The COVID-19 puzzle: a global nightmare

Identification of Hammerhead-variant ribozyme sequences in SARS-CoV-2

The SARS-CoV-2 RNA virus and variants, responsible for the COVID-19 pandemic has become endemic, raised a need for further understanding of the viral genome and biology. Despite vast research on SARS-CoV-2, no ribozymes have been found in the virus genome. Here we report the identification of 39 Hammerhead-variant ribozyme sequences (CoV-HHRz) in SARS-CoV-2. These sequences are highly conserved within SARS-CoV-2 variants but show large diversity among other coronaviruses. In vitro CoV-HHRz sequences possess the characteristics of typical ribozymes; cleavage is pH and ion dependent, although their activity is relatively low and Mn2+ is required for cleavage. The cleavage sites of four CoV-HHRz coincide with the breakpoint of expressed subgenomic RNA (sgRNAs) in SARS-CoV-2 transcriptome data suggesting in vivo activity. The CoV-HHRz are involved in processing sgRNAs for ORF7b, ORF 10 and ORF1ab nsp13 which are essential for viral packaging and life cycle.

Plant-Derived Natural Non-Nucleoside Analog Inhibitors (NNAIs) against RNA-Dependent RNA Polymerase Complex (nsp7/nsp8/nsp12) of SARS-CoV-2

The emergence of fast-spreading SARS-CoV-2 mutants has sparked a new phase of COVID-19 pandemic. There is a dire necessity for antivirals targeting highly conserved genomic domains on SARS-CoV-2 that are less prone to mutation. The nsp12, also known as the RNA-dependent RNA-polymerase (RdRp), the core component of 'SARS-CoV-2 replication-transcription complex', is a potential well-conserved druggable antiviral target. Several FDA-approved RdRp 'nucleotide analog inhibitors (NAIs)' such as remdesivir, have been repurposed to treat COVID-19 infections. The NAIs target RdRp protein translation and competitively block the nucleotide insertion into the RNA chain, resulting in the inhibition of viral replication. However, the replication proofreading function of nsp14-ExoN could provide resistance to SARS-CoV-2 against many NAIs. Conversely, the 'non-nucleoside analog inhibitors (NNAIs)' bind to allosteric sites on viral polymerase surface, change the redox state; thereby, exert antiviral activity by altering interactions between the enzyme substrate and active core catalytic site of the RdRp. NNAIs neither require metabolic activation (unlike NAIs) nor compete with intracellular pool of nucleotide triphosphates (NTPs) for anti-RdRp activity. The NNAIs from phytonutrient origin are potential antiviral candidates compared to their synthetic counterparts. Several in-silico studies reported the antiviral spectrum of natural phytonutrient-NNAIs such as Suramin, Silibinin (flavonolignan), Theaflavin (tea polyphenol), Baicalein (5,6,7-trihydroxyflavone), Corilagin (gallotannin), Hesperidin (citrus bioflavonoid), Lycorine (pyrrolidine alkaloid), with superior redox characteristics (free binding energy, hydrogen-bonds, etc.) than antiviral drugs (i.e. remdesivir, favipiravir). These phytonutrient-NNAIs also exert anti-inflammatory, antioxidant, immunomodulatory and cardioprotective functions, with multifunctional therapeutic benefits in the clinical management of COVID-19.

Towards novel nano-based vaccine platforms for SARS-CoV-2 and its variants of concern: Advances, challenges and limitations

Vaccination is the most effective tool available for fighting the spread of COVID-19. Recently, emerging variants of SARS-CoV-2 have led to growing concerns about increased transmissibility and decreased vaccine effectiveness. Currently, many vaccines are approved for emergency use and more are under development. This review highlights the ongoing advances in the design and development of different nano-based vaccine platforms. The challenges, limitations, and ethical consideration imposed by these nanocarriers are also discussed. Further, the effectiveness of the leading vaccine candidates against all SARS-CoV-2 variants of concern are highlighted. The review also focuses on the possibility of using an alternative non-invasive routes of vaccine administration using micro and nanotechnologies to enhance vaccination compliance and coverage.

