Comparative Susceptibility of Respiratory Viruses to Recombinant Interferons-α2band -β

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Abstract
Intranasal recombinant interferon-.alpha.2b (rIFN-.alpha.2b) protects against natural colds due to rhinoviruses, but apparently not against those caused by viruses. Because rIFN-.beta.serine17 (rIFN-.beta.ser) appears less active than rIFN-.alpha.2b in preventing natural rhinovirus colds, we compared the two IFNs in two in vitro assays against selected respiratory viruses. In a yield reduction assay, both IFNs had comparable activity against rhinovirus types 39 and 1A and coronavirus 229E, which were inhibited by 90% or more at IFN concentrations of 10-11 to 10-10 gram of protein/ml (approximately 2-20 IU/ml). Similar activities were observed with rIFN-.beta.ser against rhinoviruses isolated from clinical specimens. At concentrations of 10-9 gram protein/ml, both IFNs inhibited the growth of influenza A and parainfluenza viruses, but not of adenovirus or respiratory syncytial virus in the cell culture systems tested. Thus, the different clinical protection conferred by rIFN-.alpha.2b and rIFN-.beta.ser in studies of natural rhinovirus colds are not accounted for by differences in their in vitro activity against these viruses, and other explanations must be found.