Biology subjects

Seshu, J.

Publications and source records attributed to Seshu, J..

4 recordsLinked to original sources

bioRxiv2026

A lipid-binding protein in black-legged tick saliva selectively recognizes Borrelia burgdorferi lipids

A proteomic analysis of Ixodes scapularis nymph saliva identified 252 proteins, including six tubular lipid-binding proteins (TULIPs). Comparing nymphs fed on mice that were uninfected or infected with Borrelia burgdorferi, twelve salivary proteins showed significant differences in the amounts detected, including XP_040079658.2, which we refer to as TULIP2. Considering the known immunity-related functions of some TULIPs, we expressed and purified TULIP2 from Escherichia coli and analyzed its interaction with B. burgdorferi lipids. The purification of TULIP2 from E. coli presented many obstacles, due to insolubility, which is consistent with previous reports from studies of other TULIP family members. The binding results showed specificity for B. burgdorferi lipids, with evidence for cholesteryl {beta}-galactoside as a major binding target. Molecular modeling of TULIP2 did not show any strong lipid binding sites. We used molecular dynamics simulation of TULIP2 to explore its conformational landscape by thermal unfolding. The earliest unfolding intermediate opened a hydrophobic pocket to which cholesteryl {beta}-galactoside was predicted to bind strongly. We propose that a specific lipid bilayer interaction with TULIP2 triggers the opening of the ligand-binding site.

biochemistry↗

bioRxiv2026

Efficacy of Purified Borrelial Lipoproteins (PBL) as an oral formulation in reducing transmission of Lyme spirochetes from reservoir hosts to Ixodes scapularis ticks

Blocking transmission of Borrelia burgdorferi (Bb), the causative agent of Lyme disease (LD), from reservoir hosts to humans via Ixodes scapularis ticks represents an alternative strategy to reduce LD incidence. Here, we evaluated Purified Borrelial Lipoproteins (PBL) with a combination of adjuvants, for their ability to limit Bb transmission using C3H/HeN mice and Peromyscus leucopus reservoir models. Immunization with PBL as oral gavage, either alone or nanoparticle-encapsulated, elicited increased antibody responses and reduced pathogen burden in fed larvae and select host tissues. A formulation combining PBL with a recombinant fusion protein adjuvant consisting of Cholera Toxin B subunit, Outer surface protein A, and two-tandem repeats of an M-cell-targeting peptide (rCOM) induced durable protective immunity for up to 10 months in C3H/HeN mice. This oral regimen significantly reduced Bb burden in host tissues, in fed larvae from vaccinated hosts, molted nymphs, and nymph-challenged naive mice. Immunization with PBL+rCOM elevated peripheral levels of Bb-specific IgG isotypes and increased antigen-specific T cell responses producing IFN-{gamma} and IL-4 at days 28 and 65 post-immunization. Significant protective responses were observed in P. leucopus, including strong antibody responses, reduced Bb burden in tissues and reduced Bb transmission to naive larvae, independent of sex but influenced by challenge dose. Sodium chloride content in oral formulation modulated vaccine induced protective responses. Notably, Bb burden in infected nymphs was reduced during the bloodmeal on vaccinated hosts with decreased pathogen transmission to both vertebrate hosts. These findings support PBL+rCOM as a promising oral, reservoir-targeted, transmission-blocking biologic for controlling Lyme disease. Lay AbstractNumerous vertebrate hosts serve as reservoirs of pathogens that are transmitted to humans via the bite of blood feeding vectors such as ticks. Lyme disease, caused by Borrelia burgdorferi (Bb), is the most common tick-borne disease in the US. Bb is transmitted to humans following the bite of infected Ixodes scapularis ticks. In nature, ticks acquire Bb and other pathogens from a variety of reservoir hosts, notably Peromyscus leucopus. Therefore, strategies that limit pathogen burden in reservoir hosts or block their transmission via ticks are options to prevent human infectious diseases, circumventing need for human vaccines and therapeutics. An oral, reservoir host-targeted, pathogen-derived, biologic prepared by extracting immunogenic lipoproteins (Purified Borrelial Lipoproteins) from Bb and combining them with a mucosal adjuvant derived by fusing Cholera-Toxin B subunit, Outer surface protein A of Bb and 2 repeats of an M-cell targeting peptide was tested in C3H/HeN mice and Peromyscus leucopus hosts. Single or two dose regimens via the oral route resulted in significant increases in peripheral Bb specific antibody responses, select T cell responses, blocking the transmission of Bb to naive Is larvae, reducing pathogen burden in vaccinated hosts, and interfering with the infectious cycle of the agent of Lyme disease.

