994 resultados para Optimal regulation


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Endogenous glucocorticoids and serotonin have been implicated in the pathophysiology of depression, anxiety and schizophrenia. This thesis investigates the potential of downregulating expression of central Type II glucocorticoid receptors (GR) both in vitro and in vivo, with empirically-designed antisense oligodeoxynucleotides (ODN), to characterise GR modulation of 5-HT2A receptor expression using quantitative RT-PCR, Western blot analysis and radioligand binding. The functional consequence of GR downregulation is also determined by measuring 1-(2,5-dimethoxy 4-iodophenyl)-2-amino propane hydrochloride (DOI) mediated 5-HT2A receptor specific headshakes. Using a library of random antisense ODN probes, RNAse H accessibility mapping of T7-primed, in vitro transcribed GR mRNA revealed several potential cleavage sites and identified an optimally effect GR antisense ODN sequence of 21-mer length (GRAS5). In vitro efficacy studies using rat C6 glioma cells showed a 56% downregulation in GR mRNA levels and 80% downregulation in GR protein levels. In the same cells a 29% upregulation in 5-HT2A mRNA levels and 32% upregulation in 5-HT2A protein levels was revealed. This confirmed the optimal nature of the GRAS5 sequence to produce marked inhibition of GR gene expression, and also revealed GR modulation of the 50-HT2A receptor subtype in C6 glioma cells to be a tonic repression of receptor expression. The distribution of a fluorescently-labelled GRAS5 ODN was detected in diverse areas of the rat brain after single ICV administration, although this fluorescence signal was not sustained over a period of 5 days. However, fluorescently-labelled GRAS5 ODN, when formulated in polymer microspheres, showed diverse distribution in the brain which was maintained for 5 days following a single ICV administration. This produced no apparent neurotoxic effects on rat behaviour and hypothalamic-pituitary-adrenal (HPA) axis homeostasis. Furthermore, a single polymer microsphere injection ICV proved to be an effective means of delivering antisense ODNs and this was adopted for the in vivo efficacy studies. In vivo characterisation of GRAS5 revealed marked downregulation of GR mRNA in rat brain regions such as the frontal cortex (26%), hippocampus (35%), and hypothalamus (39%). Downregulation of GR protein was also revealed in frontal cortex (67%), hippocampus (76%), and hypothalamus (80%). In the same animals upregulation of 5-HT2A mRNA levels was shown in frontal cortex (13%), hippocampus (7%), and hypothalamus (5%) while upregulation in 5-HT2A protein levels was shown in frontal cortex (21 %). This upregulation in 5-HT2A receptor density as a result of antisense-mediated inhibition of GR was further confirmed by a 55% increase in DOl-mediated 5-HT2A receptor specific headshakes. These results demonstrate that GR is involved in tonic inhibitory regulation of 5-HT2A receptor expression and function in vivo, thus providing the potential to control 5-HT2A-linked disorders through corticosteroid manipulation. These experiments have therefore established an antisense approach which can be used to investigate pharmacological characteristics of receptors.

