Tissue Damage And Inflammation-related Genes Expression In The Liver Of Broilers Infected With FAdV-4

Fowl adenovirus serotype 4(FAdV-4)infection can cause poultry pericardial syndrome(Hydropericardium syndrome,HPS).Autopsy lesions of broilers infected with FAdV-4 showed the pericardial cavity filling a large number of yellow liquid,enlargement and necrosis of liver.The typical histopathological changes in the infected liver are the basophilic intranuclear inclusion bodies in the hepatocytes.The liver is the main target organ of FAdV-4,however,there are few reports about the mechanism of FAdV-4 inflammatory d a m a g e i n broiler liver.In this study,3-week-old white featherAvian broilers were experimentally infected with FAdV-4,and the tissue lesions and the viral load in the liver at the indicated time points post infection was detected by haematoxylin and eosin(H&E)and real-time PCR respectively.Furthermore,real-time RT-PCR was used to detect the liver expression of inflammation-related genes at different times of infection.T h e a i m i s t o r e v e a l t h e m e c h a n i s m o f l i v e r i n f l a m m a t i o n d a m a g e i n b r o i l e rchickens infected with FAdV-4.The test results are as follows:1.FAdV-4 isolate can cause HPS in non-immune white feather Avian broilers.The non infected broilers were infected with FAd V-4,and livers tissue was collected at indicated days post inoculation(dpi).Eight infected broilers were killed at 1dpi,3dpi,4dpi,5dpi,7dpi,9dpi,11 dpi and 15 dpi respectively,and the liver was obtained by aseptic operation.FAdV-4 infected broilers die suddenly on 4dpi,5dpi disease chicken show mental weakness,anorexia and so on.The main changes of autopsy were pericardial effusion and hepatic necrosis.The liver HE showed that a large number of inflammatory cell infiltration,liver cell degeneration,necrosis,and basophilic inclusion bodies in the liver nucleus.2.A method for detecting real-time PCR of FAd V-4 Hexon gene was established.Based on the conserved sequence of Hexon gene published in Gen Bank,FAdV-4 primers were designed to establish a method for detecting the Real-time and PCR of FAdV-4 Hexon gene.FAdV-4 was detected in the livers of chickens infected at different time points,and the viral load reached the peak at 4dpi.3.Real-time RT-PCR was used to detect the expression of major inflammation-related genes mRNA in broiler liver at different times after FAdV-4 infection.IL-2 gene was significantly up-regulated in the liver(P <0.001),IL-6 / IFN-? gene was up-regulated.The IFN-? gene was down-regulated at the early stage of infection and was significantly up-regulated at 4 dpi(P <0.01).The expression of CXCLi1,CXCLi2 and CCR5 genes up-regulated,and CXCLi2 gene uptake was the highest(P <0.001).IL-4 and IL-10 genes were up-regulated,and IL-4 gene was significantly up-regulated at 3 dpi(P <0.001).The expression of TGF-?1 and TGF-?2genes down-regulated at 1 dpi,followed by up-regulation,with the TGF-?2 gene up-regulated at 4 dpi(P <0.001).To sum up,FAdV-4 infected white feather Avian broilers can cause severe pathological changes in the liver,and can cause the expression of inflammation related genes mRNA in liver tissues to change markedly.The current results provide experimental data for revealing inflammatory damage in FAdV-4 infected broiler liver tissue.