Morphology: spherical (80–220 nm) Envelop: bilayer lipid Genome type: single stranded positive RNA, infectious Genome size: 27–31 kb Replication site: cytoplasm Recombination rate: very high (10–4 substitution per year and per site) Structural proteins: envelope (E), membrane (M), spike (S), nucleocapsid (N) and in few coronaviruses hemagglutinin‐esterase (HE) Main antigenic protein: spike protein Main immunogenic protein: spike protein Most conserved genes: the envelope (E) and membrane (M) protein genes Most variable genes: the spike (S) protein genes Resistance: 9 days in dry state for the SARS‐CoV, 22 days in water at 25°C for the TGEV, 7 days for the MHV (mouse hepatitis virus) in sewage Susceptibility: heat (30 min at 56°C), alcohol based solutions (30 s to 1 min)