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While Moringa oleifera Lam. is gaining importance in Africa, especially sub-Saharan Africa, it is unclear whether research is following the quick pace of its development on the continent. Therefore, this article analyzes the landscape of research dealing with moringa in Africa. This systematic review draws upon 299 eligible articles identified through a search carried out on the Web of Science in April 2023. Research on M. oleifera is rather recent in Africa but interest is increasing among scholars. While the research field is multidisciplinary and cross-sectoral, the literature seems to focus on biological and environmental sciences. Moreover, research is performed mainly in South Africa, Nigeria, Egypt, and Ghana. The analysis suggests a significant potential contribution of moringa to food security and nutrition, climate change mitigation/adaptation, farming systems resilience, and livelihoods. Its versatility and diverse applications and uses make moringa particularly interesting for developing countries, such as African ones. However, this review also underscores some factors hindering its development. Therefore, there is a need to strengthen research on moringa to unlock its potential in Africa. Investments in research, innovation, and development can help address the many challenges that Africa faces and contribute to the transition towards sustainable and resilient food systems.

Motivation: Neoantigen vaccines make use of tumor-specific mutations to enable the patient's immune system to recognize and eliminate cancer. Selecting vaccine elements, however, is a complex task which needs to take into account not only the underlying antigen presentation pathway but also tumor heterogeneity., Results: Here, we present NeoAgDT, a two-step approach consisting of: (i) simulating individual cancer cells to create a digital twin of the patient's tumor cell population and (ii) optimizing the vaccine composition by integer linear programming based on this digital twin. NeoAgDT shows improved selection of experimentally validated neoantigens over ranking-based approaches in a study of seven patients., Availability and Implementation: The NeoAgDT code is published on Github: https://github.com/nec-research/neoagdt., (© The Author(s) 2024. Published by Oxford University Press.)

The highly pathogenic avian influenza viruses of clade 2.3.4.4b have caused unprecedented deaths in South American wild birds, poultry, and marine mammals. In September 2023, pinnipeds and seabirds appeared dead on the Uruguayan Atlantic coast. Sixteen influenza virus strains were characterized by real-time reverse transcription PCR and genome sequencing in samples from sea lions ( Otaria flavescens ), fur seals ( Arctocephalus australis ), and terns ( Sterna hirundinacea ). Phylogenetic and ancestral reconstruction analysis showed that these strains have pinnipeds most likely as the ancestral host, representing a recent introduction of clade 2.3.4.4b in Uruguay. The Uruguayan and closely related strains from Peru (sea lions) and Chile (sea lions and a human case) carry mammalian adaptative residues 591K and 701N in the viral polymerase basic protein 2 (PB2). Our findings suggest that clade 2.3.4.4b strains in South America may have spread from mammals to mammals and seabirds, revealing a new transmission route., Competing Interests: None declared., (© The Author(s) 2024. Published by Oxford University Press.)

Despite being an increasingly important source of genes for crop breeding aimed at improving food security and climate change adaptation, crop wild relatives (CWRs) are globally threatened. A root cause of CWR conservation challenges is a lack of institutions and payment mechanisms by which the beneficiaries of CWR conservation services (such as breeders) could compensate those who can supply them. Given that CWR conservation generates important public good values, for the significant proportion of CWRs found outside of protected areas, there is a strong justification for the design of incentive mechanisms to support landowners whose management practices positively contribute to CWR conservation. This paper contributes to facilitating an improved understanding of the costs of in situ CWR conservation incentive mechanisms, based on a case study application of payments for agrobiodiversity conservation services across 13 community groups in three districts in Malawi. Results demonstrate a high willingness to participate in conservation activities, with average conservation tender bids per community group being a modest MWK 20,000 (USD 25) p.a. and covering 22 species of CWRs across 17 related crops. As such, there appears to be significant potential for community engagement in CWR conservation activities that is complementary to that required in protected areas and can be achieved at modest cost where appropriate incentive mechanisms can be implemented.

