بررسي جراحات و تروپيسم بافتي ويروس آنفلوانزاي طيور تحت تيپ H9N2 در ماكيان گوشتي

Histologic lesions and tissue tropism ofH9N2 avian influenza vims in 6roiCer chickens

Background: Avian influenza virus (AIV) subtype (H9N2), not only causes great economic losses in poultry industry of the Middle East countries, but also has some public health significance as well. The aim of this study was to assess the pathological effects of AIV subtype (H9N2) on different organs of broiler chickens and to detect the virus antigen in these organs. Methods: A number of fifty 1-day-old broiler chicks (Ross breed) were randomly divided into two equal (experiment and control) groups and at days 1, 2, 4, 6, 8 and 11 after inoculating virus, antibody titer against H9N2 subtype of AIV was detected in experiment group and tissue samples from trachea, lung, kidney, spleen, thymus, bursa of fabricius, duodenum, pancreas, liver and brain were collected for histopathology and immunofluorescence studies. Results: The antibody titer against H9N2 AIV at days 1, 2, 4, 6, 8 and 11, post-inoculation, in experiment group was 3, 2.4, 1.7, 3.3, 4.2 and 5.6 and in control group, 3, 2.7, 2.34, 1.8, 1.24 and 0, respectively. Histologic lesions in treatment group were observed as follow: lymphoid and reticuloendothelial cell hyperplasia in the spleen and duodenum, lymphoid depletion in the thymus, lymphoid atrophy in bursa of fabricius, lymphocyte infiltration and mild vacuolation of cells in pancreas. Histologic lesions were absent in the liver and brain of inoculated chickens. The H9N2 AIV antigen was detected in the trachea, lung and kidney of inoculated chickens using indirect immunofluorescence technique. Conclusion: H9N2 avian influenza virus is low pathogenic subtype and has epitheliotropic effect in chickens. In intranasal inoculation, it has tissue tropism and pathogenicity for trachea, lung (pneumotropic) and kidney (nephrotropic).