Within betacoronaviruses, there are 4 lineages: lineage A contains human coronaviruses HKU1 and OC43, lineage B to which SARS-CoV (Severe Acute Respiratory Syndrome Coronavirus) belongs, lineage C belongs to MERS-CoV (Middle East Respiratory Coronavirus Syndrome) and the lineage D has the bat coronaviruses HKU4 and HKU5 who are close to MERS-CoV.