畢業(yè)設計(論文)外文參考資料及譯文-中國高致病性豬繁殖與呼吸綜合征病毒的起源-文庫吧
2024-12-28 21:27 本頁面
【正文】 ino acid sequences of these PRRSVs were aligned and pared by using previous methods . Whole genomebased phylogeic analysis showed that these 67 PRRSVs could be divided into 4 subgroups . Ten classic PRRSVs from China, together with the North American prototype virus VR2332 and the vaccine virus RespPRRS/Repromodified live vaccine, were classified into subgroup 1. The first Chinese isolate, CH1a, and its 3 derivatives (CH2022, CH2022, and CH2022) were classifi ed into subgroup 2. All 35 HPPRRSVs were classified into subgroup 4, and they shared high homology (99%) in their genomic sequences. The other 4 Chinese PRRSVs, including HB1(sh)/2022,HB2(sh)/2022, Em2022, and SHB,belonged to subgroup 3, an intermediate subgroup between subgroups 2and 4. Phylogeically, HPPRRSVs had a close relationship with subgroups 2 and 3. Four conserved deletions were shown among all HPPRRSVs, including an adenosine deletion at position 122 in the 5′untranslated region, a guanosine deletion at position 15,278 in the 3′untranslated region, and 2 discontinuous deletions in the NSP2, including a single amino acid deletion at position 482 (L482 ) and a second deletion of 29 amino acids between positions 533 and 561 (S533 –A561 ). The presence of these 4 deletions among subgroup 4 viruses is a unique phenomenon, which may be used as a distinctive molecular marker for HPPRRSVs. The occurrence of these 4 deletions might be explained as a stepwise accumulation from subgroup 2 to subgroup 4. None of the 4 deletions were found in subgroup 2. Among viruses in su
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