畢業(yè)設(shè)計(jì)(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-在線瀏覽
2025-08-08 02:34本頁面
【正文】 ions 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 subgroup 3, one, 2, or 3 of the 4 deletions occurred. For example, a single deletion was present at 122 nt in Em2021, double deletions at 122 nt and 15,278 nt in HB1(sh)/2021 and SHB, and triple deletions at 122 nt,15,278 nt, and 482 aa in GD32021(this sequence was not submitted to GenBank until now). In 2021, Ma etal. pared GD32021 with several PRRSVS and reported the homology within them, pointing out that the 2 deletions in NSP2 were identical to the HPPRRSV . After careful analysis, we found the GD32021 more interesting than what was reported by Ma et al.。 subgroup 4 contained I39 only. The existence of either F39 or I39 in subgroup 3 PNE indicates its intermediate position between subgroups 2 and 4 in the evolution of HPPRRSVs. Pairwise parison of subgroups 2, 3, and 4 did not find rebination or large fragment replacement,which suggests that all HPPRRSVs originated from the same ancestor by gradual evolution. Notably, the recently isolated intermediate PRRSVS mentioned above (SHB, Em2021,and GD32021) were isolated in the region of South China where the outbreak of HPPRRS initially occurred. Furthermore, the epidemiologic data show that the outbreak of HPPRRSV emerged from 1 partic
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