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

The research conducted a genomic sequence analysis of Chinese donkey leukocyte attenuated equine infectious anemia virus vaccine and its parent virus. The study revealed significant variations in various regions between the two viruses.

Research Methodology

• The team extracted proviral DNA from a Chinese donkey leukocyte infected with the Chinese donkey leukocyte attenuated equine infectious anemia virus (DLA-EIAV).
• The proviral DNA was also extracted from the peripheral blood lymphocytes of a horse infected with the virulent EIAV strain Liaoning (EIAV L).
• The complete proviral DNA from both viruses was then cloned and sequenced.

Findings and Analysis

• The full genomic sequences in the DLA-EIAV and EIAV L provirus were found to be of different lengths – 8266 base pairs and 8235 base pairs, respectively.
• Upon sequence comparison, it was revealed that DLA-EIAV shares 97.0% and 97.5% sequence homology with EIAV L and the donkey-adapted equine infectious anemia virus (DA-EIAV), respectively.
• A considerable number of variations were found in the long terminal repeat regions (U3, R, U5), open reading frame S2, and the env regions in both DLA-EIAV and EIAV L.
• There were varying percentage differences in the nucleotide sequences of the two viruses in different regions: U3, R, U5, ORF S2, and env; these were 13.2%, 7.5%, 5.1%, 3.9%, and 2.7%, respectively.
• Further investigation into predicted amino acid sequence differences in the coding regions of env and S2 pointed out differences of 4.4% and 8.8%, respectively.
• Six conserved regions were characterized in Gp90 – the envelope glycoprotein of the virus.

Genetic Differences and Implications

• A GATA motif noted in DLA-EIAV and EIAV L, an enhancer that sets off transcription, indicates transcription regulation in these strains.
• DLA-EIAV showed the absence of two N-linked glycosylation sites in comparison to EIAV L.
• DLA-EIAV had a new bHLH transcription factor binding consensus sequence found in its long terminal repeat, which was absent in EIAV L.
• A mutation in the stem of DLA-EIAV’s Trans-Activation Response (TAR) resulted in the formation of a uridine tuber.
• The team acknowledges the need for further studies to uncover the relationship between these sequence changes and their functional effects in DLA-EIAV and EIAV L.