day mortality and independently associated factors. Results. Of 90 854 reported cases, the average age was 37.27 years, and half were men. Initial symptoms included being asymptomatic (51.66%), having mild symptoms (35.60%), or experiencing severe symptoms requiring nonurgent (11.27%) or urgent referral (1.47%). The 28-day mortality rate was 0.80%. Factors associated with 28-day mortality included older age, male gender, higher body mass index, severity of initial symptoms, and time to admission. Conclusions. The Home Isolation program was able to manage a high volume of patients, including severe cases, exceeding its initial design. Thailand's COVID-19 mortality rate remained relatively low compared with other countries. Proactive bed surge planning and continuous plan improvement were crucial for future preparedness. (Am J Public Health. 2025;115(4):605-616. https://doi.org/10.2105/AJPH.2024.307922).

Genetic and pathogenic characteristics of a novel recombinant GI-19 infectious bronchitis virus strain isolated from northeastern China

Since the 1980s, despite vaccination, the infectious bronchitis virus (IBV) infection rate in commercial broilers and layers in China has continued to rise significantly, causing substantial economic losses to the poultry industry. In this study, an IBV strain was isolated from a layer farm in northeast China and named CK/CH/LN/2302. The whole genome sequence analysis revealed that CK/CH/LN/2302 shared a high level of homology (96.41 %) with the GI-19 strain SC/SDL/19. The phylogenetic tree based on the S1 gene indicates that CK/CH/LN/2302 belongs to the GI-19 lineage. Notably, recombination analysis using RDP5 and SimPlot software suggested that the GI-19 strain and a 4/91-like strain likely contributed to four recombination events in the CK/CH/LN/2302 genome. Phylogenetic analysis of these four regions further supported this conclusion. Protein structure analysis revealed that most of the nonstructural protein 2 (nsp2), main protease (Mpro), S1, and 5a protein regions were replaced by sequences from the 4/91-like strain. After infecting 1-day-old SPF chickens, CK/CH/LN/2302 presented a mortality rate as high as 60 %. Higher viral loads were detected in tissues such as the larynx, trachea, lungs, duodenum, jejunum and kidneys, indicating the multitissue tropism of this strain. Neutralization assay results revealed that the serum from 28-day-old commercial chickens immunized with the H120 vaccine was unable to effectively neutralize CK/CH/LN/2302. Compared with the S1 subunit of H120, CK/CH/LN/2302 demonstrated conformational changes, particularly in the hypervariable regions (HVRs), which may facilitate immune evasion. The genetic characteristics and pathogenicity of CK/CH/LN/2302 highlight the ongoing evolution of GI-19 IBV strains in China, emphasizing the urgent need for appropriate control strategies.

Structural Changes at the Zinc Active Site of ACE2 on Binding the SARS-CoV-2 Spike Protein Receptor Binding Domain

The causative agent of Covid-19 is the SARS-CoV-2 virus. Initiation of cell entry by SARS-CoV-2 is critically dependent upon binding of the SARS-CoV-2 spike protein to angiotensin-converting enzyme 2 (ACE2, EC 3.4.17.23). The mechanism of binding of the SARS-CoV-2 spike receptor binding domain to ACE2 is among the most intensively studied infection mechanisms of any pathogen, including a very large number of structural studies. ACE2 is a membrane-associated zinc carboxypeptidase, comprising three domains, the protease domain, a neck domain, and a membrane-spanning α-helical domain. In addition to its role as a carboxypeptidase, ACE2 is also a chaperone for a Na+-amino acid cotransporter called B0AT1, and in the presence of B0AT1, full-length ACE2 forms dimers. Most studies to date related to Covid-19 have employed just the ACE2 protease domain and have neglected any possible roles of the Zn2+-containing ACE2 active site. We show here that ACE2, including the neck domain in addition to the protease domain (and in the absence of B0AT1), is dimeric and shows distinctive allostery in its catalytic activity. In contrast, the intensively studied protease domain is monomeric and shows no allostery. Binding of the spike receptor binding domain (RBD) to dimeric ACE2 eliminates its allostery. X-ray absorption spectroscopy of Zn2+ ACE2 shows distinctive changes in the active site structure upon binding of spike RBD but only in the dimeric form. Taken together, our results indicate that the Zn2+-containing active site exhibits a notable level of flexibility and that the dimeric form of ACE2, including both protease and neck domains, likely presents a superior model for the study of ACE2-spike interactions than the monomeric ACE2.

The effect of COVID-19 pandemic on new-onset adult diabetes and its one-year follow-up

AIMS

Bidirectional detrimental relationships between COVID-19 infection and diabetes have been described globally. However, new-onset diabetes in adults and its follow-up during the pandemic have not been sufficiently investigated. In this study, new-onset autoimmune and type 2 diabetes cases during the pandemic were compared to those before the pandemic, and the clinical course of new-onset diabetes during the pandemic was examined.

METHODS

In this single-center retrospective cohort study, clinical and laboratory characteristics of new-onset diabetes patients before the pandemic (n = 161) and during the pandemic (n = 144) were evaluated between March 2018 and March 2022.

RESULTS

A 1.85-fold increase in new-onset adult diabetes cases was observed during the pandemic compared to pre-pandemic period (p = 0.010), while the proportion of autoimmune and type 2 diabetes (T2D) did not change. During the pandemic, there was a 6.2-fold increase in autoimmune diabetes presented with DKA (p = 0.003). Insulin was preferred 1.7 times more frequently as initial treatment during the pandemic (p = 0.014), and mean HbA1c (p = 0.003) and C-peptide (p = 0.010) were higher. Clinical and laboratory data did not differ between PCR (+) and PCR (-) patients. At one-year follow-up, while only HbA1c decreased in the autoimmune diabetes; in T2D group fasting glucose, HbA1c, C-peptide, and lipid profile were significantly improved.

CONCLUSIONS

The pandemic led to increased new-onset adult diabetes presented with DKA. However, clinical and laboratory features were similar between PCR positive and negative cases. PCR-confirmed COVID-19 may not adversely affect the medium-term clinical course of new diabetes in adults.

Aptamer and DNAzyme Based Colorimetric Biosensors for Pathogen Detection

The detection of pathogens is critical for preventing and controlling health hazards across clinical, environmental, and food safety sectors. Functional nucleic acids (FNAs), such as aptamers and DNAzymes, have emerged as versatile molecular tools for pathogen detection due to their high specificity and affinity. This review focuses on the in vitro selection of FNAs for pathogens, with emphasis on the selection of aptamers for specific biomarkers and intact pathogens, including bacteria and viruses. Additionally, the selection of DNAzymes for bacterial detection is discussed. The integration of these FNAs into colorimetric biosensors has enabled the development of simple, cost-effective diagnostic platforms. Both non-catalytic and catalytic colorimetric biosensors are explored, including those based on gold nanoparticles, polydiacetylenes, protein enzymes, G-quadruplexes, and nanozymes. These biosensors offer visible detection through color changes, making them ideal for point-of-care diagnostics. The review concludes by highlighting current challenges and future perspectives for advancing FNA-based colorimetric biosensing technologies for pathogen detection.

Conformational dynamics of the membrane protein of MERS-CoV in comparison with SARS-CoV-2 in ERGIC complex

The present study explores the conformational dynamics of the membrane protein of Middle East Respiratory Syndrome Coronavirus (MERS-CoV) within the Endoplasmic Reticulum-Golgi Intermediate Compartment (ERGIC) complex using an all-atomistic molecular dynamics simulation approach. Significant structural changes were observed in the N-terminal, C-terminal, transmembrane, and beta-sheet sandwich domains of the MERS-CoV membrane protein. This study also highlights the structural similarities between the MERS-CoV and the SARS-CoV-2 membrane proteins, particularly in how both exhibit a distinct kink in the transmembrane helix caused by aromatic residue-lipid interactions. A structural expansion below the transmembrane and above the beta-sheet sandwich domain within the dimer was observed in all the M-proteins. This site on the beta-sheet sandwich domains near the C-terminal end could serve as a potential drug-binding site. Notably, a stable helical structure was identified in the C-terminal domain of the MERS-CoV membrane protein, whereas a proper secondary structural conformation was not observed in the SARS-CoV-2 membrane protein. Further, the SARS-CoV-2 membrane protein exhibited stronger binding to the lipid bilayer than the MERS-CoV, indicating its greater structural stability within the ERGIC complex. The structural similarity between the membrane protein of MERS-CoV and SARS-CoV-2 suggests the feasibility of employing a common inhibitor against these beta-coronaviruses. Furthermore, this analysis enhances our understanding of the membrane protein's interactions with proteins and lipids, paving the way for therapeutic developments against these viruses.

