Cloning And Sequence Analysis Of Complete Genomic Sequence From The Inner Mongolia Strain Of Endogenous Jaagsiekte Sheep Retrovirus

In order to amplify the complete genome of enJSRV from the strain of inner Mongolia (enJSRV-NM),by using enJSRV-specific and exJSRV-specific DNA probes in dot blot hybridization. The total DNA of enJSRV was extracted from uterus tissue of healthy domestic sheep by Clinical and pathologic examination. Seven pairs of primers were designed based on Genbank sequences. Seven fragments were obtained by PCR and were cloned into the PMD19-T vectors. The recombinant plasmids were sequenced and the complete sequences were analyzed with DNAstar software. The results showed that the genome was 7942bp in length and contained four overlapping open reading frames of the gag, pro, pol and env genes as well as an additional open reading frame (orf-x) that overlaps 3' end of the pol gene. The nucleotide acid sequences of enJSRV-NM loci were compared with the sequences of South Africa enJS56A1 strain and USA JSRV21 strain. The nucleotide acid identities were 99.2%,92.3%, respectively. Two zinc fingers were found in the region of NC in the predicted amino acid sequence. A ScaⅠrestriction site in gag was not found in the sheep genome, the YXXM motif was not found in the region of TM, which are reliable molecular markers for the infectious exogenous virus. It was found that the enJSRV-NM are 90～98% identical at the amino acid level to their exogenous infectious counterparts in most of the retroviral genome,enJSRVs consistently differ from JSRV isolates in three variable regions (VRs). VR1 and VR2 are found in gag, whereas VR3 is at the transmembrane domain of env.This is the first nucleotide sequence of enJSRV reported in China.The protein structure prediction showed that the gag-enJSRV-NM and env-enJSRV-NM protein are a loose protein.These results pave the way for future developments on OPA.