Rhinoviruses replicate effectively at lower airway temperatures

Rhinoviruses are epidemiologically connected to the majority of acute asthma exacerbations; however, their ability to infect and replicate in the lower airways is disputed. A frequent argument against this possibility involves the temperature preference for rhinovirus replication, generally accepted to be 33°C, the temperature of the nasal passages. However, this argument is based on studies with a single rhinovirus serotype. In this study, differences in temperature preferences were evaluated between several serotypes and relative titers were determined than can be achieved at upper and lower airway temperatures. Rhinovirus serotypes 1b, 2, 7, 9, 14, 16, 41, and 70 were titrated in Ohio-HeLa cell cultures at either 33°C or 37°C. Possible selection by culture temperature was examined by continuous culture at 33°C and 37°C for 2–4 passages and subsequent titration at both temperatures. Finally, nasal aspirate samples derived from patients with wild-type rhinoviral common colds were cultured at 33°C and 37°C and RT-PCR was used to assess rhinovirus replication at each temperature. The majority of the serotypes and wild-type viruses replicated slightly better at 33°C than at 37°C. However, titers achieved after one or more replicative cycles at 37°C were still high enough to initiate infection. Furthermore, in some instances equal or even better replication was observed at 37°C. It is concluded that temperature preferences may vary between rhinoviruses and are not likely to be a prohibitive factor for infection of the lower airways. J. Med. Virol. 58:100–104, 1999. © 1999 Wiley-Liss, Inc.