Comparative Susceptibility of Respiratory Viruses to Recombinant Interferons-α 2b and -β

Abstract

Intranasal recombinant interferon-α_2b (rIFN-α_2b) protects against natural colds due to rhinoviruses, but apparently not against those caused by viruses. Because rIFN-βserine₁₇ (rIFN-βser) appears less active than rIFN-α_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-βser 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-α_2b and rIFN-βser 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.