Association between intimin (eae) and EspB gene subtypes in attaching and effacing Escherichia coli strains isolated from diarrhoeic lambs and goat kids

Attaching and effacing Escherichia coli (AEEC) strains isolated from diarrh oeic lambs and goat kids were characterized for intimin (eae) and EspB (esp B) gene subtypes by PCR and sequencing, and for genetic relatedness by PFGE . Fifty (23 ovine and 27 caprine) AEEC strains of 398 (246 ovine and 152 ca prine) analysed were detected by colony blot hybridization. These strains w ere epidemiologically unrelated since they were isolated from different out breaks of neonatal diarrhoea over a long period. Ovine AEEC strains belonge d to serogroups 02, 04, 026, 080, 091 or were untypable, and caprine strain s belonged to serogroups 03, 0153 and 0163. Two intimin subtypes were detec ted among the ovine and caprine strains studied. Most of the strains (43/50 ) had the beta type intimin gene, but seven ovine strains possessed a varia nt gamma type intimin gene (gamma (v)). Analysis of deduced amino acid sequ ences of the eae gene revealed that the sequences of beta intimin of ovine and caprine strains were virtually identical to those of beta intimin of ra bbit EPEC, human EPEC clone 2 and swine AEEC, whereas the gamma (v) intimin present in seven ovine strains had 75-76% identity with gamma intimin of h uman EHEC clone 1 strains, and 96% of identity with intimin of the human EH EC strain 95NR1 of serotype 0111:H-. A PCR test was developed to identify t he three different espB gene subtypes, espB of human EPEC clone 1 (espB alp ha), espB of human EHEC clone 1 (espB gamma) and espB of rabbit EPEC and hu man EPEC clone 2 (espB beta). There was close correlation between the intim in beta type and the espB beta gene subtype in the ovine and caprine AEEC s trains. The seven ovine strains possessing the gamma (v) intimin gene posse ssed the espB alpha gene subtype. None of the strains studied possessed the espB gamma gene found in human 0157:H7 EHEC strains. PFGE analysis of geno mic DNA of selected strains showed a great diversity among strains. Cluster analysis of PFGE patterns showed greater divergence between strains with t he gamma (v) intimin gene than between strains with the beta intimin gene. This study showed that most of the AEEC strains isolated from diarrhoeic la mbs and goat kids possessed beta intimin and espB genes identical to those of rabbit EPEC, and they may be associated with enteric disease in small ru minants.