Ongoing Evolution of Middle East Respiratory Syndrome Coronavirus, Saudi Arabia, 2023-2024

Middle East respiratory syndrome coronavirus (MERS-CoV) circulates in dromedary camels in the Arabian Peninsula and occasionally causes spillover infections in humans. MERS-CoV diversity is poorly understood because of the lack of sampling during the COVID-19 pandemic. We collected 558 swab samples from dromedary camels in Saudi Arabia during November 2023-January 2024. We found 39% were positive for MERS-CoV RNA by reverse transcription PCR. We sequenced 42 MERS-CoVs and 7 human 229E-related coronaviruses from camel swab samples by using high-throughput sequencing. Sequences from both viruses formed monophyletic clades apical to recently available genomes. MERS-CoV sequences were most similar to B5 lineage sequences and harbored unique genetic features, including novel amino acid polymorphisms in the spike protein. Further characterization will be required to understand their effects. MERS-CoV spillover into humans poses considerable public health concerns. Our findings indicate surveillance and phenotypic studies are needed to identify and monitor MERS-CoV pandemic potential.

How did home care nurses support COVID-19 patients in Japan? A qualitative study

AIM

Home care nurses support patients with COVID-19 with mild to moderate symptoms at home due to the lack of community-based support. Little is known about how nurses initiated and maintained support for patients with COVID-19. This study explored the experiences of home care nurses in supporting patients with COVID-19 at home.

METHODS

Using snowball sampling, 21 home care nurses participated in semi-structured interviews conducted either in person or online between September 2021 and February 2023. A qualitative study using a grounded theory approach was conducted.

RESULTS

Home care nurses faced a situation where "suffering patients are overflowing" due to inadequate support from public health centers and designated hospitals. Despite their anxiety, they acted as a "flexible safety net by quickly compensating for uncertain support systems" for patients, families, and local health workers. They "built tentative support systems immediately" and "updated tentative support systems, own knowledge, skills, and mindset." Home care nurses also "rushed to patient/family" to provide timely support and "avoided preventable death."

CONCLUSIONS

Home care nurses act as a flexible safety net, preventing patient deaths by quickly compensating for uncertain support systems before and after initiating care. Their efforts complemented the inadequacies of traditional infectious disease control systems, typically managed by public health centers. Strengthening secondary and tertiary prevention systems is essential for home care nurses to save lives while delivering individualized care during the COVID-19 pandemic.

Covalent DNA-Encoded Library Workflow Drives Discovery of SARS-CoV-2 Nonstructural Protein Inhibitors

The COVID-19 pandemic, exacerbated by persistent viral mutations, underscored the urgent need for diverse inhibitors targeting multiple viral proteins. In this study, we utilized covalent DNA-encoded libraries to discover innovative triazine-based covalent inhibitors for the 3-chymotrypsin-like protease (3CLpro, Nsp5) and the papain-like protease (PLpro) domains of Nsp3, as well as novel non-nucleoside covalent inhibitors for the nonstructural protein 12 (Nsp12, RdRp). Optimization through molecular docking and medicinal chemistry led to the development of LU9, a nonpeptide 3CLpro inhibitor with an IC50 of 0.34 μM, and LU10, whose crystal structure showed a distinct binding mode within the 3CLpro active site. The X-ray cocrystal structure of SARS-CoV-2 PLpro in complex with XD5 uncovered a previously unexplored binding site adjacent to the catalytic pocket. Additionally, a non-nucleoside covalent Nsp12 inhibitor XJ5 achieved a potency of 0.12 μM following comprehensive structure-activity relationship analysis and optimization. Molecular dynamics revealed a potential binding mode. These compounds offer valuable chemical probes for target validation and represent promising candidates for the development of SARS-CoV-2 antiviral therapies.

Evolutionary Relationships of Unclassified Coronaviruses in Canadian Bat Species

Bats are recognized as natural reservoirs for an array of diverse viruses, particularly coronaviruses, which have been linked to major human diseases like SARS-CoV and MERS-CoV. These viruses are believed to have originated in bats, highlighting their role in virus ecology and evolution. Our study focuses on the molecular characterization of bat-derived coronaviruses (CoVs) in Canada. Tissue samples from 500 bat specimens collected in Canada were analyzed using pan-coronavirus RT-PCR assays to detect the presence of CoVs from four genera: Alpha-CoVs, Beta-CoV, Gamma-CoV, and Delta-CoV. Phylogenetic analysis was performed targeting the RNA-dependent RNA polymerase (RdRP) gene. Our results showed an overall 1.4% CoV positivity rate in our bat sample size. Phylogenetic analysis based on the ~600 bp sequences led to the identification of an unclassified subgenus of Alpha-CoV, provisionally named Eptacovirus. The findings contribute to a better understanding of the diversity and evolution of CoVs found in the bat species of Canada. The current study underscores the significance of bats in the epidemiology of CoVs and enhances the knowledge of their genetic diversity and potential impact on global public health.

Detection and Prevalence of Coronaviruses in European Bats: A Systematic Review

Bats are known hosts for a wide range of coronaviruses (CoVs), including those that cause severe acute respiratory syndrome (SARS-CoV-1) and Middle East respiratory syndrome (MERS-CoV). With the emergence of the COVID-19 pandemic caused by the SARS-CoV-2 virus, it has become increasingly important to understand the diversity and prevalence of CoVs in bat populations. This systematic review aimed to compile studies that have sampled CoVs from bats across Europe and assessed various aspects related to the testing of bat samples, including the country where the bats were collected, the CoV genomic region studied, the CoV genera that were detected, and the identification of bat species that were found to be carrying CoV. We identified 30 studies that assessed CoVs presence in bats across multiple countries including Italy, Germany, and various other nations with one or two studies each, which tested them for CoVs using a variety of matrices. CoVs were found in nine genera of bats, and the genomic regions included RdRp, ORF1a gene, as well as full genome, detecting α- and/or β-CoVs, with most of them being detectable only in faeces. This review provides a comprehensive overview of the CoVs detected in bats across Europe and highlights the importance of continued surveillance and monitoring of bat populations for potential emerging zoonotic CoVs.

Lung-Selective Delivery of mRNA-Encoding Anti-MERS-CoV Nanobody Exhibits Neutralizing Activity Both In Vitro and In Vivo

Background/Objectives: The Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is a highly pathogenic virus causing severe respiratory illness, with limited treatment options that are mostly supportive. The success of mRNA technology in COVID-19 vaccines has opened avenues for antibody development against MERS-CoV. mRNA-based antibodies, expressed in vivo, offer rapid adaptability to viral mutations while minimizing long-term side effects. This study aimed to develop a lung-targeted lipid nanoparticle (LNP) system for mRNA-encoding neutralizing nanobodies against MERS-CoV, proposing a novel therapeutic strategy. Methods: An mRNA-encoding nanobody NbMS10 (mRNA-NbMS10) was engineered for enhanced stability and reduced immunogenicity. This mRNA was encapsulated in lung-selective LNPs using microfluidics to form the LNP-mRNA-NbMS10 system. Efficacy was assessed through in vitro assays and in vivo mouse studies, focusing on antigen-binding, neutralization, and sustained nanobody expression in lung tissues. Results: The LNP-mRNA-NbMS10 system expressed the nanobody in vitro, showing strong antigen-binding and significant MERS-CoV pseudovirus neutralization. In vivo studies confirmed selective lung mRNA delivery, with high nanobody expression sustained for up to 24 h, confirming lung specificity and prolonged antiviral activity. Conclusions: Extensive in vitro and in vivo evaluations demonstrate the LNP-mRNA-NbMS10 system's potential as a scalable, cost-effective, and adaptable alternative to current MERS-CoV therapies. This innovative platform offers a promising solution for preventing and treating respiratory infections, and countering emerging viral threats.

The links between dietary diversity and RNA virus diversity harbored by the great evening bat (Ia io)

BACKGROUND

Predator‒prey interactions and their dynamic changes provide frequent opportunities for viruses to spread among organisms and thus affect their virus diversity. However, the connections between dietary diversity and virus diversity in predators have seldom been studied. The avivorous bats, Ia io, show a seasonal pattern of dietary diversity. Although most of them primarily prey on insects in summer, they mainly prey on nocturnally migrating birds in spring and autumn.

RESULTS

In this study, we characterized the RNA virome of three populations of I. io in Southwest China during summer and autumn using viral metatranscriptomic sequencing. We also investigated the relationships between dietary diversity and RNA virus diversity by integrating DNA metabarcoding and viral metatranscriptomic sequencing techniques at the population level of I. io. We found 55 known genera belonging to 35 known families of RNA viruses. Besides detecting mammal-related viruses, which are the usual concern, we also found a high abundance of insect-related viruses and some bird-related viruses. We found that insect-related viruses were more abundant in summer, while the bird-related viruses were predominantly detected in autumn, which might be caused by the seasonal differences in prey selection by I. io. Additionally, a significant positive correlation was identified between prey diversity and total virus diversity. The more similar the prey composition, the more similar the total virus composition and the higher the count of potential new viruses. We also found that the relative abundance of Picornaviridae increased with increasing prey diversity and body mass.

