Construction and Characterization of EIAV Vaccine Infectious Clones Labeled with FLAGTM or 6 His-tag

To provide convenient and effective tool for differentiating analysis between EIAV vaccine and pathogenic strain, molecular marker of FLAG+{TM} or 6+*His was inserted into S2 gene of EIAV(equine infectious anemia virus) vaccine infectious clone pFD3, The resulted chimeric clones pFD3-FLAG and pFD3-HISADD were used to transfect fatal donkey dermal (FDD) cells. After 5 generations of in vitro passages, the supernatant was collected to further infect donkey blood leukocyte (DL) for 3 generations of passage. The replicative characteristic of pFD3-HISADD was similar to its parental clone pFD3, RT activity assay was strong positive with significant cytopathtic effect, and the virus particles could be observed under electron microscope. However, pFD3-FLAG showed a lower replication activity, RT activity was weak positive and no significant cytopathtic effect was observed. These resuts implicated that S2 gene was an important factor for viral replication in DL cell.