Biology subjects

Curran, D. M.

Publications and source records attributed to Curran, D. M..

6 recordsLinked to original sources

bioRxiv2026

A loopless subdomain of transferrin binding protein B can elicit a broadly cross-reactive humoral immune response targeting variants from both encapsulated and non-typeable Haemophilus influenzae

Haemophilus influenzae is a Gram-negative bacterium that causes pneumonia, otitis media, and invasive infections such as meningitis and bacteremia. A vaccine that confers protection against disease caused by H. influenzae serotype b is currently available and is highly effective, but infections caused by non-b serotypes and non-typeable strains are still prevalent and increasing, suggesting a need for a broadly cross-protective vaccine that will protect against infection by all H. influenzae strains. To address the need for broad cross-protection, this study focused on the surface lipoprotein component of the bipartite bacterial transferrin receptor, transferrin binding protein B (TbpB), which is universally present H. influenzae, irrespective of encapsulation status, and is essential for bacterial colonization and pathogenesis. To prevent vaccine escape, we assessed the sequence and structural diversity among TbpB variants derived from local and international H. influenzae isolates and observed that these sequences cluster independently of encapsulation status, suggesting that conferring protection against all H. influenzae strains regardless of capsule type or presence of a capsule using a TbpB-based vaccine is feasible. In addition, our diversity analysis also revealed that the C-terminal lobe (C-lobe) of TbpB contains several large, highly variable loops. After immunizing mice with a trivalent vaccine consisting of a representative set of TbpB variants, we found that the resulting antiserum demonstrated modest cross-reactivity against heterologous TbpB variants. However, immunizing with a loopless C-lobe (LCL) that lacks the large, highly variable loops we had identified elicited broad cross-reactivity against a panel of intact TbpB variants. This suggests that while the intact TbpB may only generate a moderately cross-reactive antibody response, a vaccine consisting of a single LCL may be able to elicit a sufficiently cross-reactive humoral response against diverse TbpB variants, and in turn, confer broad cross-protection targeting both encapsulated and non-typeable H. influenzae.

immunology↗

bioRxiv2025

Rationally designed minimized TbpB confers broad protection against meningococcal infection

Transferrin binding protein B (TbpB), an iron acquisition protein, has long been recognized as a promising vaccine candidate targeting the pathogenic Neisseria species, including Neisseria meningitidis, the cause of meningococcal disease, and Neisseria gonorrhoeae, the cause of gonorrhea. A challenge to the development of this protein as a vaccine immunogen is the extent of antigenic variability it exhibits, which complicates the selection of a single variant to elicit a broadly cross-protective immune response. We have utilized structure-informed antigen engineering to develop a minimized version of TbpB consisting of the proteins carboxy-terminal lobe with its variable surface loops removed. Here, we reveal the effectiveness of this "loopless C-lobe" as an independent immunogen, with structural characterization and stability studies to demonstrate its integrity, and murine immunization and challenge studies that establish its ability to elicit robust protective efficacy by using N. meningitidis invasive infection and nasopharyngeal colonization models. The breadth of protection provided, as measured by both in vitro analysis and cross-protection mouse challenge studies, indicate that a single loopless C-lobe elicits a broadly cross-protective immune response against the diverse panel of meningococcal strains tested, and that the cross-reactivity is superior to that offered by the intact TbpB or the native C-lobe. Together, this study demonstrates the utility of structure-informed antigen engineering towards the development of broadly efficacious protein-based vaccines. ImportanceSurface-exposed proteins on bacterial pathogens are enticing candidate vaccine targets, however their exposure to the immune system frequently leads to high levels of antigenic variation, a factor that complicates the development of broadly protective vaccines. Here, we undertake an antigen engineering approach to develop a minimized version of a surface lipoprotein, transferrin binding protein B, where variable regions of the protein have been removed to focus the immune response to conserved regions of this antigen. We combine structural studies and mouse infection models of Neisseria meningitidis, the cause of meningococcal disease, and Neisseria gonorrhoeae, the causative agent of gonorrhea, to reveal that our strategic minimizing of the protein immunogen focuses the immune response to extend the resulting breadth of cross-reactivity and cross-protection.

immunology↗

bioRxiv2024

Phylogeny-based selection of representative variants with Navargator: Proof of principle using humoral cross-reactivity data from two immunization studies

