Limited efficacy of aerosolized recombinant alpha interferon against virulent influenza A/HK infection in mice

Interferons: The pathways of discovery

This article analyzes the conceptual and technological context in which, over a period of 50 years, exploration of the biological and clinical significance of type I interferon has evolved. The elaboration of techniques for production and purification of mouse and human interferons and the establishment of laboratory-size production units have been of crucial importance in this process. Animal experiments have been invaluable for elucidation of mechanisms underlying the in vivo antiviral, anti-tumour and immunomodulatory potential of interferon, but have been of limited help to define the areas of clinical applicability. Proof of principle for applications as they are established today has come from clinical trials performed quite independently of evidence from animal experiments.

Protective effect of recombinant interferon (IFN)-alpha/beta on MHV-2cc-induced chronic hepatitis in athymic nude mice

The protective effects of recombinant IFN-alpha/beta on MHV-2cc-induced chronic and persistent hepatitis in athymic nude mice were examined. The mice intraperitoneally (ip) inoculated with MHV-2cc at day 0 of experiment were divided into 4 groups. Three of them were administered ip with recombinant IFN-alpha/beta at a daily dose of 1 x 10(3) IU from -1 (-1D-group), 0 (0D-group), and +1 day of experiment (+1D-group), respectively, for 3 consecutive weeks. The remaining one (control group) was given 0.1 ml/mouse of PBS from +1 day of the experiment in the same way. Three mice in each group were killed at 1, 2 and 3 weeks post inoculation (WPI) with MHV, respectively. The liver virus titer in the control group increased gradually and maintained high levels throughout the experimental period. In the IFN-groups, particularly in the -1D- and 0D-groups, the virus titers were significantly lower than that in control group. Histopathologically, focal hepatic lesions were observed at 1WPI and large irregular inflammatory lesions developed at 3WPI in the control group. Similar but somewhat less severe lesions were observed in the +1D-group. In the -1D- and 0D-groups, lesions were not observed at 1WPI and only small organized lesions with mononuclear cell infiltration were seen at 3WPI. In conclusion, it was clarified in the present study that the progression of MHV-2cc-induced chronic hepatitis in athymic nude mice was effectively prevented by extrinsic IFN-alpha/beta when administered from -1 day and 0 day of the virus infection.

Stability of recombinant consensus interferon to air-jet and ultrasonic nebulization

The stability of recombinant consensus alpha-interferon (rConIFN) to air-jet and ultrasonic nebulization was evaluated. Volumes of 10 mL of 0.5 mg/mL rConIFN in phosphate-buffered saline (PBS) at pH 6.3 were nebulized with a Collison three-jet nebulizer at 40 psig (10 L/min) for up to 25 min. The effects of pH (3.0, 6.3, and 9.0), additive (0.1% w/v Tween 80, 0.1% w/v Tween 20, and 1% w/v PEG 8000), and ionic strength (0, 0.25, and 1.0) were examined. The effects of ultrasonic nebulization were studied using three devices (DeVilbiss "Aerosonic"; Mountain Medical "Microstat", and Medix "Easimist"). Stability of rConIFN was assessed by size exclusion chromatography and native and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis (PAGE). Structural effects were examined by circular dichroism spectroscopy and bioactivity was assessed by an in vitro mitogenic inhibition bioassay. rConIFN is destabilized by air-jet nebulization. Insoluble noncovalent aggregates are produced rapidly, and only approximately 25% of the initial monomeric protein remains after 25 min of nebulization. This correlates with a decrease in in vitro bioactivity. Aggregation during nebulization is influenced by pH (9.0 < 6.3 < 3.0) but even at the highest pH, > 25% aggregation is observed. Ionic strength does not appear to influence aggregation. rConIFN is also seen to adhere to glass after nebulization. Samples from a rinse of the emptied reservoir with 0.1% w/v SDS, after thorough rinsing with water (three times), show a strong rConIFN band on SDS-PAGE gels. The use of PEG 8000 and Tween mitigate aggregate formation and adhesion (< 20%). The cumulative output collected as a wet or dry aerosol is not aggregated to the same extent as the residual protein remaining in the nebulizer. Ultrasonic nebulization also results in aggregation, but the extent of denaturation is dependent upon the nebulizer used and is related to the heating of nebulizer solutions. Cooling of the nebulizer solution during operation (< 30 degrees C) minimizes aggregation (< 5%), and bioactivity is retained.