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Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen. Several antibiotic resistant strains of P. aeruginosa are commonly found as secondary infection in immune-compromised patients leaving significant mortality and healthcare cost. Pseudomonas aeruginosa successfully avoids the process of phagocytosis, the first line of host defense, by secreting several toxic effectors. Effectors produced from P. aeruginosa Type III secretion system are critical molecules required to disrupt mammalian cell signaling and holds particular interest to the scientists studying host-pathogen interaction. Exoenzyme S (ExoS) is a bi-functional Type III effector that ADP-ribosylates several intracellular Ras (Rat sarcoma) and Rab (Response to abscisic acid) small GTPases in targeted host cells. The Rab5 protein acts as a rate limiting protein during phagocytosis by switching from a GDP- bound inactive form to a GTP-bound active form. Activation and inactivation of Rab5 protein is regulated by several Rab5-GAPs (GTPase Activating Proteins) and Rab5-GEFs (Rab5-Guanine nucleotide Exchange Factors). Some pathogenic bacteria have shown affinity for Rab proteins during infection and make their way inside the cell. This dissertation demonstrated that Rab5 plays a critical role during early steps of P. aeruginosa invasion in J774-Eclone macrophages. It was found that live, but not heat inactivated, P. aeruginosa inhibited phagocytosis that occurred in conjunction with down-regulation of Rab5 activity. Inactivation of Rab5 was dependent on ExoS ADP-ribosyltransferase activity, and more than one arginine sites in Rab5 are possible targets for ADP-ribosylation modification. However, the expression of Rin1, but not other Rab5GEFs (Rabex-5 and Rap6) reversed this down-regulation of Rab5 in vivo. Further studies revealed that the C-terminus of Rin1 carrying Rin1:Vps9 and Rin1:RA domains are required for optimal Rab5 activation in conjunction with active Ras. These observations demonstrate a novel mechanism of Rab5 targeting to phagosome via Rin1 during the phagocytosis of P. aeruginosa. The second part of this dissertation investigated antimicrobial activities of Dehydroleucodine (DhL), a secondary metabolite from Artemisia douglasiana, against P. aeruginosa growth and virulence. Populations of several P. aeruginosa strains were completely susceptible to DhL at a concentration between 0.48~0.96 mg/ml and treatment at a threshold concentration (0.12 mg/ml) inhibited growth and many virulent activities without damaging the integrity of the cell suggesting anti-Pseudomonas activity of DhL.

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I explore and analyze a problem of finding the socially optimal capital requirements for financial institutions considering two distinct channels of contagion: direct exposures among the institutions, as represented by a network and fire sales externalities, which reflect the negative price impact of massive liquidation of assets.These two channels amplify shocks from individual financial institutions to the financial system as a whole and thus increase the risk of joint defaults amongst the interconnected financial institutions; this is often referred to as systemic risk. In the model, there is a trade-off between reducing systemic risk and raising the capital requirements of the financial institutions. The policymaker considers this trade-off and determines the optimal capital requirements for individual financial institutions. I provide a method for finding and analyzing the optimal capital requirements that can be applied to arbitrary network structures and arbitrary distributions of investment returns.

In particular, I first consider a network model consisting only of direct exposures and show that the optimal capital requirements can be found by solving a stochastic linear programming problem. I then extend the analysis to financial networks with default costs and show the optimal capital requirements can be found by solving a stochastic mixed integer programming problem. The computational complexity of this problem poses a challenge, and I develop an iterative algorithm that can be efficiently executed. I show that the iterative algorithm leads to solutions that are nearly optimal by comparing it with lower bounds based on a dual approach. I also show that the iterative algorithm converges to the optimal solution.

Finally, I incorporate fire sales externalities into the model. In particular, I am able to extend the analysis of systemic risk and the optimal capital requirements with a single illiquid asset to a model with multiple illiquid assets. The model with multiple illiquid assets incorporates liquidation rules used by the banks. I provide an optimization formulation whose solution provides the equilibrium payments for a given liquidation rule.

I further show that the socially optimal capital problem using the ``socially optimal liquidation" and prioritized liquidation rules can be formulated as a convex and convex mixed integer problem, respectively. Finally, I illustrate the results of the methodology on numerical examples and

discuss some implications for capital regulation policy and stress testing.

