Structural basis for burkholderia cepacia complex pili mediated adherence in cystic fibrosis

The National Institute of Allergy and Infectious Diseases awarded the University of Alabama at Birmingham $131,307 on October 21, 2026, under the Allergy and Infectious Diseases Research program (CFDA 93.855) to characterize the structural and functional roles of pili produced by Burkholderia cepacia complex bacteria in cystic fibrosis infection.

The research will elucidate the dynamics of BCC pili production and their contribution to bacterial adherence, colonization, and biofilm formation in CF airway epithelium. Aim 1 explores the effect of different growth conditions on pili production and characterizes their role in adherence to epithelial cells using cryogenic-electron microscopy, adherence assays, and mutagenesis methods. Aim 2 investigates the interaction of BCC cells with CF epithelial cells in situ. The project addresses a therapeutic gap: BCC species cause severe infections in people with cystic fibrosis but are inherently antibiotic-resistant, making pili an alternative target for intervention. The work also examines how highly effective CFTR modulator therapies influence BCC infection dynamics at the host-cell interface, a relationship not yet characterized.

Performance of the research will occur in Birmingham, Alabama. The period of performance runs from October 21, 2026, through April 22, 2028. The award is classified as a Project Grant.

Abstract

Cystic fibrosis (CF) is caused by a dysfunctional cystic fibrosis transmembrane conductance regulator (cftr) protein, leading to impaired mucociliary clearance and the accumulation of thick mucus in the airway, often resulting in chronic bacterial infections. Bacteria within the burkholderia cepacia complex (BCC) are associated with severe infections in people with CF (pwcf). BCC species are inherently antibiotic-resistant, making effective treatments for BCC infections scarce. One potential therapeutic target for BCC treatment is the pili that mediate virulence factors like adherence and biofilm formation. One type of chaperone usher pathway (cup) pilus, known as cable pilus, is often implicated in facilitating host adherence and drive biofilm formation in the BCC. However, IT remains unknown whether the cable pilus is the sole pilus type produced during different stages of BCC infections, and no structures of BCC pili have been characterized. Currently, highly effective cftr modulator therapies (hemt) are commonly used in pwcf. However, the influence and interaction of BCC infection with host cells under hemt remain unclear. This F31 proposal aims to elucidate the dynamics of BCC pili production and characterize the functions of these pili in CF infection. We hypothesize that multiple types of BCC pili are present and contribute differently at various stages of infection, including adherence, colonization, and biofilm formation. Aim 1 of this proposal explores the effect of different growth conditions on BCC pili production and the roles of pili in adherence to epithelial cells. We will utilize cryogenic-electron microscopy (cryo-EM) and adherence assays, and mutagenesis methods to characterize the pili produced by BCC and their role in adherence. Aim 2 investigates the interaction of BCC cells with CF epithelial cells in situ. We will use cryo-electron tomography (cryo-ET) to visualize interfaces of CF cells with BCC in the presence and absence of ETI hemt.