Regulated dynamic subcellular GLUT4 localization revealed by proximal proteome mapping in human muscle cells.

Regulation of glucose transport, which is central for control of whole-body metabolism, is determined by the amount of GLUT4 glucose transporter (also known as SLC2A4) in the plasma membrane (PM) of fat and muscle cells. Physiologic signals [such as activated insulin receptor or AMP-activated protein kinase (AMPK)] increase PM GLUT4. Here, we show that the distribution of GLUT4 between the PM and interior of human muscle cells is dynamically maintained, and that AMPK promotes PM redistribution of GLUT4 by regulating exocytosis and endocytosis. Stimulation of exocytosis by AMPK is mediated by Rab10 and the Rab GTPase-activating protein TBC1D4. APEX2 proximity mapping reveals that GLUT4 traverses both PM-proximal and PM-distal compartments in unstimulated muscle cells, further supporting retention of GLUT4 by a constitutive retrieval mechanism. AMPK-stimulated translocation involves GLUT4 redistribution among the same compartments traversed in unstimulated cells, with a significant recruitment of GLUT4 from the Golgi and trans-Golgi network compartments. Our comprehensive proximal protein mapping provides an integrated, high-density, whole-cell accounting of the localization of GLUT4 at a resolution of ∼20 nm that serves as a structural framework for understanding the molecular mechanisms regulating GLUT4 trafficking downstream of different signaling inputs in a physiologically relevant cell type.

Statistical Applications of Virtual Control Groups to Nonrodent Animal Toxicity Studies: an Initial Evaluation.

Utilization of data from historical control animals to form virtual control groups (VCGs) is an innovative approach to embody the 3Rs (reduce, refine, and replace use of control animals) principle in research. However, there is no available systematic comparison of statistical performance between concurrent control groups (CCGs) and VCGs in nonrodent safety assessment. The optimal selection criteria and combination of VCGs and CCGs also remain unclear. This study retrospectively evaluated VCGs' statistical performance to detect test article effects on body weight and clinical pathology endpoints in dog and nonhuman primate (NHP) systemic toxicity studies. Body weight and six clinical pathology endpoints were analyzed against the reported study findings from a cohort of 22 previously reported nonrodent 1-month oral gavage toxicity using three different methods of generating VCGs. When the fold change from baseline is used, VCGs yield a similar or higher statistical sensitivity to detect test article relatedness than CCGs. Compared to simple random sampling or using fixed criteria, the propensity score matching by BW, age, and year of study initiation yielded higher sensitivities . Our analysis supports the hypothesis that VCGs can be a viable instrument in nonrodent toxicity studies.

A Novel C-C Chemoattractant Cytokine (Chemokine) Receptor 6 (CCR6) Antagonist (PF-07054894) Distinguishes between Homologous Chemokine Receptors, Increases Basal Circulating CCR6+ T Cells, and Ameliorates Interleukin-23-Induced Skin Inflammation.