Advances in Pathogenesis, Progression, Potential Targets and Targeted Therapeutic Strategies in SARS-CoV-2-Induced COVID-19

As the new year of 2020 approaches, an acute respiratory disease quietly caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), also known as coronavirus disease 2019 (COVID-19) was reported in Wuhan, China. Subsequently, COVID-19 broke out on a global scale and formed a global public health emergency. To date, the destruction that has lasted for more than two years has not stopped and has caused the virus to continuously evolve new mutant strains. SARS-CoV-2 infection has been shown to cause multiple complications and lead to severe disability and death, which has dealt a heavy blow to global development, not only in the medical field but also in social security, economic development, global cooperation and communication. To date, studies on the epidemiology, pathogenic mechanism and pathological characteristics of SARS-CoV-2-induced COVID-19, as well as target confirmation, drug screening, and clinical intervention have achieved remarkable effects. With the continuous efforts of the WHO, governments of various countries, and scientific research and medical personnel, the public's awareness of COVID-19 is gradually deepening, a variety of prevention methods and detection methods have been implemented, and multiple vaccines and drugs have been developed and urgently marketed. However, these do not appear to have completely stopped the pandemic and ravages of this virus. Meanwhile, research on SARS-CoV-2-induced COVID-19 has also seen some twists and controversies, such as potential drugs and the role of vaccines. In view of the fact that research on SARS-CoV-2 and COVID-19 has been extensive and in depth, this review will systematically update the current understanding of the epidemiology, transmission mechanism, pathological features, potential targets, promising drugs and ongoing clinical trials, which will provide important references and new directions for SARS-CoV-2 and COVID-19 research.

A Comprehensive Investigation Regarding the Differentiation of the Procurable COVID-19 Vaccines

COVID-19 caused by coronavirus SARS-CoV-2 became a serious threat to humankind for the past couple of years. The development of vaccine and its immediate application might be the only to escape from the grasp of this demoniac pandemic. Approximately 343 clinical trials on COVID-19 vaccines are ongoing currently, and almost all countries are motivating ongoing researches at warp speed for the development of vaccines against COVID-19. This review explores the progress in the development of the vaccines, their current status of ongoing clinical research, mechanisms, and regulatory approvals. Many pharmaceutical companies are already in the endgame for manufacturing various vaccines of which some are already being marketed across the globe, while others are yet to get approval for marketing. The primary aim of this review is to compare regulatory accepted vaccines in terms of their composition, doses, regulatory status, and efficacy. The study is conducted by grouping into approved and unapproved vaccines for marketing. Different routes of administration of vaccines along with the efficacy of the routes are also presented in the review. A wide range of database and clinical trial data is reviewed for sorting out the information on different vaccines. Unfortunately, many mutations (alpha, beta, gamma, delta, kappa, omicron etc.) of SARS-CoV-2 have attacked people in very short time, which is the great challenge for investigational vaccines. Moreover, some vaccines like Pfizer's BNT162, Oxford's ChAdOx1, Moderna's mRNA-1273, and Bharat Biotech's Covaxin have got regulatory approval in some countries for its distribution which may prove to stand tall against the pandemic.

SARS-CoV-2 Infection: New Molecular, Phylogenetic, and Pathogenetic Insights. Efficacy of Current Vaccines and the Potential Risk of Variants

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly discovered coronavirus responsible for the coronavirus disease 2019 (COVID-19) pandemic. COVID-19 has rapidly become a public health emergency of international concern. Although remarkable scientific achievements have been reached since the beginning of the pandemic, the knowledge behind this novel coronavirus, in terms of molecular and pathogenic characteristics and zoonotic potential, is still relatively limited. Today, there is a vaccine, or rather several vaccines, which, for the first time in the history of highly contagious infectious diseases that have plagued mankind, has been manufactured in just one year. Currently, four vaccines are licensed by regulatory agencies, and they use RNA or viral vector technologies. The positive effects of the vaccination campaign are being felt in many parts of the world, but the disappearance of this new infection is still far from being a reality, as it is also threatened by the presence of novel SARS-CoV-2 variants that could undermine the effectiveness of the vaccine, hampering the immunization control efforts. Indeed, the current findings indicate that SARS-CoV-2 is adapting to transmission in humans more efficiently, while further divergence from the initial archetype should be considered. In this review, we aimed to provide a collection of the current knowledge regarding the molecular, phylogenetic, and pathogenetic insights into SARS-CoV-2. The most recent findings obtained with respect to the impact of novel emerging SARS-CoV-2 variants as well as the development and implementation of vaccines are highlighted.

Preparedness of Health Care Workers and Medical Students in University Hospital in Krakow for COVID-19 Pandemic within the CRACoV Project

