From Alpha to Omicron SARS-CoV-2 variants: What their evolutionary signatures can tell us?

Targeting DPP4-RBD interactions by sitagliptin and linagliptin delivers a potential host-directed therapy against pan-SARS-CoV-2 infections

Highly mutated SARS-CoV-2 is known aetiological factor for COVID-19. Here, we have demonstrated that the receptor binding domain (RBD) of the spike protein can interact with human dipeptidyl peptidase 4 (DPP4) to facilitate virus entry, in addition to the usual route of ACE2-RBD binding. Significant number of residues of RBD makes hydrogen bonds and hydrophobic interactions with α/β-hydrolase domain of DPP4. With this observation, we created a strategy to combat COVID-19 by circumventing the catalytic activity of DPP4 using its inhibitors. Sitagliptin, linagliptin or in combination disavowed RBD to establish a heterodimer complex with both DPP4 and ACE2 which is requisite strategy for virus entry into the cells. Both gliptins not only impede DPP4 activity, but also prevent ACE2-RBD interaction, crucial for virus growth. Sitagliptin, and linagliptin alone or in combination have avidity to impede the growth of pan-SARS-CoV-2 variants including original SARS-CoV-2, alpha, beta, delta, and kappa in a dose dependent manner. However, these drugs were unable to alter enzymatic activity of PLpro and Mpro. We conclude that viruses hijack DPP4 for cell invasion via RBD binding. Impeding RBD interaction with both DPP4 and ACE2 selectively by sitagliptin and linagliptin is an potential strategy for efficiently preventing viral replication.

The importance of equally accessible genomic surveillance in the age of pandemics

Genomic epidemiology is now a core component in investigating the spread of a disease during an outbreak and for future preparedness to tackle emerging zoonoses. During the last decades, several viral diseases arose and emphasized the importance of molecular epidemiology in tracking the dispersal route, supporting proper mitigation measures, and appropriate vaccine development. In this perspective article, we summarized what has been done so far in the genomic epidemiology field and what should be considered in the future. We traced back the methods and protocols employed over time for zoonotic disease response. Either to small outbreaks such as the severe acute respiratory syndrome (SARS) outbreak identified first in 2002 in Guangdong, China, or to a global pandemic like the one that we are experiencing now since 2019 when the severe acute respiratory syndrome 2 (SARS-CoV-2) virus emerged in Wuhan, China, following several pneumonia cases, and subsequently spread worldwide. We explored both the benefits and shortages encountered when relying on genomic epidemiology, and we clearly present the disadvantages of inequity in accessing these tools around the world, especially in countries with less developed economies. For effectively addressing future pandemics, it is crucial to work for better sequencing equity around the globe.

Global emerging Omicron variant of SARS-CoV-2: Impacts, challenges and strategies

Newly emerging variants of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are continuously posing high global public health concerns and panic resulting in waves of coronavirus disease 2019 (COVID-19) pandemic. Depending on the extent of genomic variations, mutations and adaptation, few of the variants gain the ability to spread quickly across many countries, acquire higher virulency and ability to cause severe disease, morbidity and mortality. These variants have been implicated in lessening the efficacy of the current COVID-19 vaccines and immunotherapies resulting in break-through viral infections in vaccinated individuals and recovered patients. Altogether, these could hinder the protective herd immunity to be achieved through the ongoing progressive COVID-19 vaccination. Currently, the only variant of interest of SARS-CoV-2 is Omicron that was first identified in South Africa. In this review, we present the overview on the emerging SARS-CoV-2 variants with a special focus on the Omicron variant, its lineages and hybrid variants. We discuss the hypotheses of the origin, genetic change and underlying molecular mechanism behind higher transmissibility and immune escape of Omicron variant. Major concerns related to Omicron including the efficacy of the current available immunotherapeutics and vaccines, transmissibility, disease severity, and mortality are discussed. In the last part, challenges and strategies to counter Omicron variant, its lineages and hybrid variants amid the ongoing COVID-19 pandemic are presented.