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Compulsory education laws oblige primary and secondary schools to give each pupil positive encouragement in, for example, social, emotional, cognitive, creative, and ethical respects. This is a fairly smooth process for most pupils, but it is not as easy to achieve with others. A pattern of pupil, home or family, and school variables turns out to be responsible for a long-term process that may lead to a pupil’s dropping out of education. A systemic approach will do much to introduce more clarity into the diagnosis, potential reduction and possible prevention of some persistent educational problems that express themselves in related phenomena, for example low school motivation and achievement; forced underachievement of high ability pupils; concentration of bullying and violent behaviour in and around some types of classes and schools; and drop-out percentages that are relatively constant across time. Such problems have a negative effect on pupils, teachers, parents, schools, and society alike. In this address, I would therefore like to clarify some of the systemic causes and processes that we have identified between specific educational and pupil characteristics. Both theory and practice can assist in developing, implementing, and checking better learning methods and coaching procedures, particularly for pupils at risk. This development approach will take time and require co-ordination, but it will result in much better processes and outcomes than we are used to. First, I will diagnose some systemic aspects of education that do not seem to optimise the learning processes and school careers of some types of pupils in particular. Second, I will specify cognitive, social, motivational, and self-regulative aspects of learning tasks and relate corresponding learning processes to relevant instructional and wider educational contexts. I will elaborate these theoretical notions into an educational design with systemic instructional guidelines and multilevel procedures that may improve learning processes for different types of pupils. Internet-based Information and Communication Technology, or ICT, also plays a major role here. Third, I will report on concrete developments made in prototype research and trials. The development process concerns ICT-based differentiation of learning materials and procedures, and ICT-based strategies to improve pupil development and learning. Fourth, I will focus on the experience gained in primary and secondary educational practice with respect to implementation. We can learn much from such practical experience, in particular about the conditions for developing and implementing the necessary changes in and around schools. Finally, I will propose future research. As I hope to make clear, theory-based development and implementation research can join forces with systemic innovation and differentiated assessment in educational practice, to pave the way for optimal “learning for self-regulation” for pupils, teachers, parents, schools, and society at large.

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This thesis discusses market design and regulation in electricity systems, focusing on the information exchange of the regulated grid firm and the generation firms as well as the regulation of the grid firm. In the first chapter, an economic framework is developed to consistently analyze different market designs and the information exchange between the grid firm and the generation firms. Perfect competition between the generation firms and perfect regulation of the grid firm is assumed. A numerical algorithm is developed and its feasibility demonstrated on a large-scale problem. The effects of different market designs for the Central Western European (CWE) region until 2030 are analyzed. In the second chapter, the consequences of restricted grid expansion within the current market design in the CWE region until 2030 are analyzed. In the third chapter the assumption of efficient markets is modified. The focus of the analysis is then, whether and how inefficiencies in information availability and processing affect different market designs. For different parameter settings, nodal and zonal pricing are compared regarding their welfare in the spot and forward market. In the fourth chapter, information asymmetries between the regulator and the regulated firm are analyzed. The optimal regulatory strategy for a firm, providing one output with two substitutable inputs, is defined. Thereby, one input and the absolute quantity of inputs is not observable for the regulator. The result is then compared to current regulatory approaches.

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This work explores regulation of forward speed, step length, and slope walking for the passive-dynamic class of bipedal robots. Previously, an energy-shaping control for regulating forward speed has appeared in the literature; here we show that control to be a special case of a more general time-scaling control that allows for speed transitions in arbitrary time. As prior work has focused on potential energy shaping for fully actuated bipeds, we study in detail the shaping of kinetic energy for bipedal robots, giving special treatment to issues of underactuation. Drawing inspiration from features of human walking, an underactuated kinetic-shaping control is presented that provides efficient regulation of walking speed while adjusting step length. Previous results on energetic symmetries of bipedal walking are also extended, resulting in a control that allows regulation of speed and step length while walking on any slope. Finally we formalize the optimal gait regulation problem and propose a dynamic programming solution seeded with passive-dynamic limit cycles. Observations of the optimal solutions generated by this method reveal further similarities between passive dynamic walking and human locomotion and give insight into the structure of minimum-effort controls for walking.

