Prevalence Survey And Pathological Study Of Avian Leukosis On Shouguang Chickens In Shandong Province

In recent years，avian leukosis with fast speed spread to the world of poultry and hasalso brought huge losses. In the past ten years, Chinese scientists had done a lot of studiesand relevant reports. Different subgroups of ALV had also been found among local chickengroups. To reduce the great economic losses, the purification work towards ALV ispromoted on a national scale at present.This study consists of four sections: the first one is1201cloacal swabs were collected forp27antigen detection, while475serum samples were collected for detection of ALV-AB and475serum samples were collected for detection of ALV-J antibody by ELISA. In the secondsection, the tissue of heart, liver, spleen, lungs, kidneyand comb were collected to peparationof ultramicrocut and tissue slice to observe these patholo gical changes. In the thirdexperiment, eight livers tissue of the diseased chickens were detected for ALV-A, ALV–Band ALV-J PCR and analysised of genetic evolution. In the four section, we collected chickenwing vein blood with dedicated anticoagulation vacuum and tested them with automatic bloodanalyzer. Data were analyzed using the one-way analysis of variance (ANOVA) procedure ofSPSS18.0.The ELISA test results indicated that p27antigen and ALV antibody were positive in allstains of layer chickens including grandparent flock,the positive rates of antigen p27,antibody ALV-A/B and ALV-J were respectively33.39%,16.21%,0. There are also somechickens getting co-infection with ALV-A/B and ALV-J. ALV infection existed in all stainsof Shouguang chickens in Shandong province.The pathology diagnosis indicates that the tumors mainly involve myelocytoma. Thegroups getting disease were mainly hybrid chickens; even some serious samples’ bonemarrows were substituted by these cells.The results of PCR detection show that8of8samples were positive (100%) to ALV-J,3 of8samples were positive (37.5%) to ALV-A and0of8samples were positive(0) to ALV-Bin PCR. The electrophoretograms are shown as figure3. Env among the three strains fromShouguang chickens were highly divergent, and the identity ranged from34.5%to97.9%, andgp85among the eight strains from Shouguang chickens were highly concentrated, and theidentity ranged from97.4%to99.2%at the amino acid level, respectively. According to thephylogenetic trees for both env and gp85(Figure4), however, the eight strains were mostclosely related to HPRS103, and the identity ranged from95.9%to97.2%at the amino acidlevel.The levels of Shouguang chicken’s RBC, PLT, LYM, WBC and PLT are all lower thanthat of healthy control group and also distinguished significantly.While in another condition,there’s little difference in MCH,MVP, MCHC and PCT.These results indicated that infection existed in all breeding chickens in Shouguang.Myelocytoma was the main clinical symptoms of sick chickens. Different chicken groupseparation of ALV-J strain has certain variations.