CONCLUSIONS

In this study, significant links were found between RNA virus diversity and dietary diversity of I. io. The results implied that dynamic changes in predator-prey interactions may facilitate frequent opportunities for viruses to spread among organisms. Video Abstract.

Interaction between coronaviruses and the autophagic response

In recent years, the emergence and widespread dissemination of the coronavirus SARS-CoV-2 has posed a significant threat to global public health and social development. In order to safely and effectively prevent and control the spread of coronavirus diseases, a profound understanding of virus-host interactions is paramount. Cellular autophagy, a process that safeguards cells by maintaining cellular homeostasis under diverse stress conditions. Xenophagy, specifically, can selectively degrade intracellular pathogens, such as bacteria, fungi, viruses, and parasites, thus establishing a robust defense mechanism against such intruders. Coronaviruses have the ability to induce autophagy, and they manipulate this pathway to ensure their efficient replication. While progress has been made in elucidating the intricate relationship between coronaviruses and autophagy, a comprehensive summary of how autophagy either benefits or hinders viral replication remains elusive. In this review, we delve into the mechanisms that govern how different coronaviruses regulate autophagy. We also provide an in-depth analysis of virus-host interactions, particularly focusing on the latest data pertaining to SARS-CoV-2. Our aim is to lay a theoretical foundation for the development of novel coronavirus vaccines and the screening of potential drug targets.

Acquisition of a multibasic cleavage site does not increase MERS-CoV entry into Calu-3 human lung cells

Human-to-human transmission of the highly pathogenic Middle East respiratory syndrome coronavirus (MERS-CoV) is currently inefficient. However, there is concern that the virus might mutate and thereby increase its transmissibility and thus pandemic potential. The pandemic SARS-CoV-2 depends on a highly cleavable furin motif at the S1/S2 site of the viral spike (S) protein for efficient lung cell entry, transmission, and pathogenicity. Here, by employing pseudotyped particles, we investigated whether augmented cleavage at the S1/S2 site also increases MERS-CoV entry into Calu-3 human lung cells. We report that polymorphism T746K at the S1/S2 cleavage site or optimization of the furin motif increases S protein cleavage but not lung cell entry. These findings suggest that, unlike what has been reported for SARS-CoV-2, a highly cleavable S1/S2 site might not augment MERS-CoV infectivity for human lung cells.IMPORTANCEThe highly cleavable furin motif in the spike protein is required for robust lung cell entry, transmission, and pathogenicity of SARS-CoV-2. In contrast, it is unknown whether optimization of the furin motif in the spike protein of the pre-pandemic MERS-CoV increases lung cell entry and allows for robust human-human transmission. The present study indicates that this might not be the case. Thus, neither a naturally occurring polymorphism that increased MERS-CoV spike protein cleavage nor artificial optimization of the cleavage site allowed for increased spike-protein-driven entry into Calu-3 human lung cells.

Elucidating the role of PPARG inhibition in enhancing MERS virus immune response: A network pharmacology and computational drug discovery

BACKGROUND

Middle East Respiratory Syndrome (MERS) has become a severe zoonotic disease, posing significant public health concerns due to the lack of specific medications. This urgently demands the development of novel therapeutic molecules. Understanding MERS's genetic underpinnings and potential therapeutic targets is crucial for developing effective treatments.

METHODS

Two gene expression datasets (GSE81909 and GSE100504) were analyzed to identify differentially expressed genes (DEGs) using GEO2R. Furthermore, gene ontology (GO), pathway enrichment analysis, and protein-protein interaction (PPI) network were performed to understand the gene's functions. A possible drug target was identified, and an FDA-approved drug library was screened against the selected target using molecular docking and validated the findings through molecular dynamics simulation, principal component analysis, free energy landscape, and MM/GBSA calculations.

RESULTS

The study on GSE81909 and GSE100504 datasets with icMERS and MOCK samples at 24 and 48 h revealed an upregulation in 73 and 267 DEGs, respectively. In the network pharmacology, STAT1, MX1, DDX58, EIF2AK2, ISG15, IFIT1, IFIH1, OAS1, IRF9, and OASL were identified as the top 10 hub genes. STAT1 was identified as the most connected hub gene among these top 10 hub genes, which plays a crucial role in the immune response to the MERS virus. Further study on STAT1 showed that PPARG helps reduce STAT1, which could modulate the immune response. Therefore, by inhibiting PPARG, the immunological response can be successfully enhanced. The known inhibitor of PPARG, 570 (Farglitazar), was used as a control. Further, screening using Tanimoto and K-mean clustering was performed, from which three compounds were identified: 2267, 3478, and 40326. Compound 3478 showed characteristics similar to the control, indicating robust binding to PPARG. 3478 showed the highest negative binding free energy with -41.20 kcal/mol, indicating strong binding with PPARG.

CONCLUSIONS

These findings suggest that 3478 promises to be a potential inhibitor of PPARG, and further experimental investigations can explore its potential as a MERS inhibitor.

The time between symptom onset and various clinical outcomes: a statistical analysis of MERS-CoV patients in Saudi Arabia

In this study, we investigate the impact of demographic characteristics on Middle East respiratory syndrome coronavirus (MERS-CoV) cases in Saudi Arabia, specifically focusing on the time intervals between symptom onset and key events such as hospitalization, case confirmation, reporting and death. We estimate these intervals using data from 2196 cases occurring between June 2012 and January 2020, partitioning the data into four age groups (0-24 years, 25-49 years, 50-74 years and 75-100 years). The duration from symptom onset to hospitalization varies between age cohorts, ranging from 4.03 to 4.75 days, with the 75-100 age group experiencing the longest delay. The interval from symptom onset to case confirmation spans 5.83-8.24 days, and again, the 75-100 age group faces the lengthiest delay. The interval from symptom onset and case reporting ranges from 7.0 to 9.8 days, with the 75-100 age group experiencing the longest delay. The period from symptom onset to death varies across age groups (12.3-16.1 days), with elevated mortality rates during outbreaks. Importantly, we observe age-based differences in the risk of hospitalization and other measures of infection severity, including the probability of death conditional on hospitalization. Careful quantification of epidemiological characteristics, including inference of key epidemiological periods and assessments of differences between cases of different ages, plays a crucial role in understanding the progression of MERS-CoV outbreaks and formulating effective public health strategies to mitigate their impact.

Antiseptics: An expeditious third force in the prevention and management of coronavirus diseases

Notably, severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS) and coronavirus disease 2019 (COVID-19) have all had significant negative impact on global health and economy. COVID-19 alone, has resulted to millions of deaths with new cases and mortality still being reported in its various waves. The development and use of vaccines have not stopped the transmission of SARS coronavirus 2 (SARS-CoV-2), the etiological agent of COVID-19, even among vaccinated individuals. The use of vaccines and curative drugs should be supplemented with adoption of simple hygiene preventive measures in the fight against the spread of the virus, especially for healthcare workers. Several virucidal topical antiseptics, such as povidone-iodine (PVP-I), citrox, cyclodextrins among others, have been demonstrated to be efficacious in the inactivation of SARS-CoV-2 and other coronaviruses in both in vitro and in vivo studies. The strategic application of these virucidal formulations could provide the additional impetus needed to effectively control the spread of the virus. We have here presented a simple dimension towards curtailing the dissemination of COVID-19, and other coronaviruses, through the application of effective oral, nasal and eye antiseptics among patients and medical personnel. We have further discussed the mechanism of action of some of these commonly available virucidal solutions while also highlighting some essential controversies in their use.

Cold-adapted live attenuated MERS-CoV vaccine strain remains attenuated in mice after multiple passages in Vero cells at 37 °C

Middle East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic disease affecting camels and humans. The live attenuated vaccine represents a candidate human vaccine because it can induce strong immune responses in immunized hosts. The attenuated vaccine strain of the highly pathogenic virus can also be used to produce a cell-based vaccine in the BSL2 GMP facility. In this study, we evaluated the reversion potential of pathogenicity to pathogenic wild-type virus to ensure the safety of the live attenuated vaccine strain. We passaged our previously developed cold-adapted live attenuated MERS-CoV vaccine strain at 22 °C (EMC2012-CA22°C) in Vero cells at 37 °C as often as 15 times to determine the potential of pathogenicity reversion in hDPP4 (human dipeptidyl peptidase 4)-transgenic mice, K18-hDPP4. The serial passage of EMC2012-CA22°C in Vero cells at 37 °C up to 15 times did not result in pathogenicity reversion to wild-type MERS-CoV. In K18-hDPP4 mice infected with this virus, no weight loss or mortality was observed, and no virus was detected in tissues such as the lung, kidney, brain, and nasal turbinate. In addition, mice immunized with this virus produced a robust neutralizing antibody response and were fully protected from lethal challenge with wild-type MERS-CoV. The cold-adapted attenuated MERS-CoV vaccine strain (EMC2012-CA22°C) was not reverted to wild-type pathogenic virus after 15 passages in Vero cells at 37 °C.

