What is SARS？
SARS is Severe acute respiratory syndrome，caused by SARS-CoV. SARS can cause more severe respiratory illnesses like pneumonia with symptoms of cough (initially dry), fever, chills, fatigue, myalgia, headache. SARS first emerged in 2002, which caused 8098 people were infected with a case fatality rate of 9.6%. Different from MERS, there is no more cases reported since 2004. At the moment, no specific therapy for SARS-CoV-2, SARS-CoV, MERS-CoV and the other HCoVs infection is available. Symptomatic and supportive treatment is the mainstay of therapy for patients infected by HCoVs.
SARS-CoV belongs to Betacornavirus. The genome size of the SARS-CoV varies from 29.0 kb to 30.2 kb which can encodes structural proteins Spike, envelope (E), membrane (M), N proteins and non-structural proteins papain-like protease(s) (PLpro), chymotrypsin-likeprotease (3CLpro), RNA-dependent RNA polymerase (RdRp) and helicase (Hel). Haemagglutinin-esterase gene is absent from the genome of SARS-CoV.
The spike (S) protein is the most important antigen of SARS-CoV. It is composed of two subunits; the S1 subunit contains a receptor-binding domain (RBD) that engages with the host cell receptor angiotensin-converting enzyme 2 (ACE2) and the S2 subunit mediates fusion between the viral and host cell membranes. The S protein plays key parts in the induction of neutralizing-antibody and T-cell responses, as well as protective immunity, during infection with SARS-CoV.
(Ref:Hayes K.H. Luka.Molecular epidemiology, evolution and phylogeny of SARS coronavirus.Infection, Genetics and Evolution.2019)