Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, 1600 S. 16th Street, Ames, IA 50011, USA.
Vet Microbiol. 2011 Sep 28;152(3-4):235-46. doi: 10.1016/j.vetmic.2011.05.005. Epub 2011 May 11.
The objective of this study was to determine the effect of porcine reproductive and respiratory syndrome virus (PRRSV) infection on porcine circovirus type 2 (PCV2) subtypes a (PCV2a) or b (PCV2b) viremia and shedding characteristics in oral, nasal and fecal samples in experimentally infected pigs. Twenty-three, 2- to 6-week-old pigs were randomly divided into five groups: negative control (n=3), PCV2a-I (n=5), PCV2a-PRRSV-CoI (n=5), PCV2b-I (n=5), and PCV2b-PRRSV-CoI (n=5). Blood, oral, nasal and fecal swabs were collected in regular intervals from day post inoculation (dpi) 0 until dpi 70 and tested by quantitative real-time PCR for the presence and amount of PCV2 DNA and by ELISA for the presence of PCV2-specific antibodies. The results indicate that there were significantly (P<0.05) higher loads of PCV2a and PCV2b DNA in serum, oral swabs, nasal swabs and fecal swabs and a higher prevalence of detectable PCV2 antigen in tissues of pigs concurrently infected with PCV2 and PRRSV compared to pigs singularly infected with PCV2 further confirming that PRRSV enhances replication of PCV2. Moreover, PRRSV infection significantly prolonged the presence of PCV2 DNA in serum and increased the amount of PCV2 DNA in oral and nasal secretions and fecal excretions in the later stages of infection between dpi 28 and 70. Shedding patterns were similar between groups infected with PCV2a and PCV2b, indicating that there was no subtype-specific interaction with the PRRSV isolate used in this study. The results from this study highlight the interaction between PRRSV and PCV2 and the importance of controlling PRRSV infection in order to reduce PCV2 virus loads in pig populations.
本研究旨在确定猪繁殖与呼吸综合征病毒（PRRSV）感染对实验感染猪口腔、鼻腔和粪便样本中猪圆环病毒 2 型（PCV2）亚群 a（PCV2a）或 b（PCV2b）病毒血症和排毒特征的影响。23 头 2-6 周龄猪被随机分为五组：阴性对照组（n=3）、PCV2a-I 组（n=5）、PCV2a-PRRSV-CoI 组（n=5）、PCV2b-I 组（n=5）和 PCV2b-PRRSV-CoI 组（n=5）。从接种后第 0 天（dpi）至第 70 天，定期采集血液、口腔、鼻腔和粪便拭子，并通过定量实时 PCR 检测 PCV2 DNA 的存在和数量，通过 ELISA 检测 PCV2 特异性抗体的存在。结果表明，与单独感染 PCV2 的猪相比，同时感染 PCV2 和 PRRSV 的猪血清、口腔拭子、鼻腔拭子和粪便拭子中 PCV2a 和 PCV2b DNA 载量明显更高（P<0.05），组织中可检测到的 PCV2 抗原的阳性率更高，进一步证实 PRRSV 增强了 PCV2 的复制。此外，PRRSV 感染显著延长了 PCV2 DNA 在血清中的存在时间，并在感染后期（dpi 28 至 70 天）增加了口腔和鼻腔分泌物以及粪便排泄物中 PCV2 DNA 的量。感染 PCV2a 和 PCV2b 的猪的排毒模式相似，表明与本研究中使用的 PRRSV 分离株没有亚群特异性相互作用。本研究结果强调了 PRRSV 与 PCV2 之间的相互作用，以及控制 PRRSV 感染以减少猪群中 PCV2 病毒载量的重要性。
