Innate Immune-mediated Antiviral Response to SARS-CoV-2 and Convalescent sera a potential Prophylactic and Therapeutic Agent to Tackle COVID-19

Abdullah, Abdullah; Faisal, Shah; Aman, Komal; Rahman, Anees ur

The whole world is confronting the pandemic of SARS-CoV-2. Unfortunately there is no vaccine to prevent from novel coronavirus infection. Beside several experimental drugs, the strong immune responses and convalescent sera are the current two potential options to tackle COVID-19 infection. Innate immune-mediated antiviral responses is initiated by the recognition of viral invasion through PAMPs. In coronavirus the pathogen associated molecular patterns are recognized by toll like receptors (TLR-3 & 7), endosomal ribonucleic acid receptors, RNA in cytosol and by pattern recognition receptor (PRR RIG-1) in the alveolar cells and site of invasion. Nuclear factor (NF-κB) and interferon regulatory transcription factor (IRF3) are activated in response to above recognition episode and translocate to nucleus. These transcription factors in the nucleus initiate the expression of interferon type 1 and pro-inflammatory cytokine storm, which leads to first line of defense at the site of viral entrance. The effectiveness of innate immune system is greatly relies on type 1 interferons and its cascade, because of their role in inhibition of viral replication and initiation of adaptive immune responses. The successful interferon type 1 response put down the viral replication and transmission at prompt point. Passive immunization is the administering of antibodies into infected patients which is taken from recovered individuals. The convalescent sera of the recovered COVID-19 patients are containing antiviral neutralizing antibodies and is used therapeutically for infected individuals by SARS-CoV-2 and for the purpose of prophylaxis in exposed individuals. The convalescent sera is found effective when administered early at the onset of symptoms.