Middle East Respiratory Syndrome Coronavirus Could be a Priority Pathogen to Cause Public Health Emergency: Noticeable Features and Counteractive Measures

Middle East respiratory syndrome (MERS) is caused by a specific strain of the 6 types of human coronaviruses (HCoV). MERS-CoV has spread unchecked since it was first discovered in Saudi Arabia in 2012. The virus most likely spreads through nosocomial and zoonotic channels. Genetic analyses suggest that bats were the initial hosts and that the disease spread to camels. Person-to-person transmission occurs with varying frequency, being most prevalent in clinical settings and the least common among the general population and among close relatives. Due to the severity of the illness, high fatality rate, potential for epidemic spread, and lack of adequate medical countermeasures, the World Health Organization (WHO) continues to list MERS-CoV as a priority pathogen. While no specific antiviral medicines exist, a combination of antivirals has shown promise in recent clinical trials. Vaccines against MERS-CoV are critically needed and are currently being developed. Early diagnosis and implementing appropriate infection control measures are keys to preventing hospital-associated outbreaks. Preventive measures include avoiding raw or undercooked meats and other animal products, ensuring proper hand hygiene in healthcare settings and around dromedaries, educating the public and healthcare personnel about the disease, and adhering to other recommended practices. Countries with a high prevalence of MERS should adhere to regulations designed to limit the transmission of the virus. The recent spread of MERS-CoV highlights the importance of public awareness regarding the significance of reporting symptoms so that appropriate control measures can be adopted. The narrative review discusses the incidence of MERS, its clinical presentation, potential transmission routes, recent reports, preventative and control measures, and current therapeutic options.

The Interplay between Airway Cilia and Coronavirus Infection, Implications for Prevention and Control of Airway Viral Infections

Coronaviruses (CoVs) are a class of respiratory viruses with the potential to cause severe respiratory diseases by infecting cells of the upper respiratory tract, bronchial epithelium, and lung. The airway cilia are distributed on the surface of respiratory epithelial cells, forming the first point of contact between the host and the inhaled coronaviruses. The function of the airway cilia is to oscillate and sense, thereby defending against and removing pathogens to maintain the cleanliness and patency of the respiratory tract. Following infection of the respiratory tract, coronaviruses exploit the cilia to invade and replicate in epithelial cells while also damaging the cilia to facilitate the spread and exacerbation of respiratory diseases. It is therefore imperative to investigate the interactions between coronaviruses and respiratory cilia, as well as to elucidate the functional mechanism of respiratory cilia following coronavirus invasion, in order to develop effective strategies for the prevention and treatment of respiratory viral infections. This review commences with an overview of the fundamental characteristics of airway cilia, and then, based on the interplay between airway cilia and coronavirus infection, we propose that ciliary protection and restoration may represent potential therapeutic approaches in emerging and re-emerging coronavirus pandemics.

Immunological characterization and comparison of children with COVID-19 from their adult counterparts at single-cell resolution

Introduction

The immunological characteristics that could protect children with coronavirus disease 2019 (COVID-19) from severe or fatal illnesses have not been fully understood yet.

Methods

Here, we performed single-cell RNA sequencing (scRNA-seq) analysis on peripheral blood samples of 15 children (8 with COVID-19) and compared them to 18 adults (13 with COVID-19).

Results

The child-adult integrated single cell data indicated that children with the disease presented a restrained response to type I interferon in most of the major immune cell types, along with suppression of upstream interferon regulatory factor and toll-like receptor expression in monocytes, which was confirmed by in vitro interferon stimulation assays. Unlike adult patients, children with COVID-19 showed lower frequencies of activated proinflammatory CD14+ monocytes, possibly explaining the rareness of cytokine storm in them. Notably, natural killer (NK) cells in pediatric patients displayed potent cytotoxicity with a rich expression of cytotoxic molecules and upregulated cytotoxic pathways, whereas the cellular senescence, along with the Notch signaling pathway, was significantly downregulated in NK cells, all suggesting more robust cytotoxicity in NK cells of children than adult patients that was further confirmed by CD107a degranulation assays. Lastly, a modest adaptive immune response was evident with more naïve T cells but less activated and proliferated T cells while less naïve B cells but more activated B cells in children over adult patients.

Conclusion

Conclusively, this preliminary study revealed distinct cell frequency and activation status of major immune cell types, particularly more robust NK cell cytotoxicity in PBMC that might help protect children from severe COVID-19.

Mathematical assessment of control strategies against the spread of MERS-CoV in humans and camels in Saudi Arabia

A new mathematical model for the transmission dynamics and control of the Middle Eastern respiratory syndrome (MERS), a respiratory virus caused by MERS-CoV coronavirus (and primarily spread to humans by dromedary camels) that first emerged out of the Kingdom of Saudi Arabia (KSA) in 2012, was designed and used to study the transmission dynamics of the disease in a human-camel population within the KSA. Rigorous analysis of the model, which was fitted and cross-validated using the observed MERS-CoV data for the KSA, showed that its disease-free equilibrium was locally asymptotically stable whenever its reproduction number (denoted by $ {\mathbb R}_{0M} $) was less than unity. Using the fixed and estimated parameters of the model, the value of $ {\mathbb R}_{0M} $ for the KSA was estimated to be 0.84, suggesting that the prospects for MERS-CoV elimination are highly promising. The model was extended to allow for the assessment of public health intervention strategies, notably the potential use of vaccines for both humans and camels and the use of face masks by humans in public or when in close proximity with camels. Simulations of the extended model showed that the use of the face mask by humans who come in close proximity with camels, as a sole public health intervention strategy, significantly reduced human-to-camel and camel-to-human transmission of the disease, and this reduction depends on the efficacy and coverage of the mask type used in the community. For instance, if surgical masks are prioritized, the disease can be eliminated in both the human and camel population if at least 45% of individuals who have close contact with camels wear them consistently. The simulations further showed that while vaccinating humans as a sole intervention strategy only had marginal impact in reducing the disease burden in the human population, an intervention strategy based on vaccinating camels only resulted in a significant reduction in the disease burden in camels (and, consequently, in humans as well). Thus, this study suggests that attention should be focused on effectively combating the disease in the camel population, rather than in the human population. Furthermore, the extended model was used to simulate a hybrid strategy, which combined vaccination of both humans and camels as well as the use of face masks by humans. This simulation showed a marked reduction of the disease burden in both humans and camels, with an increasing effectiveness level of this intervention, in comparison to the baseline scenario or any of the aforementioned sole vaccination scenarios. In summary, this study showed that the prospect of the elimination of MERS-CoV-2 in the Kingdom of Saudi Arabia is promising using pharmaceutical (vaccination) and nonpharmaceutical (mask) intervention strategies, implemented in isolation or (preferably) in combination, that are focused on reducing the disease burden in the camel population.

3-Fucosyllactose-mediated modulation of immune response against virus infection

Viral pathogens, particularly influenza and SARS-CoV-2, pose a significant global health challenge. Given the immunomodulatory properties of human milk oligosaccharides, in particular 2'-fucosyllactose and 3-fucosyllactose (3-FL), we investigated their dietary supplementation effects on antiviral responses in mouse models. This study revealed distinct immune modulations induced by 3-FL. RNA-sequencing data showed that 3-FL increased the expression of interferon receptors, such as Interferon Alpha and Beta Receptor (IFNAR) and Interferon Gamma Receptor (IFNGR), while simultaneously downregulating interferons and interferon-stimulated genes, an effect not observed with 2'-fucosyllactose supplementation. Such modulation enhanced antiviral responses in both cell culture and animal models while attenuating pre-emptive inflammatory responses. Nitric oxide concentrations in 3-FL-supplemented A549 cells and mouse lung tissues were elevated exclusively upon infection, reaching 5.8- and 1.9-fold increases over control groups, respectively. In addition, 3-FL promoted leukocyte infiltration into the site of infection upon viral challenge. 3-FL supplementation provided protective efficacy against lethal influenza challenge in mice. The demonstrated antiviral efficacy spanned multiple influenza strains and extended to SARS-CoV-2. In conclusion, 3-FL is a unique immunomodulator that helps protect the host from viral infection while suppressing inflammation prior to infection.

Study of key residues in MERS-CoV and SARS-CoV-2 main proteases for resistance against clinically applied inhibitors nirmatrelvir and ensitrelvir

The Middle East Respiratory Syndrome Coronavirus (MERS-CoV) is an epidemic, zoonotically emerging pathogen initially reported in Saudi Arabia in 2012. MERS-CoV has the potential to mutate or recombine with other coronaviruses, thus acquiring the ability to efficiently spread among humans and become pandemic. Its high mortality rate of up to 35% and the absence of effective targeted therapies call for the development of antiviral drugs for this pathogen. Since the beginning of the SARS-CoV-2 pandemic, extensive research has focused on identifying protease inhibitors for the treatment of SARS-CoV-2. Our intention was therefore to assess whether these protease inhibitors are viable options for combating MERS-CoV. To that end, we used previously established protease assays to quantify inhibition of SARS-CoV-2, MERS-CoV and other main proteases. Nirmatrelvir inhibited several of these proteases, whereas ensitrelvir was less broadly active. To simulate nirmatrelvir's clinical use against MERS-CoV and subsequent resistance development, we applied a safe, surrogate virus-based system. Using the surrogate virus, we previously selected hallmark mutations of SARS-CoV-2-Mpro, such as T21I, M49L, S144A, E166A/K/V and L167F. In the current study, we selected a pool of MERS-CoV-Mpro mutants, characterized the resistance and modelled the steric effect of catalytic site mutants S142G, S142R, S147Y and A171S.

