Fraile L, Segalés J, Ticó G, López-Soria S, Valero O, Nofrarías M, Huerta E, Llorens A, López-Jiménez R, Pérez D, Sibila M
Departament de Producció Animal, ETSEA, Universitat de Lleida, 25198 Lleida, Spain.
Centre de Recerca en Sanitat Animal (CReSA), UAB-IRTA, Campus de la Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallés), Spain; Departament de Sanitat i d'Anatomia Animals, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallés), Spain.
Prev Vet Med. 2015 May 1;119(3-4):153-61. doi: 10.1016/j.prevetmed.2015.02.017. Epub 2015 Feb 24.
The present study describes the virological and serological profiles of PCV2 vaccinated (V) and non-vaccinated (NV) piglet subpopulations coming from V and NV sows in a PCV2 subclinically infected farm. Four hundred seventy-six piglets born from V or NV sows were further subdivided in a total of four groups: NV sows-NV pigs (NV-NV), NV sows-V pigs (NV-V); V sows-NV pigs (V-NV) and V sows-V pigs (V-V). Seventy-five pigs were randomly selected at the beginning of the trial from each group and they were bled at 4, 8, 12, 16, 21 and 25 weeks of age. All animals included in the trial were weighed at 4 and 25 weeks of age and their average daily weight gain (ADWG) was calculated. Serum samples obtained at different time points were used to assess PCV2 infection (viremia) and the level of antibodies by means of immunoperoxidase monolayer assay (IPMA) against this pathogen. IPMA titers (classified in high, medium or low) and PCR results (positive or negative) were analyzed using a multiple correspondence and K-means cluster analysis. According to these tests, animals included in the study were classified into the following four clusters: (1) 93 piglets that were viremic mainly from 12 to 25 weeks of age and with PCV2 antibody titers increasing over time; (2) 75 piglets with late PCV2 infection and seroconversion (later than 16 weeks of age); (3) 26 piglets with high but decreasing PCV2 antibody titers and low percentages of PCV2 PCR positive serum samples; and (4) 105 piglets with medium and high IPMA titers throughout the trial and sporadic PCR positive samples. The defined subpopulations of piglets were observed in all experimental groups (NV-NV, NV-V, V-NV and V-V) although in variable percentages. Thus, animals from clusters 1 and 2 belonged mainly to the NV-NV and V-NV groups and animals from clusters 3 and 4 were distributed mainly into the NV-V and V-V groups. Finally, the ADWG of pigs belonging to clusters 3 and 4 was significantly higher (p=0.02) than that of pigs belonging to clusters 1 and 2. Within each cluster, no statistically significant differences were found in ADWG between treatment groups.
本研究描述了来自一个猪圆环病毒2型（PCV2）亚临床感染猪场中，接种（V）和未接种（NV）PCV2疫苗的母猪所产仔猪亚群的病毒学和血清学特征。476头由接种或未接种PCV2疫苗的母猪所产仔猪被进一步细分为四组：未接种疫苗的母猪-未接种疫苗的仔猪（NV-NV）、未接种疫苗的母猪-接种疫苗的仔猪（NV-V）；接种疫苗的母猪-未接种疫苗的仔猪（V-NV）和接种疫苗的母猪-接种疫苗的仔猪（V-V）。在试验开始时，从每组中随机选取75头仔猪，并在4、8、12、16、21和25周龄时采血。对试验中纳入的所有动物在4周龄和25周龄时称重，并计算其平均日增重（ADWG）。利用免疫过氧化物酶单层试验（IPMA），检测不同时间点采集的血清样本中PCV2感染情况（病毒血症）和抗体水平。使用多重对应分析和K均值聚类分析对IPMA滴度（分为高、中或低）和PCR结果（阳性或阴性）进行分析。根据这些检测，将研究中的动物分为以下四类：（1）93头仔猪，主要在12至25周龄时出现病毒血症，且PCV2抗体滴度随时间升高；（2）75头仔猪，PCV2感染和血清转化较晚（16周龄后）；（3）26头仔猪，PCV2抗体滴度高但呈下降趋势，且PCV2 PCR阳性血清样本百分比低；（4）105头仔猪，在整个试验过程中IPMA滴度为中高，且有零星的PCR阳性样本。虽然各实验分组（NV-NV、NV-V、V-NV和V-V）中仔猪亚群的比例各不相同，但所有组中均可观察到上述所定义的仔猪亚群。因此，第1类和第2类中的动物主要属于NV-NV组和V-NV组，第3类和第4类中的动物主要分布在NV-V组和V-V组。最后，第3类和第4类仔猪的ADWG显著高于第1类和第2类仔猪（p=0.02）。在每一类中，各处理组之间的ADWG未发现统计学显著差异。
