Sandia Labs FY22 Laboratory Directed Research & Development Annual Report

FY22 ANNUAL REPORT

RECONFIGURING THE RESPIRATORY TRACT MICROBIOME TO PREVENT AND TREAT INFECTIOUS DISEASE.

Burkholderia pseudomallei, a bacterial respiratory pathogen that is intrinsically resistant to many antibiotics, is the causative agent of the infectious disease melioidosis, which has an estimated case fatality rate of approximately 35%. This LDRD sought to reconfigure the airway microbiome to enhance defense against respiratory pathogens like B. pseudomallei. Bacteria were recovered from the mouse airway, propagated in culture, and then re-introduced into the airway. Eight isolates, candidate probiotics (CP), consistently re-colonized the airway. Genome sequencing revealed that the six best colonizers are Bacillus strains. Both colonizing and non-colonizing

Bacillus CPs were assessed for ability to mitigate respiratory infection caused by B. thailandensis, a surrogate for B. pseudomallei. The top-performing CP (a colonizer) robustly protected mice against otherwise lethal infection when administered as early as seven days prior to pathogen challenge. This successful proof of concept for airway probiotics uniquely positions Sandia and collaborators at Lawrence Livermore National Laboratory, and Alliance partners Georgia Tech and University of California Berkeley, to pursue translation to clinical and veterinary use, as well as development of engineered versions that produce therapeutic compounds or sensor molecules in situ. This three-year project has resulted

in a Technical Advance on “Airway Probiotics to Counter Respiratory Infection” and a publication in ACS Infectious Diseases . (PI: Steve Branda)

CPs (10 6 CFU) were administered to the mouse airway via oropharyngeal aspiration (OPA). 3-7 days later, B. thailandensis (5x10 5 CFU) was administered via OPA. Mice were monitored for 10 days post-challenge. Results from 5-25 mice (1-5 studies x 5 mice/cohort) are shown. Green font: Colonizing CP. Red font: Non-colonizing CP. Blue asterisk: CP survival curve significantly differs from no-CP survival curve (pval < 0.001 in Cox-Mantel log-rank test with Bonferroni correction for multiple comparisons).

Treatment with candidate probiotics significantly increases the survival rate for mice challenged with an otherwise lethal dose of respiratory pathogen Burkholderia thailandensis.

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