A qui administrer le vaccin anti-pneumococcique? [We should received and pneumococcal immunization?]

Alors que l'immunisation active contre l'influenza semble être actuellement largement entrée dans la pratique médicale, force est de constater que c'est loin d'être le cas pour les infections à pneumocoque. La vaccination anti-pneumocoque. La vaccination anti-pneumococcique, qui est incluse dans les schémas d'immunisation de nombreux pays, ne fait actuellement pas l'objet de recommendations particulières en Suisse et son utilisation y reste marginale. Compte tenu du nombre élevé d'infections sévères et de décès potentiellement évitables, sa généralisation à tous les groupes à risque doit être encouragée. De plus, cette stratégie pourrait se révéler utile face à la progression inexorable de la proportion de souches résistantes à la pénicilline et aux autres microbes.

Ex vivo analysis of human antigen-specific CD8+ T-cell responses: quality assessment of fluorescent HLA-A2 multimer and interferon-gamma ELISPOT assays for patient immune monitoring.

The authors developed a standardized approach for immune monitoring of antigen-specific CD8+ T cells within peripheral blood lymphocytes (PBLs) that combines direct ex vivo analysis of Melan-A/MART-1 and influenza-specific CD8+ T cells with HLA-A2/peptide multimers and interferon-gamma ELISPOT assays. Here the authors assessed the quality of results obtained with 180 PBLs from healthy donors and melanoma patients. Reproducibility of the multimer assay was good (average of 15% variation). In the absence of in vivo antigen-specific T-cell responses, physiologic fluctuations of multimer-positive T cells was low, with variation coefficients of 20% for Melan-A and 28% for influenza-specific T cells. In contrast, patients with vaccination-induced T-cell responses had significantly increased T-cell frequencies clearly exceeding physiologic fluctuations. Comparable results were obtained with ELISPOT assays. In conclusion, this approach is well suited to assess T-cell responses as biologic endpoints in clinical vaccine studies.

Analysis of viral- and tumor antigen-specific CD4 T cell responses in healthy donors and melanoma patients

