Noroviruses, an important cause of acute gastroenteritis, have been found to recognize human histo-blood group antigens (HBGAs) as receptors. Four strain-specific binding patterns to HBGAs have been described in our previous report. In this study, we have extended the binding patterns to seven based on 14 noroviruses examined. The oligosaccharide-based assays revealed additional epitopes that were not detected by the saliva-

Campylobacter coli VC167, which undergoes an antigenic flagellar variation, contains two full-length flagellin genes, flaA and flaB, that are located adjacent to one another in a tandem orientation and are 91.5%homologous. The gene product offlaB, which has an Mr of 58,946, has 93% sequence homology to the gene product of flaA, which has an M, of 58,916 (S. M. Logan, T. J. Trust, and P. Guerry, J. Bacteriol. 171:3031-3038, 1989). Mutational analyses and primer extension experiments indicated that the two genes are transcribed under the control of distinct promoters but that they are expressed concomitantly in the same cell, regardless of the antigenic phase of flagella being produced. TheflaA gene, which was expressed at higher levels than theflaB gene in both phases, was transcribed from a typical 2.8-type promoter, whereas theflaB promoter was unusual. A mutant producing only the flaB gene product did not synthesize a flagellar filament and was nonmotile. Southern blot analysis indicated that flagellar antigenic variation involves a rearrangement of flagellin sequence information rather than the alternate expression of the two distinct genes.Campylobacterjejuni and Campylobacter coli are important gastrointestinal pathogens of humans, most commonly producing an acute enteritis (6,8,39). An essential step in the establishment of Campylobacter enteritis is the colonization of the viscous mucous blanket covering the epithelium of the small intestine. The motility imparted by the polar flagellum of the Campylobacter cell appears to play a significant role in the colonization of this mucous niche (23,30,31), since nonmotile variants appear unable to colonize the gastrointestinal tract of experimental animals or human volunteers (4, 7). Flagellin is also the immunodominant protein antigen recognized during infection, so flagella are clearly important virulence determinants of the thermophilic campylobacters.Flagellar expression in Campylobacter spp. is subject to both phase and antigenic variation (7,12). Phase variation refers to ability of some Campylobacter strains to exhibit a bidirectional transition between flagellated and nonflagellated phenotypes (7). Antigenic variation refers to the ability of other strains to reversibly express flagella of different antigenic specificities (12). In the case of C. coli VC167, the reversible variation corresponds to the production of flagellar filaments containing antigenically distinguishable flagellin monomers of apparent subunit molecular weight 61,500 in antigenic phase 1 (P1) cells and 59,500 in antigenic phase 2 (P2) cells. Importantly, recent studies with C. coli VC167 have demonstrated an in vivo preference for one flagellar phase, P2, during colonization in an animal model (19), further emphasizing the functional importance of this locomotory organelle in gastrointestinal colonization by Campylobacter spp.Phase and antigenic variation of surface antigens has been described for other pathogenic bacteria, including fimbrialphase variation in Escherichia coli (1), Mor...

Gastroenteritis caused by enterotoxigenic E. coli and shigella resistant to a number of drugs was a major problem that frequently interfered with the duties of U.S. troops during Operation Desert Shield.

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Adherence to HEp-2 tissue culture cells has been proposed as a virulence characteristic of enteropathogenic Escherichia coli (EPEC). A preliminary study revealed that E. coli that adhered to HEp-2 cells, but did not produce conventional enterotoxins and did not belong to recognized EPEC serogroups, could be isolated from adults from the United States who acquired diarrhea in Mexico. The purpose of this study was to determine the prevalence of these enteroadherent E. coli (EAEC) in 188 travelers with diarrhea and in 92 well travelers. EAEC were found in 14.9% of patients with diarrhea and in 7.6% of well individuals. Compared with well travelers, patients with diarrhea in whom no recognized enteropathogen could be identified had a 30.4% prevalence of EAEC (P less than .0003). These results further support our finding that EAEC are associated with diarrhea in travelers to Mexico and may help to explain the effect of antibiotics in the prevention and therapy for travelers' diarrhea in patients with no recognized bacterial enteropathogens.