Abstract：
This study compared the different sequential order of infection of porcine circovirus type 2d (PCV2d) and Mycoplasma hyopneumoniae. Thirty-six pigs were allocated randomly across six different groups. Pigs underwent various inoculation sequences: M. hyopneumoniae administered 14 days before PCV2d, simultaneous PCV2d-M. hyopneumoniae, PCV2d given 14 days before M. hyopneumoniae, PCV2d only, M. hyopneumoniae only, or a mock inoculum. Overall, the pigs inoculated with M. hyopneumoniae 14 days prior to PCV2d (Mhyo-PCV2 group) and those inoculated simultaneously with PCV2d and M. hyopneumoniae (PCV2+Mhyo group) displayed notably higher clinical disease severity and experienced a significant decrease of their average daily weight gain than pigs inoculated with PCV2d 14 days prior to M. hyopneumoniae (PCV2-Mhyo group). M. hyopneumoniae infection potentiated PCV2 blood and lymph node viral loads, as well as PCV2-associated lesions, while the infection of PCV2d did not impact the intensity of M. hyopneumoniae infection. Tumor necrosis factor-α (TNF-α) sera levels were significantly increased in the Mhyo-PCV2 and PCV2+Mhyo groups as compared to the PCV2-Mhyo, PCV2, and Mhyo groups. The most important information was that the potentiation effect of M. hyopneumoniae on PCV2d was found only in pigs inoculated with either M. hyopneumoniae followed by PCV2d (Mhyo-PCV2 group) or a simultaneous inoculation of PCV2d and M. hyopneumoniae (PCV2+Mhyo group). The sequential infection order of PCV2d and M. hyopneumoniae resulted in divergent clinical outcomes.
摘要：
本研究比较了猪圆环病毒2d型（PCV2d）和猪肺炎支原体感染的不同顺序。将36头猪随机分配到六个不同的组中。猪接受不同的接种顺序：猪肺炎支原体在PCV2d前14天，同时PCV2d-M。猪肺炎,猪肺炎支原体前14天给予PCV2d，仅限PCV2d,仅猪肺炎支原体，或者模拟接种物.总的来说,在PCV2d前14天接种猪肺炎支原体(Mhyo-PCV2组)和同时接种PCV2d和猪肺炎支原体(PCV2+Mhyo组)的猪表现出明显更高的临床疾病严重程度,平均日增重明显低于在猪肺炎支原体前14天接种PCV2d的猪(PCV2-Mhyo组).猪肺炎支原体感染增强PCV2血液和淋巴结病毒载量，以及PCV2相关病变，PCV2d感染对猪肺炎支原体感染强度无影响。与PCV2-Mhyo相比，Mhyo-PCV2和PCV2Mhyo组的肿瘤坏死因子-α（TNF-α）血清水平显着增加，PCV2和Mhyo组。最重要的信息是，猪肺炎支原体对PCV2d的增强作用仅在接种猪肺炎支原体后再接种PCV2d（Mhyo-PCV2组）或同时接种PCV2d和猪肺炎支原体（PCV2Mhyo组）的猪中发现。PCV2d和猪肺炎支原体的顺序感染导致不同的临床结果。
