# Targeting of interaction between BB0323-BB0238 informs new paradigms in Lyme disease therapeutics

## TL;DR

Researchers discovered a key protein interaction in the Lyme disease bacterium and identified drugs that can disrupt it, offering a new treatment approach.

## Contribution

The study identifies a novel protein-protein interaction in Borrelia burgdorferi and demonstrates its disruption as a therapeutic strategy.

## Key findings

- The BB0238-BB0323 protein interaction is essential for B. burgdorferi survival in mammals.
- Three small molecule inhibitors were identified, including lomibuvir, which reduces pathogen persistence in a murine model.
- Targeted disruption of this protein interaction is proposed as a new therapeutic strategy for Lyme disease.

## Abstract

Borrelia burgdorferi, one of the most prevalent tick-borne pathogens, can cause a complex and multisystem illness called Lyme disease, where there has been an unmet need for novel therapeutic or preventive strategies. We previously identified an essential protein-protein interaction (PPI) event in B. burgdorferi involving two unique proteins, BB0323 and BB0238; herein, we show that this PPI is indispensable for long-term borrelial survival in mammals and explore its potential as a novel target for small molecule therapeutics. Using X-ray crystallography, we solved the structure of the BB0238-BB0323 complex and identified the hotspot residues that form the biomolecular PPI interface area of ~1000 square Ångstroms. We then performed quantitative high-throughput drug screens of 62,740 diverse small molecules utilizing an amplified luminescent proximity homogeneous assay linked immunosorbent assay (AlphaLISA). Following a comprehensive pipeline to confirm small molecule hits, we short-listed three distinct PPI inhibitors of BB0238-BB0323. One of these inhibitors, called lomibuvir (VX-222, VCH-222), displayed robust PPI inhibition inside B. burgdorferi cells and was shown to affect pathogen persistence in a tick-borne murine model of Lyme disease. Our study highlights targeted PPI disruption as a new therapeutic strategy against B. burgdorferi and may foster future antimicrobial discovery efforts to resolve clinical complications associated with Lyme disease.

Borrelia burgdorferi, a common tick-borne bacterial pathogen, causes a complex illness called Lyme disease, where a human vaccine is unavailable. Although early antibiotic treatment is effective, many patients develop relapsing symptoms unresponsive to further treatment. Therefore, a better understanding of the infection biology of Lyme disease, and the development of novel therapeutic strategies, is warranted. We leveraged a unique protein-protein interaction (PPI) in B. burgdorferi that is indispensable for borrelial survival in mammals as a novel small molecule therapeutic strategy. Using structural biology and high-throughput drug screening, we identified compounds that can inhibit the PPI and reduce infection. Our finding highlights targeted PPI disruption as a potential therapeutic strategy against B. burgdorferi infection.