Protection from Pneumonic Infection withBurkholderiaSpecies by Inhalational Immunotherapy

Abstract

Burkholderia mallei and B. pseudomallei are important human pathogens and cause the diseases glanders and melioidosis, respectively. Both organisms are highly infectious when inhaled and are inherently resistant to many antimicrobials, thus making it difficult to treat pneumonic Burkholderia infections. We investigated whether it was possible to achieve rapid protection against inhaled Burkholderia infection by using inhaled immunotherapy. For this purpose, cationic liposome DNA complexes (CLDC), which are potent activators of innate immunity, were used to elicit the activation of pulmonary innate immune responses. We found that mucosal CLDC administration before or shortly after bacterial challenge could generate complete or nearly complete protection from inhalational challenge with 100% lethal doses of B. mallei and B. pseudomallei. Protection was found to be dependent on the CLDC-mediated induction of gamma interferon responses in lung tissues and was partially dependent on the activation of NK cells. However, CLDC-mediated protection was not dependent on the induction of inducible nitric oxide synthase, as assessed by depletion studies. We concluded that the potent local activation of innate immune responses in the lung could be used to elicit rapid and nonspecific protection from aerosol exposure to both B. mallei and B. pseudomallei.

A Burkholderia pseudomallei Δ purM Mutant Is Avirulent in Immunocompetent and Immunodeficient Animals: Candidate Strain for Exclusion from Select-Agent Lists

“…approximately 900 CFU (17). We therefore first determined whether the purM deletion reduced the virulence of the resulting strain in BALB/c mice following i.n.…”

MyD88-Dependent Recruitment of Monocytes and Dendritic Cells Required for Protection from Pulmonary Burkholderia mallei Infection

“…The 50% lethal dose (LD 50 ) following i.n. infection of C57BL/6 mice with B. mallei was previously determined to be 8.4 ϫ 10 2 CFU according to the Reed-Muench method (11,21). Mice were infected either with ϳ500 CFU i.n.…”

“…Burkholderia mallei strain ATCC 23344 was used in these studies and was kindly provided by Herbert Schweitzer, Colorado State University. The B. mallei organism used in these studies was initially serially passaged three times in BALB/c mice, and stocks were then prepared and frozen at Ϫ80°C, as described previously (11). Prior to each challenge study, fresh broth cultures of B. mallei were grown in brucella broth with 4% glycerol (BB4G) (Remel, Lenexa, KS) until bacteria reached the log phase of growth.…”

The Burkholderia pseudomallei Δ asd Mutant Exhibits Attenuated Intracellular Infectivity and Imparts Protection against Acute Inhalation Melioidosis in Mice

“…During the assay, medium was removed from the wells at three time points (2,6, and 24 h postinfection), and the infected cell monolayers were washed twice with 1ϫ PBS and then lysed with 0.1% Triton X-100. Serial dilutions of the lysates were plated on Brucella agar (Difco) plus 4% (vol/vol) glycerol (BAG) medium at 37°C, as described previously (6,14). BAG medium was supplemented with 200 g/ml of DAP when enumerating B. pseudomallei ⌬asd/rfp colonies.…”

“…We first tested the ⌬asd mutant for attenuation in vivo. The 50% lethal dose (LD 50 ) of B. pseudomallei 1026b in BALB/c mice has been determined to be approximately 900 CFU via the inhalation route (14). An i.n.…”