注射pGRF基因质粒对由脂多糖或三联疫苗诱导的免疫应激仔猪生长和免疫指标的影响

Effects of Injecting pGRF Gene Plasmid on Performance and Immunological Indices of Immunological Stress Piglets Induced by LPS or Triple Vaccine

为研究猪生长激素释放因子（pGRF）基因质粒对由脂多糖或三联苗诱导的免疫应激仔猪生长性能和免疫指标的影响，选用36头（28±2）d断奶的杜长大（Duroc×Landrace× Yorkshire，DLY）三元杂交仔猪，按体重相近、阎公猪和母猪各1／2的原则，分为对照组（不注射pGRF基因质粒、大肠杆菌LPS或三联苗）、注射pGRF组、注射脂多糖（LPS）组、注射pGRF＋LPS组、注射三联疫苗组（猪瘟兔化弱毒，猪丹毒杆菌G4T10弱毒，猪源多杀性巴氏杆菌E0630弱毒）和注射pGRF＋三联疫苗6个处理，每个处理6个重复，每个重复1头猪。试验开始时，pGRF组、pGRF＋LPS组、pGRF＋三联疫苗组的仔猪大腿肌肉分别注射1．0mgpGRF基因质粒；试验的第11天给LPS组、pGRF＋LPS组仔猪注射100ug／kgLPS生理盐水溶液，三联疫苗组以及pGRF＋三联疫苗组注射2头份三联苗生理盐水溶液，对照组和pGRF组注射生理盐水；第18天时按照第11天的操作重复进行。结果表明，在2次注射LPS或三联苗后，即10-17d和17-24d阶段，pGRF＋LPS组仔猪的ADG显著（10-17d，Pd0．05）或极显著（17-24d，P〈0．01）高于LPS组，F／G均显著低于LPS组（P〈0．05）；pGRF＋疫苗组仔猪ADG均显著高于疫苗组（P〈0．05），F／G显著低于疫苗组（P〈0．05）。在第11天和第18天，pGRF＋LPS组仔猪的血清细胞因子（IL-1、IL-6）水平均极显著低于LPS组（P％0．01），类胰岛素生长因子（IGF-I）和IgG浓度均极显著高于LPS组（P〈0．01）；pGRF＋疫苗组仔猪的血清IL-1和IL-6浓度显著低于疫苗组（P〈0．05），IgG浓度极显著（11d，P〈0．01）或显著（18d，P（0．05）高于疫苗组，IGF-I浓度显著（11d，P〈0．05）或极显著（18d，P〈0．01）高于疫苗组。证明pGRF基因质粒能缓解由LPS或三联疫苗免疫应激引起的仔猪生长抑制；能够抑制由脂多糖或三联苗诱导的血清IL-1和IL-6浓度的上升和血清IGF—I浓度的降低，同时能提高免疫应激仔猪的血清IgG浓度。

The purpose of this study was to evaluate the effects of pGRF gene plasmid on the performance and immunological indices of immunological stress weaned piglets induced by LPS or Triple vaccine. Thirty-six DLY （Duroc × Landrace × York- shire） pigs, weaned at the age of （28 ± 2） d, were assigned to 6 groups with six replicates in each group and one piglet in each replicate, which were contronl group, pGRF gene plasmid group, LPS （lipopolysaccharide） group, pGRF ＋ LPS group, triple vaccine group and pGRF ＋ triple vaccine group. In the beginning of the experiment, each pig of pGRF gene plasmid group, pGRF ＋ LPS group and pGRF ＋ triple vaccine group were injected 1.0 mg pGRF gene plasmid. On the 11th day of the experiment, pigs of pGRF ＋ LPS group and LPS group were injected lipopolysaccharide 100 ug/kg; pigs of pGRF ＋ triple vaccine group and triple vaccine group were injected double dose triple vaccine; and pigs of pGRF gene plasmid group and control were injected normal saline. On the 18^th day, the manipulation was the same as on the 11^th day. The results showed that, at the the stage of 10-17 d and 17-24 d, ADG of piglets in pGRF ＋ LPS group were significant higher than those in LPS group （10-17 d, P〈0.05; 17-24 d, P〈0.01）, F/G of piglets in pGRF ＋ LPS group were significant lower than those in LPS group （P〈0.05） ; ADG of piglets in pGRF ＋ triple vaccine group were significant higher than those in triple vaccine group （P〈0.05） and F/G of piglets in pGRF ＋ triple vaccine group were lower than those in triple vaccine group （P〈0.05）. On the 11^th day and the 18^th day, after being injected the LPS or triple vaccine, the serumal IL-1 and IL-6 levels of piglets in pGRF ＋ LPS groups and pGRF ＋ triple vaccine group were respectively significant lower than those in LPS group （P（0.01） and triple vaccine group （P〈0.05）; the serumal IGF-I and IgG levels of piglets in pGRF ＋ LPS group were both significant higher（P〈0.01）than those in LPS groups; the serumal IGF-I levels of piglets in the pGRF ＋ triple vaccine group were significant higher than those in triple vaccine group （11 d, P〈0.01, 18 d, P〈0.05） and the serumal IgG levels of piglets in the pGRF ＋ triple vaccine group were significant higher than those in triple vaccine group （11 d, P〈 0.05, 18 d, P（0.01）. In conclusion, pGRF could relieve the adverse effects of immunological stress on growth performance of the piglets, which were injected with lipopolysaccharide or triple vaccine, and could inhibit increase of the serumal IL-1 and IL-6 levels and decrease of the serumal IGF-I levels of immunological stress piglets ,and could improve the serumal IgG levels of immunological stress piglets.