Isolation And Identification Of ALV From Local Strain Chickens And The Infection Research Of ALV-J Strains Triggered Acute Fibrosarcoma

On the one hand, this study did the epidemiological study on the grandparents and parents of the local strain chicken. Then the avian leukosis purification research was carried out. The sterile serum of the ELISA antigen test-positive individuals were used to infect DF1/CEF cell lines, and then as the template the cell genomic DNA was used to amplify env gene of ALV. After that, the sequences of env were compared with referent strains from GenBank. On the other hand, to study the infectivity of defective virus to nude mouse, we infected nude mice respectively with the filtrate of the acute fibrosarcoma by abdominal injection and with the fresh cell suspension liquid of chickens’ acute fibrosarcoma by underarm injection.Isolation and identification of avian leukemia virus showed that two ALV-B strains and eight ALV-J strains were isolated from local strain chickens respectly. Sequence analysis revealed that gp85genes of GX-J-15had over91.7%of identity to4reference strains of subgroup B, and had over98.1%identity to SDAY09C2especially. The homology of GX-J-14to4reference strains of subgroup B was in the range of89%-90%for gp85genes. But the gp85genes in the two isolates exhibited less than50%identity to reference strains of subgroup J. gp85genes of eight isolates of subgroup J showed over92%identity to reference strains of subgroup J, and the homology to reference strains of subgroups A, B, C, D, E was as low as54%. gp85genes of GX-J-12display high identity (96.1%) to HPRS-103. Two ALV-B strains and eight ALV-J strains were isolated from local strain chickens in this study, while ALV-A and ALV-E were isolated from local strain chickens in the previous studies of our research group. These data reflected that all subgroups of ALV were prevalent already in Guangxi area which posses the most abundant species of local strain chickens. By comparative sequence analysis, gp85genes of local strain viruses displayed high identity to reference strains of all subgroups, but the3’LTR sequence had the large variability. gp85genes of GX-J-15had over98.1%identity to SDAY09C2, and the restructuring may be derived from the same virus.SPF chicks were inoculated with the filtrate of acute fibrosarcoma, after that the chicks’ tumor appeared at14days of age and chicks died one by one at the18-day-old. The fresh cell suspension liquid of chickens’acute fibrosarcoma was inoculated into nude mice, and grinding tissue filtrate which can cause acute fibrosarcoma clinically was injected into nude mice, then continued to observe for40days. The growth of nude mice was in good condition. Tumors and pathological changes visible did not reveal in the dissection, the histopathologic slide observation was negative, as well as nucleic acid amplification result, which indicated that acute fibrosarcoma cells are not easy to induce tumors in nude mice, and also proved that defective ALV-J fibrosarcoma tissue filtrate can not cause tumorigenesis and infections in the nude mice.