Human Coronaviruses

Management of SARS-CoV-2 Prevention Methods in Dental Offices-A Cross-Sectional Study in Bucharest, Romania

We compared the managing of prevention methods for SARS-CoV-2 infections in dental offices before and immediately after the COVID-19 pandemic. The purpose of this study was to find out the varieties of infection prevention methods used by dentists before and during the pandemic and compare them. We designed a digital transversal questionnaire with 15 closed questions that was sent to 150 dentists in Bucharest, Romania. We received n = 112 valid answers during July-August 2021 from dentists of all age groups (25-60 years), with a sex ratio of 0.36, which agreed to anonymously participate in this study. The results showed an increase in types and amount of personal protection equipment (i.e., ocular/facial protection, supplemental gown, and upgrading the FFP1 masks to FFP2 or FFP3). Ocular protection showed statistical significance by gender but not by age group. Vaccination rate against SARS-CoV-2 was at 80% of the participant dentists at the time of the survey and had statistical significance. However, vaccination status of the patients did not alter dentists' protection protocol.

Cannabis effectiveness on immunologic potency of pulmonary contagion

Respiratory illnesses and its repercussions are becoming more prevalent worldwide. It is necessary to research both innovative treatment and preventative techniques. Millions of confirmed cases and fatalities from the COVID-19 epidemic occurred over the previous two years. According to the review research, cannabinoids are a class of medicines that should be considered for the treatment of respiratory conditions. Cannabinoids and inhibitors of endocannabinoid degradation have illustrated advantageous anti-inflammatory, asthma, pulmonary fibrosis, and pulmonary artery hypotension in numerous studies (in vitro and in vivo). It has been also noted that CB2 receptors on macrophages and T-helper cells may be particularly triggered to lower inflammation in COVID-19 patients. Since the majority of lung tissue contains cannabinoid receptors, cannabis can be an effective medical tool for treating COVID-19 as well as pulmonary infections. Notably, CB2 and CB1 receptors play a major role in immune system modulation and anti-inflammatory activities. In this review, we put forth the idea that cannabis might be helpful in treating pulmonary contagion brought on by viral integration, such as that caused by SARS-CoV-2, haemophilus influenza type b, Streptococcus pneumoniae, influenza virus, and respiratory syncytial virus. Also, a detailed overview of CB receptors, intricate mechanisms, is highlighted connecting link with COVID-19 viral structural modifications along with molecular basis of CB receptors in diminishing viral load in pulmonary disorders supported through evident literature studies. Further, futuristic evaluations on cannabis potency through novel formulation development focusing on in vivo/in vitro systems can produce promising results.

A novel class of broad-spectrum active-site-directed 3C-like protease inhibitors with nanomolar antiviral activity against highly immune-evasive SARS-CoV-2 Omicron subvariants

Antivirals with broad coronavirus activity are important for treating high-risk individuals exposed to the constantly evolving SARS-CoV-2 variants of concern (VOCs) as well as emerging drug-resistant variants. We developed and characterized a novel class of active-site-directed 3-chymotrypsin-like protease (3CLpro) inhibitors (C2-C5a). Our lead direct-acting antiviral (DAA), C5a, is a non-covalent, non-peptide with a dissociation constant of 170 nM against recombinant SARS-CoV-2 3CLpro. The compounds C2-C5a exhibit broad-spectrum activity against Omicron subvariants (BA.5, BQ.1.1, and XBB.1.5) and seasonal human coronavirus-229E infection in human cells. Notably, C5a has median effective concentrations of 30-50 nM against BQ.1.1 and XBB.1.5 in two different human cell lines. X-ray crystallography has confirmed the unique binding modes of C2-C5a to the 3CLpro, which can limit virus cross-resistance to emerging Paxlovid-resistant variants. We tested the effect of C5a with two of our newly discovered host-directed antivirals (HDAs): N-0385, a TMPRSS2 inhibitor, and bafilomycin D (BafD), a human vacuolar H+-ATPase [V-ATPase] inhibitor. We demonstrated a synergistic action of C5a in combination with N-0385 and BafD against Omicron BA.5 infection in human Calu-3 lung cells. Our findings underscore that a SARS-CoV-2 multi-targeted treatment for circulating Omicron subvariants based on DAAs (C5a) and HDAs (N-0385 or BafD) can lead to therapeutic benefits by enhancing treatment efficacy. Furthermore, the high-resolution structures of SARS-CoV-2 3CLpro in complex with C2-C5a will facilitate future rational optimization of our novel broad-spectrum active-site-directed 3C-like protease inhibitors.

