Haemato-chemical, histopathological and immunological studies on chicks infected with low pathogenic avian influenza virus (H5N2)

The haematochemical, histopathological and immunological studies were carried out on chicks experimentally infected with the low pathogenic avian influenza virus (LPAIV) (A/Turkey/CA/209092/02) H5N2. Eighty SPF one day old chicks were serologically negative for specific antibodies against avian influenza virus. The birds were devided into 2 groups, birds in the 1st group were inoculated with the virus via the intraocular and intranasal routs, while the other group was kept as non-infected control. Five birds were sacrificed from both groups at 5, 7, 10, 15, and 21 days post inoculation. Sera and heparinized blood as well as tissue specimens from lung, liver, spleen, trachea, small intestine and bursa of Fabricius were collected. Estimation of haemagglutination inhibition antibodies response against AI, liver and kidney function tests, rate of proliferation of T-lymphocyte were conducted. The experimentally infected birds showed general signs of illness with 80% morbidity and 6 % mortality. There was an increase in aniline aminotransferase (ALT) and asparate aminotransferase (AST) enzymes which reflected liver damage. High urea and creatinine values were also detected in sera of infected birds which proved kidney dysfunction. There was no significant proliferation of T-lymphocyte among examined groups. Very low haemagglutinating inhibiting (HI) antibodies was detected in infected birds. Histopathological examination displayed conspicuous depletion and necrosis of the lymphocytic aggregation in the organs of the haemobiotic system (Bursa of Fabricius, spleen and thymus). Such finding may decipher the low sero-conversion as well as the unproliferation of T-lymphocyte. The necrobiotic changes in liver and kidney sections in addition to congestion and edema elucidate the increased parameters in their functions. Also, the epithelial hyperplasia of the tracheal mucosa and the sloughing in the lining mucosal epithelium are indicative for the epithelio-tropism of the AI virus.