Protection against the anthrax toxin can be achieved with high affinity recombinant anti-PA antibody fragments.
The Bacillus anthracis bacterium excretes a tripartite exotoxin containing a protective antigen (PA) polypeptide that binds to the surface of macrophages and causes the symptoms of anthrax. In June Nature Biotechnology Jennifer Maynard and colleagues from University of Texas at Austin, US, show that high affinity recombinant anti-PA antibody fragments may offer efficient protection against anthrax (Nat Biotechnol 2002, 20:597-601).
Maynard et al. engineered a panel of toxin-neutralizing antibodies, including single-chain variable fragments (scFvs) and scFvs fused to a human constant κ domain (scAbs), that bind to the PA subunit of the toxin with a variety of equilibrium dissociation constants. They observed that protection against anthrax toxin challenge in an in vitro cell culture assay and in a rat model correlated strongly with affinity, with the highest-affinity antibody conferring the best protection.
These results suggest that high-affinity, recombinant anti-PA antibodies "are likely to prove valuable for...
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