Mishra N, Rajukumar K, Vilcek S, Tiwari A, Satav J S, Dubey S C
High Security Animal Disease Laboratory, Indian Veterinary Research Institute, Anand Nagar, Bhopal 462021, Madhya Pradesh, India.
Vet Microbiol. 2008 Jul 27;130(1-2):88-98. doi: 10.1016/j.vetmic.2008.01.005. Epub 2008 Jan 25.
The wide spread prevalence of bovine viral diarrhea virus type 1 (BVDV-1) in cattle and recent identification of BVDV-2 in goats in India warranted pestivirus surveillance in sheep. Nested reverse transcription-polymerase chain reaction (RT-PCR) was used to detect BVDV-2 in one of 1561 blood samples collected randomly from 78 sheep flocks in 11 states of India. Antigenic characterization of the isolated pestivirus using polyclonal and monoclonal antibodies typed the isolate as BVDV-2. When analyzed at genetic level in N(pro) (N-terminal autoprotease) and entire gene region coding structural proteins, namely capsid (C) protein and envelope proteins E(rns) (ribonuclease secreted), E1 and E2 genomic organization was the same for all pestiviruses, the nucleic acid and amino acid sequences showed highest similarity with those of BVDV-2. When compared with BVDV-2 isolate 890, the sequence homology was 83.7% for C, 84.6% for E(rns) and E1, and 81.5% for E2. The cleavage site C/E(rns) was found totally conserved while N(pro)/C was conserved only from C-terminus of N(pro), E(rns)/E1 site was conserved only from C-terminus of E(rns) and E1/E2 site was conserved only from C-terminus of E1. Phylogenetic analysis of nucleotide sequences in 5' untranslated regions (UTR), N(pro), E2, NS3 and NS5B regions placed the sheep isolate in a separate clade within BVDV-2 subtype b. This was supported by the presence of unique mutations in the structural protein coding regions beside NS3 and NS5B. To our knowledge this is the first report on the sequence analysis of the entire structural gene coding region of a BVDV-2b isolate. This is also the first occurrence of BVDV-2 subtype b in sheep, providing the evidence that this subtype can also occur in species other than cattle.
牛病毒性腹泻病毒1型（BVDV - 1）在牛群中广泛流行，且最近在印度山羊中发现了BVDV - 2，因此有必要对绵羊进行瘟病毒监测。采用巢式逆转录聚合酶链反应（RT - PCR），在从印度11个邦的78个羊群中随机采集的1561份血液样本中的1份中检测到了BVDV - 2。使用多克隆抗体和单克隆抗体对分离出的瘟病毒进行抗原特性鉴定，将该分离株鉴定为BVDV - 2。在N（pro）（N端自蛋白酶）以及编码结构蛋白（即衣壳（C）蛋白和包膜蛋白E（rns）（分泌的核糖核酸酶）、E1和E2）的整个基因区域进行遗传水平分析时，所有瘟病毒的基因组结构相同，核酸和氨基酸序列与BVDV - 2的序列相似度最高。与BVDV - 2分离株890相比，C的序列同源性为83.7%，E（rns）和E1为84.6%，E2为81.5%。发现裂解位点C/E（rns）完全保守，而N（pro）/C仅在N（pro）的C端保守，E（rns）/E1位点仅在E（rns）的C端保守，E1/E2位点仅在E1的C端保守。对5'非翻译区（UTR）、N（pro）、E2、NS3和NS5B区域的核苷酸序列进行系统发育分析，将绵羊分离株置于BVDV - 2 b亚型内的一个单独分支中。NS3和NS5B之外的结构蛋白编码区域存在独特突变也支持了这一点。据我们所知，这是关于BVDV - 2 b分离株整个结构基因编码区域序列分析的首次报道。这也是BVDV - 2 b亚型首次在绵羊中出现，证明该亚型也可在牛以外的物种中出现。
