Muscle-invasive bladder cancer in elderly and frail people: Is hypofractionated radiotherapy a feasible approach when no other local options are available?

AIM: The study aims to report the feasibility and safety of palliative hypofractionated radiotherapy targeting macroscopic bladder tumors in a monocentric cohort of frail and elderly bladder cancer patients not eligible for curative treatments. METHODS: Patients who underwent hypofractionated radiotherapy to the gross disease or to the tumor bed after transurethral resection of bladder tumor from 2017 to 2021 at the European Institute of Oncology IRCCS, were retrospectively considered. Schedules of treatment were 30 and 25 Gy in 5 fractions (both every other day, and consecutive days). Treatment response was evaluated with radiological investigation and/or cystoscopy. Toxicity assessment was carried out according to RTOG/EORTC v2.0 criteria. RESULTS: A total of 16 patients were included in the study, of these 11 received hypofractionated radiotherapy on the macroscopic target volume and five on the tumor bed after transurethral resection of bladder tumor. No grade (G) >2 acute toxicities were described after treatment for both groups. Only one patient in the group receiving radiotherapy on the macroscopic disease reported G4 GU late toxicity. Ten patients had available follow-up status (median FU time 18 months), of them six had complete response, one had stable disease, and three had progression of disease. The overall response rate and disease control rate were 60% and 70%, respectively. CONCLUSION: Our preliminary data demonstrate that palliative hypofractionated radiotherapy for bladder cancer in a frail and elderly population is technically feasible, with an acceptable toxicity profile. These outcomes emphasize the potential of this approach in a non-radical setting and could help to provide more solid indications in this underrepresented setting of patients.

In vitro analysis of Porcine Endogenous Retroviruses in different pig cell types.

The shortage of organs for human transplantation is a topic of extreme interest, and xenotransplantation with porcine organs has been recognized as a promising solution. However, the potential spillover linked to infectious agents present in pigs remains a concern. Among these, Pig Endogenous Retroviruses (PERVs), whose proviral DNAs are integrated in the genome of all pig breeds, represent an extremely important biological risk. This study aims to evaluate PERVs distribution in several swine cell lines and samples of domestic and feral pigs. Moreover, the capacity of PERVs to infect human and non-human primate cells and to integrate in the cellular genome was tested by Real-Time PCR and by Reverse Transcriptase assay. Results indicated a widespread diffusion of PERVs both in cell lines and samples analysed: the viral genome was found in all the established cell lines, in 40% of the primary cell lines and in 60% of the tissue samples tested. The assays indicated that the virus can be transmitted from porcine to human cells: in the specific case, infected NSK and NPTr cells allow passage to human 293 and MRC-5 cells with active production of the virus demonstrable via PCR and RT assay. In light of these aspects and also the lack of studies on PERVs, it appears clear that there are still many questions to be clarified, also by means of future studies, before xenotransplantation can be considered microbiologically safe.

Investigating Nutritional and Inflammatory Status as Predictive Biomarkers in Oligoreccurent Prostate Cancer-A RADIOSA Trial Preliminary Analysis.

(1) Background: In the RADIOSA phase II randomized clinical trial (NCT03940235), the biology task entails the identification of predictive and prognostic biomarkers in the context of oligorecurrent, castration-sensitive prostate cancer in order to distinguish polymetastatic from oligometastatic disease. This may lay the groundwork for personalized treatments for those patients who could really benefit from metastasis-directed therapies. (2) Methods: Oligorecurrent PCa pts with three or fewer bone or lymph nodal localizations were randomized 1:1 to receive SBRT alone (arm A) or SBRT + 6 months of ADT (arm B). Common serum-derived biomarkers were collected at baseline, and at 3 months after RT. The prognostic nutritional index, an immune and nutrition-based prognostic score, and the controlling nutritional status (CONUT) score, a scoring system for evaluating patient's nutritional status, were calculated in accordance with the body of available literature. As inflammatory indicators, neutrophil-lymphocyte ratio (NLR) and the NLR-albumin ratio (NLRAR) were assessed. Changes in these parameters between baseline and the 3-month timepoint were evaluated both in absolute and relative values. Changes in these parameters between baseline and the 3-month timepoint were evaluated. Significant differences in the trend of these parameters were assessed using the non-parametric Wilcoxon rank-sum test. A network analysis to analyze the relationships between different features stratifying patients according to the arm of study and site of metastases was performed. (3) Results: The current analysis comprised 88 patients (45 arm A, SBRT only, and 43 arm B, SBRT + ADT). When patients were stratified by ADT administration, cholesterol values showed an increasing trend in the group receiving ADT (p = 0.005) which was no longer significant at 1 year. When patients were stratified by site of metastases (52 lymph nodal, 29 bone localizations), the value of NLR was found to be increased in patients with bone localizations (p < 0.05). In addition, the network analysis showed that BMI and NRI are strongly and directly linked for patients at baseline and that this correlation is no longer found at three months. Finally, when patients were divided according to time from surgery to oligorecurrence (enrollment) the patients with a longer time (>6.7 years) showed an increase in CONUT score from baseline. All the other nutritional and inflammatory scores or parameters investigated in the present analysis showed no statistically significant differences at baseline, three months, 1 year, and in absolute change. (4) Conclusions: The nutritional and inflammatory parameters do not seem to represent valuable candidates for possible use in clinical decision making in our cohort of patients and a reliable biological characterization of the oligometastatic state in prostate cancer still seems far from being achieved. Ongoing molecular analysis will show if there is a role of mutational landscape in the definition of the oligometastatic state.

