Basic Informations

C.V

Master Title

Clinico-pathological studies on respiratory diseases experimentally induced by viral infections in broiler chickens

Master Abstract

Infectious bronchitis virus (IBV) is a major respiratory disease of chickens. The high mutation rate and recombination of the RNA genome generates IBV variants that are difficult to be controlled by currently available vaccines. This study gives specific perspective of carvacrol essential oil effect on early immune response, leucogram, serum biochemical parameters, oxidative stress profile for lung and kidney, viral shedding titer, histopathology of trachea, lung and kidney and clinical consequences in broiler chickens experimentally infected with IBV. One hundred and twenty-one-day old commercial broiler chicks were equally divided into 4 groups. The first group was control group. The second group was orally given carvacrol at the dose of 250 µL, the birds in the third group was infected with 106 Median embryo infectious dose (EID50/0.5 ml) of titrated IBV through intratracheal route (IB) and the fourth one was orally given carvacrol and infected with IBV as previously mentioned doses (CA.oil+IB). The experiment extended for 10-day post infection (DPI) and the samples were collected at the 2nd, 5th ,7th and 10th DPI. In the CA.oil group, carvacrol significantly reduced serum interleukin 6 (IL-6) and alpha-1 acid glycoprotein (a1-AGP) concentrations and gene expression level of chicken interferon-inducible transmembrane protein 3 (chIFITM3) in trachea at the 2nd, 5th DPI as well as the significant decrease of heterophil number at the 5th and 7th DPI and the heterophil / lymphocyte ratio (H/L ratio) at the 2nd, 5th and 7th DPI. The infection with IBV, in both infected groups, induced marked leukocytosis accompanied by lymphocytosis, heterophilia, eosinophilia and monocytosis with elevation of H/L ratio. A significant upregulation of chIFITM3 gene expression in trachea and elevation of serum concentrations of a1-AGP, IL-6 at the 2nd, 5th DPI; besides, increment of uric acid and creatinine concentrations at the 5th and 7th DPI were also observed. Whereas a significant elevation in phosphorus (P) level at the 2nd and 5th DPI and reduction in sodium level at the 5th and 7th DPI only in IB group. For oxidative status in lung and kidney following IBV infection, there were increment of malondialdehyde (MDA) level and reduction of superoxide dismutase (SOD) activity throughout the experiment while the reduced glutathione (GSH) content significantly decreased only at the 7th DPI in the kidney of IB group. The infection with IBV induced marked histopathological alterations in trachea, lung and kidney at the 2nd, 5th and 7th DPI. The oral treatment with carvacrol before IBV infection had a positive impact as it significantly reduced clinical signs intensity (especially at the first 4 DPI), tracheal viral shedding titer, leucocytic response and H/L ratio throughout the experimental period. Also, the carvacrol was able to reduce chIFITM3 gene expression, concentrations of IL-6, a1-AGP and uric acid and antibody titer against IBV in the serum as well as relieving oxidative stress and histopathological alterations in both lung and kidney (with minimal effect in lung). In conclusion, the current results elucidated that the carvacrol could be of value on reduction of viral shedding titer, modulation of acute phase response and amelioration the oxidative stress, histopathological alterations and serum biochemical changes induced by IBV infection in broiler chickens.

PHD Title

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PHD Abstract

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