The Deleterious Effects of Shiga Toxin Type 2 Are Neutralized In Vitro by FabF8:Stx2 Recombinant Monoclonal Antibody

DANIELA LUZ; FERNANDO D. GÓMEZ; RAÍSSA L. FERREIRA; BRUNA S. MELO; BEATRIZ E. C. GUTH; WAGNER QUINTILIO; ANA MARIA MORO; AGOSTINA PRESTA; FLAVIA SACERDOTI; CRISTINA IBARRA; GANG CHEN; SACHDEV S. SIDHU; MARÍA MARTA AMARAL ; ROXANE M. F. PIAZZA

Celebrating 120 Years of Butantan Institute Contributions for Toxinology

MDPI

Lugar: Basel; Año: 2022; p. 189 - 202

Hemolytic Uremic Syndrome (HUS) associated with Shiga-toxigenic Escherichia coli (STEC)infections is the principal cause of acute renal injury in pediatric age groups. Shiga toxin type 2(Stx2) has in vitro cytotoxic effects on kidney cells, including human glomerular endothelial (HGEC)and Vero cells. Neither a licensed vaccine nor effective therapy for HUS is available for humans.Recombinant antibodies against Stx2, produced in bacteria, appeared as the utmost tool to preventHUS. Therefore, in this work, a recombinant FabF8:Stx2 was selected from a human Fab antibodylibrary by phage display, characterized, and analyzed for its ability to neutralize the Stx activity fromdifferent STEC-Stx2 and Stx1/Stx2 producing strains in a gold standard Vero cell assay, and the Stx2cytotoxic effects on primary cultures of HGEC. This recombinant Fab showed a dissociation constantof 13.8 nM and a half maximum effective concentration (EC50) of 160 ng/mL to Stx2. Additionally,FabF8:Stx2 neutralized, in different percentages, the cytotoxic effects of Stx2 and Stx1/2 from differentSTEC strains on Vero cells. Moreover, it significantly prevented the deleterious effects of Stx2 in adose-dependent manner (up to 83%) in HGEC and protected this cell up to 90% from apoptosis andnecrosis. Therefore, this novel and simple anti-Stx2 biomolecule will allow further investigation as anew therapeutic option that could improve STEC and HUS patient outcomes.