Comparative profile of the human coronaviruses

The coronavirus disease (COVID-19), a respiratory illness is caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is a strain of human corona virus (HCoV) and is infectious in humans. Seven types of human coronaviruses, namely, human coronavirus 229E (HCoV-229E), human coronavirus OC43 (HCoV-OC43), severe acute respiratory syndrome coronavirus SARS-CoV-1, human coronavirus NL63 (HCoV-NL63), human coronavirus HKU1 (HCoV-HKU1), middle east respiratory syndrome-related coronavirus (MERS-CoV) and SARS-CoV-2 have been identified so far. Almost all these viruses spread between people through respiratory droplets produced from coughs or sneezes; the target cells being the epithelial cells of the respiratory tract. In this review, a brief comparative study of these pathogenic CoVs in humans is done which enables an understanding of the evolution in these diseases over a span of almost a century. This review will provide an insight into all HCoVs identified till date.