Intranasal tolerance and histopathologic effects of a novel synthetic interferon, rIFN-alpha Con1

Intranasal administration of alpha interferon reduces seasonal influenza A virus morbidity in ferrets

The type I interferon (IFN) response represents one of the first lines of defense against influenza virus infections. In this study, we assessed the protective potential of exogenous IFN-alpha against seasonal and highly pathogenic influenza viruses in ferrets. Intranasal treatment with IFN-alpha several hours before infection with the H1N1 influenza A virus strain A/USSR/90/77 reduced viral titers in nasal washes at least 100-fold compared to mock-treated controls. IFN-treated animals developed only mild and transient respiratory symptoms, and the characteristic fever peak seen in mock-treated ferrets 2 days after infection was not observed. Repeated application of IFN-alpha substantially increased the protective effect of the cytokine treatment. IFN-alpha did not increase survival after infection with the highly pathogenic H5N1 avian influenza A virus strain A/Vietnam/1203/2004. However, viral titers in nasal washes were significantly reduced at days 1 and 3 postinfection. Our study shows that intranasal application of IFN-alpha can protect ferrets from seasonal influenza viruses, which replicate mainly in the upper respiratory tract, but not from highly pathogenic influenza viruses, which also disseminate to the lung. Based on these results, a more intensive evaluation of IFN-alpha as an emergency drug against pandemic influenza A is warranted.

WITHDRAWN: Antivirals for the common cold

BACKGROUND

The common cold is a ubiquitous short and usually mild illness for which preventive and treatment interventions have been under development since the mid-40s. As our understanding of the disease has increased, more experimental antivirals have been developed. This review attempts to draw together experimental evidence of the effects of these compounds.

OBJECTIVES

To identify, assemble, evaluate and (if possible) synthesise the results of published and unpublished randomised controlled trials of the effects of antivirals to prevent or minimise the impact of the common cold.

SEARCH STRATEGY

We searched electronic databases, corresponded with researchers and handsearched the archives of the MRC's Common Cold Unit (CCU).

SELECTION CRITERIA

We included original reports of randomised and quasi-randomised trials assessing the effects of antivirals on volunteers artificially infected and in individuals exposed to colds in the community.

DATA COLLECTION AND ANALYSIS

We included 241 studies assessing the effects of Interferons, interferon-inducers and other antivirals on experimental and naturally occurring common colds, contained in 230 reports. We structured our comparisons by experimental or community setting.

MAIN RESULTS

Although intranasal interferons have high preventive efficacy against experimental colds (protective efficacy 46%, 37% to 54%) and to a lesser extent against natural colds (protective efficacy 24%, 21% to 27%) and are also significantly more effective than placebo in attenuating the course of experimental colds (WMD 15.90, 13.42 to 18.38), their safety profile makes compliance with their use difficult. For example, prolonged prevention of community colds with interferons causes blood-tinged nasal discharge (OR 4.52, 3.78 to 5.41). Dipyridamole (protective efficacy against natural colds 49%, 30% to 62%), ICI 130, 685 (protective efficacy against experimental colds 58%, 35% to 74% ), Impulsin (palmitate) (protective efficacy against natural colds 44%, CI 35% to 52% ) and Pleconaril (protective efficacy against experimental colds 71%, 15% to 90% ) appear to have important antiviral properties and are well-tolerated. The evidence of effectiveness of other compounds in the treatment of experimental or natural colds is sparse.

AUTHORS' CONCLUSIONS

There are no licensed effective antivirals for the common cold. Because prolonged intranasal administration causes a clinical picture which is not distinguishable from the common cold, interferons have no place in everyday use. Further assessment of the effects of dipyridamole, ICI 130, 685, Impulsin (palmitate) and Pleconaril in preventing the common cold should be carried out. Given the multi-agent nature of the causes of the common cold, future research efforts should focus on non virus-specific compounds.

Interferon-alpha hybrids

The alpha-interferons (IFN-alpha) belong to a family of polypeptides comprising several subtypes. Using recombinant DNA technology, it has been possible to create IFN hybrids that provide novel combinations of the amino acid residues from the parental protein sequences. They have been used to study structure-activity relationships of IFN-alpha and interactions with the IFN-alpha receptor, and to create analogs of natural IFNs with novel properties for potential therapeutic application. The biological data obtained with these hybrids are now evaluated in terms of the published structural and homology models of IFN-beta and -alpha.