Pilus antigen 987P produced by strains of Escherichia coli serotypes O141:K--, H- and O8:K85:H--

Escherichia coli strains isolated from the alimentary tract of 68 weaned and 44 unweaned pigs with diarrhoea in various parts of Hungary, were tested for the presence of pilus antigens K88, K99 and 987P. K88 was detected in 30% of the strains from newborn pigs and in 12% of the strains isolated from weaned pigs. One strain carried K99. Based on agglutination test and immunoelectron microscopic studies with specific absorbed antisera, five non-haemolytic E. coli strains isolated from newborn pigs were found to produce so-called 987P pili. Three of these strains were designated serologically as O8:K85:H--,987P+ and two as O141: K--:H--,987P+. The Y1 cell assay, the infant mouse assay, and the ligated intestinal loop assay in less than 3-week-old pigs indicated that none of the strains produced heat-labile enterotoxin but all produced a heat-stable enterotoxin detectable in infant mice and in pig loops (STa). All the strains induced diarrhoea in newborn, colostrum deprived pigs and colonized the lower small intestine by adhesion to the villous epithelium. The results have confirmed earlier findings about adhesive virulence attributes caused by 987P pili.