Single domain llama antibodies as specific intracellular inhibitors of SpvB, the actin ADP-ribosylating toxin of Salmonella typhimurium

VANINA ALZOGARAY, WELBECK DANQUAH, ANDRE´S AGUIRRE, MARIELA URRUTIA, PAULA BERGUER, ELEONORA GARCÍA VE´SCOVI, FRIEDRICH HAAG, FRIEDRICH KOCH-NOLTE, AND FERNANDO A. GOLDBAUM

FASEB JOURNAL

FEDERATION AMER SOC EXP BIOL

Lugar: Bethesda; Año: 2011 vol. 25 p. 526 - 534

0892-6638

ADP-ribosylation of host cell proteins is a common mode of cell intoxication by pathogenicbacterial toxins. Antibodies induced by immunization with inactivated ADP-ribosylating toxins provide efficient protection in case of some secreted toxins, e.g., diphtheria and pertussis toxins. However, other ADPribosylating toxins, such as Salmonella SpvB toxin, are secreted directly from the Salmonella-containing vacuole into the cytosol of target cells via the SPI-2 encoded bacterial type III secretion system, and thus are inaccessible to conventional antibodies. Small-molecule ADP-ribosylation inhibitors are fraught with potential side effects caused by inhibition of endogenous ADPribosyltransferases. Here, we report the development of a single-domain antibody from an immunized llama that blocks the capacity of SpvB to ADP-ribosylate actin at a molar ratio of 1:1. The single-domain antibody, when expressed as an intrabody, effectively protected cells from the cytotoxic activity of a translocation competent chimeric C2IN-C/SpvB toxin. Transfected cells were also protected against cytoskeletal alterations induced by wild-type SpvB-expressing strains of Salmonella. This proof of principle paves the way for developingnew antidotes against intracellular toxins.