The MARC-145 cell line is commonly used to isolate porcine reproductive and respiratory syndrome virus (PRRSV) for diagnostics, research, and vaccine production, but it yields frustratingly low success rates of virus isolation (VI). The ZMAC cell line, derived from porcine alveolar macrophages, has become available, but its utilization for PRRSV VI from clinical samples has not been evaluated. This study compared PRRSV VI results in ZMAC and MARC-145 cells from 375 clinical samples (including 104 lung, 140 serum, 90 oral fluid, and 41 processing fluid samples). The PRRSV VI success rate was very low in oral fluids and processing fluids regardless of whether ZMAC cells or MARC-145 cells were used. Success rates of PRRSV VI from lung and serum samples were significantly higher in ZMAC than in MARC-145 cells. Lung and serum samples with threshold cycle (C_T) values of <30 had better VI success. PRRSV-2 in genetic lineages 1 and 8 was isolated more successfully in ZMAC cells than in MARC-145 cells, whereas PRRSV-2 in genetic lineage 5 was isolated in the two cell lines with similar success rates. For samples with positive VI in both ZMAC and MARC-145 cells, 14 of 23 PRRSV-2 isolates had similar titers in the two cell lines. A total of 51 of 95 (53.7%) ZMAC-obtained PRRSV-2 or PRRSV-1 isolates grew in MARC-145 cells, and all 46 (100%) MARC-145-obtained isolates grew in ZMAC cells. In summary, ZMAC cells allow better isolation of a wide range of PRRSV field strains; however, not all of the ZMAC-obtained PRRSV isolates grow in MARC-145 cells. This report provides important guidelines to improve isolation of PRRSV from clinical samples for further characterization and/or for producing autogenous vaccines.

中文翻译：

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ZMAC 和 MARC-145 细胞系在改善猪繁殖和呼吸综合征临床样本病毒分离方面的比较

MARC-145 细胞系通常用于分离猪繁殖与呼吸综合征病毒 (PRRSV)，用于诊断、研究和疫苗生产，但其病毒分离 (VI) 的成功率低得令人沮丧。源自猪肺泡巨噬细胞的 ZMAC 细胞系已经可用，但尚未评估其对来自临床样本的 PRRSV VI 的利用。本研究比较了来自 375 个临床样本（包括 104 个肺、140 个血清、90 个口腔液和 41 个处理液样本）的 ZMAC 和 MARC-145 细胞的 PRRSV VI 结果。无论使用 ZMAC 细胞还是 MARC-145 细胞，PRRSV VI 在口腔液和加工液中的成功率都非常低。ZMAC 中肺和血清样本 PRRSV VI 的成功率显着高于 MARC-145 细胞。ç _Ť) <30 的值有更好的 VI 成功。在 ZMAC 细胞中分离遗传谱系 1 和 8 中的 PRRSV-2 比在 MARC-145 细胞中更成功，而遗传谱系 5 中的 PRRSV-2 在两种细胞系中以相似的成功率分离。对于在 ZMAC 和 MARC-145 细胞中均具有阳性 VI 的样品，23 个 PRRSV-2 分离株中有 14 个在两种细胞系中具有相似的滴度。95 个 (53.7%) ZMAC 获得的 PRRSV-2 或 PRRSV-1 分离株中有 51 个在 MARC-145 细胞中生长，所有 46 个（100%）MARC-145 分离株在 ZMAC 细胞中生长。总之，ZMAC 细胞可以更好地分离各种 PRRSV 野毒株；然而，并非所有从 ZMAC 获得的 PRRSV 分离株都在 MARC-145 细胞中生长。