Résumé Des tentatives pour développer des traitements anti-cancéreux basés sur l'utilisation d'antigènes tumoraux ont commencé il y a plus de 10 ans. Depuis quelques années, un certain intérêt s'est portée sur une sous-population particulière des cellules du système immunitaire, les lymphocytes T CD4. Ces cellules jouent un rôle central dans les réponses immunitaires tant contre les virus que contre les cellules tumorales. Comme d'autres lymphocytes T, ces cellules sont activées de manière spécifique en reconnaissant un morceau d'antigène, appelé peptide. Ces peptides proviennent soit de protéines des cellules de l'hôte, soit des protéines étrangères (virus ou bactéries) soit de cellules transformées (cellules tumorales) et sont présentés aux lymphocytes T par des molécules du soi appelées CMH (complexe majeur d'histocompatibilité). Dans le cas des lymphocytes T CD4, ces molécules sont plus précisément des molécules du CMH de classe II (CMH II). Mis à part l'intérêt porté aux réponses médiées par les lymphocytes T cytotoxiques, un intérêt croissant pour les lymphocytes T CD4 s'est développé à cause de la place centrale qu'occupent ces cellules dans les réponses immunitaires. L'identification d'épitopes présentés par des molécules du CMH de classe II dérivés d'un grand nombre d'antigènes tumoraux, ainsi que le développement de techniques permettant de suivre les réponses immunitaires, offre des opportunités pour étudier de manière quantitative et qualitative les lymphocytes T CD4 spécifiques pour un antigène particulier chez des patients cancéreux. De plus, ces épitopes permettent d'induire des réponses médiées par les lymphocytes T CD4 et CD8 chez ces mêmes patients. Dans ce travail, notre premier but était de valider l'utilisation de multimères formés par des complexes peptide:molécules de CMH de class II (pCMH II) pour quantifier la réponse des cellules T CD4 dirigée contre l'épitope HA307-319 dérivé de la protéine hémaglutinine du virus de la grippe et présenté par HLA-DRB1*0401. En analysant des échantillons provenant de volontaires sains ayant reçus un vaccin contre la grippe, nous avons pu démontrer une expansion et une activation transitoires des lymphocytes T CD4 spécifiques pour le peptide HA307-319 après vaccination. De plus, les multimères pCMH II nous ont permis d'analyser plus en détails hétérogénéité des cellules T CD4 spécifiques pour le peptide HA307-319 présents dans le sang périphérique d'individus sains. Par la suite, notre but a été d'analyser les réponses des lymphocytes T CD4 spécifiques pour l'antigène Melan-A chez des patients atteints de mélanome métastatique. Nous avons tout d'abord démontré la présence de cellules T CD4 spécifiques pour l'épitope Melan-A51-73, présenté par HLA-DRBl*0401, qui avait déjà été préalablement décrit. Ensuite, nous avons décrit et caractérisé 2 nouveaux peptides issus de Melan-A qui sont présentés aux cellules T CD4 par différentes molécules du CMH de clans II. Des cellules spécifiques pour ces deux épitopes ont été trouvées chez 9/ 16 patients analysés. De plus, des multimères pCMH II chargés avec un des épitopes nous ont permis de détecter ex vivo des lymphocytes T CD4 spécifiques pour Melan-A dans le sang périphérique d'un patient atteint de mélanome. Mis ensemble, tous ces résultats suggèrent une potentielle utilisation des multimères pCMH II pour analyser en détail les lymphocytes T CD4 spécifiques d'antigènes définis. Cependant, le suivi ex vivo de telles cellules ne semble être possible que dans des cas bien particuliers. Néanmoins, les nouveaux épitopes issus de Melan-A et présentés par des molécules du CMH de classe II que nous avons décrits dans cette étude aideront à étudier plus en détails les lymphocytes T CD4 spécifiques pour Melan-A chez des patients atteints de mélanome, un sujet d'étude sur lequel peu de résultats sont à ce jour disponibles. Summary Attempts to develop cancer vaccines based on molecularly defined tumorassociated antigens were initiated more than 10 years ago. Apart from CTLmediated anti-tumor immunity, interests are. now focused on CD4 T cells that are central players of immune responses. The identification of MHC class-II-restricted epitopes from numerous tumor antigens together with the development of monitoring tools offers the opportunity to quantitatively and qualitatively study antigen-specific CD4 T lymphocytes in cancer patients and to induce both CTL and T helper responses in cancer patients. In this work, we first aimed at validating the use of peptide:MHC class II complex (pMHC II) multimers to quantitate the CD4 T cell response against the hemagglutinin-derived epitope HAso~-si9 from influenza virus presented by HLA-DRBl*0401. By analysing samples from healthy volunteers vaccinated with ananti-influenza vaccine, we could demonstrate a transient expansion and activation of HA-specific CD4 T cells after treatment. Moreover, pMHC II multimers helped us to study the heterogeneity of HAspecific CD4 T cells found in peripheral blood of healthy individuals. Then, we aimed to analyse Melan-A-specific CD4 T cell responses in metastatic melanoma patients. We first demonstrated the presence of CD4 T cells specific for the previously described Melan-A51_73 epitope presented by HLA-DRB 1 *0401 in peripheral blood of those patients. Second, we described and characterised 2 new Melan-A-derived peptides that are presented by different MHC II molecules to CD4 T cells. Specific cells for these epitopes were found in 9/ 16 rnelánoma patients analysed. In addition, pMHC II multimers loaded with one of the two epitopes allowed us to detect ex vivo Melan-A-specific CD4 T cells in peripheral blood of a melanoma patient. Together, these results suggest a potential use of pMHC II multimers in analysing in detail antigen-specific CD4 T cells. However, ex vivo monitoring of such cells will be possible only in particular conditions. Nevertheless, the new Melan-A-derived MHC II-restricted epitopes described here will help to study in more detail Melan-A-specific CD4 T cells in melanoma patients, a field where only scarce data are available.

Hepatitis E virus: a zoonosis adapting to humans.

