Microbiology of Post-Treatment Lyme Disease Syndrome

- Project 3, Microbiology of Post-Treatment Lyme Disease Syndrome The inability of antibiotic treatment to fully eliminate bacteria or bacterial products may foster pathological immune responses that lead to PTLDS. In addition, the ability of Borrelia burgdorferi (Bb) to disseminate has been associated with both the development and severity of PTLDS. Several manifestations of LD are associated with microbial genotype, but because Bb can only be reliably cultured at the time of acute illness whereas PTLDS is a late complication, PTLDS-associated strains have not been collected and the role of microbial diversity in PTLDS is unknown. We will utilize strains collected by our Clinical Coordination Core to genotypically compare PTLDS- and RLD-associated strains and determine whether some strains are associated with PTLDS. We will then characterize PTLDS and RLD-associated strains for antibiotic tolerance, persistence, and the capacity to disseminate, factors that may shape PTLDS development. In Aim 1, we will identify associations between PTLDS and spirochete genotype, focusing on genotype associations and pathways of known importance for immunity and antigenic persistence. By sequencing the genomes of collected strains, we will determine whether genotypes are associated with PTLDS, with particular focus on genetic variation in two classes of proteins. First, lipoproteins display remarkable allelic variability and many of the ~80 surface lipoproteins interface with the host, highlighting the need to study their variation. Second, the Bb peptidoglycan (“PGBb”), which forms the cell wall and is the target of beta-lactam antibiotics, is: (a) unique in structure; (b) highly proinflammatory; (c) shed during growth; and (d) retained in the synovium of Lyme arthritis patients. We will determine if PTLDS and RLD isolates can be distinguished based on the 14 Bb genes involved in PG metabolism and the 80 Bb genes encoding surface lipoproteins. In Aim 2, we will determine the impact of antibiotic tolerance, persister formation, and retention of PGBb in the host on PTLDS risk. Bb antibiotic-tolerant “persister” cells have been hypothesized to contribute to PTLDS and we will compare strains from PTLDS and RLD patients for their rate of persister formation and in their susceptibility to antibiotics. Residual PGBb, like viable bacteria, may trigger damaging immune responses. We will determine whether the PTLDS and RLD strains differ in the structure, content, or secretion of PGBb and test if serum or urine PGBb levels differ between PTLDS and RLD patients. In Aim 3, we will characterize mechanistic correlates of PTLDS-causing strains in immune stimulation, immune evasion, and the mouse model of LD. PTLDS severity and risk are associated with disseminated infection, which requires the spirochete to counteract bloodstream complement and invade tissues. We will compare PTLDS and RLD strains for the ability to resist complement killing or to bind mammalian cells. After tick infection of mice, we will assess PTLDS and RLD strains for the ability to (a) elicit proinflammatory cytokine responses; or (b) cause disseminated infection. Project Number: 5P01AI181934-02 | Fiscal Year: 2025 | NIH Institute/Center: National Institute of Allergy and Infectious Diseases (NIAID) | Principal Investigator: Linden Hu | Institution: TUFTS UNIVERSITY BOSTON, BOSTON, MA | Award Amount: $495,862 | Activity Code: P01 | Study Section: ZAI1-MS-M(J1) View on NIH RePORTER: https://reporter.nih.gov/project-details/5P01AI18193402