Opriessnig T, Yu S, Gallup J M, Evans R B, Fenaux M, Pallares F, Thacker E L, Brockus C W, Ackermann M R, Thomas P, Meng X J, Halbur P G
Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, IA 50011, USA.
Vet Pathol. 2003 Sep;40(5):521-9. doi: 10.1354/vp.40-5-521.
The objective of this study was to determine whether vaccination with bacterins commonly used in the USA, when administered at a time typical of US protocol, enhances porcine circovirus type 2 (PCV2) replication and the incidence and severity of clinical signs and lesions characteristic of postweaning multisystemic wasting syndrome (PMWS) in conventional pigs. Sixty-one pigs free of PCV2 were randomly assigned to four groups. Groups 1 (n = 15) and 2 (n = 15) pigs served as sham-inoculated negative controls. Groups 3 (n = 14) and 4 (n = 17) pigs were inoculated intralymphoid with PCV2 field isolate ISU-40895. Pigs in groups 2 and 4 were vaccinated with Actinobacillus pleuropneumoniae (APP) and Mycoplasma hyopneumoniae (M. hyopneumoniae) bacterins 21 days before and again 1 day before inoculation with PCV2. Mild transient respiratory disease and diarrhea were observed from 13 to 34 days postinoculation (DPI) in pigs in groups 3 and 4. Half the pigs from each group were necropsied at 22 and 34 DPI, respectively. Moderately enlarged, tan-colored lymph nodes were observed in the majority of pigs in groups 3 and 4. There was a significantly (P < 0.05) longer length of viremia (2.14 +/- 0.26 versus 4.44 +/- 0.23 weeks), a higher copy number of the PCV2 genome in serum, a wider range of tissue distribution of PCV2 antigen, and an increased severity of lymphoid depletion in pigs vaccinated with commercial APP and M. hyopneumoniae vaccines and inoculated with PCV2 compared with PCV2-inoculated unvaccinated pigs. Swine producers and veterinarians may need to consider changes in vaccination protocols in herds with recurrent PCV2-associated PMWS.
本研究的目的是确定在美国常用的菌苗进行疫苗接种时，按照美国方案的典型时间接种，是否会增强猪圆环病毒2型（PCV2）的复制以及传统猪断奶后多系统消耗综合征（PMWS）特征性临床症状和病变的发生率及严重程度。61头无PCV2的猪被随机分为四组。第1组（n = 15）和第2组（n = 15）的猪作为假接种阴性对照。第3组（n = 14）和第4组（n = 17）的猪经淋巴内接种PCV2田间分离株ISU - 40895。第2组和第4组的猪在接种PCV2前21天和接种前1天再次接种胸膜肺炎放线杆菌（APP）和猪肺炎支原体（M. hyopneumoniae）菌苗。接种后13至34天（DPI），第3组和第4组的猪出现轻度短暂性呼吸道疾病和腹泻。每组分别在22 DPI和34 DPI时对一半的猪进行剖检。第3组和第4组的大多数猪观察到淋巴结中度肿大、呈棕褐色。与未接种疫苗仅接种PCV2的猪相比，接种商业APP和猪肺炎支原体疫苗并接种PCV2的猪的病毒血症持续时间显著更长（2.14±0.26对4.44±0.23周），血清中PCV2基因组拷贝数更高，PCV2抗原的组织分布范围更广，淋巴组织耗竭的严重程度增加。猪生产者和兽医可能需要考虑在反复发生与PCV2相关的PMWS的猪群中改变疫苗接种方案。
