猪肠毒性大肠杆菌(ETEC)病抗病育种研究

Approach of Resistance Breeding for Enterotoxigenic E.Coli (ETEC)Disease in Pig

猪肠毒性大肠杆菌 (ETEC)是仔猪黄痢、白痢等腹泻疾病的主要病原菌 ,发病率和死亡率分别占总发病率和死亡率的 5 6 .2 %和 2 4 .7%。按其特异菌毛产生的粘附素不同有 K88、K99、987P等多种类型 ,K88又可分为 ab、ac、ad血清型 ,现已知 ETEC K88能否致病 ,取决于宿主小肠粘膜上皮细胞刷状缘有无受体 ,并受制于 1对等位基因 ,有受体 (敏感型 )为显性 (S) ,无受体 (抗性型 )为隐性 (s)。该位点位于 1 3号染色体长臂 3.1区段 ,与转铁蛋白 (Tf)连锁 (相距7.4 c M) ,且 Tf基因频率与 K88抗性存在一定关系 ,抗性型与敏感型的小肠粘液理化性质也存在差异 ,据此 ,有可能采用生化及分子生物技术筛选抗性遗传标记 ,开展抗病育种。

ETEC are main pathogene of piglet diarrhea.The incidence and death percentage of this disease occupy 56 2% and 24 7% respectively of those the total.According to the adhesin from specific fimbriae there are many types of the ETEC such as K88,K99,987P.The K88 can be divided into ab,ac,ad serum tyeps.Whether the ETEC K88 can cause disease or not depends on the existance of specific receptor for K88 in porcine intestinal mucosa brush border membrane.The adhesion character seems to be controlled by a single Mendelian Locus with dominant S (susceptible)and recessive s (resistant)alleies.This regional localization on chromosome 13 q 1 3 is in relation with transferrin (Tf) loci (distance 7 4 cM).There is relationship between the Tf frequency and K88 resistance.The physical and chemical characters of piglet intestinal mucus deffer in susceptible and resistant types.According to what is mentional above,the genetic markers of resistance can be screened by biochemical and molecular biotechnology methods,so the resistance breeding can be carried out.