U.S. Department of Agriculture: Agricultural Research Service, Lincoln, Nebraska


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Date of this Version



Infection and Immunity, 61(5): (May 1993), p. 2249-2252


A DNA probe derived from the subunit gene of a cloned 987P determinant was used to characterize the locations of the 987P genes in several Escherichia coli strains. We examined E. coli 987, a nonpiliated mutant of strain 987 (136) that does not express 987P in vitro, and a variant of I36 that expressed 987P following growth in vivo. We found that plasmid and chromosomal copies of the 987P subunit gene could be differentiated in strain 987 by restriction endonuclease analysis and Southern blot hybridization. The nonpiliated mutant 136 had lost the plasmid copy but retained the chromosomal copy of the 987P gene. A 987P-piliated variant of 136, which did not contain the 987P plasmid, colonized and caused diarrhea in neonatal pigs similarly to wild-type 987. The plasmid that hybridized with the 987P probe was transferred from strain 987 to an E. coli K-12 strain by conjugation. We were unable to demonstrate expression of 987P by these transconjugants. The data suggest that the chromosomal and plasmid copies of the 987P genes may interact to influence 987P expression.