INMUNIZACIÓN DE VACAS PREÑADAS CON STX2 INDUCEN ALTOS TÍTULOS DE ANTICUERPOS EN EL CALOSTRO QUE NEUTRALIZAN LA INFECCIÓN DE RATONES AL DESTETE CON E. COLI O157:H7 PRODUCTOR DE TOXINA SHIGA

ALBANESE, A; FERNÁNDEZ BRANDO, ROMINA J; RABINOVITS, B; PALERMO, MARINA S; CATALDI, A; IBARRA, C

Mar del Plata

Congreso; LX Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica-Reunión Anual de la Sociedad de Fisiología; 2015

SAIC-SAFIS

Introduction.EnterohemorrhagicEscherichia coli (EHEC)O157:H7 are responsible for intestinal disease and hemolytic uremic syndrome (HUS), a serious systemic complication frequentlyassociated with Shiga toxin type 2 (Stx2). The aim of this study wasto evaluate the ability to bovine hyperimmune colostrum antibody against Stx2 to prevent thepathogenicity of EHEC O157:H7.MethodsThree pregnant cows were intramuscular immunized at 40and 20 days before delivery with 100 mg of inactivated Stx2 and colostrum were obtainedwithin the first 24 h after parturition. The IgG hyperimmune anti-Stx2 waspurified by affinity chromatography and neutralizing capacity was determinedfor viability assay in Vero and HTC-8 cells in the presence of Stx2.  Colonloops of male SD rats were incubated overnight with either Stx2 or Stx2pre-incubated 30 min at 37ºCwith IgG hyperimmune. In other experiments, colon loops were inoculated with O157:H7 EHEC grown toexponential phase and then treated or non-treated with IgG hyperimmune. Colon loops were rapidly removed, measured for lengthand fluid content, and prepared for histochemistry.  BalB-c weaned mice were inoculated intragastrically with lethal dose ofO157:H7 EHEC (2,4 1010 CFU/Kg).Some mice received one or two doses of IgG (7.5 mg/dose) 1 h before and 2 h afterEHEC challenge. O157:H7 EHEC strain 125/99 stx2+ used belongs to the hypervirulentclade 8 isolated from a pediatric HUS patient.Resultsand DiscussionHigh titers (1/5000)of purified IgG antibody against Stx2 was observed in vaccinated cows using Vero and HCT-8 assays.The rat colon loops treated with Stx2 or O157:H7 EHEC previouslyincubated with IgG hyperimmune prevent secretion of bloody fluid and histologicalalterations. Preliminary results treating BalB-c weaned mice withIgG hyperimmune by oral route showed a dose-dependent partial protectionagainst a lethal bacterial challenge ImplicationsThese results suggest that the presence ofanti-Stx2 antibodies in hyperimmune bovine colostrum could be used asnutraceuticals in children at risk for HUS