saa (STEC) autoagglutinating

LUCCHESI, PAULA M. A.; KRÜGER, ALEJANDRA

sitio web

Otro; ACLI-Open learning on Enteric Pathogens website; 2006

ACLI (Sassari), in collaboration with Consorzio SIS (Sviluppo Impresa Sociale), the University of sassari and the Regione sardegna (funds from legge regionale nº19).

Verocytotoxin Escherichia coli (VTEC), also called shiga toxin-producing E. coli (STEC), can cause diarrhea, hemorrhagic colitis and hemolytic uremic syndrome (HUS) in humans. The pathogenesis of VTEC infection in humans is multifactorial and not fully understood, being the verocytotoxins the principal virulence factor. Most strains causing serious diseases also possess the eae gene that encodes the adhesin intimin, but its presence is not essential for virulence as there are some cases caused by eae-negative strains. Saa gene, described from an eae-negative VTEC strain responsible for an outbreak of HUS, encodes an outer membrane protein which appears to function as an autoagglutinating adhesion. Saa proteins from diverse VTEC strains show marked variation in size, due largely to differences in the number of copies of a 37-aa repeat unit in the C-terminal region. Based on these findings, we designed PCR primers to amplify the region coding for these differences and then investigated the distribution of saa gene variants in a collection of VTEC strains isolated from cattle and meat in Argentina. Gene saa was detected in 36 (31.6%) eae-negative strains and 5 variants were found. Two of them, those with a higher number of repeats, correspond to novel saa variants.