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.
Keywords: RNA viruses, SARS-CoV, Molecular epidemiology, Coronavirus, A typical pneumonia, Spike (S) proteins.