Sequence Variability in Staphylococcal Enterotoxin Genes seb, sec, and sed.
Ingestion of staphylococcal enterotoxins preformed by Staphylococcus aureus in food leads to staphylococcal food poisoning, the most prevalent foodborne intoxication worldwide. There are five major staphylococcal enterotoxins: SEA, SEB, SEC, SED, and SEE. While variants of these toxins have been described and were linked to specific hosts or levels or enterotoxin production, data on sequence variation is still limited. In this study, we aim to extend the knowledge on promoter and gene variants of the major enterotoxins SEB, SEC, and SED. To this end, we determined seb, sec, and sed promoter and gene sequences of a well-characterized set of enterotoxigenic Staphylococcus aureus strains originating from foodborne outbreaks, human infections, human nasal colonization, rabbits, and cattle. New nucleotide sequence variants were detected for all three enterotoxins and a novel amino acid sequence variant of SED was detected in a strain associated with human nasal colonization. While the seb promoter and gene sequences exhibited a high degree of variability, the sec and sed promoter and gene were more conserved. Interestingly, a truncated variant of sed was detected in all tested sed harboring rabbit strains. The generated data represents a further step towards improved understanding of strain-specific differences in enterotoxin expression and host-specific variation in enterotoxin sequences.
Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland. sophia.johler@uzh.ch.
Sophia
S
Johler
Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland. henna-maria.sihto@uzh.ch.
Henna-Maria
HM
Sihto
National Reference Laboratory for Coagulase-Positive Staphylococci including <i>Staphylococcus aureus</i>, Istituto Zooprofilattico Sperimentale del Piemonte, Liguria e Valle d'Aosta, Via Bologna 148, 10154 Torino, Italy. guerrino.macori@izsto.it.
Guerrino
G
Macori
Institute for Food Safety and Hygiene, Vetsuisse Faculty University of Zurich, Winterthurerstrasse 272, 8057 Zurich, Switzerland. stephanr@fsafety.uzh.ch.
Roger
R
Stephan
D000595:Amino Acid Sequence; D000818:Animals; D001427:Bacterial Toxins / Q000235:genetics*; D001483:Base Sequence; D002417:Cattle; D004269:DNA, Bacterial / Q000235:genetics; D004768:Enterotoxins / Q000235:genetics*; D005798:Genes, Bacterial / Q000235:genetics; D006801:Humans; D009297:Nasal Mucosa / Q000382:microbiology; D011401:Promoter Regions, Genetic; D011817:Rabbits; D013211:Staphylococcus aureus / Q000235:genetics*
D001427:Bacterial Toxins; D004269:DNA, Bacterial; D004768:Enterotoxins
Staphylococcus aureus; enterotoxin; promoter; seb; sec; sed; sequence variation