Esmaeil Ghorbanalinezhad,1,*Shohreh Moradkhani,2
1. Faculty of Department of Microbiology, Islamic Azad University of Tonekabon branch, Tonekabon, Iran 2. Master student of Food Microbiology, Iran University of Medical Sciences, Tehran, Iran
Introduction: SARS-CoV-2 is a novel coronavirus belongs to family Coronaviridae. It is a single-stranded RNA virus within a capsid comprised of matrix protein. The severity of COVID-19 is mainly related to host factors, especially cellular immune responses in patients. The immune system responds to SARS-CoV-2 with a innate and a combined adaptive responses where the body makes specific antibodies and T-cells. SARS-CoV-2 has managed to rattle the host immune system. During the infection of SARS-CoV-2, ACE2 is the receptor present in the host cells and hence the B cell epitope site. The immune response in patients with fatal severe COVID-19 includes three stages: normal or hypofunction, hyperactivation, and anergy.
Methods: Laboratory tests that detect antibodies to SARS-CoV-2 including rapid immunodiagnostic tests. Antibodies produces in response to MERS and SARS cross react with SARS-CoV-2 antibodies. The betacoronavirus genome encodes the S protein as a major inducer of host immune responses and elicits an immune response. A condensed report on several patents that describe vaccines for generating immunity such as Attenuated virus vaccines, DNA-based vaccines, Protein-based vaccines, Virus-like Particle Vaccines, mRNA-based vaccines.
Results: COVID-19, through hACE2 receptor, transduces genomic material into the host and mediates pattern recognition receptors (PRRs), especially TLR-3, TLR-7 and TLR-8, which detect persistence of viral particles in the cytoplasm, thus mediating a series of immune mechanisms and proinflamatory cytokines to induce CD8+ and CD4+ T cells. SARS-CoV-2 antigen peptide pools-stimulated-IL-2 and -IFN-γresponse can distinguish COVID-19 convalescent individuals from healthy donors.IL-6 results in the onset of respiratory distress and failure. The S protein is a targetable using antibodies. Current evidence indicates that Th1 response is key to the successful control of SARS-CoV-2. The kinetics of immune responses during COVID-19, determined that type I interferon (IFN) could be administered to patients with severe COVID-19 in the hypofunctional stage, and intravenous immunoglobulin (IVIG) and glucocorticoid therapy, low molecular weight heparin (LMWH) anticoagulation therapy and anti-infective therapy with antibiotics could be administered in the immune hyperactivation stage.
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Conclusion: Reduction of circulating NK cells and T-cell subsets in the Bronch oalveolar lavage fluid of patients with pneu¬monia, IgM antibodies detectable 7-10 day after disease onset and serocoversion developed in most patients recovered and antibody specificity for the RBD domain of S protein is infrequent. Patients with COVID-19 mounted IgG and IgM responses to SARS-CoV-2 proteins, especially NP and S-RBD, and suggest that patients who are infected could maintain their IgG levels, at least for 2 weeks. The development of neutralizing antibody is associated with the activation of T cells and NK cells.