Dynamic Evolution Of Gp90 Gene Of Proviral DNA Of Equine Infectious Anemia Virus Attenuated Strain In Experimentally Infected Ponies

To elucidate the genetic variation of proviral gp90 gene in the attenuation process of EIAV-DLA (Chinese Equine Infectious Anemia Virus Donkey Leukocyte Attenuated strain). One healthy horse was infected with EIAV-L (Equine Infectious Anemia Virus Liao strain), after death, gp90 gene of proviral DNA of EIAV-L was amplified from spleen tissue by nested-PCR; Another healthy horse was infected with EIAV-D (Equine Infectious Anemia Virus Donkey strain), meanwhile other two healthy horses were respectively inoculated with EIAV-DLA, gp90 gene of proviral DNA were amplified from PBMC of horses inoculated with EIAV-DLA and EIAV-D during five episodes(15,45,75,105 and 135 days postinoculation).One gp90 gene of EIAV-L and one hundred gp90 genes of EIAV-DLA were obtained. We compared the nucleotide acids and amino acids of the 101 gp90 genes and found that the lowest and the highest nucleotide sequence homology between EIAV-L and EIAV-DLA were 96.1% and 97.4%, the lowest and the highest amino acids sequence homology were 91.6% and 95.8%. The sequenced results show that from the first to the fifth episode post vaccination average divergence of nucleotide sequence are respectively 3.295%, 3.145%, 3.3%, 3.185%, 3.645%, compared with EIAV-L. Average divergence of amino-acid sequence are respectively 5.52%, 5.51%, 5.565%, 5.56%, 6.365%, compared with EIAV-L. There exists a series of regular variations among the gp90 genes of EIAV-DLA, compared with gp90 gene of EIAV-L. These variations mainly included mutations and deletions, mutative sites of amino acids of one horse inoculated with EIAV-DLA at each episode are conservative, and tendency of variations is highly consistent .However, from the alignment of gp90 deduecd amino-acid sequences in vivo of two vaccined horses at the 5 sampling episodes, mutative sites of amino acids at each episode are not completely same, compared with other episodes.The EIAV-L gp90 has 20 N-linked glycosylation sites, The EIAV-DLA gp90 has averagely 17.2 N-linked glycosylation sites, of which has 11 highly conservative N-linked glycosylation sites. On principal neutralizing domain (PND), there exists 3 unstable mutations. The results of comparison of gp90 sequences between EIAV-DLA and EIAV-D show that: the quasispecies of gp90 from the same vaccined horse have closely evolutional relationship, quasispecies of gp90 from the different vaccined horses have a certain divergence, which may be associated with the different hosts environment EIAV-DLA in vivo. The quasispecies of gp90 of EIAV-DLA are more homogeneous than EIAV-D. The variation of gp90 of EIAV-D in vivo is more significant than EIAV-DLA with the lapse of the time. The evolutionary rate of gp90 of EIAV-DLA is slower than EIAV-D. The variation of gp90 of EIAV may be not related with immune selected pressure.