A novel host restriction factor MRPS6 mediates the inhibition of PDCoV infection in HIEC-6 cells

Introduction

Porcine deltacoronavirus (PDCoV) is a zoonotic pathogen with a global distribution, capable of infecting both pigs and humans. To mitigate the risk of cross-species transmission and potential outbreaks, it is crucial to characterize novel antiviral genes, particularly those from human hosts.

Methods

This research used HIEC-6 to investigate PDCoV infection. HIEC-6 cells were infected with PDCoV. Samples were collected 48 h postinfection for proteomic analysis.

Results

We discovered differential expression of MRPS6 gene at 48 h postinfection with PDCoV in HIEC-6 cells. The gene expression initially increased but then decreased. To further explore the role of MRPS6 in PDCoV infection, we conducted experiments involving the overexpression and knockdown of this gene in HIEC-6 and Caco2 cells, respectively. Our findings revealed that overexpression of MRPS6 significantly inhibited PDCoV infection in HIEC-6 cells, while knockdown of MRPS6 in Caco2 cells led to a significant increase of virus titer. Furthermore, we investigated the correlation between PDCoV infection and the expression of MRPS6. Subsequent investigations demonstrated that MRPS6 exerted an augmentative effect on the production of IFN-β through interferon pathway activation, consequently impeding the progression of PDCoV infection in cellular systems. In conclusion, this study utilized proteomic analysis to investigate the differential protein expression in PDCoV-infected HIEC-6 cells, providing evidence for the first time that the MRPS6 gene plays a restrictive role in PDCoV virus infection.

Discussion

Our findings initially provide the validation of MRPS6 as an upstream component of IFN-β pathway, in the promotion of IRF3, IRF7, STAT1, STAT2 and IFN-β production of HIEC-6 via dual-activation from interferon pathway.

Pulmonary infections in the returning traveler

PURPOSE OF REVIEW

The recent COVID-19 pandemic has shaped the epidemiology of other infectious diseases globally. International tourist arrivals are increasing and recovering to prepandemic levels. This review focuses on respiratory infections in travelers, highlighting the characteristics of the main imported viral, bacterial, fungal, and parasitic infections with pulmonary involvement.

RECENT FINDINGS

A recent systematic review estimated a prevalence of respiratory symptoms in travelers of around 35%, increasing to nearly 65% in the context of mass gatherings. Common viral and bacterial pathogens account for the majority of respiratory infections with an identified cause; however, recent data focus on the need for surveillance of emerging infections such as MERS-CoV, henipaviruses and multidrug resistant bacteria, which may be spread through travel. Fungal and parasitic respiratory infections are less common, and acquisition is usually associated with specific risk factors or exposure in endemic areas. Special risk groups, such as immunocompromised travelers, may be particularly vulnerable, presenting with severe disease or reactivation of latent infections.

SUMMARY

The next significant international epidemic could involve another new infectious agent causing respiratory disease and spreading via mobile populations. Official protocols should be adhered to, and public health interventions implemented for effective control. Continued and globally coordinated investments in research for new vaccines, therapeutic agents, disease modeling, and digital tracking strategies are essential.

Identification of receptors and factors associated with human coronaviruses in the oral cavity using single-cell RNA sequencing

Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) ravaged the world, and Coronavirus Disease 2019 (COVID-19) exhibited highly prevalent oral symptoms that had significantly impacted the lives of affected patients. However, the involvement of four human coronavirus (HCoVs), namely SARS-CoV-2, SARS-CoV, MERS-CoV, and HCoV-229E, in oral cavity infections remained poorly understood. We integrated single-cell RNA sequencing (scRNA-seq) data of seven human oral tissues through consistent normalization procedure, including minor salivary gland (MSG), parotid gland (PG), tongue, gingiva, buccal, periodontium and pulp. The Seurat, scDblFinder, Harmony, SingleR, Ucell and scCancer packages were comprehensively used for analysis. We identified specific cell clusters and generated expression profiles of SARS-CoV-2 and coronavirus-associated receptors and factors (SCARFs) in seven oral regions, providing direction for predicting the tropism of four HCoVs for oral tissues, as well as for dental clinical treatment. Based on our analysis, it appears that various SCARFs, including ACE2, ASGR1, KREMEN1, DPP4, ANPEP, CD209, CLEC4G/M, TMPRSS family proteins (including TMPRSS2, TMPRSS4, and TMPRSS11A), and FURIN, are expressed at low levels in the oral cavity. Conversely, BSG, CTSB, and CTSL exhibit enrichment in oral tissues. Our study also demonstrates widespread expression of restriction factors, particularly IFITM1-3 and LY6E, in oral cells. Additionally, some replication, assembly, and trafficking factors appear to exhibit broad oral tissues expression patterns. Overall, the oral cavity could potentially serve as a high-risk site for SARS-CoV-2 infection, while displaying a comparatively lower degree of susceptibility towards other HCoVs (including SARS-CoV, MERS-CoV and HCoV-229E). Specifically, MSG, tongue, and gingiva represent potential sites of vulnerability for four HCoVs infection, with the MSG exhibiting a particularly high susceptibility. However, the expression patterns of SCARFs in other oral sites demonstrate relatively intricate and may only be specifically associated with SARS-CoV-2 infection. Our study sheds light on the mechanisms of HCoVs infection in the oral cavity as well as gains insight into the characteristics and distribution of possible HCoVs target cells in oral tissues, providing potential therapeutic targets for HCoVs infection in the oral cavity.

Evaluating COVID-19 vaccine acceptance among parents in Saudi Arabia: a systematic review examining attitudes, hesitancy, and intentions

Introduction

The COVID-19 pandemic, affecting adults and children equally, has caused significant disruption to countries worldwide, including Saudi Arabia. In Saudi Arabia, the fast preventative measures and mass vaccine enrollment were vital to contain the devastating impact of the pandemic. However, vaccine hesitancy, especially among parents toward vaccinating their children, was a significant obstacle to vaccine uptake.

Methods

This systematic review followed PRISMA guidelines to assess parental willingness to vaccinate their children against COVID-19, determine the key determinants influencing such intention and attitudes, and underline the significant concerns and misconceptions regarding the vaccine among parents. The Joanne Briggs Institute (JBI) checklist for prevalence studies was used to assess included studies for risk of bias.

Results

Twenty-three studies were included in this systematic review, representing a total of 20,926 participants, with over 66% of them were female. Over 37% of the participants were willing to vaccinate their children against COVID-19. Parents' age, gender, level of education, and income were the main determinants of their intention to vaccinate their children. The parents' main concerns were the potential vaccine side effects, safety, and efficacy. Major misconceptions about the COVID-19 vaccine included it being dangerous to children and that children are at lower risk of severe infection; hence, vaccines were not needed.

Discussion

This seminal review provides insights to public health policymakers, which should be considered and taken together in light of other studies addressing parental vaccine hesitancy.

Early predictors of intensive care unit admission among COVID-19 patients in Qatar

Background

COVID-19 is associated with significant morbidity and mortality. This study aimed to explore the early predictors of intensive care unit (ICU) admission among patients with COVID-19.

Methods

This was a case-control study of adult patients with confirmed COVID-19. Cases were defined as patients admitted to ICU during the period February 29-May 29, 2020. For each case enrolled, one control was matched by age and gender.

Results

A total of 1,560 patients with confirmed COVID-19 were included. Each group included 780 patients with a predominant male gender (89.7%) and a median age of 49 years (interquartile range = 18). Predictors independently associated with ICU admission were cardiovascular disease (adjusted odds ratio (aOR) = 1.64, 95% confidence interval (CI): 1.16-2.32, p = 0.005), diabetes (aOR = 1.52, 95% CI: 1.08-2.13, p = 0.016), obesity (aOR = 1.46, 95% CI: 1.03-2.08, p = 0.034), lymphopenia (aOR = 2.69, 95% CI: 1.80-4.02, p < 0.001), high AST (aOR = 2.59, 95% CI: 1.53-4.36, p < 0.001), high ferritin (aOR = 1.96, 95% CI: 1.40-2.74, p < 0.001), high CRP (aOR = 4.09, 95% CI: 2.81-5.96, p < 0.001), and dyspnea (aOR = 2.50, 95% CI: 1.77-3.54, p < 0.001).