immunology↗

bioRxiv2025

Protective efficacy of mutant strains of Borrelia burgdorferi as potential reservoir host-targeted biologics against Lyme disease

Lyme disease (LD), caused by Borrelia burgdorferi (Bb), is the most common vector-borne disease in the United States. Novel strategies to control transmission of Bb to humans via ticks are critical for prevention of LD. One such strategy is to leverage non-infectious mutant strains of Bb for pathogen-derived biologics to block Bb transmission during the natural infectious cycle. Deletion of Borrelia host-adaptation Regulator ({Delta}badR) and replacement of 8 conserved residues with alanines in Carbon Storage Regulator A of Bb (8S) resulted in mutants, with upregulation of RpoS and several immunogenic lipoproteins, that were incapable of colonization in C3H/HeN mice. Intradermal vaccination of mice with the live mutant strains resulted in significant anti-borrelial antibody responses and a reduction in Bb acquisition by naive Ixodes scapularis larvae following needle challenge with Bb B31-A3. While vaccination with {Delta}badR mutant conferred significant reduction in the percentage of infected mice, ML23 and 8S mutants conferred variable levels of protection. Comparative proteomic analysis of Purified Borrelial Lipoproteins (PBLs) from parental and mutant strains revealed similar and unique antigenic components. Infection derived mouse serum and serum from Lyme disease patients exhibited reactivity to lysates and PBLs from these mutants. Immunization with PBLs from B31-A3 and 8S strains conferred significant protection against challenge with Bb infected nymphs, underscoring the utility of PBLs as protective formulations. Overall, non-infectious mutant strains, or their lipoproteins, can be exploited as biologics to block the acquisition of Bb by naive larvae from reservoir hosts, disrupting the enzootic transmission cycle of the agent of Lyme disease.

microbiology↗

bioRxiv2024

Role of Dual Specificity Phosphatase 1 (DUSP1) in influencing inflammatory pathways in macrophages modulated by Borrelia burgdorferi lipoproteins

Borrelia burgdorferi (Bb), the spirochetal agent of Lyme disease, has a large array of lipoproteins that play a significant role in mediating host-pathogen interactions within ticks and vertebrates. Although there is substantial information on the effects of B. burgdorferi lipoproteins (BbLP) on immune modulatory pathways, the application of multi-omics methodologies to decode the transcriptional and proteomic patterns associated with host cell responses induced by lipoproteins in murine bone marrow-derived macrophages (BMDMs) has identified additional effectors and pathways. Single-cell RNA-Seq (scRNA-Seq) performed on BMDMs treated with various concentrations of borrelial lipoproteins revealed macrophage subsets within the BMDMs. Differential expression analysis showed that genes encoding various receptors, type I IFN-stimulated genes, signaling chemokines, and mitochondrial genes are altered in BMDMs in response to lipoproteins. Unbiased proteomics analysis of lysates of BMDMs treated with lipoproteins corroborated several of these findings. Notably, dual specificity phosphatase 1 (Dusp1) gene was upregulated during the early stages of BMDM exposure to BbLP. Pre-treatment with benzylidene-3-cyclohexylamino-1-indanone hydrochloride (BCI), an inhibitor of both DUSP1 and 6 prior to exposure to BbLP, demonstrated that DUSP1 negatively regulates NLRP3-mediated pro-inflammatory signaling and positively regulates the expression of interferon-stimulated genes and those encoding Ccl5, Il1b, and Cd274. Moreover, DUSP1, IkB kinase complex and MyD88 also modulate mitochondrial changes in BMDMs treated with borrelial lipoproteins. These findings advance the potential for exploiting DUSP1 as a therapeutic target to regulate host responses in reservoir hosts to limit survival of B. burgdorferi during its infectious cycle between ticks and mammalian hosts. ImportanceBorrelia burgdorferi, the agent of Lyme disease, encodes numerous lipoproteins that play a crucial role as a pathogen associated molecular pattern affecting interactions with tick- and vertebrate-host cells. Single cell transcriptomics validated using unbiased proteomics and conventional molecular biology approaches have demonstrated significant differences in gene expression patterns in a dose- and time-dependent manner following treatment of murine bone marrow derived macrophages with borrelial lipoproteins. Distinct populations of macrophages, alterations in immune signaling pathways, cellular energy production and mitochondrial responses were identified and validated using primary murine macrophages and human reporter cell lines. Notably, the role of Dual Specificity Phosphatase 1 (DUSP1) in influencing several inflammatory, metabolic and mitochondrial responses of macrophages were observed in these studies using known pharmacological inhibitors. Significant outcomes include novel strategies to interfere with immunomodulatory and survival capabilities of B. burgdorferi in reservoir hosts affecting its natural infectious life cycle between ticks and vertebrate hosts.

immunology↗