Abstract: An equine infectious anemia virus donkey adapted strain (designated as DV), which has lethal virulence to horse and donkey, was obtained through serials passaging in donkeys in vivo used a wide-type EIAV isolate. Three fragments covering entire genome of DV were amplified by PCR techniques from DV infected donkey leucocyte culture. The full-length genome was cloned into a low-copy number vector pLG338 using molecular clone strategies and a recombinant plasmid (designated pD70344) was obtained. pD70344 was used to transfect fetal donkey dermal cell culture in vitro and passaged in donkey leucocyte cells. The supernatants of passages were tested to be positive by reverse transcriptase activity (RT) assay and EIAV special RT-PCR. Cytopathogenic effects were observed by 5-6 days post infection in donkey leukocyte infected with the pD70344 derived virus. EIAV-like virions were also observed by electronic microscope in donkey leukocyte passages. And sequence analysis of this derived virus shows highly coincident with original DV strain. Tow donkeys were inoculated with this virus and developed typical equine infectious anemia symptom. These results showed that a pathogenic infectious molecular clone of EIAV DV was obtained, and it has provided an important tool for evaluating of gene function on EIAV attenuation.

Key words: Equine infectious anemia virus, Donkey adapted virus, Molecular clone