Blocking chemokine receptor C-C chemoattractant cytokine (chemokine) receptor (CCR) 6-dependent T cell migration has therapeutic promise in inflammatory diseases. PF-07054894 is a novel CCR6 antagonist that blocked only CCR6, CCR7, and C-X-C chemoattractant cytokine (chemokine) receptor (CXCR) 2 in a ß-arrestin assay panel of 168 G protein-coupled receptors. Inhibition of CCR6-mediated human T cell chemotaxis by (R)-4-((2-(((1,4-Dimethyl-1H-pyrazol-3-yl)(1-methylcyclopentyl)methyl)amino)-3,4-dioxocyclobut-1-en-1-yl)amino)-3-hydroxy-N,N-dimethylpicolinamide (PF-07054894) was insurmountable by CCR6 ligand, C-C motif ligand (CCL) 20. In contrast, blockade of CCR7-dependent chemotaxis in human T cells and CXCR2-dependent chemotaxis in human neutrophils by PF-07054894 were surmountable by CCL19 and C-X-C motif ligand 1, respectively. [3H]-PF-07054894 showed a slower dissociation rate for CCR6 than for CCR7 and CXCR2 suggesting that differences in chemotaxis patterns of inhibition could be attributable to offset kinetics. Consistent with this notion, an analog of PF-07054894 with fast dissociation rate showed surmountable inhibition of CCL20/CCR6 chemotaxis. Furthermore, pre-equilibration of T cells with PF-07054894 increased its inhibitory potency in CCL20/CCR6 chemotaxis by 10-fold. The functional selectivity of PF-07054894 for inhibition of CCR6 relative to CCR7 and CXCR2 is estimated to be at least 50- and 150-fold, respectively. When administered orally to naïve cynomolgus monkeys, PF-07054894 increased the frequency of CCR6+ peripheral blood T cells, suggesting that blockade of CCR6 inhibited homeostatic migration of T cells from blood to tissues. PF-07054894 inhibited interleukin-23-induced mouse skin ear swelling to a similar extent as genetic ablation of CCR6. PF-07054894 caused an increase in cell surface CCR6 in mouse and monkey B cells, which was recapitulated in mouse splenocytes in vitro. In conclusion, PF-07054894 is a potent and functionally selective CCR6 antagonist that blocks CCR6-mediated chemotaxis in vitro and in vivo. SIGNIFICANCE STATEMENT: The chemokine receptor, C-C chemoattractant cytokine (chemokine) receptor 6 (CCR6) plays a key role in the migration of pathogenic lymphocytes and dendritic cells into sites of inflammation. (R)-4-((2-(((1,4-Dimethyl-1H-pyrazol-3-yl)(1-methylcyclopentyl)methyl)amino)-3,4-dioxocyclobut-1-en-1-yl)amino)-3-hydroxy-N,N-dimethylpicolinamide (PF-07054894) is a novel CCR6 small molecule antagonist that illustrates the importance of binding kinetics in achieving pharmacological potency and selectivity. Orally administered PF-07054894 blocks homeostatic and pathogenic functions of CCR6, suggesting that it is a promising therapeutic agent for the treatment of a variety of autoimmune and inflammatory diseases.

Fosaprepitant for the prevention of nausea and vomiting in patients receiving BEAM or high-dose melphalan before autologous hematopoietic stem cell transplant.

PURPOSE: To assess the impact of single-dose fosaprepitant on nausea and emesis after BEAM and high-dose melphalan conditioning regimens for autologous hematopoietic stem cell transplantation. METHODS: In a single-center cohort study patients receiving melphalan containing hematopoietic stem cell transplantation regimens who received a one-time dose of 150 mg IV fosaprepitant (n = 56) were compared to a historical control (n = 70). RESULTS: The primary endpoint of no emesis from melphalan administration through five days afterward was 80% for the fosaprepitant group versus 66% in the control group (p = 0.068). Addition of fosaprepitant demonstrated significant improvement in emetic episodes per patient during the entire assessment period (p = 0.011) and days 1-5 after melphalan (p = 0.045). Fosaprepitant resulted in no substantial nausea during the entire assessment period in 37% of high-dose melphalan patients and 57% of BEAM patients. CONCLUSIONS: Further studies are suggested to investigate the optimal number and timing of doses of fosaprepitant in this setting.

GLUT4 dynamic subcellular localization is controlled by AMP kinase activation as revealed by proximal proteome mapping in human muscle cells.

Regulation of glucose transport into muscle and adipocytes, central for control of whole-body metabolism, is determined by the amount of GLUT4 glucose transporter in the plasma membrane ( PM ). Physiologic signals (activated insulin receptor or AMP kinase [ AMPK ]), acutely increase PM GLUT4 to enhance glucose uptake. Here we show in kinetic studies that intracellular GLUT4 is in equilibrium with the PM in unstimulated cultured human skeletal muscle cells, and that AMPK promotes GLUT4 redistribution to the PM by regulating both exocytosis and endocytosis. AMPK-stimulation of exocytosis requires Rab10 and Rab GTPase activating protein TBC1D4, requirements shared with insulin control of GLUT4 in adipocytes. Using APEX2 proximity mapping, we identify, at high-density and high-resolution, the GLUT4 proximal proteome, revealing GLUT4 traverses both PM proximal and distal compartments in unstimulated muscle cells. These data support intracellular retention of GLUT4 in unstimulated muscle cells by a dynamic mechanism dependent on the rates of internalization and recycling. AMPK promoted GLUT4 translocation to the PM involves redistribution of GLUT4 among the same compartments traversed in unstimulated cells, with a significant redistribution of GLUT4 from the PM distal Trans Golgi Network Golgi compartments. The comprehensive proximal protein mapping provides an integrated, whole cell accounting of GLUT4's localization at a resolution of ∼20 nm, a structural framework for understanding the molecular mechanisms regulating GLUT4 trafficking downstream of different signaling inputs in physiologically relevant cell type and as such, sheds new light on novel key pathways and molecular components as potential therapeutic approaches to modulate muscle glucose uptake.

