Proviral genomic sequence analysis of Chinese donkey leukocyte attenuated equine infectious anemia virus vaccine and its parental virus strain Liaoning.

Proviral DNA was extracted from donkey leukocyte infected with Chinese donkey leukocyte attenuated equine infectious anemia virus (DLA-EIAV), and peripheral blood lymphocytes (PBL) from a horse infected with the virulent EIAV strain Liaoning (EIAV L). The entire proviral DNA from both viruses was cloned and sequenced. The lengths of complete genomic sequences of DLA-EIAV and EIAV L provirus were 8266 bp and 8235 bp, respectively. Sequence comparison indicated that DLA-EIAV shares 97.0% and 97.5% in sequence homology with EIAV L and donkey-adapted EIAV (DA-EIAV), respectively. Lots of variations occurred in long terminal repeat ( LTR, consisting of U3, R, U5), ORF S2, and env regions between DLA-EIAV and EIAV L. The nucleotide sequence differences of the two viruses in U3, R, U5, ORF S2, and env are 13.2%, 7.5%, 5.1%, 3.9%, and 2.7%, respectively, and predicted amino acid sequence differences in env and S2 coding regions are 4.4% and 8.8%, respectively. Six conserved regions are characterized in Gp90. There is a cis-activating GATA motif in ENH of DLA-EIAV and EIAV L. Two N-linked glycosylation sites disappeared in DLA-EIAV Gp90 in comparison with that of EIAV L. A bHLH transcription factor binding consensus sequence was found in LTR of DLA-EIAV but not in EIAV L. Furthermore, there is a mutation in the stem of DLA-EIAV TAR resulting in formation of a uridine tuber. Further study is needed to uncover the relationship between sequence changes and their biological functions of DLA-EIAV and L. [ABSTRACT FROM AUTHOR]