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

ALZOGARAY, VANINA; DANQUAH, WELBECK; AGUIRRE, ANDRÉS; URRUTIA, MARIELA; BERGUER, BERGER; GARCÍA VÉSCOVI, ELEONORA; HAAG, FRIEDRICH ; KOCH-NOLTE, FRIEDRICH; GOLDBAUM, FERNANDO A.

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 pathogenic bacterial 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 ADP ribosylating toxins, such as Salmonella SpvB toxin, are secreted directly from the Salmonella containing vacuole into the cytosol of target cells via the SPI2 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 ADP ribosyltransferases. 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 to 1. The single domain antibody, when expressed as an intrabody, effectively protected cells from the cytotoxic activity of a translocation competent chimeric C2IN.CSpvB 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 developing new antidotes against intracellular toxins.