Gene therapy of Usher syndrome type 1B (USH1B) due to mutations in the large Myosin VIIA ( MYO7A ) gene is limited by the packaging capacity of adeno-associated viral (AAV) vectors. To overcome this, we have previously developed dual AAV8 vectors which encode human MYO7A (dual AAV8. MYO7A ). Here we show that subretinal administration of 1.37E+9 to 1.37E+10 genome copies of a good-manufacturing-practice-like lot of dual AAV8. MYO7A improves the retinal defects of a mouse model of USH1B. The same lot was used in non-human primates at doses 1.6× and 4.3× the highest dose proposed for the clinical trial which was based on mouse efficacy data. Long-lasting alterations in retinal function and morphology were observed following subretinal administration of dual AAV8. MYO7A at the high dose. These findings were modest and improved over time in the low-dose group, as also observed in other studies involving the use of AAV8 in non-human primates and humans. Biodistribution and shedding studies confirmed the presence of vector DNA mainly in the visual pathway. Accordingly, we detected human MYO7A mRNA expression predominantly in the retina. Overall, these studies pave the way for the clinical translation of subretinal administration of dual AAV vectors in USH1B subjects., Competing Interests: A.A. is Scientific Founder and Chief Scientific Officer of AAVantgarde BIO Srl, a company that has licensed dual AAV8.MYO7A and is further developing this program into the clinic. R.F. is currently an employee of AAVantgarde BIO Srl. J.-B.M. is an employee of Genosafe, a contract research organization involved in the further development of this program into the clinic. M.F., A.N., F.G., and V.A. are employees of Reithera Srl, a contract development and manufacturing organization involved in the further development of this program into the clinic. S.C. is Scientific Founder and Chief of Technology of Reithera Srl., (© 2023 The Authors.)

Motivation: We present a multi-sequence generalization of Variational Information Bottleneck and call the resulting model Attentive Variational Information Bottleneck (AVIB). Our AVIB model leverages multi-head self-attention to implicitly approximate a posterior distribution over latent encodings conditioned on multiple input sequences. We apply AVIB to a fundamental immuno-oncology problem: predicting the interactions between T-cell receptors (TCRs) and peptides., Results: Experimental results on various datasets show that AVIB significantly outperforms state-of-the-art methods for TCR-peptide interaction prediction. Additionally, we show that the latent posterior distribution learned by AVIB is particularly effective for the unsupervised detection of out-of-distribution amino acid sequences., Availability and Implementation: The code and the data used for this study are publicly available at: https://github.com/nec-research/vibtcr., Supplementary Information: Supplementary data are available at Bioinformatics online., (© The Author(s) 2022. Published by Oxford University Press.)

Several recent studies investigate TCR-peptide/-pMHC binding prediction using machine learning or deep learning approaches. Many of these methods achieve impressive results on test sets, which include peptide sequences that are also included in the training set. In this work, we investigate how state-of-the-art deep learning models for TCR-peptide/-pMHC binding prediction generalize to unseen peptides. We create a dataset including positive samples from IEDB, VDJdb, McPAS-TCR, and the MIRA set, as well as negative samples from both randomization and 10X Genomics assays. We name this collection of samples TChard . We propose the hard split , a simple heuristic for training/test split, which ensures that test samples exclusively present peptides that do not belong to the training set. We investigate the effect of different training/test splitting techniques on the models' test performance, as well as the effect of training and testing the models using mismatched negative samples generated randomly, in addition to the negative samples derived from assays. Our results show that modern deep learning methods fail to generalize to unseen peptides. We provide an explanation why this happens and verify our hypothesis on the TChard dataset. We then conclude that robust prediction of TCR recognition is still far for being solved., Competing Interests: Authors FG, AM, PM and IA are employed by NEC Laboratories Europe. KL and MM are employed by NEC Laboratories America. The remaining author declares that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Grazioli, Mösch, Machart, Li, Alqassem, O’Donnell and Min.)

Scientific research is shedding light on the interaction of the gut microbiome with the human host and on its role in human health. Existing machine learning methods have shown great potential in discriminating healthy from diseased microbiome states. Most of them leverage shotgun metagenomic sequencing to extract gut microbial species-relative abundances or strain-level markers. Each of these gut microbial profiling modalities showed diagnostic potential when tested separately; however, no existing approach combines them in a single predictive framework. Here, we propose the Multimodal Variational Information Bottleneck (MVIB), a novel deep learning model capable of learning a joint representation of multiple heterogeneous data modalities. MVIB achieves competitive classification performance while being faster than existing methods. Additionally, MVIB offers interpretable results. Our model adopts an information theoretic interpretation of deep neural networks and computes a joint stochastic encoding of different input data modalities. We use MVIB to predict whether human hosts are affected by a certain disease by jointly analysing gut microbial species-relative abundances and strain-level markers. MVIB is evaluated on human gut metagenomic samples from 11 publicly available disease cohorts covering 6 different diseases. We achieve high performance (0.80 < ROC AUC < 0.95) on 5 cohorts and at least medium performance on the remaining ones. We adopt a saliency technique to interpret the output of MVIB and identify the most relevant microbial species and strain-level markers to the model's predictions. We also perform cross-study generalisation experiments, where we train and test MVIB on different cohorts of the same disease, and overall we achieve comparable results to the baseline approach, i.e. the Random Forest. Further, we evaluate our model by adding metabolomic data derived from mass spectrometry as a third input modality. Our method is scalable with respect to input data modalities and has an average training time of < 1.4 seconds. The source code and the datasets used in this work are publicly available., Competing Interests: The authors have declared that no competing interests exist.