Evolutionary trend of SARS-CoV-2 inferred by the homopolymeric nucleotide repeats

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the current global COVID-19 pandemic, in which millions of lives have been lost. Understanding the zoonotic evolution of the coronavirus may provide insights for developing effective vaccines, monitoring the transmission trends, and preventing new zoonotic infections. Homopolymeric nucleotide repeats (HP), the most simple tandem repeats, are a ubiquitous feature of eukaryotic genomes. Yet the HP distributions and roles in coronavirus genome evolution are poorly investigated. In this study, we characterize the HP distributions and trends in the genomes of bat and human coronaviruses and SARS-CoV-2 variants. The results show that the SARS-CoV-2 genome is abundant in HPs, and has augmented HP contents during evolution. Especially, the disparity of HP poly-(A/T) and ploy-(C/G) of coronaviruses increases during the evolution in human hosts. The disparity of HP poly-(A/T) and ploy-(C/G) is correlated to host adaptation and the virulence level of the coronaviruses. Therefore, we propose that the HP disparity can be a quantitative measure for the zoonotic evolution levels of coronaviruses. Peculiarly, the HP disparity measure infers that SARS-CoV-2 Omicron variants have a high disparity of HP poly-(A/T) and ploy-(C/G), suggesting a high adaption to the human hosts.

Evaluation of deep learning-based approaches for COVID-19 classification based on chest X-ray images

The COVID-19, novel coronavirus or SARS-Cov-2, has claimed hundreds of thousands of lives and affected millions of people all around the world with the number of deaths and infections growing exponentially. Deep convolutional neural network (DCNN) has been a huge milestone for image classification task including medical images. Transfer learning of state-of-the-art models have proven to be an efficient method of overcoming deficient data problem. In this paper, a thorough evaluation of eight pre-trained models is presented. Training, validating, and testing of these models were performed on chest X-ray (CXR) images belonging to five distinct classes, containing a total of 760 images. Fine-tuned models, pre-trained in ImageNet dataset, were computationally efficient and accurate. Fine-tuned DenseNet121 achieved a test accuracy of 98.69% and macro f1-score of 0.99 for four classes classification containing healthy, bacterial pneumonia, COVID-19, and viral pneumonia, and fine-tuned models achieved higher test accuracy for three-class classification containing healthy, COVID-19, and SARS images. The experimental results show that only 62% of total parameters were retrained to achieve such accuracy.

Recent advances, approaches and challenges in targeting pathways for potential COVID-19 vaccines development

During the COVID-19 pandemic in a modern era, there is a global consensus on the need for the rapid development of a vaccine against SARS-CoV-2 for effective and sustainable control. Developing these vaccines is fundamental to public health. This urgent need is supported by the scientific explosion in structural and genomic biology that facilitates the urgent development of an ideal COVID-19 vaccine, using new pathways to facilitate its large-scale development, testing, and manufacture. Here, we summarize the types of COVID-19 candidate vaccines, their current stage in early testing in human clinical trials, and the challenges for their implementation.

Neurological injuries in COVID-19 patients: direct viral invasion or a bystander injury after infection of epithelial/endothelial cells

A subset of patients with coronavirus 2 disease (COVID-19) experience neurological complications. These complications include loss of sense of taste and smell, stroke, delirium, and neuromuscular signs and symptoms. The etiological agent of COVID-19 is SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), an RNA virus with a glycoprotein-studded viral envelope that uses ACE2 (angiotensin-converting enzyme 2) as a functional receptor for infecting the host cells. Thus, the interaction of the envelope spike proteins with ACE2 on host cells determines the tropism and virulence of SARS-CoV-2. Loss of sense of taste and smell is an initial symptom of COVID-19 because the virus enters the nasal and oral cavities first and the epithelial cells are the receptors for these senses. Stroke in COVID-19 patients is likely a consequence of coagulopathy and injury to cerebral vascular endothelial cells that cause thrombo-embolism and stroke. Delirium and encephalopathy in acute and post COVID-19 patients are likely multifactorial and secondary to hypoxia, metabolic abnormalities, and immunological abnormalities. Thus far, there is no clear evidence that coronaviruses cause inflammatory neuromuscular diseases via direct invasion of peripheral nerves or muscles or via molecular mimicry. It appears that most of neurologic complications in COVID-19 patients are indirect and as a result of a bystander injury to neurons.

What's New With the Old Coronaviruses?

Coronaviruses contribute to the burden of respiratory diseases in children, frequently manifesting in upper respiratory symptoms considered to be part of the "common cold." Recent epidemics of novel coronaviruses recognized in the 21st century have highlighted issues of zoonotic origins of transmissible respiratory viruses and potential transmission, disease, and mortality related to these viruses. In this review, we discuss what is known about the virology, epidemiology, and disease associated with pediatric infection with the common community-acquired human coronaviruses, including species 229E, OC43, NL63, and HKU1, and the coronaviruses responsible for past world-wide epidemics due to severe acute respiratory syndrome and Middle East respiratory syndrome coronavirus.