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3.
Immunobiology ; 226(1): 152021, 2021 01.
Article in English | MEDLINE | ID: covidwho-908903

ABSTRACT

SARS-CoV-2 is a highly contagious virus that has caused serious health crisis world-wide resulting into a pandemic situation. As per the literature, the SARS-CoV-2 is known to exploit humanACE2 receptors (similar toprevious SARS-CoV-1) for gaining entry into the host cell for invasion, infection, multiplication and pathogenesis. However, considering the higher infectivity of SARS-CoV-2 along with the complex etiology and pathophysiological outcomes seen in COVID-19 patients, it seems that there may be an alternate receptor for SARS-CoV-2. I performed comparative protein sequence analysis, database based gene expression profiling, bioinformatics based molecular docking using authentic tools and techniques for unveiling the molecular basis of high infectivity of SARS-CoV-2 as compared to previous known coronaviruses. My study revealed that SARS-CoV-2 (previously known as 2019-nCoV) harbors a RGD motif in its receptor binding domain (RBD) and the motif is absent in all other previously known SARS-CoVs. The RGD motif is well known for its role in cell-attachment and cell-adhesion. My hypothesis is that the SARS-CoV-2 may be (via RGD) exploiting integrins, that have high expression in lungs and all other vital organs, for invading host cells. However, an experimental verification is required. The expression of ACE2, which is a known receptor for SARS-CoV-2, was found to be negligible in lungs. I assume that higher infectivity of SARS-CoV-2 could be due to this RGD-integrin mediated acquired cell-adhesive property. Gene expression profiling revealed that expression of integrins is significantly high in lung cells, in particular αvß6, α5ß1, αvß8 and an ECM protein, ICAM1. The molecular docking experiment showed the RBD of spike protein binds with integrins precisely at RGD motif in a similar manner as a synthetic RGD peptide binds to integrins as found by other researchers. SARS-CoV-2 spike protein has a number of phosphorylation sites that can induce cAMP, PKC, Tyr signaling pathways. These pathways either activate calcium ion channels or get activated by calcium. In fact, integrins have calcium & metal binding sites that were predicted around and in vicinity of RGD-integrin docking site in our analysis which suggests that RGD-integrins interaction possibly occurs in calcium-dependent manner. The higher expression of integrins in lungs along with their previously known high binding affinity (~KD = 4.0 nM) for virus RGD motif could serve as a possible explanation for high infectivity of SARS-CoV-2. On the contrary, human ACE2 has lower expression in lungs and its high binding affinity (~KD = 15 nM) for spike RBD alone could not manifest significant virus-host attachment. This suggests that besides human ACE2, an additional or alternate receptor for SARS-CoV-2 is likely to exist. A highly relevant evidence never reported earlier which corroborate in favor of RGD-integrins mediated virus-host attachment is an unleashed cytokine storm which causes due to activation of TNF-α and IL-6 activation; and integrins role in their activation is also well established. Altogether, the current study has highlighted possible role of calcium and other divalent ions in RGD-integrins interaction for virus invasion into host cells and suggested that lowering divalent ion in lungs could avert virus-host cells attachment.


Subject(s)
COVID-19/virology , Calcium/metabolism , Chelation Therapy , Edetic Acid/therapeutic use , Integrins/metabolism , Receptors, Immunologic/metabolism , Receptors, Peptide/metabolism , SARS-CoV-2/pathogenicity , Spike Glycoprotein, Coronavirus/metabolism , Angiotensin-Converting Enzyme 2/metabolism , Binding Sites/genetics , Calcium Channels/metabolism , Gene Expression Profiling , Humans , Integrins/chemistry , Intercellular Adhesion Molecule-1/metabolism , Interleukin-6/metabolism , Lung/metabolism , Molecular Docking Simulation , Oligopeptides/chemistry , Oligopeptides/metabolism , Protein Binding , Receptors, Virus/metabolism , SARS-CoV-2/metabolism , Sequence Alignment , Signal Transduction/genetics , Spike Glycoprotein, Coronavirus/chemistry , Spike Glycoprotein, Coronavirus/genetics , Tumor Necrosis Factor-alpha/metabolism , Virus Attachment , COVID-19 Drug Treatment
4.
J Pak Med Assoc ; 70(Suppl 3)(5): S69-S73, 2020 May.
Article in English | MEDLINE | ID: covidwho-609358

ABSTRACT

Novel coronavirus disease (COVID-19) infection is a global pandemic, of high infectivity, variable mortality, with currently no established treatment. This review summarizes different molecules which are being evaluated for COVID19 treatment. PubMed and Medline, search for articles published to March 2020 was done using terms "COVID19" OR "corona-virus 2019" OR "2019-nCoV" or "severe acute respiratory syndrome coronavirus" AND "treatment". As of today, we have >350 RCTs happening with different agents. COVID19 treatment agents can be broadly classified into immuno-modulators (prevent hyperimmune-activation and cytokine storm) and anti-viral therapies (prevent virus entry, replication or viricidal). Hydroxychloroquine/chloroquine, Interferon-l, glucocorticoids, interleukin antagonists, Ulinastatin, intravenous immunoglobulins, plasmapheresis are main immunomodulators showing initial positive outcomes. Umifenovir. Lopinavir/Ritonavir, Ribavirin, remdesivir and Ravipiravir are some of the major antiviral agents showing initial encouraging results. It may be concluded that the most successful regimen is going to be multi-drug therapy, a combination of immunomodulatory agent with anti-viral agent.


Subject(s)
Betacoronavirus , Coronavirus Infections/drug therapy , Pneumonia, Viral/drug therapy , Antiviral Agents/therapeutic use , COVID-19 , Chelation Therapy , Humans , Immunoglobulins, Intravenous/therapeutic use , Pandemics , SARS-CoV-2 , COVID-19 Drug Treatment
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