High-affinity, human antibody-like antibody fragment (single-chain variable fragment) neutralizing the lethal factor (LF) of Bacillus anthracis by inhibiting protective antigen-LF complex formation.

The anthrax lethal toxin (LT) consists of two subunits, the protective antigen (PA) and the lethal factor (LF), and is essential for anthrax pathogenesis. Several recombinant antibodies directed against PA and intended for medical use have been obtained, but none against LF, despite the recommendations of anthrax experts. Here we describe an anti-LF single-chain variable fragment (scFv) that originated from an immunized macaque (Macaca fascicularis) and was obtained by phage display.

Attempted passive prophylaxis with a monoclonal anti-Burkholderia pseudomallei exopolysaccharide antibody in a murine model of melioidosis.

Melioidosis is a severe gram-negative infection caused by the facultative intracellular bacterium Burkholderia pseudomallei, which is responsible for a broad spectrum of symptoms in both humans and animals. No licensed vaccine currently exists. This study evaluated the protective effect of a monoclonal antibody (Mab Ps6F6) specific to B.

Selection of a macaque Fab with framework regions like those in humans, high affinity, and ability to neutralize the protective antigen (PA) of Bacillus anthracis by binding to the segment of PA between residues 686 and 694.

Human anthrax infection cannot always be treated successfully by antibiotics, as highlighted by recent bioterrorist attacks; thus, adjunct therapies are clearly needed for the future. There is a particular need to further develop adjunct therapies that can neutralize secreted toxins, such as antibodies directed towards the 83-kDa protective antigen (PA(83)). In the absence of human donors, we immunized a macaque (Macaca fascicularis) with PA(83) to obtain such antibodies suitable as an adjunct therapy for human anthrax infection.