Disease relevance of saa

• Introduction of saa cloned in pBC results in a 9.7-fold increase in adherence of E. coli JM109 to HEp-2 cells and a semilocalized adherence pattern [1].
• Rhizobium meliloti genes involved in sulfate activation: the two copies of nodPQ and a new locus, saa [2].

High impact information on saa

• Mutagenesis of saa in 98NK2, or curing the wild-type strain of its megaplasmid, resulted in a significant reduction in adherence [1].
• Certain strains of Shiga toxin-producing Escherichia coli (STEC) which do not have the locus of enterocyte effacement pathogenicity island carry the STEC autoagglutinating adhesin (saa) gene [3].
• Moreover, all strains were lacking the genes for enterohemolysin (ehxA), porcine A/E associated protein (paa), STEC autoagglutinating adhesin (saa) and the serin protease EspI (espI) [4].
• These results show that the saa gene is commonly associated with bovine eae-negative VTEC strains but not with ovine or caprine VTEC strains [5].
• Eighty-two percent of the strains showed further putative virulence factors: 13% were eae-, 60% ehxA- and 67% saa-positive [6].

Analytical, diagnostic and therapeutic context of saa

• Based on these findings, we designed PCR primers to amplify the region coding for these differences to detect saa gene variants present in VTEC strains isolated in Argentina from cattle and meat [7].

References