Backgrounds Health care workers' (HCWs) knowledge of and compliance with personal protective procedures is a key for patients' and personnel safety. The aim of this study was to assess which factors are associated with higher self-evaluations of training on infection prevention and control (IPC) and higher self-assessment of IPC practices used by HCWs regarding COVID-19 in University Hospital in Krakow, Poland, in January 2021. Material and methods This was an online survey on the preparedness for COVID-19 epidemic of medical/non-medical staff and medical students. Questions included in the survey concerned participants' socio-demographic characteristics, hospital staff involvement in the training, knowledge about the hand hygiene, and adherence to IPC measures. Knowledge and Performance Index (K&PI) based on selected questions was constructed for to reflect both subjective (self-evaluation) of preparedness and objective IPC knowledge and skills of HCWs participated in the IPC training. Results A total of 1412 health care workers, including 129 medical students, participated in the study. The largest group, 53.6%, was made up of nurses and paramedics. Age of respondents significantly correlated with knowledge of IPC and with K&PI. The mean age of workers with high K&PI was 42.39 ± 12.53, and among those with low, 39.71 ± 13.10, p < 0.001. 51% UHK workers participated in IPC training, but 11.3% of physicians, 28.8% of other HCWs, and 55.8% of students did not know the IPC standard precaution. Most participants, 72.3%, felt that they had received sufficient training; however, 45.8% of students declined this. There was no correlation between self-reported preparedness and the K&PI, indicating that self-reported preparedness was inadequate for knowledge and skills. Nurses and paramedics assessed their knowledge most accurately. Participants with low K&PI and high subjective evaluation constituted a substantial group in all categories. Students least often overestimated (23.8%) and most often (9.6%) underestimated their knowledge and skills. Conclusions Our study revealed inadequate IPC practice, especially as it refers to the training programme. We confirmed the urgent need of including theory and practice of IPC in curricula of health professions' training in order to provide students with knowledge and skills necessary not only for future pandemic situations but also for everyday work.

Computer-Aided Prediction and Identification of Phytochemicals as Potential Drug Candidates against MERS-CoV

The Middle East respiratory syndrome coronavirus (MERS-CoV) is the major leading cause of respiratory infections listed as blueprint of diseases by the World Health Organization. It needs immediate research in the developing countries including Saudi Arabia, South Korea, and China. Still no vaccine has been developed against MERS-CoV; therefore, an effective strategy is required to overcome the devastating outcomes of MERS. Computer-aided drug design is the effective method to find out potency of natural phytochemicals as inhibitors of MERS-CoV. In the current study, the molecular docking approach was employed to target receptor binding of CoV. A total of 150 phytochemicals were docked as ligands in this study and found that some of the phytochemicals successfully inhibited the catalytic triad of MERS-CoV. The docking results brought novel scaffolds which showed strong ligand interactions with Arg178, Arg339, His311, His230, Lys146, and Arg139 residues of the viral domains. From the top ten ligands found in this study (i.e., rosavin, betaxanthin, quercetin, citromitin, pluviatilol, digitogenin, ichangin, methyl deacetylnomilinate, kobusinol A, and cyclocalamin) based on best $S$ -score values, two phytochemicals (i.e., pluviatilol and kobusinol A) exhibited all drug-likeness properties following the pharmacokinetic parameters which are important for bioavailability of drug-like compounds, and hence, they can serve as potential drug candidates to stop the viral load. The study revealed that these phytochemicals would serve as strong potential inhibitors and a starting point for the development of vaccines and proteases against MERS-CoV. Further, in vivo studies are needed to confirm the efficacy of these potential drug candidates.

An in silico approach to target RNA-dependent RNA polymerase of COVID-19 with naturally occurring phytochemicals

The novel coronavirus disease 2019 (COVID-19) was firstly reported from Wuhan city of China and found as a highly contagious, transmittable and pathogenic viral infection. The World Health Organization declared COVID-19 as a pandemic since its emergence from China. The RNA-dependent RNA polymerase (nsp-12) is a complex with nsp-7 and nsp-8 cofactors and is a major constituent of viral replication and RNA synthesis machinery. In the current study, the RdRp of the virus was selected as a receptor protein for computational drug discovery. Computational homology modelling was done in order to find the hidden secondary structures and structural assessment of the viral protein to target them via antiviral drugs. The study was based on molecular docking of different phytochemicals to check their potentials against viral replicative proteins. Out of 200 ligands used in this study from different plants, the best ten were selected based on drug discovery parameters such as S-score, ligand interactions, hydrophobic interactions and druglikeness. The ten best selected ligands were found to be verbenalin, epigallocatechin, swertisin, nobiletin, pinoresinol, caftaric acid, hesperetin, islandicin, neochlorogenic acid and sesamin that exploit the potency as antagonists of viral protein. Among binding interactions of all ligands, Arg339 centred as the main interacting residue among almost all the ligands. Till now, many antiviral agents have shown potency in only mild cases of SARS-CoV-2, but no effective drug has been found for critical pulmonary cases. In clinical trials, many broad-spectrum antiviral agents have been still in trial periods of testing against SARS-CoV-2. Till date, no effective drug or vaccine has been validated with significant efficacy and potency against the SARS-CoV-2; therefore, there is an urgent need to design effective vaccine against nCoV-19 infection.