Research note: Antiviral effect of remdesivir against experimental Newcastle disease virus infection in chickens

Newcastle disease (ND), caused by the Newcastle disease virus (NDV), has no approved therapy, and vaccination often fails to eradicate infection in endemic areas. In this study, the antiviral effect of remdesivir was tested against experimental ND in broilers. First, the NDV was isolated and identified from an outbreak in a broiler farm in Sulaymaniyah, Iraq. Then, it was propagated in embryonated chicken eggs, and its median embryo lethal dose (ELD₅₀) was determined. This ELD₅₀ was used to infect broilers when the antiviral effect of remdesivir was tested. Forty-eight Ross-308 broiler chicks were assigned into six equal groups. Group 1 was the negative control and did not undergo any treatment. Group two (positive control) was intranasally infected with NDV when the chicks reached 17 days and left without treatment. Groups 3 to 5 were infected with the virus on day 17 and treated with remdesivir at 2 mg/kg, 4 mg/kg, and 6 mg/kg, respectively. Remdesivir treatment started simultaneous with the experimental infection, and the drug was administered twice daily for seven days through the subcutaneous route at the chest area. Group 6 administered remdesivir at 6 mg/kg twice daily for seven days without infection. The survival rate in the groups treated with 4 mg/kg and 6 mg/kg remdesivir was 100 %, and the chicks were free from the virus after two weeks. Remdesivir inhibits NDV infection in broilers when administered simultaneously with the virus.