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This thesis aims to understand how cells coordinate their motion during collective migration. As previously shown, the motion of individually migrating cells is governed by wave-like cell shape dynamics. The mechanisms that regulate these dynamic behaviors in response to extracellular environment remain largely unclear. I applied shape dynamics analysis to Dictyostelium cells migrating in pairs and in multicellular streams and found that wave-like membrane protrusions are highly coupled between touching cells. I further characterized cell motion by using principle component analysis (PCA) to decompose complex cell shape changes into a serial shape change modes, from which I found that streaming cells exhibit localized anterior protrusion, termed front narrowing, to facilitate cell-cell coupling. I next explored cytoskeleton-based mechanisms of cell-cell coupling by measuring the dynamics of actin polymerization. Actin polymerization waves observed in individual cells were significantly suppressed in multicellular streams. Streaming cells exclusively produced F-actin at cell-cell contact regions, especially at cell fronts. I demonstrated that such restricted actin polymerization is associated with cell-cell coupling, as reducing actin polymerization with Latrunculin A leads to the assembly of F-actin at the side of streams, the decrease of front narrowing, and the decoupling of protrusion waves. My studies also suggest that collective migration is guided by cell-surface interactions. I examined the aggregation of Dictyostelim cells under distinct conditions and found that both chemical compositions of surfaces and surface-adhesion defects in cells result in altered collective migration patterns. I also investigated the shape dynamics of cells suspended on PEG-coated surfaces, which showed that coupling of protrusion waves disappears on touching suspended cells. These observations indicate that collective migration requires a balance between cell-cell and cell-surface adhesions. I hypothesized such a balance is reached via the regulation of cytoskeleton. Indeed, I found cells actively regulate cytoskeleton to retain optimal cell-surface adhesions on varying surfaces, and cells lacking the link between actin and surfaces (talin A) could not retain the optimal adhesions. On the other hand, suspended cells exhibited enhanced actin filament assembly on the periphery of cell groups instead of in cell-cell contact regions, which facilitates their aggregation in a clumping fashion.

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In this paper, a real-time optimal control technique for non-linear plants is proposed. The control system makes use of the cell-mapping (CM) techniques, widely used for the global analysis of highly non-linear systems. The CM framework is employed for designing approximate optimal controllers via a control variable discretization. Furthermore, CM-based designs can be improved by the use of supervised feedforward artificial neural networks (ANNs), which have proved to be universal and efficient tools for function approximation, providing also very fast responses. The quantitative nature of the approximate CM solutions fits very well with ANNs characteristics. Here, we propose several control architectures which combine, in a different manner, supervised neural networks and CM control algorithms. On the one hand, different CM control laws computed for various target objectives can be employed for training a neural network, explicitly including the target information in the input vectors. This way, tracking problems, in addition to regulation ones, can be addressed in a fast and unified manner, obtaining smooth, averaged and global feedback control laws. On the other hand, adjoining CM and ANNs are also combined into a hybrid architecture to address problems where accuracy and real-time response are critical. Finally, some optimal control problems are solved with the proposed CM, neural and hybrid techniques, illustrating their good performance.

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This study aimed at evaluating the functional activation and activating receptors expression on resting, short- and long-term NK and NK-like T cells from blood of ovarian neoplasia patients. Blood from patients with adnexal benign alterations (n = 10) and ovarian cancer (grade I-IV n = 14) were collected after signed consent. Effector cells activation was evaluated by the expression of the CD107a molecule. Short-term culture was conducted overnight with IL-2 and long-term culture for 21 days, by a method designed to expand CD56(+) lymphocytes. Short-term culture significantly increased NK cells activation compared to resting NK cells (p<0.05), however, the long-term procedure supported an even higher increase (p<0.001). Resting NK-like T cells showed poor activation, which was not altered by the culture procedures. The long-term culture effectively increased the expression of the activating receptors on NK and NK-like T cells, either by increasing the number of cells expressing a given receptor and/or by up-regulating their expression intensity. As a conclusion, the long-term culture system employed, resulted in a high number of functional NK cells. The culture system was particularly efficient on the up-regulation of NKp30 and DNAM-1 receptors on NK cells.

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In Brazil, the consumption of extra-virgin olive oil (EVOO) is increasing annually, but there are no experimental studies concerning the phenolic compound contents of commercial EVOO. The aim of this work was to optimise the separation of 17 phenolic compounds already detected in EVOO. A Doehlert matrix experimental design was used, evaluating the effects of pH and electrolyte concentration. Resolution, runtime and migration time relative standard deviation values were evaluated. Derringer's desirability function was used to simultaneously optimise all 37 responses. The 17 peaks were separated in 19min using a fused-silica capillary (50μm internal diameter, 72cm of effective length) with an extended light path and 101.3mmolL(-1) of boric acid electrolyte (pH 9.15, 30kV). The method was validated and applied to 15 EVOO samples found in Brazilian supermarkets.