Conclusion

Having cardiovascular disease, diabetes, obesity, lymphopenia, dyspnea, and increased AST, ferritin, and CRP were independent predictors for ICU admission in patients with COVID-19.

Development of an Intelligent Reactive Oxygen Species-Responsive Dual-Drug Delivery Nanoplatform for Enhanced Precise Therapy of Acute Lung Injury

Introduction

Acute lung injury (ALI) and its most severe form acute respiratory distress syndrome (ARDS) are commonly occurring devastating conditions that seriously threaten the respiratory system in critically ill patients. The current treatments improve oxygenation in patients with ALI/ARDS in the short term, but do not relieve the clinical mortality of patients with ARDS.

Purpose

To develop the novel drug delivery systems that can enhance the therapeutic efficacy of ALI/ARDS and impede adverse effects of drugs.

Methods

Based on the key pathophysiological process of ARDS that is the disruption of the pulmonary endothelial barrier, bilirubin (Br) and atorvastatin (As) were encapsulated into an intelligent reactive oxygen species (ROS)-responsive nanocarrier DSPE-TK-PEG (DPTP) to form nanoparticles (BA@DPTP) in which the thioketal bonds could be triggered by high ROS levels in the ALI tissues.

Results

BA@DPTP could accumulate in inflammatory pulmonary sites through passive targeting strategy and intelligently release Br and As only in the inflammatory tissue via ROS-responsive bond, thereby enhancing the drugs effectiveness and markedly reducing side effects. BA@DPTP effectively inhibited NF-κB signaling and NLRP3/caspase-1/GSDMD-dependent pyroptosis in mouse pulmonary microvascular endothelial cells. BA@DPTP not only protected mice with lipopolysaccharide-induced ALI and retained the integrity of the pulmonary structure, but also reduced ALI-related mortality.

Conclusion

This study combined existing drugs with nano-targeting strategies to develop a novel drug-targeting platform for the efficient treatment of ALI/ARDS.

Nanotechnology's frontier in combatting infectious and inflammatory diseases: prevention and treatment

Inflammation-associated diseases encompass a range of infectious diseases and non-infectious inflammatory diseases, which continuously pose one of the most serious threats to human health, attributed to factors such as the emergence of new pathogens, increasing drug resistance, changes in living environments and lifestyles, and the aging population. Despite rapid advancements in mechanistic research and drug development for these diseases, current treatments often have limited efficacy and notable side effects, necessitating the development of more effective and targeted anti-inflammatory therapies. In recent years, the rapid development of nanotechnology has provided crucial technological support for the prevention, treatment, and detection of inflammation-associated diseases. Various types of nanoparticles (NPs) play significant roles, serving as vaccine vehicles to enhance immunogenicity and as drug carriers to improve targeting and bioavailability. NPs can also directly combat pathogens and inflammation. In addition, nanotechnology has facilitated the development of biosensors for pathogen detection and imaging techniques for inflammatory diseases. This review categorizes and characterizes different types of NPs, summarizes their applications in the prevention, treatment, and detection of infectious and inflammatory diseases. It also discusses the challenges associated with clinical translation in this field and explores the latest developments and prospects. In conclusion, nanotechnology opens up new possibilities for the comprehensive management of infectious and inflammatory diseases.

Development and characterization of three novel mouse monoclonal antibodies targeting spike protein S1 subunit of Middle East respiratory syndrome corona virus

BACKGROUND

Middle East Respiratory Syndrome Coronavirus is a highly pathogenic virus that poses a significant threat to public health.

OBJECTIVE

The purpose of this study is to develop and characterize novel mouse monoclonal antibodies targeting the spike protein S1 subunit of the Middle East Respiratory Syndrome Corona Virus (MERS-CoV).

METHODS

In this study, three mouse monoclonal antibodies (mAbs) against MERS-CoV were generated and characterized using hybridoma technology. The mAbs were evaluated for their reactivity and neutralization activity. The mAbs were generated through hybridoma technology by the fusion of myeloma cells and spleen cells from MERS-CoV-S1 immunized mice. The resulting hybridomas were screened for antibody production using enzyme-linked immunosorbent assays (ELISA).

RESULTS

ELISA results demonstrated that all three mAbs exhibited strong reactivity against the MERS-CoV S1-antigen. Similarly, dot-ELISA revealed their ability to specifically recognize viral components, indicating their potential for diagnostic applications. Under non-denaturing conditions, Western blot showed the mAbs to have robust reactivity against a specific band at 116 KDa, corresponding to a putative MERS-CoV S1-antigen. However, no reactive bands were observed under denaturing conditions, suggesting that the antibodies recognize conformational epitopes. The neutralization assay showed no in vitro reactivity against MERS-CoV.

CONCLUSION

This study successfully generated three mouse monoclonal antibodies against MERS-CoV using hybridoma technology. The antibodies exhibited strong reactivity against MERS-CoV antigens using ELISA and dot ELISA assays. Taken together, these findings highlight the significance of these mAbs for potential use as valuable tools for MERS-CoV research and diagnosis (community and field-based surveillance and viral antigen detection).

The Potential Role of Nitric Oxide as a Therapeutic Agent against SARS-CoV-2 Infection

The global coronavirus disease 2019 (COVID-19) pandemic caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become the greatest worldwide public health threat of this century, which may predispose multi-organ failure (especially the lung) and death despite numerous mild and moderate symptoms. Recent studies have unraveled the molecular and clinical characteristics of the infectivity, pathogenicity, and immune evasion of SARS-CoV-2 and thus improved the development of many different therapeutic strategies to combat COVID-19, including treatment and prevention. Previous studies have indicated that nitric oxide (NO) is an antimicrobial and anti-inflammatory molecule with key roles in pulmonary vascular function in the context of viral infections and other pulmonary disease states. This review summarized the recent advances of the pathogenesis of SARS-CoV-2, and accordingly elaborated on the potential application of NO in the management of patients with COVID-19 through antiviral activities and anti-inflammatory properties, which mitigate the propagation of this disease. Although there are some limits of NO in the treatment of COVID-19, it might be a worthy candidate in the multiple stages of COVID-19 prevention or therapy.

An immobilization-free electrochemical biosensor based on CRISPR/Cas13a and FAM-RNA-MB for simultaneous detection of multiple pathogens

To better respond to biosecurity issues, we need to build good technology and material reserves for pathogenic microorganism screening. Here, we designed an electrochemical/optical signal probe with a common fluorophore and an electrochemically active group, breaking the previous perception that the signal probe is composed of a fluorophore and a quenching group and realizing the response of three signals: electrochemistry, fluorescence, and direct observation. Then, we proposed a homogeneous electrochemical nucleic acid detection system based on CRISPR/Cas named "HELEN-CR" by integrating free electrochemical/optical signal probes and Cas13a cleavage, achieving a limit of detection of 1 pM within 25 min. To improve the detection sensitivity, we applied recombinase polymerase amplification to amplify the target nucleic acid, achieving a limit of detection of 30 zM within 45 min. Complemented by our self-developed multi-chamber microfluidic chip and portable electrochemical instrument, simultaneous detection of multiple pathogens can be achieved within 50 min, facilitating minimally trained personnel to obtain detection results quickly in a difficult environment. This study proposes a simple, scalable, and general idea and solution for the rapid detection of pathogenic microorganisms and biosecurity monitoring.

SARS-CoV-2 variants, its recombinants and epigenomic exploitation of host defenses

Since 2003, we have seen the emergence of novel viruses, such as SARS-CoV-1, MERS, ZIKA, swine flu virus H1N1, Marburg, Monkeypox, Ebola, and SARS-CoV-2, but none of them gained pandemic proportions similar to SARS-CoV-2. This could be attributed to unique viral traits, allowing its rapid global dissemination following its emergence in October 2019 in Wuhan, China, which appears to be primarily driven by the emergence of highly transmissible and virulent variants that also associate, in some cases, with severe disease and considerable mortality caused by fatal pneumonia, acute respiratory distress syndrome (ARDS) in infected individuals. Mechanistically, several factors are involved in viral pathogenesis, and epigenetic alterations take the front seat in host-virus interactions. The molecular basis of all viral infections, including SARS-CoV-2, tightly hinges on the transitory silencing of the host gene machinery via epigenetic modulation. SARS-CoV-2 also hijacks and subdues the host gene machinery, leading to epigenetic modulation of the critical host elements responsible for antiviral immunity. Epigenomics is a powerful, unexplored avenue that can provide a profound understanding of virus-host interactions and lead to the development of epigenome-based therapies and vaccines to counter viruses. This review discusses current developments in SARS-CoV-2 variation and its role in epigenetic modulation in infected hosts. This review provides an overview, especially in the context of emerging viral strains, their recombinants, and their possible roles in the epigenetic exploitation of host defense and viral pathogenesis. It provides insights into host-virus interactions at the molecular, genomic, and immunological levels and sheds light on the future of epigenomics-based therapies for SARS-CoV-2 infection.

