Isolation And Identification And Studies On Oncogenic Mechanism Of Inner Mongolia Strains Of Avian Leukosis Virus Subgroup J(ALV-J)

Avian leukosis virus subgroup J (ALV-J) was first reported as a new subgroup of ALV by Payne in 1991. ALV-J induced avian myelcytomatosis (ML)in meat-type chickens. MLwas first discovered in Inner Mongolia in 1999. ALV-J infection rate of meat-type chickens was 8.33%~28.12%, and that of laying chickens was 0% by ELISA investigation. Histologically, eosinophil granulated myelocytes proliferated in the bone marrow of various bones and in the periosteum of the ribs, sternum, vertebrae and entrails. The serious lesions were seen in bone marrow, liver, heart, overy. A set of primer was designed on the basis of HPRS-103 env gp85 gene. The template was DNA of infected cells genome. The length of PCR product was 924bp. The sensitivity and accuracy of PCR were higher than ELISA. ALV-J virus-like was seen in infected SPF CEF that had cultured for 7 days. Cloning and sequencing the Inner Mongolia strain env gp85 gene, the predicted amino acid sequences of Inner Mongolia strain with SD9901, ADOL-R5-4 and EAV-HP gp85 protein were 97.40%, 95.13%, 86.69%, and 85.06% in homology, respectively. So the Inner Mongolia strain was named after NM8761. By experimental abdomen inoculation of NM8761 and NM9996, ALV-J antibody (ELISA) and provirus (PCR) detection and tissue lesions observation, the results indicated that ALV-J virus infection rate of group 1~5 was 71.4%(10/14), 64.3%(9/14), 0%(0/3), 0%(0/3) and 20.0%(2/10), and ALV-J antibody positive rate was 21.4%(3/14), 0%(0/14), 0%(0/9), 0%(0/11), 0%(0/16), and the incidence was 50.0%(7/14), 46.7%(9/14), 9.1%(1/11), 40.0%(6/15), 0%(0/16). The first typical lesion of group 1 was observed at 5th week, and most organs had tumor cells at 10th week. So the virus toxicity was strong, and experimental abdomen inoculation was successful. Purified the cloned gene of NM8761 env gp85, then labelled by DIG with random primer method as probe. Study of viral gene transcripts and expression. The results of in situ hybridization and immunohistochemistry were identity. The greatest Env expression was observed in cells specific to the tumor, liver, heart, kidney's parenchymal cells, myeloid linear cells, overy parenchymal cells, spleen mononuclear phagocyte in redpulp. Viral gene expression could not be detected in the bursa of Fabricius, thymus, brain, ischiadic nerve by the above mentioned methods. Field chickens have the similar reaction with experimental inoculation chickens. Whether ALV-J provirus can insert host cells genome was indispensable to form myelocytes neoplasia. The tumor cells might invade periosteum by Haversian and Volkman's canals and might invade other tissues by blood stream.