Human iPSC-Derived 3D Hepatic Organoids in a Miniaturized Dynamic Culture System.

The process of identifying and approving a new drug is a time-consuming and expensive procedure. One of the biggest issues to overcome is the risk of hepatotoxicity, which is one of the main reasons for drug withdrawal from the market. While animal models are the gold standard in preclinical drug testing, the translation of results into therapeutic intervention is often ambiguous due to interspecies differences in hepatic metabolism. The discovery of human induced pluripotent stem cells (hiPSCs) and their derivatives has opened new possibilities for drug testing. We used mesenchymal stem cells and hepatocytes both derived from hiPSCs, together with endothelial cells, to miniaturize the process of generating hepatic organoids. These organoids were then cultivated in vitro using both static and dynamic cultures. Additionally, we tested spheroids solely composed by induced hepatocytes. By miniaturizing the system, we demonstrated the possibility of maintaining the organoids, but not the spheroids, in culture for up to 1 week. This timeframe may be sufficient to carry out a hypothetical pharmacological test or screening. In conclusion, we propose that the hiPSC-derived liver organoid model could complement or, in the near future, replace the pharmacological and toxicological tests conducted on animals.

siRNAs pools generated in Escherichia coli exhibit strong RNA-interference activity against influenza virus genomic sequences.

Due to the recurrent pandemic outbreaks that occurred during the last century, Influenza A viruses are considered a serious potential danger to human health. Among the innate immune pathways in eukaryotes, RNA interference plays a significant role in the interaction between viruses and host cells. RNA interference is addressed by small dsRNA molecules produced by the host itself (miRNAs, i.e. "micro-RNAs") but can be triggered also by the administration of exogenous short RNAs (siRNAs, "short interfering RNAs"). In this work, artificial siRNA pools targeting NP and PB genomic regions of the Influenza virus were produced in engineered Escherichia coli, adapting a published protocol. In a MDCK cell in vitro model, these preparations were challenged against reporter vectors bearing viral genomic sequences. A strong and specific RNA interference activity was observed, and the details of this action were indagated.

Hep3Gel: A Shape-Shifting Extracellular Matrix-Based, Three-Dimensional Liver Model Adaptable to Different Culture Systems.

Drug-induced hepatotoxicity is a leading cause of clinical trial withdrawal. Therefore, in vitro modeling the hepatic behavior and functionalities is not only crucial to better understand physiological and pathological processes but also to support drug development with reliable high-throughput platforms. Different physiological and pathological models are currently under development and are commonly implemented both within platforms for standard 2D cultures and within tailor-made chambers. This paper introduces Hep3Gel: a hybrid alginate-extracellular matrix (ECM) hydrogel to produce 3D in vitro models of the liver, aiming to reproduce the hepatic chemomechanical niche, with the possibility of adapting its shape to different manufacturing techniques. The ECM, extracted and powdered from porcine livers by a specifically set-up procedure, preserved its crucial biological macromolecules and was embedded within alginate hydrogels prior to crosslinking. The viscoelastic behavior of Hep3Gel was tuned, reproducing the properties of a physiological organ, according to the available knowledge about hepatic biomechanics. By finely tuning the crosslinking kinetics of Hep3Gel, its dualistic nature can be exploited either by self-spreading or adapting its shape to different culture supports or retaining the imposed fiber shape during an extrusion-based 3D-bioprinting process, thus being a shape-shifter hydrogel. The self-spreading ability of Hep3Gel was characterized by combining empirical and numerical procedures, while its use as a bioink was experimentally characterized through rheological a priori printability evaluations and 3D printing tests. The effect of the addition of the ECM was evident after 4 days, doubling the survival rate of cells embedded within control hydrogels. This study represents a proof of concept of the applicability of Hep3Gel as a tool to develop 3D in vitro models of the liver.

