ASSOCIATION OF K-1 CAPSULE, SMOOTH LIPOPOLYSACCHARIDES, TRAT GENE, AND COLICIN-V PRODUCTION WITH COMPLEMENT RESISTANCE AND VIRULENCE OF AVIAN ESCHERICHIA-COLI

A group of complement-resistant, virulent avian Escherichia coli isola tes were compared with a group of complement-sensitive, avirulent avia n isolates for the presence of K-1 capsule, smooth lipopolysaccharides (LPS), the traT gene, and Colicin V (ColV) production. These paramete rs were selected because of their reported association with complement resistance and virulence in E. coli. Lethality in chicken embryos has also been shown to be correlated with virulence of avian E. coli for chickens. The complement-resistant, virulent E. coli isolates did not possess a K-1 capsule. Production of ColV and the presence of smooth L PS were significantly correlated with embryo lethality. There was no c orrelation between the presence of traT and embryo lethality. These re sults suggest that complement resistance and virulence in avian E. col i are associated with ColV production and smooth LPS but not with K-1 antigen or traT.