大肠杆菌F4在3个品种猪中的黏附模式

大肠杆菌F4是引起仔猪断奶前腹泻的一种主要细菌,F4黏附于小肠上皮细胞是其致病的前提。小肠上皮细胞的F4受体是由常染色体上的基因编码的,如果无受体,仔猪表现为大肠杆菌抗性。为了研究黏附的遗传机制,本实验利用大白、长白、松辽黑猪的小肠刷状缘细胞与F4ab、F4ac、F4ad进行离体黏附实验,结果发现3品种(系)猪之间黏附情况存在显著差别(P<0.01),松辽黑猪以非黏附型为主,而长白猪中黏附型比例较高,在同一品种猪内,3种菌株的黏附比例在松辽黑猪内和大白猪内有极显著差异,但在长白猪中无显著差异。从3种细菌与刷状缘的黏附模式来看,F4ab、F4ac和F4ad分别有3种不同的受体,它们可能是由3个不同的基因座编码的。

Adhesive Patterns of Escherichia coli F4 in Piglets of Three Breeds

Escherichia coli expressing F4 fimbriae is the major pathogenic bacteria that causes diarrhea in piglets before weaning. The adhesion of E. coli to the brush borders of the epithelial cells of piglets is the precondition leading to diarrhea, which in turn is due to the presence of the F4 receptors determined by an autosomal recessive gene on the brush borders of the epithelial cells. In order to clarify the genetic mechanism of the adhesion, an in vitro adhesion experiment was carried out for three variants of E. coli F4 (ab, ac, and ad) in 366 piglets of three pig breeds Landrace (LR), Large White (LW), and Songliao Black (SB)]. The results showed that there existed significant differences (P<0.001) in the adhesion percentage among the three breeds. Most SB piglets were nonadhesive for all the three variants, whereas most LR piglets were adhesive. Within each breed except for LR, the propor-tions of the three F4 variants adhering to the brush borders differed significantly. According to the patterns of the adhesion of the three F4 variants in the three breeds, it is very likely that the three F4 variants F4ab, F4ac, and F4ad have different receptors that are controlled by three different loci.