Cloning and Sequencing Analysis of the Complete Genome of Jaagsiekte Sheep Retrovirus Inner Mongolia Strain

In order to amplify the complete genome of Jaagsiekte sheep retrovirus (JSRV) Inner Mongolia Strain, eight pairs of primers were designed based on Genbank sequences. Eight fragments were obtained by PCR and were cloned into the pMD-18 T vectors . The recombinant plasmids were sequenced and the complete sequences were analyed with DNA Star. The results showed that the genome was 7430bp in length and contained four overlapping open reading frames of the gag, pro, pol and env genes. The nucleotide and amino acid sequences of NM strain were compared with the sequences of South Africa strain (type I, Accession No. NC-001494) and USA strain (type II, Accession No. AF105220). The nucleotide and amino acid identities were 90.4% and 90%, 90% and 89.1%, respectively. Two zinc fingers were found in the region of NC in the predicted amino acid sequence. A ScaⅠ restriction site in gag was found in the sheep genome, The “YXXM” motif was found in the region of TM, which are reliable molecular markers for the infectious exogenous virus. The exJSRV-2 specific DNA fragment probe was labeled with digoxigenin (Dig) and the Jaagsiekte retrovirus NM strain RNA and proviral DNA in the lung tissue of OPA were detected by in situ hybridization. The results showed JSRV-NM mRNA and provirus DNA in sheep lung tumor cells had very strong hybridization signals while the control group did not have a positive signal. This is the first nucleotide sequence of exJSRV reported in China.