Discovery of the Potent and Selective MC4R Antagonist PF-07258669 for the Potential Treatment of Appetite Loss.

The melanocortin-4 receptor (MC4R) is a centrally expressed, class A GPCR that plays a key role in the regulation of appetite and food intake. Deficiencies in MC4R signaling result in hyperphagia and increased body mass in humans. Antagonism of MC4R signaling has the potential to mitigate decreased appetite and body weight loss in the setting of anorexia or cachexia due to underlying disease. Herein, we report on the identification of a series of orally bioavailable, small-molecule MC4R antagonists using a focused hit identification effort and the optimization of these antagonists to provide clinical candidate 23. Introduction of a spirocyclic conformational constraint allowed for simultaneous optimization of MC4R potency and ADME attributes while avoiding the production of hERG active metabolites observed in early series leads. Compound 23 is a potent and selective MC4R antagonist with robust efficacy in an aged rat model of cachexia and has progressed into clinical trials.

Label-free detection of micro-RNA hybridization using surface-enhanced Raman spectroscopy and least-squares analysis.

Label-free surface-enhanced Raman spectroscopy (SERS) detection of nucleic acid hybridization is impeded by poor spectral reproducibility and the fact that the chemical signatures of hybridized and unhybridized sequences are highly similar. To overcome these issues, highly reproducible silver nanorod SERS substrates along with a straightforward least-squares (LS) technique have been employed for the quantitative determination of the relative ratios of the four nucleotide components A, C, G, and T/U before and after hybridization using a clinically relevant micro-RNA sequence.

Clinical utility of a serum biomarker panel in distinguishing prostate cancer from benign prostate hyperplasia.

Prostate-specific antigen (PSA) screening for prostate cancer (PCa) is limited by the lack of specificity but is further complicated in the benign prostatic hyperplasia (BPH) population which also exhibit elevated PSA, representing a clear unmet need to distinguish BPH from PCa. Herein, we evaluated the utility of FLNA IP-MRM, age, and prostate volume to stratify men with BPH from those with PCa. Diagnostic performance of the biomarker panel was better than PSA alone in discriminating patients with negative biopsy from those with PCa, as well as those who have had multiple prior biopsies (AUC 0.75 and 0.87 compared to AUC of PSA alone 0.55 and 0.57 for patients who have had single compared to multiple negative biopsies, respectively). Of interest, in patients with PCa, the panel demonstrated improved performance than PSA alone in those with Gleason scores of 5-7 (AUC 0.76 vs. 0.56) and Gleason scores of 8-10 (AUC 0.74 vs. 0.47). With Gleason scores (8-10), the negative predictive value of the panel is 0.97, indicating potential to limit false negatives in aggressive cancers. Together, these data demonstrate the ability of the biomarker panel to perform better than PSA alone in men with BPH, thus preventing unnecessary biopsies.

Selective pharmacological inhibition of the sodium-dependent phosphate cotransporter NPT2a promotes phosphate excretion.

The sodium-phosphate cotransporter NPT2a plays a key role in the reabsorption of filtered phosphate in proximal renal tubules, thereby critically contributing to phosphate homeostasis. Inadequate urinary phosphate excretion can lead to severe hyperphosphatemia as in tumoral calcinosis and chronic kidney disease (CKD). Pharmacological inhibition of NPT2a may therefore represent an attractive approach for treating hyperphosphatemic conditions. The NPT2a-selective small-molecule inhibitor PF-06869206 was previously shown to reduce phosphate uptake in human proximal tubular cells in vitro. Here, we investigated the acute and chronic effects of the inhibitor in rodents and report that administration of PF-06869206 was well tolerated and elicited a dose-dependent increase in fractional phosphate excretion. This phosphaturic effect lowered plasma phosphate levels in WT mice and in rats with CKD due to subtotal nephrectomy. PF-06869206 had no effect on Npt2a-null mice, but promoted phosphate excretion and reduced phosphate levels in normophophatemic mice lacking Npt2c and in hyperphosphatemic mice lacking Fgf23 or Galnt3. In CKD rats, once-daily administration of PF-06869206 for 8 weeks induced an unabated acute phosphaturic and hypophosphatemic effect, but had no statistically significant effect on FGF23 or PTH levels. Selective pharmacological inhibition of NPT2a thus holds promise as a therapeutic option for genetic and acquired hyperphosphatemic disorders.