Background: Ethnobotanical field studies concerning migrant groups are crucial for understanding temporal changes of folk plant knowledge as well as for analyzing adaptation processes. Italy still lacks in-depth studies on migrant food habits that also evaluate the ingredients which newcomers use in their domestic culinary and herbal practices., Methods: Semi-structured and open in-depth interviews were conducted with 104 first- and second-generation migrants belonging to the Albanian and Moroccan communities living in Turin and Bra, NW Italy. The sample included both ethnic groups and genders equally., Results: While the number of plant ingredients was similar in the two communities (44 plant items among Albanians vs 47 plant items among Moroccans), data diverged remarkably on three trajectories: (a) frequency of quotation (a large majority of the ingredients were frequently or moderately mentioned by Moroccan migrants whereas Albanians rarely mentioned them as still in use in Italy); (b) ways through which the home country plant ingredients were acquired (while most of the ingredients were purchased by Moroccans in local markets and shops, ingredients used by Albanians were for the most part informally "imported" during family visits from Albania); (c) quantitative and qualitative differences in the plant reports mentioned by the two communities, with plant reports recorded in the domestic arena of Moroccans nearly doubling the reports recorded among Albanians and most of the plant ingredients mentioned by Moroccans representing "medicinal foods"., Conclusion: A large portion of the differences shown by the two communities are linked to different methods of procurement of home country gastronomic botanical ingredients, the different transnational informal exchanges that exist between Italy and migrants' home countries, the presence of markets and ethnic shops in Italy selling these items, and the different degree of difficulty in accessing public health services. The observed divergences were also clearly related to very diverse adaptation strategies, i.e., processes of negotiating and elaborating Albanian and Moroccan cultural identities.

Background and Objectives: Missed visits are common in office-based buprenorphine treatment (OBOT). The feasibility of text message (TM) appointment reminders among OBOT patients is unknown., Methods: This 6-month prospective cohort study provided TM reminders to OBOT program patients (N = 93). A feasibility survey was completed following delivery of TM reminders and at 6 months., Results: Respondents reported that the reminders should be provided to all OBOT patients (100%) and helped them to adhere to their scheduled appointment (97%). At 6 months, there were no reports of intrusion to their privacy or disruption of daily activities due to the TM reminders. Most participants reported that the TM reminders were helpful in adhering to scheduled appointments (95%), that the reminders should be offered to all clinic patients (95%), and favored receiving only TM reminders rather than telephone reminders (95%). Barriers to adhering to scheduled appointment times included transportation difficulties (34%), not being able to take time off from school or work (31%), long clinic wait-times (9%), being hospitalized or sick (8%), feeling sad or depressed (6%), and child care (6%)., Conclusions: This study demonstrated the acceptability and feasibility of TM appointment reminders in OBOT. Older age and longer duration in buprenorphine treatment did not diminish interest in receiving the TM intervention. Although OBOT patients expressed concern regarding the privacy of TM content sent from their providers, privacy issues were uncommon among this cohort. Scientific Significance Findings from this study highlighted patient barriers to adherence to scheduled appointments. These barriers included transportation difficulties (34%), not being able to take time off from school or work (31%), long clinic lines (9%), and other factors that may confound the effect of future TM appointment reminder interventions. Further research is also required to assess 1) the level of system changes required to integrate TM appointment reminder tools with already existing electronic medical records and appointment records software; 2) acceptability among clinicians and administrators; and 3) financial and resource constraints to healthcare systems. (Am J Addict 2017;26:581-586)., (© 2017 American Academy of Addiction Psychiatry.)