Structure and function of SARS-CoV and SARS-CoV-2 main proteases and their inhibition: A comprehensive review

Severe acute respiratory syndrome-associated coronavirus (SARS-CoV) identified in 2003 infected ∼8000 people in 26 countries with 800 deaths, which was soon contained and eradicated by syndromic surveillance and enhanced quarantine. A closely related coronavirus SARS-CoV-2, the causative agent of COVID-19 identified in 2019, has been dramatically more contagious and catastrophic. It has infected and caused various flu-like symptoms of billions of people in >200 countries, including >6 million people died of or with the virus. Despite the availability of several vaccines and antiviral drugs against SARS-CoV-2, finding new therapeutics is needed because of viral evolution and a possible emerging coronavirus in the future. The main protease (Mpro) of these coronaviruses plays important roles in their life cycle and is essential for the viral replication. This article represents a comprehensive review of the function, structure and inhibition of SARS-CoV and -CoV-2 Mpro, including structure-activity relationships, protein-inhibitor interactions and clinical trial status.

Obtaining a high titer of polyclonal antibodies from rats to the SARS-CoV-2 nucleocapsid protein and its N- and C-terminal domains for diagnostic test development

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is an enveloped, plus-stranded RNA virus responsible for the Coronavirus Disease 2019 (COVID-19). Patients infected with COVID-19 may be asymptomatic or have symptoms ranging from mild manifestations to severe cases of the disease that could lead to death. The SARS-CoV-2 genome encodes 4 structural proteins, including the Spike protein (S), the Nucleocapsid protein (N), Membrane protein (M) and, the Envelope protein (E). The N protein forms a major component of the ribonucleoprotein complex within the virus particle and play a vital role in its transcription and replication. Nevertheless, the S protein was the most important protein in the development of vaccines against COVID-19. However, the decrease in number of registered immunizations against the disease and the rapid drop in neutralizing antibody titers together with looser preventive measures for virus transmission, favored the rapid appearance of new variants of concerns (VOCs) that primarily show mutations in the S protein. This fact makes the N protein a good candidate for the development of diagnostic tests, due to its stability, amino acid conservation, high immunogenicity, and the smaller likelihood of mutation. With the aim of developing a new diagnostic kit based on the N protein, we evaluated the humoral response in female Wistar rats against this target. Three constructions of the N protein were used to inoculate the animals: the full-length protein (Cfull), the N- (NTD), and the C-terminal (CTD) portion of the protein. The immunizations induced the animal's immune response, with specific polyclonal IgG antibodies against the Cfull protein and its fragments. There were not non-specific bind to the protein used as negative control. Anti-Cfull antibodies demonstrated high efficiency in binding to the NTD protein and the antibodies present in the anti-CTD and anti-NTD sera have recognized the Cfull protein, but they were not able to recognize the NTD and CTD proteins, respectively. Our results indicate an efficient protocol for obtaining high antibody titers against the N recombinant protein of SARS-CoV-2 and its fragments highlighting the Cfull protein, which can be used in the development of new diagnostic kits.

Vaccine-mediated protection against Merbecovirus and Sarbecovirus challenge in mice

The emergence of three highly pathogenic human coronaviruses-severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003, Middle Eastern respiratory syndrome (MERS)-CoV in 2012, and SARS-CoV-2 in 2019-underlines the need to develop broadly active vaccines against the Merbecovirus and Sarbecovirus betacoronavirus subgenera. While SARS-CoV-2 vaccines protect against severe COVID-19, they do not protect against other sarbecoviruses or merbecoviruses. Here, we vaccinate mice with a trivalent sortase-conjugate nanoparticle (scNP) vaccine containing the SARS-CoV-2, RsSHC014, and MERS-CoV receptor-binding domains (RBDs), which elicited live-virus neutralizing antibody responses. The trivalent RBD scNP elicited serum neutralizing antibodies against bat zoonotic Wuhan Institute of Virology-1 (WIV-1)-CoV, SARS-CoV, SARS-CoV-2 BA.1, SARS-CoV-2 XBB.1.5, and MERS-CoV live viruses. The monovalent SARS-CoV-2 RBD scNP vaccine only protected against Sarbecovirus challenge, whereas the trivalent RBD scNP vaccine protected against both Merbecovirus and Sarbecovirus challenge in highly pathogenic and lethal mouse models. This study demonstrates proof of concept for a single pan-sarbecovirus/pan-merbecovirus vaccine that protects against three highly pathogenic human coronaviruses spanning two betacoronavirus subgenera.

The prospect of universal coronavirus immunity: characterization of reciprocal and non-reciprocal T cell responses against SARS-CoV2 and common human coronaviruses

T cell immunity plays a central role in clinical outcomes of Coronavirus Infectious Disease 2019 (COVID-19) and T cell-focused vaccination or cellular immunotherapy might provide enhanced protection for some immunocompromised patients. Pre-existing T cell memory recognizing SARS-CoV-2 antigens antedating COVID-19 infection or vaccination, may have developed as an imprint of prior infections with endemic non-SARS human coronaviruses (hCoVs) OC43, HKU1, 229E, NL63, pathogens of "common cold". In turn, SARS-CoV-2-primed T cells may recognize emerging variants or other hCoV viruses and modulate the course of subsequent hCoV infections. Cross-immunity between hCoVs and SARS-CoV-2 has not been well characterized. Here, we systematically investigated T cell responses against the immunodominant SARS-CoV-2 spike, nucleocapsid and membrane proteins and corresponding antigens from α- and β-hCoVs among vaccinated, convalescent, and unexposed subjects. Broad T cell immunity against all tested SARS-CoV-2 antigens emerged in COVID-19 survivors. In convalescent and in vaccinated individuals, SARS-CoV-2 spike-specific T cells reliably recognized most SARS-CoV-2 variants, however cross-reactivity against the omicron variant was reduced by approximately 47%. Responses against spike, nucleocapsid and membrane antigens from endemic hCoVs were significantly more extensive in COVID-19 survivors than in unexposed subjects and displayed cross-reactivity between α- and β-hCoVs. In some, non-SARS hCoV-specific T cells demonstrated a prominent non-reciprocal cross-reactivity with SARS-CoV-2 antigens, whereas a distinct anti-SARS-CoV-2 immunological repertoire emerged post-COVID-19, with relatively limited cross-recognition of non-SARS hCoVs. Based on this cross-reactivity pattern, we established a strategy for in-vitro expansion of universal anti-hCoV T cells for adoptive immunotherapy. Overall, these results have implications for the future design of universal vaccines and cell-based immune therapies against SARS- and non-SARS-CoVs.

Characteristics of the pulmonary microbiota in patients with mild and severe pulmonary infection

Background

Lung infection is a global health problem associated with high morbidity and mortality and increasing rates of hospitalization. The correlation between pulmonary microecology and infection severity remains unclear. Therefore, the purpose of this study was to investigate the differences in lung microecology and potential biomarkers in patients with mild and severe pulmonary infection.

Method

Patients with pulmonary infection or suspected infection were divided into the mild group (140 cases) and the severe group (80 cases) according to pneomonia severity index (PSI) scores. Here, we used metagenomic next-generation sequencing (mNGS) to detect DNA mainly from bronchoalveolar lavage fluid (BALF) collected from patients to analyze changes in the lung microbiome of patients with different disease severity.

Result

We used the mNGS to analyze the pulmonary microecological composition in patients with pulmonary infection. The results of alpha diversity and beta diversity analysis showed that the microbial composition between mild and severe groups was similar on the whole. The dominant bacteria were Acinetobacter, Bacillus, Mycobacterium, Staphylococcus, and Prevotella, among others. Linear discriminant analysis effect size (LEfSe) results showed that there were significant differences in virus composition between the mild and severe patients, especially Simplexvirus and Cytomegalovirus, which were prominent in the severe group. The random forest model screened 14 kinds of pulmonary infection-related pathogens including Corynebacterium, Mycobacterium, Streptococcus, Klebsiella, and Acinetobacter. In addition, it was found that Rothia was negatively correlated with Acinetobacter, Mycobacterium, Bacillus, Enterococcus, and Klebsiella in the mild group through co-occurrence network, while no significant correlation was found in the severe group.

Conclusion

Here, we describe the composition and diversity of the pulmonary microbiome in patients with pulmonary infection. A significant increase in viral replication was found in the severe group, as well as a significant difference in microbial interactions between patients with mild and severe lung infections, particularly the association between the common pathogenic bacteria and Rothia. This suggests that both pathogen co-viral infection and microbial interactions may influence the course of disease. Of course, more research is needed to further explore the specific mechanisms by which microbial interactions influence disease severity.