Social, affective, and non-motoric bodily cues to the Sense of Agency: A systematic review of the experience of control.

While the Sense of Agency (SoA) - the experience of controlling actions - is linked to motoric processes, the effects of non-motoric cues remain uncertain. We performed a systematic review investigating whether SoA is modulated by social, affective, and non-motoric bodily cues like internal bodily signals (IBSs) and Sense of Ownership (SoO). We searched Scopus and Pubmed and checked additional sources (e.g., citation searching). We identified 160 articles investigating social (67), affective (71) and non-motoric bodily cues (28), and calculated the percentage of studies supporting SoA modulation. SoA is influenced by social cues (92.54%), like the presence of interactive agents, and their status. Concerning affective cues (88.73%), reward-related information and affective states modulate SoA, but the effects of outcome valence are inconsistent. Regarding bodily cues (78.57%), SoO informs SoA, but the impact of IBSs is unclear. Overall, we show that diverse non-motoric cues modulate SoA. We submit that the brain evaluates different non-motoric cues in partially distinct circuits, before comparing them in a fronto-parietal network grounding SoA modulation.

3D Cell Cultures: Evolution of an Ancient Tool for New Applications.

Recently, research is undergoing a drastic change in the application of the animal model as a unique investigation strategy, considering an alternative approach for the development of science for the future. Although conventional monolayer cell cultures represent an established and widely used in vitro method, the lack of tissue architecture and the complexity of such a model fails to inform true biological processes in vivo. Recent advances in cell culture techniques have revolutionized in vitro culture tools for biomedical research by creating powerful three-dimensional (3D) models to recapitulate cell heterogeneity, structure and functions of primary tissues. These models also bridge the gap between traditional two-dimensional (2D) single-layer cultures and animal models. 3D culture systems allow researchers to recreate human organs and diseases in one dish and thus holds great promise for many applications such as regenerative medicine, drug discovery, precision medicine, and cancer research, and gene expression studies. Bioengineering has made an important contribution in the context of 3D systems using scaffolds that help mimic the microenvironments in which cells naturally reside, supporting the mechanical, physical and biochemical requirements for cellular growth and function. We therefore speak of models based on organoids, bioreactors, organ-on-a-chip up to bioprinting and each of these systems provides its own advantages and applications. All of these techniques prove to be excellent candidates for the development of alternative methods for animal testing, as well as revolutionizing cell culture technology. 3D systems will therefore be able to provide new ideas for the study of cellular interactions both in basic and more specialized research, in compliance with the 3R principle. In this review, we provide a comparison of 2D cell culture with 3D cell culture, provide details of some of the different 3D culture techniques currently available by discussing their strengths as well as their potential applications.

Engineered nanoparticles toxicity on adipose tissue derived mesenchymal stem cells: A preliminary investigation.

Nanoscience and nanotechnologies have recently gained importance in several fields, such as industry and medicine. A big issue of the increasing application of nanomaterials is the poor literature regarding their potential toxicity in humans and animals. Recently, adult stem cells have been proposed as putative targets of nanoparticles (NPs). This study aims to investigate the effects of zerovalent-metallic NPs on isolated and amplified equine Adipose tissue derived Mesenchymal Stem Cells (eAdMSCs). Cells were treated with Cobalt (Co-), Iron (Fe-), and Nickel (Ni-) nanoparticles (NPs) at different concentrations and were characterized for the cytotoxic and genotoxic effects of exposure. Treatment with NPs resulted in reduced cell viability and proliferative capability in comparison with untreated cells. However, this did not influence eAdMSCs potency, as treated cells were able to differentiate towards the adipogenic and osteogenic lineages. Ni- and Fe-NPs showed cytoplasmic localization, while Co-NPs entered the nucleus and mitochondria, suggesting a potential genotoxic activity. Regarding p53 expression, it was enhanced in the first 48 h after treatments, with a drastic reduction of expression within 72 h. Higher p53 expression was reported in the case of Co-NP treatment, suggesting the tumorigenic potential of these NPs. Telomerase activity was enhanced by Fe- and Ni-NP treatments in a concentration- and time-dependent way. This was not true for Co-NP treated samples, suggesting a reduced replicative capacity of eAdMSCs upon Co-NP exposure. The present study is a preliminary investigation of the influence exerted by NPs on eAdMSC physiological activity in terms of cytotoxic and genotoxic effects. The present results revealed eAdMSC physiology to be strongly influenced by NPs in a dose-, time- and NP-dependent way.