Unlabelled: Adenoviral vectors encoding hepatitis C virus (HCV) nonstructural (NS) proteins induce multispecific, high-magnitude, durable CD4(+) and CD8(+) T-cell responses in healthy volunteers. We assessed the capacity of these vaccines to induce functional HCV-specific immune responses and determine T-cell cross-reactivity to endogenous virus in patients with chronic HCV infection. HCV genotype 1-infected patients were vaccinated using heterologous adenoviral vectors (ChAd3-NSmut and Ad6-NSmut) encoding HCV NS proteins in a dose escalation, prime-boost regimen, with and without concomitant pegylated interferon-α/ribavirin therapy. Analysis of immune responses ex vivo used human leukocyte antigen class I pentamers, intracellular cytokine staining, and fine mapping in interferon-γ enzyme-linked immunospot assays. Cross-reactivity of T cells with population and endogenous viral variants was determined following viral sequence analysis. Compared to healthy volunteers, the magnitude of HCV-specific T-cell responses following vaccination was markedly reduced. CD8(+) HCV-specific T-cell responses were detected in 15/24 patients at the highest dose, whereas CD4(+) T-cell responses were rarely detectable. Analysis of the host circulating viral sequence showed that T-cell responses were rarely elicited when there was sequence homology between vaccine immunogen and endogenous virus. In contrast, T cells were induced in the context of genetic mismatch between vaccine immunogen and endogenous virus; however, these commonly failed to recognize circulating epitope variants and had a distinct partially functional phenotype. Vaccination was well tolerated but had no significant effect on HCV viral load., Conclusion: Vaccination with potent HCV adenoviral vectored vaccines fails to restore T-cell immunity except where there is genetic mismatch between vaccine immunogen and endogenous virus; this highlights the major challenge of overcoming T-cell exhaustion in the context of persistent antigen exposure with implications for cancer and other persistent infections., (© 2015 The Authors. HEPATOLOGY published by Wiley Periodicals, Inc., on behalf of the American Association for the Study of Liver Diseases.)

Respiratory Syncytial Virus (RSV) is a leading cause of severe respiratory disease in infants and the elderly. No vaccine is presently available to address this major unmet medical need. We generated a new genetic vaccine based on chimpanzee Adenovirus (PanAd3-RSV) and Modified Vaccinia Ankara RSV (MVA-RSV) encoding the F, N, and M2-1 proteins of RSV, for the induction of neutralizing antibodies and broad cellular immunity. Because RSV infection is restricted to the respiratory tract, we compared intranasal (IN) and intramuscular (M) administration for safety, immunogenicity, and efficacy in different species. A single IN or IM vaccination completely protected BALB/c mice and cotton rats against RSV replication in the lungs. However, only IN administration could prevent infection in the upper respiratory tract. IM vaccination with MVA-RSV also protected cotton rats from lower respiratory tract infection in the absence of detectable neutralizing antibodies. Heterologous prime boost with PanAd3-RSV and MVA-RSV elicited high neutralizing antibody titers and broad T-cell responses in nonhuman primates. In addition, animals primed in the nose developed mucosal IgA against the F protein. In conclusion, we have shown that our vectored RSV vaccine induces potent cellular and humoral responses in a primate model, providing strong support for clinical testing.

A protective vaccine against hepatitis C virus (HCV) remains an unmet clinical need. HCV infects millions of people worldwide and is a leading cause of liver cirrhosis and hepatocellular cancer. Animal challenge experiments, immunogenetics studies, and assessment of host immunity during acute infection highlight the critical role that effective T cell immunity plays in viral control. In this first-in-man study, we have induced antiviral immunity with functional characteristics analogous to those associated with viral control in natural infection, and improved upon a vaccine based on adenoviral vectors alone. We assessed a heterologous prime-boost vaccination strategy based on a replicative defective simian adenoviral vector (ChAd3) and modified vaccinia Ankara (MVA) vector encoding the NS3, NS4, NS5A, and NS5B proteins of HCV genotype 1b. Analysis used single-cell mass cytometry and human leukocyte antigen class I peptide tetramer technology in healthy human volunteers. We show that HCV-specific T cells induced by ChAd3 are optimally boosted with MVA, and generate very high levels of both CD8(+) and CD4(+) HCV-specific T cells targeting multiple HCV antigens. Sustained memory and effector T cell populations are generated, and T cell memory evolved over time with improvement of quality (proliferation and polyfunctionality) after heterologous MVA boost. We have developed an HCV vaccine strategy, with durable, broad, sustained, and balanced T cell responses, characteristic of those associated with viral control, paving the way for the first efficacy studies of a prophylactic HCV vaccine., (Copyright © 2014, American Association for the Advancement of Science.)

