免疫生长激素受体胞外域N端片段对鸡生长的影响研究

为了探讨通过与生长激素受体（growth hormone receptor，GHR）胞外域（extracellular domain，ECD）特异结合的抗体能否激活或抑制GHR的信号传导，从而调节动物的生长，本试验首先通过基因工程途径制备了鸡GHR N端120个氨基酸残基的GHR ECD重组蛋白，并以此蛋白作为抗原免疫生长鸡，观察对鸡采食、生长和胴体组成的影响。高、低剂量组血液中抗GHR抗体水平在免疫后极显著上升（P<0.01），并在试验期间处于极显著高于对照组的非特异水平（P<0.01）。免疫GHR ECD显著抑制了鸡的生长（P<0.05），使高、低剂量组鸡在首免后第30天体重就已经显著低于对照组鸡并持续至试验结束（P<0.05）。在增重受抑制后，免疫GHR鸡在后期的采食量也显著降低（P<0.05）。屠宰时对照组的体重、屠宰率、半净膛率、全净膛率和腹脂率都高于2免疫组。以上数据说明，对生长鸡免疫GHR ECD所产生的抗GHR抗体将显著抑制鸡的生长，这一方法并不能促进鸡或其他动物的生长性能，但有可能被应用于其他需要限制动物生长如后备种鸡的培育方面。

Study on Effects of Immunization against Growth Hormone Receptor Extracellular Domain on Chicken Growth Performances

The aim of this study was to investigate whether antibodies specific to growth hormone receptor (GHR) extracellular domain (ECD) could activate or inhibit GHR signal transduction, and whether the antibodies could be used to regulate animal growth performance. Firstly, an N-terminal 120-amino acid residue chicken GHR ECD was prepared by recombinant technology, and was used as the antigen to immunize growing pullets. Anti-GHR antibody titres rapidly increasedafter the primary immunization in both high and low groups (P<0.01), and were similar in both GHR ECD immunized groups, but were significantly higher than the non-specific levels in the control group throughout the experiment (P<0.05). Immunization against GHR ECD was significantly (P<0.01) inhibited live weight gain in both high and low group pullets, that the live weights were already lower only 30 d following the primary immunization than that of control group (P<0.05). Following suppression of weight gain, GHR ECD immunized groups also exhibited significant (P<0.05) depression in daily feed intake at the later stage of the experiment. Upon slaughter, the control pullets had higher carcass weight, slaughter rate, semi-enviseration and enviseration percentages, and higher abdominal fat ratio than did the high and low groups. These results demonstrated that immunization against GHR ECD inhibited chicken growth, which implied the antibodies to GHR exhibited a GHR signal transduction blockade effect. The results also implied that immunization against GHR ECD would be unlikely to be used to promote animal growth, but might be applicable to restrict animal growth as in the case of breeder pullet rearing.