Characterization of cachexia in the human fibrosarcoma HT-1080 mouse tumour model.

BACKGROUND: Cancer cachexia is a complex metabolic disease with unmet medical need. Although many rodent models are available, none are identical to the human disease. Therefore, the development of new preclinical models that simulate some of the physiological, biochemical, and clinical characteristics of the human disease is valuable. The HT-1080 human fibrosarcoma tumour cell line was reported to induce cachexia in mice. Therefore, the purpose of this work was to determine how well the HT-1080 tumour model could recapitulate human cachexia and to examine its technical performance. Furthermore, the efficacy of ghrelin receptor activation via anamorelin treatment was evaluated, because it is one of few clinically validated mechanisms. METHODS: Female severe combined immunodeficient mice were implanted subcutaneously or heterotopically (renal capsule) with HT-1080 tumour cells. The cachectic phenotype was evaluated during tumour development, including body weight, body composition, food intake, muscle function (force and fatigue), grip strength, and physical activity measurements. Heterotopic and subcutaneous tumour histology was also compared. Energy balance was evaluated at standard and thermoneutral housing temperatures in the subcutaneous model. The effect of anamorelin (ghrelin analogue) treatment was also examined. RESULTS: The HT-1080 tumour model had excellent technical performance and was reproducible across multiple experimental conditions. Heterotopic and subcutaneous tumour cell implantation resulted in similar cachexia phenotypes independent of housing temperature. Tumour weight and histology was comparable between both routes of administration with minimal inflammation. Subcutaneous HT-1080 tumour-bearing mice presented with weight loss (decreased fat mass and skeletal muscle mass/fibre cross-sectional area), reduced food intake, impaired muscle function (reduced force and grip strength), and decreased spontaneous activity and voluntary wheel running. Key circulating inflammatory biomarkers were produced by the tumour, including growth differentiation factor 15, Activin A, interleukin 6, and TNF alpha. Anamorelin prevented but did not reverse anorexia and weight loss in the subcutaneous model. CONCLUSIONS: The subcutaneous HT-1080 tumour model displays many of the perturbations of energy balance and physical performance described in human cachexia, consistent with the production of key inflammatory factors. Anamorelin was most effective when administered early in disease progression. The HT-1080 tumour model is valuable for studying potential therapeutic targets for the treatment of cachexia.

Bootstrapping Time-Course Gene Expression Data for Gene Networks: Application to Gene Relevance Networks.

Identification of gene regulatory networks (GRNs) is a fundamental step to understand the molecular role of each gene and it helps to develop treatment and cure of a disease. To identify GRNs, time-course gene expression data are widely used. However, the identification is hampered by intrinsic attributes of the data such as small sample size, a large number of variables, and complex error structures with high variation. Under this situation, most GRN inference methods utilize point estimators or make numerous assumptions that are often incompatible with the experimental data. Moreover, different inference methods often provide inconsistent results. An alternative to alleviate this problem can be the bootstrap method because it provides more reliable outcomes by integrating results from multiple bootstrap samples without any distributional assumptions. In this study, we propose a bootstrap method for dependent time-course gene expression data and we mainly focus on its application to gene relevance networks. The proposed method is applied to gene networks for zebrafish retina.

Clinical Validation of a Serum Protein Panel (FLNA, FLNB and KRT19) for Diagnosis of Prostate Cancer.

This study reports on the development of a novel serum protein panel of three prostate cancer biomarkers, Filamin A, Filamin B and Keratin-19 (FLNA, FLNB and KRT19) using multivariate models for disease screening and prognosis. ELISA and IPMRM (LC-MS/MS) based assays were developed and analytically validated by quantitative measurements of the biomarkers in serum. Retrospectively collected and clinically annotated serum samples with PSA values and Gleason scores were analyzed from subjects who underwent prostate biopsy, and showed no evidence of cancer with or without indication of prostatic hyperplasia, or had a definitive pathology diagnosis of prostatic adenocarcinoma. Probit linear regression models were used to combine the analytes into score functions to address the following clinical questions: does the biomarker test augment PSA for population screening? Can aggressive disease be differentiated from lower risk disease, and can the panel discriminate between prostate cancer and benign prostate hyperplasia? Modelling of the data showed that the new prostate biomarkers and PSA in combination were better than PSA alone in identifying prostate cancer, improved the prediction of high and low risk disease, and improved prediction of cancer versus benign prostate hyperplasia.