Ebolavirus disease causes high mortality, and the current outbreak has spread unabated through West Africa. Human adenovirus type 5 vectors (rAd5) encoding ebolavirus glycoprotein (GP) generate protective immunity against acute lethal Zaire ebolavirus (EBOV) challenge in macaques, but fail to protect animals immune to Ad5, suggesting natural Ad5 exposure may limit vaccine efficacy in humans. Here we show that a chimpanzee-derived replication-defective adenovirus (ChAd) vaccine also rapidly induced uniform protection against acute lethal EBOV challenge in macaques. Because protection waned over several months, we boosted ChAd3 with modified vaccinia Ankara (MVA) and generated, for the first time, durable protection against lethal EBOV challenge.

Despite viral vectors being potent inducers of antigen-specific T cells, strategies to further improve their immunogenicity are actively pursued. Of the numerous approaches investigated, fusion of the encoded antigen to major histocompatibility complex class II-associated invariant chain (Ii) has been reported to enhance CD8(+) T-cell responses. We have previously shown that adenovirus vaccine encoding nonstructural (NS) hepatitis C virus (HCV) proteins induces potent T-cell responses in humans. However, even higher T-cell responses might be required to achieve efficacy against different HCV genotypes or therapeutic effect in chronically infected HCV patients. In this study, we assessed fusion of the HCV NS antigen to murine and human Ii expressed by the chimpanzee adenovirus vector ChAd3 or recombinant modified vaccinia Ankara in mice and nonhuman primates (NHPs). A dramatic increase was observed in outbred mice in which vaccination with ChAd3 expressing the fusion antigen resulted in a 10-fold increase in interferon-γ(+) CD8(+) T cells. In NHPs, CD8(+) T-cell responses were enhanced and accelerated with vectors encoding the Ii-fused antigen. These data show for the first time that the enhancement induced by vector vaccines encoding li-fused antigen was not species specific and can be translated from mice to NHPs, opening the way for testing in humans.

Currently, no vaccine exists for hepatitis C virus (HCV), a major pathogen thought to infect 170 million people globally. Many studies suggest that host T cell responses are critical for spontaneous resolution of disease, and preclinical studies have indicated a requirement for T cells in protection against challenge. We aimed to elicit HCV-specific T cells with the potential for protection using a recombinant adenoviral vector strategy in a phase 1 study of healthy human volunteers. Two adenoviral vectors expressing NS proteins from HCV genotype 1B were constructed based on rare serotypes [human adenovirus 6 (Ad6) and chimpanzee adenovirus 3 (ChAd3)]. Both vectors primed T cell responses against HCV proteins; these T cell responses targeted multiple proteins and were capable of recognizing heterologous strains (genotypes 1A and 3A). HCV-specific T cells consisted of both CD4+ and CD8+ T cell subsets; secreted interleukin-2, interferon-γ, and tumor necrosis factor-α; and could be sustained for at least a year after boosting with the heterologous adenoviral vector. Studies using major histocompatibility complex peptide tetramers revealed long-lived central and effector memory pools that retained polyfunctionality and proliferative capacity. These data indicate that an adenoviral vector strategy can induce sustained T cell responses of a magnitude and quality associated with protective immunity and open the way for studies of prophylactic and therapeutic vaccines for HCV.

Replication-defective adenovirus vectors based on human serotype 5 (Ad5) induce protective immune responses against diverse pathogens and cancer in animal models, as well as elicit robust and sustained cellular immunity in humans. However, most humans have neutralizing antibodies to Ad5, which can impair the immunological potency of such vaccines. Here, we show that rare serotypes of human adenoviruses, which should not be neutralized in most humans, are far less potent as vaccine vectors than Ad5 in mice and nonhuman primates, casting doubt on their potential efficacy in humans. To identify novel vaccine carriers suitable for vaccine delivery in humans, we isolated and sequenced more than 1000 adenovirus strains from chimpanzees (ChAd). Replication-defective vectors were generated from a subset of these ChAd serotypes and screened to determine whether they were neutralized by human sera and able to grow in human cell lines. We then ranked these ChAd vectors by immunological potency and found up to a thousandfold variation in potency for CD8+ T cell induction in mice. These ChAd vectors were safe and immunologically potent in phase 1 clinical trials, thereby validating our screening approach. These data suggest that the ChAd vectors developed here represent a large collection of non-cross-reactive, potent vectors that may be exploited for the development of new vaccines.

