[Sequence and promoter efficacy analysis of avian leukosis virus subgroup J strains of different pathotypes]

To characterize the long terminal repeat (LTR) of the ALV-J strain which can induce hemangioma, fragments of provirus LTR of the three different ALV-J strains SCAU-HN06, NX0101 and JS-nt were amplified with a pair of specific primers, then cloned and subjected to sequence analysis. In comparison with the prototype ALV-J strains HPRS-103 and ADOL-7501, the LTRs of domestic strains (SCAU-HN06, NX0101, JS-nt and SD07lk1) had an 88.0%-97.2% nucleotide sequence identity; the U5 and R regions in the LTR had a high nucleotide similarity, while the U3 region in the LTR showed significant variance. The LTR fragments from the different ALV-J strains were inserted into the upstream of bacterial CAT gene of the plasmid pCAT-Basic, respectively. The resultant recombinant plasmids were transfected into DF-1 cells. The transfected cells were harvested 48 h post-transfection, and cell lysates were prepared for CAT expression detection. The CAT assay was performed using CAT-ELISA. The results showed that the promoter activity of the LTRSCAU-HNO6 was a little higher than those of LTRJS-nt and LTRNX0101, but there was no significant difference in the promoter activity among the compared LTRs.