Archives of Razi Institute (Jul 2010)
Experimental Assessment of the Pathogenicity of Avian Influenza Virus H9N2 Subtype in Japanese Quail (Coturnix Coturnix Japanica)
Abstract
H9N2 avian influenza A viruses are endemic in poultry of many Eurasian countries and have caused repeated human infections in Asia since 1998. It has been also reported that H9N2 can cause high mortality in commercial broiler farms in Iran previously. However there was no report of H9N2 outbreak in any other species. In order to evaluate the pathogenicity of H9N2 virus in Japanese quail, 145 Japanese quail were randomly divided into 5 separate groups (116 quails in the treatment and 29 quails in the control groups). The experimental groups infected via oral rout, eye drop, intramuscular injection and spray method at the age of 32 days with 106.5 EID50/bird. The virus A/chicken/Iran/ZMT-101/98(H9N2) was kindly provided obtained from Razi vaccine& serum institute with EID50=108. The blood samples were experimented the day before use to show freedom from antibodies to influenza A and more specifically, the H9 subtype. The clinical signs and antibody titer of the infected chicks were also monitored. Five birds of each group were bled at 10 and 20 days post infection (DPI), and 20 birds of each group at 30 DPI were bled. The immune response to infection was measured by Haemmaglutination Inhibition (HI) test using the H9N2 virus as antigen. Feed & water consumption were recorded on daily bases before and after inoculation. Body weight of each group was also recorded on weekly bases before and after inoculation. During the current study clinical signs such as sneezing, gasping, depression observed in challenged groups followed by decreasing in laying (1-17%). High HI antibody titers of AIV subtype H9 was seen in 10 DPI. The quails exhibited no decrease in food and water consumption and all quails were growing well and did not show any abnormality.
