Structural and biological characterization of Staphylococcus aureus enterotoxin O

NOLI TRUANT S; FERNÁNDEZ LYNCH MJ; ANTONOGLOU MB; SARRATEA MB; DE MARZI MC ; MALCHIODI EL; , FERNÁNDEZ MM

Buenos Aires

Congreso; II Congreso Argentino ?Francés de Inmunología, LXIII Reunión Anual de la SAI, IV Congreso LASID; 2015

Sociedad Argentina de Inmunología

Staphylococcal Superantigens (SAgs) are   enterotoxins which bind in a non-classical wayto TCR-MHC-II complexes inducing a peptide-non-specific proliferation ofT-lymphocytes and a massive cytokine release. Staphylococcus aureus produces awide range of enterotoxins, which produce toxic shock syndrome (TSS). Thissyndrome could be lethal in hours. Glucocorticoids are the traditionaltreatment for TSS but recently cases of Sag inducing resistance weredescribed.  .We have previously reported that autochthonous strainsof S.aureus have high prevalence of the egc operon, which includes the Sags:seg, sei, sem, sen and seo. Initially, we studied this operon's SAgs SEG andSEI which display complementary biological activity; we have continued withthis study, and recently characterized in a molecular and biological way theSAg SEO.MethodsSEO was cloned, produced and purified as a His-Tagged protein.To test its superantigen activity and virulence, we exposed SEO to differentcell cultures, and evaluated its proliferation by using [methyl-3H] thymidinewith and without glucocorticoids supplementation.In addition, we modeled SEO 3D appearance based on itssequence similarity with SEA, using bioinformatics tools as Phyton andModeller.ResultsSEO shows: 1- typical SAgs compact globular structure;2-cytotoxic effect upon macrophages' precursors, 3- induce resistant toglucocorticoid treatment.ConclusionsSEO appear to be a new virulence factor, exhibitingsuperantigen effect at the innate response level and showing resistance to theconventional treatment of corticoids for Sags related diseases, as it has beenobserved for other Sags of the egc operon.