| Maedi-visna virus(Maedi-visna virus,MVV)is the pathogen that causes Madeivisna disease(MVD).MVV belongs to the retroviral family,a member of the genus Lentivirus.The virus can cause respiratory and nervous system diseases in sheep.The clinical symptoms are weight loss and shortness of breath.At present,the disease exists in almost all sheep-raising countries in the world except Australia and New Zealand.The incubation period is long.Once discovered,it will basically develop to the late stage of the disease,and eventually die from various secondary infections.There is no effective prevention and treatment method.To understand the molecular structure characteristics and genetic variation of MVV in Inner Mongolia.In this study,PCR technology and histopathological methods were used to identify a case of Medi-Wisner who was naturally infected with MVV.Using the lung tissue of a positive MVV case as the test material,the treated lung tissue suspension was subjected to sucrose density gradient centrifugation to achieve the purpose of virus purification.The results showed that the sucrose layer was enriched in 30%-40%(g/m L)To the virus particles,through the method of electron microscope negative staining,virus particles with a diameter of about 80 nm were observed under the transmission electron microscope.Illumina Hiseq 4000 second-generation sequencing technology was used to determine the whole genome sequence of the MVV-positive sheep diseased lung tissue.The results showed that the sample contained 1731.5 Mb of original data.After quality control,the effective data volume was 1149.3 Mb,and the sequencing depth was188,295 times.The percentage of bases with a sequencing quality value of ?20(Q20)averages 96.64%,the percentage of bases with a sequencing quality value of ?30(Q30)averages 90.48%,and the average GC content is 43.04%.Compare Reads to On the assembled genome sequence,the GC content and Reads coverage depth of the assembled sequence show a high concentration trend.The above data shows that the quality of the second-generation sequencing results is high.The whole length of the MVV genome after splicing and optimization in this experiment was 9193 bp,named NM1111,and the genome sequence was uploaded to the Gen Bank database with the accession number MW248464.Through genome feature analysis,the genome information of NM1111 was predicted and the genome structure map was drawn;Through homology analysis,the results showed that the homology of the nucleotide sequence of the whole genome to the nucleotide sequence of each reference strain was 74.0%?81.4%.The homology of(amino acid)is 82.8%?86.8%(74.8%?92.4%),79.9%?83.1%(83.0%?88.2%),73.6%?77.5%(68.4%?79.9%),75.1%?82.1%(73.4%?81.9%),67.7%?69.2%(60.2%?64.1%);The phylogenetic tree results show that NM1111 and A2 MVV are clustered together,belonging to A2 type;The mutation analysis results show that there is a mutation from aspartic acid(D)to glutamic acid(E)in the MHR of the Gag protein,and the Env protein is mutated To a greater extent,there are five amino acid insertions in the V4 region of the surface protein.The SU5 epitope has a completely conserved motif(VRAYTYGV)at the amino terminus and a highly variable motif at the carboxy terminus.This study provides the first complete sequence of MVV from Inner Mongolia,and filled the blank of full-length sequence of MVV genome in China in Gen Bank database,which will give a basic reference for the study of molecular biological characteristics of MVV in China. |
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