Identification of new drug candidates against Borrelia burgdorferi using high-throughput screening

Abstract

Lyme disease is the most common zoonotic bacterial disease in North America. It is estimated that >300,000 cases per annum are reported in USA alone. A total of 10%–20% of patients who have been treated with antibiotic therapy report the recrudescence of symptoms, such as muscle and joint pain, psychosocial and cognitive difficulties, and generalized fatigue. This condition is referred to as posttreatment Lyme disease syndrome. While there is no evidence for the presence of viable infectious organisms in individuals with posttreatment Lyme disease syndrome, some researchers found surviving Borrelia burgdorferi population in rodents and primates even after antibiotic treatment. Although such observations need more ratification, there is unmet need for developing the therapeutic agents that focus on removing the persisting bacterial form of B. burgdorferi in rodent and nonhuman primates. For this purpose, high-throughput screening was done using BacTiter-Glo assay for four compound libraries to identify candidates that stop the growth of B. burgdorferi in vitro. The four chemical libraries containing 4,366 compounds (80% Food and Drug Administration [FDA] approved) that were screened are Library of Pharmacologically Active Compounds (LOPAC1280), the National Institutes of Health Clinical Collection, the Microsource Spectrum, and the Biomol FDA. We subsequently identified 150 unique compounds, which inhibited >90% of B. burgdorferi growth at a concentration of <25 µM. These 150 unique compounds comprise many safe antibiotics, chemical compounds, and also small molecules from plant sources. Of the 150 unique compounds, 101 compounds are FDA approved. We selected the top 20 FDA-approved molecules based on safety and potency and studied their minimum inhibitory concentration and minimum bactericidal concentration. The promising safe FDA-approved candidates that show low minimum inhibitory concentration and minimum bactericidal concentration values can be chosen as lead molecules for further advanced studies.

Keywords:

• Lyme disease
• Borrelia burgdorferi
• BacTiter-Glo assay
• high-throughput screening
• persisters

Supplementary material

Table S1 List of identified compounds showing >95% inhibition

Acknowledgments

This work was accomplished with a generous grant from the Bay Area Lyme Foundation. The authors are indebted to Dr Robert Lane (UC Berkley, Berkley, CA, USA) for his constant support, discussion, and provision of valuable bacterial strains for the study.

Disclosure

Venkata Raveendra Pothineni and Jayakumar Rajadas are listed on the following disclosure # S16-018 “New drug combination candidates against B. burgdorferi, B. duttonii, B. garinii, B. afzelii and B. miyamotoi for the treatment of Acute and as Post-Treatment Lyme Disease Syndrome (PTLDS)” under patent application no 62/279,826 assigned to Stanford University. All other authors report no conflicts of interest in this work.