Non-obvious correlations to disease management unraveled by Bayesian artificial intelligence analyses of CMS data.

OBJECTIVE: Given the availability of extensive digitized healthcare data from medical records, claims and prescription information, it is now possible to use hypothesis-free, data-driven approaches to mine medical databases for novel insight. The goal of this analysis was to demonstrate the use of artificial intelligence based methods such as Bayesian networks to open up opportunities for creation of new knowledge in management of chronic conditions. MATERIALS AND METHODS: Hospital level Medicare claims data containing discharge numbers for most common diagnoses were analyzed in a hypothesis-free manner using Bayesian networks learning methodology. RESULTS: While many interactions identified between discharge rates of diagnoses using this data set are supported by current medical knowledge, a novel interaction linking asthma and renal failure was discovered. This interaction is non-obvious and had not been looked at by the research and clinical communities in epidemiological or clinical data. A plausible pharmacological explanation of this link is proposed together with a verification of the risk significance by conventional statistical analysis. CONCLUSION: Potential clinical and molecular pathways defining the relationship between commonly used asthma medications and renal disease are discussed. The study underscores the need for further epidemiological research to validate this novel hypothesis. Validation will lead to advancement in clinical treatment of asthma & bronchitis, thereby, improving patient outcomes and leading to long term cost savings. In summary, this study demonstrates that application of advanced artificial intelligence methods in healthcare has the potential to enhance the quality of care by discovering non-obvious, clinically relevant relationships and enabling timely care intervention.

Polymorphic Amplified Typing Sequences (PATS) Strain Typing System Accurately Discriminates a Set of Temporally and Spatially Disparate Escherichia coli O157 Isolates Associated with Human Infection.

Polymorphic Amplified Typing Sequences (PATS) is a PCR-based Escherichia coli O157 (O157) strain typing system. Here, we show that PATS compares excellently with Pulsed-Field Gel Electrophoresis (PFGE) in that both methods cluster geographically diverse O157 isolates similarly. Comparative analysis of the results obtained in this simulated "blind" study attests to the discriminating power and applicability of PATS to epidemiological/nosocomial situations.

Polymorphic Amplified Typing Sequences and Pulsed-Field Gel Electrophoresis Yield Comparable Results in the Strain Typing of a Diverse Set of Bovine Escherichia coli O157:H7 Isolates.

Polymorphic amplified typing sequences (PATS), a PCR-based Escherichia coli O157:H7 (O157) strain typing system, targets insertions-deletions and single nucleotide polymorphisms at XbaI and AvrII restriction enzyme sites, respectively, and the virulence genes (stx1, stx2, eae, hlyA) in the O157 genome. In this study, the ability of PATS to discriminate O157 isolates associated with cattle was evaluated. An in-depth comparison of 25 bovine O157 isolates, from different geographic locations across Northwest United States, showed that about 85% of these isolates shared the same dendogram clade by PATS and pulsed-field gel electrophoresis (PFGE), irrespective of the restriction enzyme sites targeted. The Pearson's correlation coefficient, r, calculated at about 0.4, 0.3, and 0.4 for XbaI-based, AvrII-based and combined-enzymes PATS and PFGE similarities, respectively, indicating that these profiles shared a good but not high correlation, an expected inference given that the two techniques discriminate differently. Isolates that grouped differently were better matched to their locations using PATS. Overall, PATS discriminated the bovine O157 isolates without interpretive biases or sophisticated analytical software, and effectively complemented while not duplicating PFGE. With its quick turnaround time, PATS has excellent potential as a convenient tool for early epidemiological or food safety investigations, enabling rapid notification/implementation of quarantine measures.

Racial disparities and barriers to colorectal cancer screening in rural areas.

INTRODUCTION: This study examined barriers to colorectal cancer (CRC) screening in people living in rural areas. METHODS: We identified 2 rural counties with high rates of CRC and randomly contacted county residents by telephone using a published listing. RESULTS: Six hundred thirty-five of the 1839 eligible respondents (34.5%) between the ages of 50 and 79 years living in McDuffie and Screven counties, Georgia, agreed to complete the survey. The mean age was 62.2 years (SD, ±7.5 years); 72.4% were women, 79.4% were white, and 19.5% were African American. African-American respondents had lower CRC screening rates (50.4%) than whites (63.4%; P = .009). Significantly more African Americans compared with whites reported barriers to CRC screening. Based on logistic regression analyses, having a physician recommend CRC screening had the strongest association with having a current CRC screening, regardless of race. CONCLUSIONS: Important racial differences existed between African Americans and whites regarding the barriers to CRC screening and factors impacting current screening. However, endorsement of a small set of questionnaire items--not race--had the strongest association with being current with screening. Physician recommendation for CRC screening had the strongest association with being current with CRC screening.