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Ki-1/57 (HABP4) and CGI-55 (SERBP1) are regulatory proteins and paralogs with 40.7% amino acid sequence identity and 67.4% similarity. Functionally, they have been implicated in the regulation of gene expression on both the transcriptional and mRNA metabolism levels. A link with tumorigenesis is suggested, since both paralogs show altered expression levels in tumor cells and the Ki-1/57 gene is found in a region of chromosome 9q that represents a haplotype for familiar colon cancer. However, the target genes regulated by Ki-1/57 and CGI-55 are unknown. Here, we analyzed the alterations of the global transcriptome profile after Ki-1/57 or CGI-55 overexpression in HEK293T cells by DNA microchip technology. We were able to identify 363 or 190 down-regulated and 50 or 27 up-regulated genes for Ki-1/57 and CGI-55, respectively, of which 20 were shared between both proteins. Expression levels of selected genes were confirmed by qRT-PCR both after protein overexpression and siRNA knockdown. The majority of the genes with altered expression were associated to proliferation, apoptosis and cell cycle control processes, prompting us to further explore these contexts experimentally. We observed that overexpression of Ki-1/57 or CGI-55 results in reduced cell proliferation, mainly due to a G1 phase arrest, whereas siRNA knockdown of CGI-55 caused an increase in proliferation. In the case of Ki-1/57 overexpression, we found protection from apoptosis after treatment with the ER-stress inducer thapsigargin. Together, our data give important new insights that may help to explain these proteins putative involvement in tumorigenic events.

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Galectin-3 (gal-3) is a β-galactoside binding protein related to many tumoral aspects, e.g. angiogenesis, cell growth and motility and resistance to cell death. Evidence has shown its upregulation upon hypoxia, a common feature in solid tumors such as glioblastoma multiformes (GBM). This tumor presents a unique feature described as pseudopalisading cells, which accumulate large amounts of gal-3. Tumor cells far from hypoxic/nutrient deprived areas express little, if any gal-3. Here, we have shown that the hybrid glioma cell line, NG97ht, recapitulates GBM growth forming gal-3 positive pseudopalisades even when cells are grafted subcutaneously in nude mice. In vitro experiments were performed exposing these cells to conditions mimicking tumor areas that display oxygen and nutrient deprivation. Results indicated that gal-3 transcription under hypoxic conditions requires previous protein synthesis and is triggered in a HIF-1α and NF-κB dependent manner. In addition, a significant proportion of cells die only when exposed simultaneously to hypoxia and nutrient deprivation and demonstrate ROS induction. Inhibition of gal-3 expression using siRNA led to protein knockdown followed by a 1.7-2.2 fold increase in cell death. Similar results were also found in a human GBM cell line, T98G. In vivo, U87MG gal-3 knockdown cells inoculated subcutaneously in nude mice demonstrated decreased tumor growth and increased time for tumor engraftment. These results indicate that gal-3 protected cells from cell death under hypoxia and nutrient deprivation in vitro and that gal-3 is a key factor in tumor growth and engraftment in hypoxic and nutrient-deprived microenvironments. Overexpression of gal-3, thus, is part of an adaptive program leading to tumor cell survival under these stressing conditions.