Exhaled patient derived aerosol dispersion during awake tracheal intubation with concurrent high flow nasal therapy

Awake Tracheal Intubation (ATI) can be performed in cases where there is potential for difficult airway management. It is considered an aerosol generating procedure and is a source of concern to healthcare workers due to the risk of transmission of airborne viral infections, such as SARS-CoV-2. At present, there is a lack of data on the quantities, size distributions and spread of aerosol particles generated during such procedures. This was a volunteer observational study which took place in an operating room of a university teaching hospital. Optical particle sizers were used to provide real time aerosol characterisation during a simulated ATI performed with concurrent high-flow nasal oxygen therapy. The particle sizers were positioned at locations that represented the different locations of clinical staff in an operating room during an ATI. The greatest concentration of patient derived aerosol particles was within 0.5-1.0 m of the subject and along their midline, 2242 #/cm3. As the distance, both radial and longitudinal, from the subject increased, the concentration decreased towards ambient levels, 36.9 ± 5.1 #/cm3. Patient derived aerosol particles < 5 µm in diameter remained entrained in the exhaled aerosol plume and fell to the floor or onto the subject. Patient derived particles > 5 µm in diameter broke away from the exhaled plume and spread radially throughout the operating room. Irrespective of distance and ventilation status, full airborne protective equipment should be worn by all staff when ATI is being performed on patients with suspected viral respiratory infections.

A MERS-CoV antibody neutralizes a pre-emerging group 2c bat coronavirus

The repeated emergence of zoonotic human betacoronaviruses (β-CoVs) dictates the need for broad therapeutics and conserved epitope targets for countermeasure design. Middle East respiratory syndrome (MERS)-related coronaviruses (CoVs) remain a pressing concern for global health preparedness. Using metagenomic sequence data and CoV reverse genetics, we recovered a full-length wild-type MERS-like BtCoV/li/GD/2014-422 (BtCoV-422) recombinant virus, as well as two reporter viruses, and evaluated their human emergence potential and susceptibility to currently available countermeasures. Similar to MERS-CoV, BtCoV-422 efficiently used human and other mammalian dipeptidyl peptidase protein 4 (DPP4) proteins as entry receptors and an alternative DPP4-independent infection route in the presence of exogenous proteases. BtCoV-422 also replicated efficiently in primary human airway, lung endothelial, and fibroblast cells, although less efficiently than MERS-CoV. However, BtCoV-422 shows minor signs of infection in 288/330 human DPP4 transgenic mice. Several broad CoV antivirals, including nucleoside analogs and 3C-like/Mpro protease inhibitors, demonstrated potent inhibition against BtCoV-422 in vitro. Serum from mice that received a MERS-CoV mRNA vaccine showed reduced neutralizing activity against BtCoV-422. Although most MERS-CoV-neutralizing monoclonal antibodies (mAbs) had limited activity, one anti-MERS receptor binding domain mAb, JC57-11, neutralized BtCoV-422 potently. A cryo-electron microscopy structure of JC57-11 in complex with BtCoV-422 spike protein revealed the mechanism of cross-neutralization involving occlusion of the DPP4 binding site, highlighting its potential as a broadly neutralizing mAb for group 2c CoVs that use DPP4 as a receptor. These studies provide critical insights into MERS-like CoVs and provide candidates for countermeasure development.

Microneedle-Mediated Transcutaneous Immunization: Potential in Nucleic Acid Vaccination

Efforts aimed at exploring economical and efficient vaccination have taken center stage to combat frequent epidemics worldwide. Various vaccines have been developed for infectious diseases, among which nucleic acid vaccines have attracted much attention from researchers due to their design flexibility and wide application. However, the lack of an efficient delivery system considerably limits the clinical translation of nucleic acid vaccines. As mass vaccinations via syringes are limited by low patient compliance and high costs, microneedles (MNs), which can achieve painless, cost-effective, and efficient drug delivery, can provide an ideal vaccination strategy. The MNs can break through the stratum corneum barrier in the skin and deliver vaccines to the immune cell-rich epidermis and dermis. In addition, the feasibility of MN-mediated vaccination is demonstrated in both preclinical and clinical studies and has tremendous potential for the delivery of nucleic acid vaccines. In this work, the current status of research on MN vaccines is reviewed. Moreover, the improvements of MN-mediated nucleic acid vaccination are summarized and the challenges of its clinical translation in the future are discussed.

Genetic diversity, recombination and cross-species transmission of a waterbird gammacoronavirus in the wild

Viruses emerging from wildlife can cause outbreaks in humans and domesticated animals. Predicting the emergence of future pathogens and mitigating their impacts requires an understanding of what shapes virus diversity and dynamics in wildlife reservoirs. In order to better understand coronavirus ecology in wild species, we sampled birds within a coastal freshwater lagoon habitat across 5 years, focussing on a large population of mute swans (Cygnus olor) and the diverse species that they interact with. We discovered and characterised the full genome of a divergent gammacoronavirus belonging to the Goose coronavirus CB17 species. We investigated the genetic diversity and dynamics of this gammacoronavirus using untargeted metagenomic sequencing of 223 faecal samples from swans of known age and sex, and RT-PCR screening of 1632 additional bird samples. The virus circulated persistently within the bird community; virus prevalence in mute swans exhibited seasonal variations, but did not change with swan age-class or epidemiological year. One whole genome was fully characterised, and revealed that the virus originated from a recombination event involving an undescribed gammacoronavirus species. Multiple lineages of this gammacoronavirus co-circulated within our study population. Viruses from this species have recently been detected in aquatic birds from both the Anatidae and Rallidae families, implying that host species habitat sharing may be important in shaping virus host range. As the host range of the Goose coronavirus CB17 species is not limited to geese, we propose that this species name should be updated to 'Waterbird gammacoronavirus 1'. Non-invasive sampling of bird coronaviruses may provide a tractable model system for understanding the evolutionary and cross-species dynamics of coronaviruses.

First Report of Alphacoronavirus Circulating in Cavernicolous Bats from Portugal

The emergence of novel coronaviruses (CoVs) has emphasized the need to understand their diversity and distribution in animal populations. Bats have been identified as crucial reservoirs for CoVs, and they are found in various bat species worldwide. In this study, we investigated the presence of CoVs of four cavernicolous bats in six locations in the centre and south of Portugal. We collected faeces, anal, and buccal swab samples, as well as air samples from the locations using a Coriolis air sampler. Our results indicate that CoVs were more readily detected in faecal samples compared to anal and buccal swab samples. No CoVs were detected in the air samples. Phylogenetic analysis showed that the detected viruses belong to the Alphacoronavirus genus. This study represents the first report of Alphacoronaviruses circulating in bats in Portugal and highlights the importance of continuous surveillance for novel CoVs in bat populations globally. Ongoing surveillance for CoVs in bat populations is essential as they are a vital source of these viruses. It is crucial to understand the ecological relationships between animals, humans, and the environment to prevent and control the emergence and transmission of infectious diseases. Further ecological studies are needed to investigate the factors contributing to the emergence and transmission of zoonotic viruses.

Aprotinin-Drug against Respiratory Diseases

Aprotinin (APR) was discovered in 1930. APR is an effective pan-protease inhibitor, a typical "magic shotgun". Until 2007, APR was widely used as an antithrombotic and anti-inflammatory drug in cardiac and noncardiac surgeries for reduction of bleeding and thus limiting the need for blood transfusion. The ability of APR to inhibit proteolytic activation of some viruses leads to its use as an antiviral drug for the prevention and treatment of acute respiratory virus infections. However, due to incompetent interpretation of several clinical trials followed by incredible controversy in the literature, the usage of APR was nearly stopped for a decade worldwide. In 2015-2020, after re-analysis of these clinical trials' data the restrictions in APR usage were lifted worldwide. This review discusses antiviral mechanisms of APR action and summarizes current knowledge and prospective regarding the use of APR treatment for diseases caused by RNA-containing viruses, including influenza and SARS-CoV-2 viruses, or as a part of combination antiviral treatment.

Gastrointestinal tract and viral pathogens

Viral gastroenteritis is the most common viral illness that affects the gastrointestinal (GI) tract, causing inflammation and irritation of the lining of the stomach and intestines. Common signs and symptoms associated with this condition include abdominal pain, diarrhea, and dehydration. The infections commonly involved in viral gastroenteritis are rotavirus, norovirus, and adenovirus, which spread through the fecal-oral and contact routes and cause non-bloody diarrhea. These infections can affect both immunocompetent and immunocompromised individuals. Since the pandemic in 2019, coronavirus gastroenteritis has increased in incidence and prevalence. Morbidity and mortality rates from viral gastroenteritis have declined significantly over the years due to early recognition, treatment with oral rehydration salts, and prompt vaccination. Improved sanitation measures have also played a key role in reducing the transmission of infection. In addition to viral hepatitis causing liver disease, herpes virus, and cytomegalovirus are responsible for ulcerative GI disease. They are associated with bloody diarrhea and commonly occur in im-munocompromised individuals. Hepatitis viruses, Epstein-Barr virus, herpesvirus 8, and human papillomavirus have been involved in benign and malignant diseases. This mini review aims to list different viruses affecting the GI tract. It will cover common symptoms aiding in diagnosis and various important aspects of each viral infection that can aid diagnosis and management. This will help primary care physicians and hospitalists diagnose and treat patients more easily.