Construction of a Chimeric Virus Based on an EIAV Vaccine Virus with Substitution of LTR from Its Parental Virus
Equine infectious anemia virus (EIAV) causes equine infectious anemia and persistent infection as well as repeated high-titer viremia in horses.The long-terminal repeat (LTR) of EIAV proviral genome contains an eukaryotic promoter which plays an important regulation role on transcription and replication of the virus.In the study,the LTRs of an infectious molecular clone derived from EIAV donkey leukocyte-attenuated vaccine virus (DLA) were substituted with those of EIAV L strain,a virulent EIAV from which DLA strain was derived,resulting in a chimeric plasmid pOK-LTR DLA/L.The purified pOK-LTR DLA/L was used to transfect leukocyte cultures from EIAV-negative donkey.Reverse transcriptase (RT) activity was detectable by the 7th passage in cell cultures of the transfection products.The cytopathogenic effects typical for EIAV infection were developed since the 8th passage of cell cultures,and virions with cone-shaped core could be observed under electron microscope.It proved that the constructed chimeric pOK-LTR DLA/L is infective and it may be used in future for exploring of molecular mechanism of pathogenesis and immunity of EIAV.