The aims of this study were to develop a new measure of impulsive aggressiveness, and to assess whether this measure was associated with deficits in mentalized affectivity and adult attachment styles in a sample of 637 non-clinical participants. Extending Fonagy and Bateman's (2004) hypothesis, the mediating role of poor affectivity mentalization in the relationship between insecure attachment styles and impulsive aggression was also evaluated. Selected insecure attachment styles (R2(adjusted) = .18, p < .001) and deficits in mentalized affectivity (R(2)(adjusted) = .25, p < .001) were significantly associated with impulsive aggressiveness. The overall regression model accounted for roughly 33% of the variance in impulsive aggressiveness. Mentalization deficits significantly mediated the effects of attachment styles on impulsive aggressiveness, although effect size measures suggested that only partial mediation occurred.

Objective: The aim of this study was to evaluate the reliability and validity of the Temperament and Character Inventory-Revised (TCI-R) in an outpatient sample., Method: The TCI-R was administered to 404 consecutively admitted subjects. The TCI-R scale 1-month test-retest reliability and TCI-R/TCI convergent validity were assessed in 2 independent subsamples., Results: The TCI-R scales showed adequate Cronbach alpha values and acceptable 1-month test-retest reliability coefficients. Although many TCI-R facets showed factorial complexity, factor analysis results were consistent with the 7-factor structure of the TCI-R scales. The predictive validity of TCI-R profiles for personality disorder diagnoses was confirmed, with different combinations of temperament dimensions being associated with specific personality disorders., Conclusions: The TCI-R was a reliable and valid instrument for assessing temperament and character features, at least among Italian outpatients. The TCI-R psychometric properties support its clinical usefulness in the assessing of personality psychopathology.

The aim of this study is to assess whether impulsive and aggressive traits can be placed on a continuum with DSM-IV Cluster B Personality Disorders (PDs) and to determine if different aspects of these personality traits are specifically associated with individual Cluster B PDs. The study group comprised 461 outpatients admitted consecutively to a clinic that specializes in the diagnosis and treatment of PDs. Principal component analyses clearly suggested a five-factor structure of both normal and psychopathological personality traits. Importantly, measures of impulsivity, aggressiveness and novelty seeking formed a part of the principal component that clustered all Cluster B PDs. Regression analyses indicated that impulsive traits were selectively associated with Borderline PD whereas different aspects of aggressiveness were useful in discriminating Narcissistic PD from Antisocial PD. Sensation seeking traits formed a part of Histrionic PD. These results indicate that impulsive/aggressive traits may be useful in explaining both why Cluster B PDs tend to covary, and why they frequently differ in clinical pictures and courses.

Notwithstanding its research and clinical relevance, the dimensionality and validity of the DSM-IV avoidant, dependent, and obsessive-compulsive personality disorders (PDs) criteria is still a largely unexplored topic. The aim of this study was to test the factor structure for DSM-IV Cluster C PD criteria in a sample of 641 consecutively admitted outpatients. Factor analysis results suggested that avoidant, dependent, and obsessive-compulsive PDs share a common latent dimension, and supported the three-factor structure of both observer and self-report ratings of DSM-IV Cluster C PD criteria. The pattern of factor loadings, however, was different from the one expected according to the DSM-IV classification.

The aim of this study was to examine the latent structure of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV), Narcissistic Personality Disorder (NPD) criteria in a group of 641 outpatients. The consecutively admitted outpatients were administered the Structured Clinical Interview for DSM-IV Axis II Personality Disorders, Version 2.0, and the Personality Questionnaire. Both confirmatory and exploratory factor analyses (CFA and EFA, respectively) were used to evaluate whether the NPD criteria measure a single latent trait. Latent class analysis was used to assess the diagnostic accuracy of the individual DSM-IV NPD criteria. Mean above minus below a cut (MAMBAC) and maximum covariance (MAXCOV) taxometric analyses were used to evaluate whether the latent distribution of the DSM-IV NPD features is actually discrete. Both CFA and EFA results showed that the 9 DSM-IV NPD criteria loaded on 2 correlated factors. The latent class analysis results suggested a 3-class solution for NPD criteria; relevant differences in diagnostic efficiency were observed among the NPD criteria. MAMBAC and MAXCOV analyses provided consistent evidence of taxonic (ie, discrete) latent structure for NPD. This study gave only partial support to the validity of the DSM-IV NPD construct. Taxometric analyses indicated that a typological model is appropriate for describing NPD, but CFA and EFA suggested the existence of 2 distinct-albeit correlated-clusters of narcissistic features. As a whole, the DSM-IV criteria discriminated NPD from other personality disorders, but diagnostic accuracy statistics did not replicate the rank order of diagnostic efficiency of NPD criteria proposed by the DSM-IV.