Immune Status of COVID-19 Patients with Reference to SARS and MERS
coronavirus, MERS-CoV, Immune status, SARS-CoV, COVID-19
During this global pandemic of COVID-19 infection, it became well known that morbidity and mortalityis especially high at the extreme of life especially in certain racial or ethnic groups like Americansand Africans. This is presumed due to low immunity associated with other comorbid conditions likediabetes, hypertension, cardiovascular disease, obesity and metabolic syndrome. But the informationavailable on the immune status of COVID-19 patients is limited. Attempts must be made to enhanceour understanding of the immune status of COVID-19 patients by revisiting our knowledge on theimmune mechanisms of already known coronaviruses such as SARS-CoV and MERS-CoV. Early elevationof the serum levels of pro-inflammatory cytokines observed in SARS and MERS infection suggests apossible same type of cytokine storm-mediated lung damage in COVID-19 patients too. Dysregulationof interferon-1 response and downstream cascade in initial innate immune response at virus entrypoint has been related to lethal pneumonia in COVID-19 patients. Adaptive response of increasedCD8+ levels in COVID-19 patients seems to be useful in mild cases where it causes deterioratingeffects in progressed severe disease patients resulting in destruction of type 2 pneumocytes henceinability to regenerate the alveolar epithelium. A phenomenon called cytokine storm activates violentimmunological reactions in the lung tissue resulting in ARDS followed by multiple organ systemdamages in COVID-19 patients. Several immune evading mechanisms are thought to be employed bysevere respiratory syndrome virus-2 (SARS-CoV-2) that might have resulted in its extremely increasedcontagiousness probably related with its frequent RNA mutations. Failure to develop adequate viruslimiting immune reactions by some cured patients warrant monitoring of all recovered patients. Thisrapid mini review is aimed to enhance our knowledge of the immune status of COVID-19 infectedpatients with reference to SARS-CoV and MERS-CoV.
Journal of Pure and Applied Microbiology