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The SLC8A1 gene, which encodes the Na(+)/Ca(2+) exchanger, plays a key role in calcium homeostasis. Our previous gene expression oligoarray data revealed SLC8A1 underexpression in penile carcinoma (PeCa). The aim of this study was to investigate whether the dysregulation of SLC8A1 expression is associated with apoptosis and cell proliferation in PeCa, via modulation of calcium concentration. The underlying mechanisms of SLC8A1 underexpression were also explored, focusing on copy number alteration and microRNA. Transcript levels of SLC8A1 gene and miR-223 were evaluated by quantitative PCR, comparing PeCa samples with normal glans tissues. SLC8A1 copy number was evaluated by microarray-based comparative genomic hybridization (array-CGH). Caspase-3 and Ki-67 immunostaining, as well as calcium distribution by Laser Ablation Imaging Inductively Coupled Plasma Mass Spectrometry [LA(i)-ICP-MS], were investigated in both normal and tumor samples. Confirming our previous data, SLC8A1 underexpression was detected in PeCa samples (P=0.001) and was not associated with gene copy number loss. In contrast, overexpression of miR-223 (P=0.002) was inversely correlated with SLC8A1 (P=0.015, r=-0.426), its putative repressor. In addition, SLC8A1 underexpression was associated with decreased calcium distribution, high Ki-67 and low caspase-3 immunoexpression in PeCa when compared with normal tissues. Down-regulation of the SLC8A1 gene, most likely mediated by its regulator miR-223, can lead to reduced calcium levels in PeCa and, consequently, to suppression of apoptosis and increased tumor cell proliferation. These data suggest that the miR-223-NCX1-calcium-signaling axis may represent a potential therapeutic approach in PeCa.

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Placental tissue injury is concomitant with tumor development. We investigated tumor-driven placental damage by tracing certain steps of the protein synthesis and degradation pathways under leucine-rich diet supplementation in MAC16 tumor-bearing mice. Cell signaling and ubiquitin-proteasome pathways were assessed in the placental tissues of pregnant mice, which were distributed into three groups on a control diet (pregnant control, tumor-bearing pregnant, and pregnant injected with MAC-ascitic fluid) and three other groups on a leucine-rich diet (pregnant, tumor-bearing pregnant, and pregnant injected with MAC-ascitic fluid). MAC tumor growth down-regulated the cell-signaling pathways of the placental tissue and decreased the levels of IRS-1, Akt/PKB, Erk/MAPK, mTOR, p70S6K, STAT3, and STAT6 phosphorylated proteins, as assessed by the multiplex Millipore Luminex assay. Leucine supplementation maintained the levels of these proteins within the established cell-signaling pathways. In the tumor-bearing group (MAC) only, the placental tissue showed increased PC5 mRNA expression, as assessed by quantitative RT-PCR, decreased 19S and 20S protein expression, as assessed by Western blot analysis, and decreased placental tyrosine levels, likely reflecting up-regulation of the ubiquitin-proteasome pathway. Similar effects were found in the pregnant injected with MAC-ascitic fluid group, confirming that the effects of the tumor were mimicked by MAC-ascitic fluid injection. Although tumor progression occurred, the degradation pathway-related protein levels were modulated under leucine-supplementation conditions. In conclusion, tumor evolution reduced the protein expression of the cell-signaling pathway associated with elevated protein degradation, thereby jeopardizing placental activity. Under the leucine-rich diet, the impact of cancer on placental function could be minimized by improving the cell-signaling activity and reducing the proteolytic process.

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Background: Francisella tularensis causes severe pulmonary disease, and nasal vaccination could be the ideal measure to effectively prevent it. Nevertheless, the efficacy of this type of vaccine is influenced by the lack of an effective mucosal adjuvant. Methodology/Principal Findings: Mice were immunized via the nasal route with lipopolysaccharide isolated from F. tularensis and neisserial recombinant PorB as an adjuvant candidate. Then, mice were challenged via the same route with the F. tularensis attenuated live vaccine strain (LVS). Mouse survival and analysis of a number of immune parameters were conducted following intranasal challenge. Vaccination induced a systemic antibody response and 70% of mice were protected from challenge as showed by their improved survival and weight regain. Lungs from mice recovering from infection presented prominent lymphoid aggregates in peribronchial and perivascular areas, consistent with the location of bronchus-associated lymphoid tissue (BALT). BALT areas contained proliferating B and T cells, germinal centers, T cell infiltrates, dendritic cells (DCs). We also observed local production of antibody generating cells and homeostatic chemokines in BALT areas. Conclusions: These data indicate that PorB might be an optimal adjuvant candidate for improving the protective effect of F. tularensis antigens. The presence of BALT induced after intranasal challenge in vaccinated mice might play a role in regulation of local immunity and long-term protection, but more work is needed to elucidate mechanisms that lead to its formation.