Reduced ownership over a virtual body modulates dishonesty.

Although studies suggest that even higher-order functions can be embodied, whether body awareness may bias moral decisions toward (dis)honesty remains underinvestigated. Here, we tested if the Sense of body Ownership (SoO) and the magnitude of monetary rewards influence the tendency to act immorally. Through a virtual body, participants played a card game in which they could lie to others to steal high or low amounts of money. To manipulate SoO, the virtual body was seen and controlled from a first-person perspective, with hands attached or detached, or from a third-person perspective. In third-person perspective, SoO was significantly reduced and more egoistic lies were produced in high reward conditions. Thus, SoO reduction and high monetary reward facilitate dishonest behavior, likely by separating the self from the dishonest actions performed through the disowned body. Because most future interactions will likely occur in a digital metaverse, our results may have crucial societal impact.

Canine Mesenchymal Cell Lyosecretome Production and Safety Evaluation after Allogenic Intraarticular Injection in Osteoarthritic Dogs.

In recent years, mesenchymal stromal cells (MSCs) have shown promise as a therapy in treating musculoskeletal diseases, and it is currently believed that their therapeutic effect is mainly related to the release of proteins and extracellular vesicles (EVs), known as secretome. In this work, three batches of canine MSC-secretome were prepared by standardized processes according to the current standard ISO9001 and formulated as a freeze-dried powder named Lyosecretome. The final products were characterized in protein and lipid content, EV size distribution and tested to ensure the microbiological safety required for intraarticular injection. Lyosecretome induced the proliferation of adipose tissue-derived canine MSCs, tenocytes, and chondrocytes in a dose-dependent manner and showed anti-elastase activity, reaching 85% of inhibitory activity at a 20 mg/mL concentration. Finally, to evaluate the safety of the preparation, three patients affected by bilateral knee or elbow osteoarthritis were treated with two intra-articular injections (t = 0 and t = 40 days) of the allogeneic Lyosecretome (20 mg corresponding 2 × 106 cell equivalents) resuspended in hyaluronic acid in one joint and placebo (mannitol resuspended in hyaluronic acid) in the other joint. To establish the safety of the treatment, the follow-up included a questionnaire addressed to the owner and orthopaedic examinations to assess lameness grade, pain score, functional disability score and range of motion up to day 80 post-treatment. Overall, the collected data suggest that intra-articular injection of allogeneic Lyosecretome is safe and does not induce a clinically significant local or systemic adverse response.

PARP Inhibitors in Combination with Radiotherapy: To Do or Not to Do?

BACKGROUND: Despite the large use of inhibitors of Poly-ADP ribose polymerase (PARP-I), the feasibility and safety of their combination with radiotherapy (RT) is unclear. AIM: We conducted a literature analysis with the aim to evaluate the efficacy and safety profile of a combination with RT and PARP-I. METHOD: The key issues for the current review were expressed in two questions according to the Population, Intervention, Control, Outcome (PICO) criteria: 1. What is the outcome and 2. What is the toxicity in patients treated with a combination of PARP-I and RT for a newly diagnosed or recurrent tumors? RESULTS: A total of 12 clinical studies met the inclusion criteria including seven single-arm dose-escalation phase I studies, two phase II (two- and three-arms controlled trials) trials, one parallel-arm phase I study, and two phase I/II studies published between 2015 and 2021. RT was performed with photon beams and several schedules according to the clinical situation. The acute toxicity ≥ grade 3 ranged between 25% and >96%, which was divided into hematological or non-hematological adverse events. CONCLUSIONS: despite the heterogeneity of the evaluated patient populations and tumor types, and the limited number of the studies, this review suggests that a combination approach is feasible even though the efficacy profile remains unclear.

