Experimental Study of Lymphoid Tissue Apoptosis Subsequent to Infection by Influenza Virus (H9N2) in SPF Chickens

Abbreviations Influenza virus causes the cell death in animals and human beings. Cell death occurs in two manners as necrosis and apoptosis. In this investigation, the types of cell death in lymphoid tissues assessed in experimentally infected chickens, with H9N2 avian influenza virus, (A/chicken/Iran/772/2000). In this survey, 20 SPF chickens at 3 weeks old were divided equally into two groups. The treatment group was infected with 0.2ml of 1:10 dilution and 10 EID50 titer of the virus intranasally and the control group was treated with saline normal in the same volume. Lymphoid organs comprising spleen, thymus and bursa of fabricius were collected after 72 hours of treatment and tissue specimens were fixed in 10% buffered formalin. The prepared microscopic sections with the thickness of 5-6 micron were stained using H&E method.. Histopathological examination of lymphoid tissues of the experimental groups indicated necrosis, apoptosis and lymphoid depletions in these organs of treatment group. Apoptotic changes in the splenic tissues were significantly different between two experimental groups. There were no significant differences between these two groups in terms of observed change in the thymus and bursa of fabricius. However, there were significant differences between these experimental groups from the viewpoint of necrotic changes and lymphoid depletions in the splenic tissues, thymus and bursa of fabricius (P<0.001). The results of this study indicate that H9N2 avian influenza virus is capable of causing lymphoid tissue damages through induction of apoptosis and necrosis. Avian influenza virus, H9N2, lymphoid tissue, Cell death, apoptosis : BLAST: Basic Local Alignment Search Tool, PCR: Polymerase chain reaction. 7.5