The mechanisms of transmission of influenza A virus (IAV) and porcine reproductive and respiratory syndrome virus (PRRSV) in pigs during the pre-weaning period are not fully elucidated. Since viable IAV and PRRSV can be found on the udder skin of lactating sows and the use of nurse sows is a common management practice, we developed a novel nurse sow model to evaluate the transmission of IAV and PRRSV from lactating sows to their adopted piglets. In two studies, we infected pigs with either IAV or PRRSV who then contaminated the udder skin of lactating dams with their nasal and oral secretions while suckling. Once the skin was confirmed virus positive for IAV and PRRSV, the sows were moved to separate empty clean rooms to adopt IAV and PRRSV negative suckling piglets. After adoption, 1 out of eight (12.5%) piglets tested IAV positive 1-day post-adoption (dpa) and the entire litter (8 out of 8) became positive by 4 dpa. In the case of PRRSV, 3 out of 11 (27.3%) pigs tested rRT-PCR positive 2 dpa and there were 7 out of 11 (63.6%) pigs positive at the termination of the study at 7 dpa. This study documented the transmission of IAV and PRRSV between litters of piglets by nurse sows and highlights the importance of the nurse sow-piglet as a unit that contributes to the maintenance of endemic infections in breeding herds. The use of nurse sows in pig farms, though beneficial for minimizing pre-weaning mortality and maximizing farm productivity, is seemingly detrimental as this practice may facilitate the transmission of IAV and PRRSV to piglets prior to weaning.

中文翻译：

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使用新型护士母猪模型传播甲型流感病毒和猪繁殖与呼吸综合征病毒：概念验证


甲型流感病毒（IAV）和猪繁殖与呼吸综合征病毒（PRRSV）在断奶前猪群中的传播机制尚未完全阐明。由于哺乳母猪的乳房皮肤上可以发现活的 IAV 和 PRRSV，并且使用保姆母猪是一种常见的管理做法，因此我们开发了一种新型保姆母猪模型来评估 IAV 和 PRRSV 从哺乳母猪到其领养仔猪的传播情况。在两项研究中，我们用 IAV 或 PRRSV 感染猪，然后猪在哺乳时的鼻腔和口腔分泌物污染了哺乳期母猪的乳房皮肤。一旦皮肤被确认为 IAV 和 PRRSV 病毒阳性，母猪就会被转移到单独的空洁净室，以收养 IAV 和 PRRSV 阴性的哺乳仔猪。收养后，八分之一 (12.5%) 的仔猪在收养后 1 天 (dpa) 检测出 IAV 呈阳性，而整窝仔猪（8 只中的 8 只）在 4 dpa 时呈阳性。就 PRRSV 而言，11 头猪中有 3 头 (27.3%) 在 2 dpa 检测出 rRT-PCR 呈阳性，并且在 7 dpa 研究结束时，11 头猪中有 7 头 (63.6%) 呈阳性。这项研究记录了保育母猪在仔猪之间传播 IAV 和 PRRSV 的情况，并强调了保育母猪-仔猪作为一个单位有助于维持种猪群地方性感染的重要性。在养猪场使用保姆母猪虽然有利于最大限度地降低断奶前死亡率和最大限度地提高农场生产力，但似乎是有害的，因为这种做法可能会促进断奶前将 IAV 和 PRRSV 传播给仔猪。