Novel monoclonal antibody protects against respiratory infection with pathogenic Burkholderia select agents

Presenters/Authors(s)

Annabelle Smith, Megan Grund, Soo Jeon Choi, Slawomir Lukomski

Abstract or Description

Burkholderia spp. are gram-negative mostly soil dwelling bacteria endemic to sub- and tropical regions. Pathogenic B. pseudomallei – etiological agent of melioidosis - and B. mallei - responsible for glanders - cause infections, with a mortality reaching 50%. Both species require BSL-3 level laboratory and are on the CDC list as category B bioterrorism select agents, because they are easy to aerosolize, have multiple mechanisms for antibiotic resistance and no effective vaccine. The objective of this study was to develop monoclonal antibodies (mAbs) against pathogenic Burkholderia. To generate mAbs, mice were immunized with heat-killed B. thailandensis, a BSL-2 level surrogate species of select agents, B. pseudomallei and B. mallei. Three distinct mAbs designated P58G, P42H, and P32H, were isolated that recognize all three species of Burkholderia in whole-cell ELISA and showed distinct immunoreactive patterns by western immunoblotting. Each mAb was of the same IgG2b isotype, whereas sequence analysis of their variable regions revealed different arrangements of unique heavy and light kappa (P58G, P42H) or lambda (P32H) chains. P58G was next tested in a murine model of respiratory melioidosis, using CD-1 outbred mice intranasally challenged with B. thailandensis expressing lux genes. Tracking of bacterial infection - done by IVIS luminescent imaging - in mice passively immunized with P58G or treated with saline showed promising statistically significant protective capability of this mAb. Here, we have generated three monoclonal antibodies that recognize pathogenic species of Burkholderia select agents. This research will allow for the future development of novel antibody therapies including antibody drug conjugates.