Dynamic rastering surface-enhanced Raman scattering (SERS) measurements on silver nanorod substrates.

Surface-enhanced Raman spectra of a thiol-modified biotin derivative on oblique-angle-deposited silver nanorod (AgNR) array substrates were measured using both static and rotating rastering methods. We find that the rotating rastering method has a strong tendency to decrease the point-to-point relative standard deviation (RSD) compared to static measurements as well as decrease the effects of cumulative excitation exposure. The AgNR substrates treated with the modified biotin typically demonstrate intra-substrate RSDs of <10%, with an average RSD of ∼3% when the rastering radius r=1 mm. The quantitative studies on the relationship between rastering radius, sampling area, and rastering frequency show that only the rastering radius appears to have significant effect on the measured RSD. Our results demonstrate that under the proper measurement and sample preparation conditions, the Ag nanorod substrates are very uniform.

The relationship of a diabetes telehealth eye care program to standard eye care and change in diabetes health outcomes.

Several studies suggest that telehealth eye care programs that combine retinal imaging, education, and some care management can improve patient adherence to annual, comprehensive eye examinations and follow-up treatments. Little is known, however, about whether such programs relate to other, more distal outcomes that affect diabetic eye disease, such as blood glucose control. This paper assesses the relationship of participation in a diabetes telehealth eye care program with standard, face-to-face eye care as well as improvements in other diabetes-related health outcomes. We conducted a retrospective study using data from electronic medical records of Joslin Diabetes Center (n=13,752). The data span 2 years: baseline and follow-up. Subjects' eye care groups were no eye care, eye care outside of the clinic, standard eye care at the clinic, or participation in the Joslin Vision Network telehealth eye care program. We analyzed the relationship of participation in the telehealth eye care program at baseline to follow-up eye care groups and changes in hemoglobin A1c, low density lipoprotein levels, and systolic blood pressure. The results show that participation in the telehealth eye care program was significantly correlated with whether subjects later obtained standard eye care, improvement in hemoglobin A1c, and improvement in low density lipoprotein. Thus, telehealth eye care programs that incorporate evaluation, education, and care planning are related to use of recommended eye care and improvements in certain diabetes-related health outcomes. Such programs can address the many aspects of care necessary to reduce risk of vision loss due to diabetic retinopathy and other diabetes-related complications. Future research might test hypotheses suggested by sociological and psychological theories regarding causation between participation in a telehealth eye care program and other diabetes care.

Identification of a protein subset of the anthrax spore immunome in humans immunized with the anthrax vaccine adsorbed preparation.

We identified spore targets of Anthrax Vaccine Adsorbed (AVA)-induced immunity in humans by screening recombinant clones of a previously generated, limited genomic Bacillus anthracis Sterne (pXO1(+), pXO2(-)) expression library of putative spore surface (spore-associated [SA]) proteins with pooled sera from human adults immunized with AVA (immune sera), the anthrax vaccine currently approved for use by humans in the United States. We identified 69 clones that reacted specifically with pooled immune sera but not with pooled sera obtained from the same individuals prior to immunization. Positive clones expressed proteins previously identified as localized on the anthrax spore surface, proteins highly expressed during spore germination, orthologs of proteins of diverse pathogens under investigation as drug targets, and orthologs of proteins contributing to the virulence of both gram-positive and gram-negative pathogens. Among the reactive clones identified by this immunological screen was one expressing a 15.2-kDa hypothetical protein encoded by a gene with no significant homology to sequences contained in databases. Further studies are required to define the subset of SA proteins identified in this study that contribute to the virulence of this pathogen. We hypothesize that optimal delivery of a subset of SA proteins identified by such studies to the immune system in combination with protective antigen (PA), the principal immunogen in AVA, might facilitate the development of defined, nonreactogenic, more-efficacious PA-based anthrax vaccines. Future studies might also facilitate the identification of SA proteins with potential to serve as targets for drug design, spore inactivation, or spore detection strategies.