Omicron SARS-CoV-2 Variants in an In Silico Genomic Comparison Study with the Original Wuhan Strain and WHO-Recognized Variants of Concern

This study aimed to determine the genetic alterations in the Omicron variants compared to other variants of concern (VOCs) to trace the evolutionary genetics of the SARS-CoV-2 variants responsible for the multiple COVID-19 waves globally. The present study is an in silico analysis determining the evolution of selected 11 VOCs compared to the original Wuhan strain. The variants included six Omicrons and one variant of Alpha, Beta, Delta, Gamma, and Mu. The pairwise alignment with the local alignment search tool of NCBI Nucleotide-BLAST and NCBI Protein-BLAST were used to determine the nucleotide base changes and corresponding amino acid changes in proteins, respectively. The genomic analysis revealed 210 nucleotide changes; most of these changes (127/210, 60.5%) were non-synonymous mutations that occurred mainly in the S gene (52/127, 40.1%). The remaining 10.5% (22/210) and 1.9% (4/210) of the mutations were frameshift deletions and frameshift insertions, respectively. The frameshift insertion (Ins22194T T22195G) led to frameshift deletion (Δ211N). Only four mutations (C241T, C3037T, C14408T, and A23403G) were shared among all the VOCs. The nucleotide changes among Omicron variants resulted in 61 amino acid changes, while the nucleotide changes in other VOCs showed 11 amino acid changes. The present study showed that most mutations (38/61, 62.3%) among Omicron variants occurred in the S gene; and 34.2% of them (13/38) occurred in the receptor-binding domain. The present study confirmed that most of mutations developed by Omicron variants occurred in the vaccine target gene (S gene).

The Deltacron conundrum: Its origin and potential health risks

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), since its outbreak in December 2019, has been capable of continuing the pandemic by mutating itself into different variants. Mass vaccinations, antibiotic treatment therapy, herd immunity, and preventive measures have reduced the disease's severity from the emerging variants. However, the virus is undergoing recombination among the current two variants: Delta and Omicron, resulting in a new variant, informally known as "Deltacron," which was controversial as it might be a product of lab contamination between Omicron and Delta samples. However, the proclamation was proved wrong, and the experts are putting more effort into better understanding the variant's epidemiological characteristics to control potential outbreaks. This review has discussed the potential mutations in the novel variant and prospective risk factors and therapeutic options in the context of this new variant. This study could be used as a guide for implementing appropriate controls in a sudden outbreak of this new variant.

Omicron variant (B.1.1.529) and its sublineages: What do we know so far amid the emergence of recombinant variants of SARS-CoV-2?

Since the start of the COVID-19 pandemic, numerous variants of SARS-CoV-2 have been reported worldwide. The advent of variants of concern (VOCs) raises severe concerns amid the serious containment efforts against COVID-19 that include physical measures, pharmacological repurposing, immunization, and genomic/community surveillance. Omicron variant (B.1.1.529) has been identified as a highly modified, contagious, and crucial variant among the five VOCs of SARS-CoV-2. The increased affinity of the spike protein (S-protein), and host receptor, angiotensin converting enzyme-2 (ACE-2), due to a higher number of mutations in the receptor-binding domain (RBD) of the S-protein has been proposed as the primary reason for the decreased efficacy of majorly available vaccines against the Omicron variant and the increased transmissible nature of the Omicron variant. Because of its significant competitive advantage, the Omicron variant and its sublineages swiftly surpassed other variants to become the dominant circulating lineages in a number of nations. The Omicron variant has been identified as a prevalent strain in the United Kingdom and South Africa. Furthermore, the emergence of recombinant variants through the conjunction of the Omicron variant with other variants or by the mixing of the Omicron variant's sublineages/subvariants poses a major threat to humanity. This raises various issues and hazards regarding the Omicron variant and its sublineages, such as an Omicron variant breakout in susceptible populations among fully vaccinated persons. As a result, understanding the features and genetic implications of this variant is crucial. Hence, we explained in depth the evolution and features of the Omicron variant and analyzed the repercussions of spike mutations on infectiousness, dissemination ability, viral entry mechanism, and immune evasion. We also presented a viewpoint on feasible strategies for precluding and counteracting any future catastrophic emergence and spread of the omicron variant and its sublineages that could result in a detrimental wave of COVID-19 cases.

