Institute of Special Wild Economic Animal and Plant Science, CAAS, No. 15, Luming Road, Jilin 132109, China.
Vet Microbiol. 2012 May 25;157(1-2):50-60. doi: 10.1016/j.vetmic.2011.12.012. Epub 2011 Dec 16.
A live-attenuated highly pathogenic porcine reproductive and respiratory syndrome (HP-PRRS) virus (HP-PRRSV) TJM vaccine strain was derived from the HP-PRRSV TJ strain by passage 92 times in the African green monkey kidney epithelial cell line Marc-145. We found that the virulence of the TJ strain to piglets was decreased greatly from passage 19. To identify mutations associated with attenuation of the TJM vaccine strain, we determined the nucleotide changes that arose during Marc-145 passage of the HP-PRRSV TJ virus. The TJM strain contains a 360 nucleotide (120 amino acids) deletion and a 118 nucleotide mutation that resulted in 48 amino acid changes. Analysis of the complete nucleotide sequences of intermediate passage-level viruses F19, F46 and F78 showed that 31 (64.6%) of the 48 amino acid mutations occurred in F19, 7 (14.6%) occurred in F46, 7 (14.6%) occurred in F78 and 3 (6.3%) occurred in F92. The 120 amino acid deletion occurred from F19 to TJM. Therefore, we hypothesized that the 31 amino acid mutations distributed in nsp1β, nsp2-nsp5, nsp7, nsp9, nsp10, GP4 and GP5 and the continuous 120 amino acid deletion in the nsp2 region from F19 provide a strong potential molecular basis for the observed attenuated phenotype.
一株猪繁殖与呼吸综合征（PRRS）活疫苗弱毒（HP-PRRSV）TJM 株是由非洲绿猴肾传代细胞系 Marc-145 连续传代 92 代，从 HP-PRRSV TJ 株衍生而来。我们发现 TJ 株对仔猪的毒力从第 19 代开始显著降低。为了鉴定与 TJM 疫苗株减毒相关的突变，我们测定了在 Marc-145 传代过程中 HP-PRRSV TJ 病毒出现的核苷酸变化。TJM 株含有 360 个核苷酸（120 个氨基酸）缺失和 118 个核苷酸突变，导致 48 个氨基酸变化。对中间传代水平病毒 F19、F46 和 F78 的完整核苷酸序列分析表明，48 个氨基酸突变中有 31 个（64.6%）发生在 F19 中，7 个（14.6%）发生在 F46 中，7 个（14.6%）发生在 F78 中，3 个（6.3%）发生在 F92 中。120 个氨基酸缺失发生在 F19 到 TJM 之间。因此，我们假设分布在 nsp1β、nsp2-nsp5、nsp7、nsp9、nsp10、GP4 和 GP5 的 31 个氨基酸突变以及 nsp2 区连续的 120 个氨基酸缺失为观察到的减毒表型提供了强有力的潜在分子基础。