Toxicity of carbon ion radiotherapy and immune checkpoint inhibitors in advanced melanoma.

We analyzed CTCAE adverse events of sequential Carbon Ion radiotherapy (CIRT) and immune checkpoint inhibitors (ICIs) in advanced melanoma patients. The frequencies of early and late adverse events (AEs) were 100% and 82% of patients, respectively. The frequency of G3+ AEs was in line with the literature.

Equine Mesenchymal Stem/Stromal Cells Freeze-Dried Secretome (Lyosecretome) for the Treatment of Musculoskeletal Diseases: Production Process Validation and Batch Release Test for Clinical Use.

In the last decades, it has been demonstrated that the regenerative therapeutic efficacy of mesenchymal stromal cells is primarily due to the secretion of soluble factors and extracellular vesicles, collectively known as secretome. In this context, our work described the preparation and characterization of a freeze-dried secretome (Lyosecretome) from adipose tissue-derived mesenchymal stromal cells for the therapy of equine musculoskeletal disorder. An intraarticular injectable pharmaceutical powder has been formulated, and the technological process has been validated in an authorized facility for veterinary clinical-use medicinal production. Critical parameters for quality control and batch release have been identified regarding (i) physicochemical properties; (ii) extracellular vesicle morphology, size distribution, and surface biomarker; (iii) protein and lipid content; (iv) requirements for injectable pharmaceutical dosage forms such as sterility, bacterial endotoxin, and Mycoplasma; and (v) in vitro potency tests, as anti-elastase activity and proliferative activity on musculoskeletal cell lines (tenocytes and chondrocytes) and mesenchymal stromal cells. Finally, proteins putatively responsible for the biological effects have been identified by Lyosecretome proteomic investigation: IL10RA, MXRA5, RARRES2, and ANXA1 modulate the inflammatory process RARRES2, NOD1, SERPINE1, and SERPINB9 with antibacterial activity. The work provides a proof-of-concept for the manufacturing of clinical-grade equine freeze-dried secretome, and prototypes are now available for safety and efficacy clinical trials in the treatment of equine musculoskeletal diseases.

Human moral decision-making through the lens of Parkinson's disease.

Parkinson's disease (PD) is a neurodegenerative disorder characterized by the loss of dopaminergic neurons in the basal ganglia (BG) and thalamocortical circuitry. While defective motor control has long been considered the defining symptom of PD, mounting evidence indicates that the BG are fundamentally important for a multitude of cognitive, emotional, and motivational processes in addition to motor function. Here, we review alterations in moral decision-making in people with PD, specifically in the context of deceptive behavior. We report that PD patients exhibit two opposite behavioral patterns: hyper- and hypo-honesty. The hyper-honest subgroup engages in deception less often than matched controls, even when lying is associated with a monetary payoff. This behavioral pattern seems to be linked to dopaminergic hypo-activity, implying enhanced harm avoidance, risk aversion, non-impulsivity, and reduced reward sensitivity. On the contrary, the hypo-honest subgroup-often characterized by the additional diagnosis of impulse control disorders (ICDs) and dopamine dysregulation syndrome (DDS)-deceives more often than both PD patients without ICDs/DDS and controls. This behavioral pattern appears to be associated with dopaminergic hyperactivity, which underpins enhanced novelty-seeking, risk-proneness, impulsivity, and reward sensitivity. We posit that these two complementary behavioral patterns might be related to dysfunction of the dopaminergic reward system, leading to reduced or enhanced motivation to deceive. Only a few studies have directly investigated moral decision-making in PD and other neurodegenerative disorders affecting the BG, and further research on the causal role of subcortical structures in shaping moral behavior is needed.

Freedom to act enhances the sense of agency, while movement and goal-related prediction errors reduce it.

