Avian influenza virus subtype H9N2 causes important economic losses in industrial poultry worldwide. Biosecurity and vaccination have not completely prevented the outbreak of avian influenza virus subtype H9N2 in poultry, and there are no appropriate medicines available. Onion is one of the plants used from the ancient times both as food and medicine. The purpose of this study was to evaluate the antiviral effects of aqueous extract of red and yellow onion against avian influenza virus subtype H9N2. First, a study was performed to evaluate the toxic effects of the extracts on the embryonated chicken eggs. For antiviral evaluation, three mixtures were prepared: mixture of the virus and the red onion extract, mixture of the virus and the yellow onion extract, and mixture of the virus and PBS, as a control group. The mixtures were separately inoculated to the chorioallantoic sac of the embryonated eggs after 2, 8 and 24 hours incubation at room temperature. Mortality rate and hemagglutination assay titers were recorded. The results indicated that the red onion extract decreases mortality of the embryos and the yellow onion extract increases the life of the embryos, and both of the extracts decrease HA titers. In conclusion, it seems that both extracts especially aqueous extract of the red onion not only destroys the avian influenza virus subtype H9N2, but also they probably decrease the propagation of the virus in the embryonated chicken eggs.
Avian Influenza, H9N2, Onion, Aqueous extract, Antivirus
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