SARS-Associated Coronavirus Quasispecies in Individual Patients

To the Editor: Quasispecies are known in RNA viruses such as hepatitis C virus and human immunodeficiency virus.1 Owing to poor fidelity of RNA polymerases, RNA-virus populations typically contain genetic variants that form a heterogeneous virus pool. The severe acute respiratory syndrome (SARS)–associated coronavirus, as a newly identified RNA virus,2 however, has been reported with relatively limited variations,3,4 and no published data have recorded the existence of quasispecies. During the SARS outbreak from March to June in 2003, 132 patients with SARS were treated in our unit, including those with the first cluster of cases in the Beijing, China, . . .