An improved embryonated chicken egg model for the evaluation of antiviral drugs against influenza A virus.

Influenza is a serious global public health problem and an economic burden. With the continual emergence of new influenza A virus strains, new antiviral drugs are needed urgently. In this study, an improved embryonated chicken egg model for evaluating antiviral activity against Influenza A virus was developed. In the model, the influenza A virus was injected into the allantoic cavity and ribavirin was injected into the albumen of the egg. The levels of influenza A virus in the allantoic fluid was titrated by the hemagglutination test after incubation for 72 h at 35.5 degrees C and 12 h at 4 degrees C. Ribavirin treatment at a dose of 25 mg/kg to 100 mg/kg decreased significantly the hemagglutination titers both of Influenza virus A/FM1, H1N1 (IVA1) (p < 0.01) and influenza virus A/Wuhan/359/95, H3N2 (IVA3) (p < 0.01). In a time-dependent drug addition assay, significant efficacy of ribavirin against both IVA1 and IVA3 was observed when the drug was administered before and shortly after viral inoculation (p < 0.01 or p < 0.05). In conclusion, ribavirin treatment showed significant antiviral activity against IVA1 and IVA3 in this model, suggesting that the improved model would be useful for evaluating the anti-influenza virus activity of potential inhibitors.