Abstract

Coronaviruses (CoVs) are a large and distinct group of RNA viruses that can affect a wide range of animal species. These are spherical-shaped viruses with spike (S) proteins positioned from the virion surface. The severe acute respiratory syndromecoronavirus (SARS-CoV) has a 30 kb RNA genome with 14 open reading frames flanked by 5′ and 3′ UTR sections. The 5′ untranslated region is 265 bp long, while the 3′ end is 342 bp long. Normally, the coronavirus S protein is fragmented into 2 subunits, S1 and S2, though in the context of SARS-CoV, an un-cleaved type one transmembrane S protein with S1 and S2 subunit homology has been discovered. CoVs are classified into four genera based on genetic and antigenic characteristics: α, β, γ, and δ. α and β CoVs only infect mammals, whereas primarily γ and δ infect birds, though some can infect mammals as well. In 29 regions and countries, many deaths and cases were reported due to the outbreak of SARS. Initially, the cases were reported in 2002 in China. In 2003, the outbreak of atypical pneumonia was first time reported by WHO, and five deaths and 306 cases were reported in China due to this outbreak. Molecular epidemiology studies revealed that the virus from the 2002–2003 South China pandemic was distinct from the unique virus isolated in similar areas in the late 2003 and early 2004 epidemics, presenting distinct species-crossing events. SARSCoV has a wide host range. Different studies also showed that this virus can proliferate in ferrets and macaques; however, in cats, no symptoms of this virus were found.