Establishment Of Animal Model Of ALV-J And Analysis Of Its Envelope Gene

In2009, the subgroup J avian leukosis virus (ALV-J) outbreak in a commercial layer farm in Jiangling count Hubei Province. In order to understand the characterization of the isolate of ALV-J HB2009, the animal disease models were established in layers inoculated experimentally with strain HB2009ALV-J.15-day-old local chick embryos were inoculated with HB2009strain ALV-J, hatched and reared. Blood samples of experimental birds selected, when reared to14weeks of age, were collected for PCR diagnosis and pathological observation. The first case of ML occurred in layer with16weeks of age. Myeloid leukosis and hemangioma were induced by a strain HB2009ALV-J in layer chickens.The env gene of HB2009was amplified in polymerase chain reactions with the specific primers designed by ADOL to terminate the password upstream of the pol gene and the3’of terminal LTRs. As a result, the samples were positive reaction, and the specific fragments of a size of approximately2.2kb. This means that it was successful to establish the model of group J avian leukosis. The ALV-J HB2009strain proviruses of PCR products were sequenced. It had85.5%-98.0%identical in the DNA region to other strains of ALV-J. Among them, it was92.5%homology to HPRS-103, ALV-J prototype strain and85.5%-95.1%identical to the strains from U.S. The strain HB2009of ALV-J was compared with six strains of ALV-J which isolated in China. It had a high homology of up to93.4%, but a strain SDo71Lk1·Envelope precursor protein predicted of ALV-J HB2009strain was87.5%～96.3%identical to strains of ALV-J,96.3%homology to strain IMC10200and SDC2ooo, and90.5%homology to ALV-J prototype strain named HPRS-103. It had a low homology from87.5%-89.1%identical to the strain1696,6803,6827and AF88which were isolated from U.S. The biological evolutionary tree shows that the variation range of the strain HB2009was between the strains AF88to the strain IMC10200.The envelope precursor protein predicted of ALV-J HB2009analysis shows that the strain HB2009of ALV-J has different degrees of variation in the entire env with other strains. The location of these variation phenomena where the gene locus is as basically the same as other selected strain variation. These mutations are mainly concentrated in the district vr3, hrl and hr2in env gene SU. The majority of amino acid variation is caused due to base substitutions. Only two bases are insertion of mutation, one is located from114to115amino acid of the hypervariable region hr1, and the other one is located from194to196amino acid of the hypervariable region hr2. The former occurred in ES (tryptophan, serine) amino acid residues of the "insertion" mutation, and the latter occurred in the NLS (asparagine, leucine and serine) amino acid residues of the "insertion" mutation.It was important realistic significance to research the pathogenicity and variability of ALV-J in layer flock, especially when ALV-J appeared constantly in local chickens which showed pathogenically enhance of ALV-J to local chickens.