| Avian leukosis virus (ALV) is defined as alpha- retrovirus in poultry, it is a transmissible neoplastic viral groups which can induce hematopoietic cells hyperplasia. ALV can be divided into A-J 10 subgroups, in which subgroup J avian leukosis (ALV-J) is endogenous recombinate exogenous ALV, since the group has been found to cause significant economic losses.Because of the diversity, the specificity of ALV virus and the lesion complexity caused by ALV, So far there is no the best way to prevent ALV, and no effective solutions,drugs and vaccines to control ALV infection.Subgroup J avian leukosis (ALV-J) that is caused by avian leukosis virus subgroup J is a kind of tumors of horizontal and vertical transmission disease. This kind of disease mainly occurs in Broiler breeder chickens. Since 1989, Payne first time isolated ALV-J prototype strain HPRS-103 in the United Kingdom, the disease has spread rapidly around the world. In recent years, several outbreaks of hemangiomas in 26-week-old Hy-line Brown laying hens were observed in China. Hemangiomasthat induced by ALV-J caused great losses in egg-type chickens industry. The clinical manifestations were as follows: failure, weight loss, blood blisters in the legs, claws department, under the face and wings. In the necropsy, almost all viscera tissues showed moderate to severe enlargement with diffuse gray-white nodules; cutting open the hemangioma, blood effused and many myeloblasts were seen in blood smear. For understanding the reasons for the outbreak of hemangioma, and finding control measures, the virus that induced hemangiomas was isolated and identified. By inoculating infected tissue suspension into DF1 cells and by indirect fluore scent assay ( IFA) with ALV-J specific monoclonal antibody JE-9,Subgroup J avian leukosis viruse (ALV-J ) was identified and isolated from sick chicken. The isolated strain was named ALV-J WS0705.Gp85 gene was cloned into the pMD18-T vector and sequence was analyzed for better understand the antigenicity of the strain of ALV-J. Phylogenetic analysis showed that gp85 amino sequences of WS0705 strain was the highest identification with the prototype HPRS-103(97.6%). Gp85 amino acid sequence comparison indicated that 84.4% ~ 97.6% identification with four international reference strains, 89.9%~94.5% indentification with eight Chinese strains from white meat-type chickens and 96.6% ~ 97.4% identification with two strains from ourlaboratory were identified. Phylogenetic tree showed that the gp85 amino sequence of WS0705 has the highest affinity with ALV-J prototype strain HPRS-103. The changes of pathotype induced by WS0705 in the layer chickens remained to be further studied.WS0705 gp85 gene was expressed by baculovirus expression vector system. The protein expressed can be used to detect hemangiomas type ALV-J. The gp85 gene from a constructed plasmid pMD18-T-WS0705gp85 was cloned into baculovirus transfer vector. rBac-WS0705gp85 was obtained by the Bac-to-Bac baculovirus expression system. The rBac-WS0705gp85 protein was analyzed by indirect immunofluorescence assay and Western blot. The results showed that positive green fluorescent was present in Sf9 cells infected with recombinant virus and a protein band molecular weight about 35 kDa was present in western blot. It is concluded that WS0705 gp85 gene was expressed in Sf9 cells infected with recombinant virus and the product WS0705 gp85 SU can bind specifically to JE9 MAb of ALV-J. The protein can be used to detect hemangiomas type ALV-J. |
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