الفهرس 
Cover Page Title in EnglishOnly 14 pages are availabe for public view
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Abstract
The main objective of this study was to screen for genes of resistance to RNA viruses by evaluating the in vitro and in vivo innate immune response of different chicken breeds to a synthetic analogue of viral dsRNA, polyinosilic: polycytidilic acid (poly I:C) The study was conducted on three specific phase 1)In vitro studies to characterize the proinflammatory cytokines and receptors response in a chicken macrophage cell line (HD11) to different size of poly I:C, Low Molecular Weight (LMW) poly I:C, High Molecular Weight (HMW) poly I:C as well as a combination of the two. Following activation of the cell line, the relative expression of 84 different inflammatory cytokine and receptor genes was evaluated using RT2 Profiler PCR array system. Results from RT2 PCR array system are summarized as follows: LMW poly I:C induced upregulation of two genes: CCL4, + 11x; CSF-3, +6x and downregulation of one gene: CCR5, -13x. While treatment with HMW poly I:C led to the upregulation of 11 different genes: CCL1, CCL4, CCL5, CSF2, CSF3, IFN-γ, IL12β, IL1 β, IL6, IL8 and TNFSF13B and downregulation of 12 genes: CCR5, CCR6, CCR7, CCR9, CRP, CX3CL1, CXCR5, IL12RB2, IL17B, IL6RA, LTB4R and SPP1. The combination of HMW and LMW poly I:C resulted in upregulation of 7 genes: CCL1, CCL4, CCL5, CSF3, IFN-γ, IL1β and IL8 and downregulation of two genes: CCR5 and LTB4R2)Determination of the response to dsRNA in vivo of 12 different chicken breeds (two week of age) on the expression levels of MDA5 gene and proinflammatory cytokines (IL4, IL12β, IFN-γ, CCL4, IL1β, TNFSF13B and IFN-α) from spleen as well as, MDA5 gene and IFN-α from blood. Results of experiments under this section are outlined next: Rhode Island Red (RIR) breed showed upregulation of all proinflammatory cytokines and the highest fold expression of MDA5 mRNA from blood,followed by White Leghorn (WL) in which only one gene (MDA5 in blood) was down- regulated. Other breeds showed either upregulation of most of genes e.g. Blue Andalusian (BlAn), Red Ranger Broiler (RRB), Barred Rock (BR) and Araucana Ameraucana (AA) or downregulation of most of the genes e.g. Black Star (BS), Delaware (D), Red Star (RS), Brown leghorn (BL), New Hampshire (NH) and Black Australorp (BA Expression of IFN-α from spleen was associated significantly with MDA5 in spleen (Adjusted R2 = 0.57). In the same way, expression of IFN-α from blood was associated significantly with MDA5 in blood (Adjusted R2 = 0.50 ) Determination of CD163 antigen expression on macrophage membrane in the young and adult members of different chicken breeds by using flow cytometric analysis Relative CD163 expression differed significantly among breeds in adult chickens but did not differ in two week old chicks. However, the regression analysis revealed dependence of CD163 on breed of chicken. Conclusions In vitro studies The treatment of HD11 cell line with high molecular weight poly I:C upregulated the expression of genes consistent with a program of pro-inflammatory (M1) activation in macrophages. Co-transfection of HD11 cells with low and high molecular weight poly I:C may inhibit the ability of chicken macrophages to promote B cell activation, survival and antibody production In vivo studies The over expression of chicken MDA5 following poly I:C treatment in different chicken breeds induced IFN-α production as well as proinflammatory cytokines The elevation of IFN-γ in combinations with IL12β, CCL4 and IL1β is consistent with the M1 program in spleen strongly suggests the presence of active T helper type 1 (Th1) immune response in chicken. Such mechanism is critical during intracellular infection to mediate cytotoxic T cell activity required to destroy the virus infected cells. The innate immune response in chicken is influenced by genetic background of the breed. Based on their rapid antiviral immune response, Rhode Island Red, White Leghorn and Blue Andalusian breeds are recommended for genetic improvement of our local breeds CD163 antigen expression is influenced by chicken breed. CD163 antigen can be used as a marker for selection for antiviral immune response in chicken.