Evaluation of the anti-influenza virus activities of 1,3,4-thiadiazol-2-ylcyanamide (LY217896) and its sodium salt

1,3,4-Thiadiazol-2-ylcyanamide (LY217896) and its sodium salt were shown to be effective against influenza A and B viruses in vitro and in the mouse model. In nondividing confluent MDCK cells, the 50% inhibitory concentration of LY217896 ranged from 0.37 to 1.19 micrograms/ml against various strains of influenza A virus and from 0.75 to 1.54 micrograms/ml against various strains of influenza B virus, with no apparent cytotoxicity. However, at a concentration of 0.31 microgram/ml, LY217896 inhibited the replication of dividing MDCK cells. LY217896 (9 mg/m2 of body surface area per day) administered in the diet, in the drinking water, by oral gavage, by intraperitoneal injection, or by aerosolization was well tolerated and protected CD-1 mice infected with a lethal dose of influenza A or B virus. Effective administration of the compound could be delayed for up to 96 h postinfection. Virus titer was reduced by 1 to 2 log10 units in lungs of mice given LY217896 in the drinking water. Mice treated initially with protective levels of LY217896 were resistant to a subsequent challenge of influenza virus in the absence of the compound, indicating that the animals were able to develop immunity to the initial infection. Administration of LY217896 to uninfected mice did not induce interferon-like activity or interfere with natural killer cell function. In the ferret, LY217896 was effective in preventing fever induced by influenza virus.

Vaccination with inactivated influenza A virus during pregnancy protects neonatal mice against lethal challenge by influenza A viruses representing three subtypes

A single intraperitoneal injection of pregnant mice with a monovalent Formalin-inactivated influenza A virus vaccine protected their offspring against a lethal challenge dose of the same influenza A virus H3N2, H2N2, and H1N1 subtypes, as well as against challenge with the other two subtypes. Degree of protection was vaccine dose related. Cross-fostering of neonates indicated that protection was conferred by breast milk antibodies. Serum virus-specific neutralizing antibodies in the mothers and neonates correlated with resistance to vaccine virus, but were detected against other subtypes only in a complement enhancement test or when high doses of vaccine were given.

Antiviral Chemotherapyand Prophylaxis of Viral Respiratory Disease

Several antiviral agents are currently available for the treatment and prophylaxis of viral respiratory disease. These include oral amantadine for influenza A and aerosolized ribavirin for respiratory syncytial virus infections. Additional agents, such as rimantadine and intranasal interferons, and newer approaches, including thе use of combination chemotherapy, offer promise for the improved management of viral respiratory tract infections.

Protection of mice from lethal influenza virus infection with high dose-short duration ribavirin aerosol

An aerosol generated from a reservoir containing 60 mg of ribavirin per ml given for 2 h twice daily for 4 days afforded the same high level of protection against lethal influenza virus infection of mice as a longer, conventional treatment schedule (20 mg/ml given for 11 h daily for 4 days). Incremental decreases in ribavirin concentration made while maintaining the 2-h intermittent schedule provided progressively less protection of mice. Mice exposed to the 60-mg/ml doses had significantly increased pulmonary and serum drug levels when compared with mice given 20 mg of drug per ml, these increases were transient, and no evidence of pulmonary intolerance was detected. These studies suggest that protective effects of ribavirin against influenza virus infection can be achieved without untoward effects if higher doses and shorter periods of administration are used.