ABSTRACT
The aim of this study was to isolate and evaluate the seroprevalence of avian influenza virus [AIV] infection in chicken in Pakistan with special reference to its serotype/H9N2. Laboratory based prospective. This study was carried out at department of Biological Sciences, Quaid-e-Azam University Islamabad and National Agricultural Research Centre Islamabad Pakistan from 2000 to 2001. The human virological aspects were dealt by AF Institute of Pathology, Rawalpindi. The chicken flocks studied belonged to different poultry farms located at Islamabad/Rawalpindi area. For the isolation of avian influenza virus, lungs and trachea specimens were processed to prepare virus inoculum and inoculated in 9-day old embryonated eggs via allantoic route. For identification of virus, haemagglutination test and immunofluorescent antibody test [IFA] were used. Serological analysis was done by Agar Gel Precipitation Test [AGPT], Haemagglutination [HA] and Haemagglutination inhibition test [HI]. This study was divided into two parts; firstly the sera of chicken with history of respiratory tract infection were tested for the presence of antibodies against H9N2 virus. Such chicken were found to have seroconverted against H9N2. Secondly, it was aimed to isolate virus from kidneys, lungs and trachea of infected birds by growing virus in 9 days old chick embryos. Out of 40 clinical samples, 9 isolates of AIV were recovered and typed serologically as serotype H9N2. In this scenario, the presence of H9N2 in poultry in the country poses a continuous threat for the emergence of more pathogenic strains of human influenza virus. For this purpose there is a constant need to carry out surveillance for influenza viruses both in birds and humans in the country