A review on the immune responses against novel emerging coronavirus (SARS-CoV-2)

Coronavirus disease 2019 (COVID-19) is a highly contagious disease caused by a newly identified coronavirus called the severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) which was initially emerged in Wuhan, China in late December 2019 and then rapidly extended to other countries worldwide. COVID-19 is now known as a pandemic threat to global public health. It possesses a wide spectrum of clinical manifestations, ranging from asymptomatic infection to mild, moderate, and ultimately severe pneumonia accompanied by multi-organ system dysfunction that can cause the death of the afflicted patients. The host immune system plays a critical role in defending against potentially pathogenic microorganisms such as coronaviruses, and it eliminates and eradicates these invading agents by triggering effective immune responses. However, there exists evidence indicating that in critically ill cases of the COVID-19, dysregulated immune responses and hyper-inflammation lead to acute respiratory distress syndrome (ARDS) and multi-organ failure. Achieving a profound understanding of the pathological immune responses involved in the pathogenesis of COVID-19 will boost our comprehending of disease pathogenesis and its progression toward severe form, contributing to the identification and rational design of effective therapies. In this review, we have tried to summarize the current knowledge regarding the role of immune responses against SARS-CoV-2 and also give a glimpse of the immune evasion strategies of this virus.