AI-based search for convergently expanding, advantageous mutations in SARS-CoV-2 by focusing on oligonucleotide frequencies

Among mutations that occur in SARS-CoV-2, efficient identification of mutations advantageous for viral replication and transmission is important to characterize and defeat this rampant virus. Mutations rapidly expanding frequency in a viral population are candidates for advantageous mutations, but neutral mutations hitchhiking with advantageous mutations are also likely to be included. To distinguish these, we focus on mutations that appear to occur independently in different lineages and expand in frequency in a convergent evolutionary manner. Batch-learning SOM (BLSOM) can separate SARS-CoV-2 genome sequences according by lineage from only providing the oligonucleotide composition. Focusing on remarkably expanding 20-mers, each of which is only represented by one copy in the viral genome, allows us to correlate the expanding 20-mers to mutations. Using visualization functions in BLSOM, we can efficiently identify mutations that have expanded remarkably both in the Omicron lineage, which is phylogenetically distinct from other lineages, and in other lineages. Most of these mutations involved changes in amino acids, but there were a few that did not, such as an intergenic mutation.

Molecular and Clinical Investigation of COVID-19: From Pathogenesis and Immune Responses to Novel Diagnosis and Treatment

The coronavirus-related severe acute respiratory syndrome (SARS-CoV) in 2002/2003, the Middle East respiratory syndrome (MERS-CoV) in 2012/2013, and especially the current 2019/2021 severe acute respiratory syndrome-2 (SARS-CoV-2) negatively affected the national health systems worldwide. Different SARS-CoV-2 variants, including Alpha (B.1.1.7), Beta (B.1.351), Gamma (P.1), Delta (B.1.617.2), and recently Omicron (B.1.1.529), have emerged resulting from the high rate of genetic recombination and S1-RBD/S2 mutation/deletion in the spike protein that has an impact on the virus activity. Furthermore, genetic variability in certain genes involved in the immune system might impact the level of SARS-CoV-2 recognition and immune response against the virus among different populations. Understanding the molecular mechanism and function of SARS-CoV-2 variants and their different epidemiological outcomes is a key step for effective COVID-19 treatment strategies, including antiviral drug development and vaccine designs, which can immunize people with genetic variabilities against various strains of SARS-CoV-2. In this review, we center our focus on the recent and up-to-date knowledge on SARS-CoV-2 (Alpha to Omicron) origin and evolution, structure, genetic diversity, route of transmission, pathogenesis, new diagnostic, and treatment strategies, as well as the psychological and economic impact of COVID-19 pandemic on individuals and their lives around the world.

Targeting the Ubiquitylation and ISGylation Machinery for the Treatment of COVID-19

Ubiquitylation and ISGylation are protein post-translational modifications (PTMs) and two of the main events involved in the activation of pattern recognition receptor (PRRs) signals allowing the host defense response to viruses. As with similar viruses, SARS-CoV-2, the virus causing COVID-19, hijacks these pathways by removing ubiquitin and/or ISG15 from proteins using a protease called PLpro, but also by interacting with enzymes involved in ubiquitin/ISG15 machinery. These enable viral replication and avoidance of the host immune system. In this review, we highlight potential points of therapeutic intervention in ubiquitin/ISG15 pathways involved in key host-pathogen interactions, such as PLpro, USP18, TRIM25, CYLD, A20, and others that could be targeted for the treatment of COVID-19, and which may prove effective in combatting current and future vaccine-resistant variants of the disease.