The Sense of Agency (SoA) is the experience of controlling one's movements and their external consequences. Accumulating evidence suggests that freedom to act enhances SoA, while prediction errors are known to reduce it. Here, we investigated if prediction errors related to movement or to the achievement of the goal of the action exert the same influence on SoA during free and cued actions. Participants pressed a freely chosen or cued-colored button, while observing a virtual hand moving in the same or in the opposite direction-i.e., movement-related prediction error-and pressing the selected or a different color-i.e., goal-related prediction error. To investigate implicit and explicit components of SoA, we collected indirect (i.e., Synchrony Judgments) and direct (i.e., Judgments of Causation) measures. We found that participants judged virtual actions as more synchronous when they were free to act. Additionally, movement-related prediction errors reduced both perceived synchrony and judgments of causation, while goal-related prediction errors impaired exclusively the latter. Our results suggest that freedom to act enhances SoA and that movement and goal-related prediction errors lead to an equivalent reduction of SoA in free and cued actions. Our results also show that the influence of freedom to act and goal achievement may be limited, respectively, to implicit and explicit SoA, while movement information may affect both components. These findings provide support to recent theories that view SoA as a multifaceted construct, by showing that different action cues may uniquely influence the feeling of control.

Veterinary Regenerative Medicine for Musculoskeletal Disorders: Can Mesenchymal Stem/Stromal Cells and Their Secretome Be the New Frontier?

Regenerative medicine aims to restore the normal function of diseased or damaged cells, tissues, and organs using a set of different approaches, including cell-based therapies. In the veterinary field, regenerative medicine is strongly related to the use of mesenchymal stromal cells (MSCs), which belong to the body repair system and are defined as multipotent progenitor cells, able to self-replicate and to differentiate into different cell types. This review aims to take stock of what is known about the MSCs and their use in the veterinary medicine focusing on clinical reports on dogs and horses in musculoskeletal diseases, a research field extensively reported in the literature data. Finally, a perspective regarding the use of the secretome and/or extracellular vesicles (EVs) in the veterinary field to replace parental MSCs is provided. The pharmaceuticalization of EVs is wished due to the realization of a Good Manufacturing Practice (GMP product suitable for clinical trials.

Violation of expectations about movement and goal achievement leads to Sense of Agency reduction.

The control of one's own movements and of their impact on the external world generates a feeling of control referred to as Sense of Agency (SoA). SoA is experienced when actions match predictions and is reduced by unpredicted events. The present study investigated the contribution of monitoring two fundamental components of action-movement execution and goal achievement-that have been most often explored separately in previous research. We have devised a new paradigm in which participants performed goal-directed actions while viewing an avatar's hand in a mixed-reality scenario. The hand performed either the same action or a different one, simultaneously or after various delays. Movement of the virtual finger and goal attainment were manipulated, so that they could match or conflict with the participants' expectations. We collected judgments of correspondence (an explicit index of SoA that overcomes the tendency to over-attribute actions to oneself) by asking participants if the observed action was synchronous or not with their action. In keeping with previous studies, we found that monitoring both movement execution and goal attainment is relevant for SoA. Moreover, we expanded previous findings by showing that movement information may be a more constant source of SoA modulation than goal information. Indeed, an incongruent movement impaired SoA irrespective of delay duration, while a missed goal did so only when delays were short. Our novel paradigm allowed us to simultaneously manipulate multiple action features, a characteristic that makes it suitable for investigating the contribution of different sub-components of action in modulating SoA in healthy and clinical populations.

BPSL1626: Reverse and Structural Vaccinology Reveal a Novel Candidate for Vaccine Design against Burkholderia pseudomallei.

Due to significant advances in computational biology, protein prediction, together with antigen and epitope design, have rapidly moved from conventional methods, based on experimental approaches, to in silico-based bioinformatics methods. In this context, we report a reverse vaccinology study that identified a panel of 104 candidate antigens from the Gram-negative bacterial pathogen Burkholderia pseudomallei, which is responsible for the disease melioidosis. B. pseudomallei can cause fatal sepsis in endemic populations in the tropical regions of the world and treatment with antibiotics is mostly ineffective. With the aim of identifying potential vaccine candidates, we report the experimental validation of predicted antigen and type I fimbrial subunit, BPSL1626, which we show is able to recognize and bind human antibodies from the sera of Burkholderia infected patients and to stimulate T-lymphocytes in vitro. The prerequisite for a melioidosis vaccine, in fact, is that both antibody- and cell-mediated immune responses must be triggered. In order to reveal potential antigenic regions of the protein that may aid immunogen re-design, we also report the crystal structure of BPSL1626 at 1.9 Å resolution on which structure-based epitope predictions were based. Overall, our data suggest that BPSL1626 and three epitope regions here-identified can represent viable candidates as potential antigenic molecules.