BackgroundThe accessibility to the immune system of bacterial surface proteins makes them attractive targets for subunit vaccines. However, this same property also means they tend to exhibit high sequence variability. Achieving broad cross-protection usually necessitates that antigens from multiple isolates are included, but the choice of sequence variant is a non-trivial problem. Visual inspection of phylogenetic trees is the norm, but this is subjective and can be greatly influenced by the choice of viewing software. This has real-world implications, as groups have shown that the selection of non-optimal antigens likely led to lower cross-protection in the commercially available vaccines against Neisseria meningitidis serogroup B. Aim / MethodsTo address this problem, we have developed Navargator, bioinformatics software that takes a phylogenetic tree as input and identifies the variants that are the most similar to the greatest number of other sequences. The underlying premise is that cross-reactivity will be correlated with phylogenetic distances extracted from the tree; this was validated by several rodent immunization studies with the proteins transferrin-binding protein B and factor H binding protein from N. meningitidis and N. gonorrhoeae, measuring antibody-based cross-reactivity between an antigen panel using a custom high-throughput ELISA. ResultsNavargator has been made freely available both as an online tool and as source code for local installation. We implemented several different clustering methods, with exact algorithms for smaller datasets, and heuristics suitable for large trees of thousands of sequences. Our immunization studies have shown that this approach is sound, and that cross-reactivity is predicted well by phylogenetic distances in a sigmoidal manner. ConclusionsThe complexity of vaccine development rises sharply with each additional antigen included, so using the minimal number required is an important consideration. Navargator attempts to facilitate this in a systematic and generalizable manner. The user can run the analysis by selecting their desired number of representatives, or they can provide any form of cross-reactivity data and have the program identify a minimum reactivity threshold via correlation with the phylogenetic tree. The program will then identify the smallest number of representatives required to satisfy this threshold.

bioinformatics↗

bioRxiv2024

Rational selection of TbpB variants elucidates a bivalent vaccine formulation with broad spectrum coverage against Neisseria gonorrhoeae

Neisseria gonorrhoeae is the causative agent of gonorrhea, an on-going public health problem due in part to the lack of success with efforts to develop an efficacious vaccine to prevent this sexually transmitted infection. An attractive candidate vaccine antigen because of its essential function and surface exposure, the gonococcal transferrin binding protein B (TbpB) exhibits high levels of antigenic variability which poses a significant obstacle in evoking a broadly protective vaccine composition. Here, we utilize phylogenetic information to rationally select TbpB variants for inclusion into a potential gonococcal vaccine and identify two TbpB variants that when formulated together elicit a highly cross-reactive antibody response in both rabbits and mice against a diverse panel of TbpB variants and clinically relevant gonococcal strains. Further, this formulation performed well in experimental proxies of real-world usage, including eliciting bactericidal activity against 8 diverse gonococcal strains and decreasing the median duration of colonization after vaginal infection in female mice by two heterologous strains of N. gonorrhoeae. Together, these data support the use of a combination of TbpB variants for a broadly protective gonococcal vaccine.

microbiology↗

bioRxiv2023

Prevalence of Slam-dependent hemophores in Gram-negative bacteria

Iron acquisition systems are crucial for pathogen growth and survival in iron-limiting host environments. To overcome nutritional immunity, bacterial pathogens evolved to use diverse mechanisms to acquire iron. Here, we examined a heme acquisition system driven by hemophores called HphAs from several Gram-negative bacteria. Structural determination of HphAs revealed a N-terminal clamp-like domain that binds heme and a C-terminal eight-stranded {beta}-barrel domain that shares the same architecture as the Slam-dependent Neisserial surface lipoproteins. The structure of these HphAs is strikingly similar to a novel hemophore discovered by Latham et al. (2019), named hemophilin1. The genetic organization of HphAs consist of genes encoding a Slam homolog and a TonB-dependent receptor (TBDR). We investigated the Slam-HphA system in the native organism or the reconstituted system in E. coli cells and found that the efficient secretion of HphA is dependent on Slam. The TBDR also played an important role for heme uptake and conferred specificity for its cognate HphA. Furthermore, bioinformatic analysis of HphA homologs revealed that HphAs are conserved in the alpha, beta, and gammaproteobacteria Together, these results show that HphA presents a new class of hemophores in Gram-negative bacteria and further expands the role of Slams in transporting soluble proteins supporting it role as a type 11 secretion system.

microbiology↗

bioRxiv2019

Modeling the metabolic interplay between a parasitic worm and its bacterial endosymbiont allows the identification of novel drug targets

The filarial nematode Brugia malayi represents a leading cause of disability in the developing world, causing lymphatic filariasis in nearly 40 million people. Currently available drugs are not well-suited to mass drug administration efforts, so new treatments are urgently required. One potential vulnerability is the endosymbiotic bacteria Wolbachia--present in many filariae--which is vital to the worm.\n\nGenome scale metabolic networks have been used to study prokaryotes and protists and have proven valuable in identifying therapeutic targets, but only recently have been applied to eukaryotic organisms. Here, we present iDC625, the first compartmentalized metabolic model of a parasitic worm. We used this model to show how metabolic pathway usage allows the worm to adapt to different environments, and predict a set of 99 reactions essential to the survival of B. malayi. We validated three of those reactions with drug tests and demonstrated novel antifilarial properties for all three compounds.

systems biology↗