• Kazuyuki Nakagome, Yury A Bochkov, Shamaila Ashraf, Rebecca A Brockman-Schneider, Michael D Evans, Thomas R Pasic, and James E Gern.
• Department of Pediatrics, School of Medicine and Public Health, University of Wisconsin, Madison, Wis.
• J. Allergy Clin. Immunol. 2014 Aug 1; 134 (2): 332-41.

BackgroundEpidemiologic studies provide evidence of differential virulence of rhinovirus species (RV). We recently reported that RV-A and RV-C induced more severe illnesses than RV-B, which suggests that the biology of RV-B might be different from RV-A or RV-C.ObjectiveTo test the hypothesis that RV-B has lower replication and induces lesser cytokine responses than RV-A or RV-C.MethodsWe cloned full-length cDNA of RV-A16, A36, B52, B72, C2, C15, and C41 from clinical samples and grew clinical isolates of RV-A7 and RV-B6 in cultured cells. Sinus epithelial cells were differentiated at the air-liquid interface. We tested for differences in viral replication in epithelial cells after infection with purified viruses (10(8) RNA copies) and measured virus load by quantitative RT-PCR. We measured lactate dehydrogenase (LDH) concentration as a marker of cellular cytotoxicity, and cytokine and/or chemokine secretion by multiplex ELISA.ResultsAt 24 hours after infection, the virus load of RV-B (RV-B52, RV-B72, or RV-B6) in adherent cells was lower than that of RV-A or RV-C. The growth kinetics of infection indicated that RV-B types replicate more slowly. Furthermore, RV-B released less LDH than RV-A or RV-C, and induced lower levels of cytokines and chemokines such as CXCL10, even after correction for viral replication. RV-B replicates to lower levels also in primary bronchial epithelial cells.ConclusionsOur results indicate that RV-B types have lower and slower replication, and lower cellular cytotoxicity and cytokine and/or chemokine production compared with RV-A or RV-C. These characteristics may contribute to reduced severity of illnesses that has been observed with RV-B infections.Copyright © 2014 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

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