Hepatitis E virus (HEV) infection is gaining global attention, not only because of the increasing burden of the disease in low endemicity countries, in terms of morbidity and mortality rates, but also due to recent advances in the molecular virology and epidemiology of this emerging pathogen. HEV infection spread can be described as the evolution of a zoonosis towards an established human infection. As known from other viruses, such as the human immunodeficiency virus or the influenza viruses, crossing the species barriers from animals to humans is a recurrent phenomenon. Albeit slow at the beginning, once the virus has adapted to humans, the person-to-person spread can proceed very quickly. Although an optimal cell culture system for HEV is not yet available, outstanding progress has been made with the in vitro expression of HEV-like particles. These new tools have fostered new research to understand the molecular, structural and immunological aspects of human HEV infection. Although some promising data from Phase II vaccine trials are available, recent discoveries will certainly open new avenues for HEV-specific prophylaxis and therapy.

Reversible major histocompatibility complex I-peptide multimers containing Ni(2+)-nitrilotriacetic acid peptides and histidine tags improve analysis and sorting of CD8(+) T cells.

MHC-peptide multimers containing biotinylated MHC-peptide complexes bound to phycoerythrin (PE) streptavidin (SA) are widely used for analyzing and sorting antigen-specific T cells. Here we describe alternative T cell-staining reagents that are superior to conventional reagents. They are built on reversible chelate complexes of Ni(2+)-nitrilotriacetic acid (NTA) with oligohistidines. We synthesized biotinylated linear mono-, di-, and tetra-NTA compounds using conventional solid phase peptide chemistry and studied their interaction with HLA-A*0201-peptide complexes containing a His(6), His(12), or 2×His(6) tag by surface plasmon resonance on SA-coated sensor chips and equilibrium dialysis. The binding avidity increased in the order His(6) < His(12) < 2×His(6) and NTA(1) < NTA(2) < NTA(4), respectively, depending on the configuration of the NTA moieties and increased to picomolar K(D) for the combination of a 2×His(6) tag and a 2×Ni(2+)-NTA(2). We demonstrate that HLA-A2-2×His(6)-peptide multimers containing either Ni(2+)-NTA(4)-biotin and PE-SA- or PE-NTA(4)-stained influenza and Melan A-specific CD8+ T cells equal or better than conventional multimers. Although these complexes were highly stable, they very rapidly dissociated in the presence of imidazole, which allowed sorting of bona fide antigen-specific CD8+ T cells without inducing T cell death as well as assessment of HLA-A2-peptide monomer dissociation kinetics on CD8+ T cells.

Prevalence of respiratory viruses among febrile children with or without acute respiratory symptoms in Tanzania

Background Respiratory viruses are the most frequent cause of febrile illnesses in infants and young children but few investigations have assessed their impact and epidemiology in Africa . We investigated their rate in febrile outpatient children attending in Tanzania. Methods Children aged 2 months -10 years with fever >38 _C were recruited prospectively between April and December 2008. Medical history and clinical examination were recorded in a standardized fashion and nasopharyngeal swabs analyzed for the presence of 12 viruses by real-time PCR (FLUAV, FLUBV, RSV, MPV, HPIV-1/3, four types of HCoV, HBoV, PIC and HAdV). Ct values were used to provide semi-quantitative viral loads.Results Of 1005 febrile children enrolled, 623 (62%) had respiratory symptoms (URTI in 66%, bronchiolitis in 7% and clinical pneumonia in 27%); 156 (16%) had febrile illness that remained of unspecified etiology and 226 (22%) had other infectious diseases and no ARI (62 malaria, 56 gastroenteritis, 36 urinary tract and 72 others). The proportions of patients with at least one respiratory virus were 70%, 61% and 47% (Pvalue < 0.001) in these three groups. When excluding picornavirus and adenovirus these proportions were 48%, 24% and 26% (P-value < 0.001). Apart from picornavirus and adenovirus, influenza A and B viruses were the most frequent followed by coronavirus and RSV. The proportion of children with presumably high viral titers (Ct < 25) was higher in the group with respiratory symptoms (31%) than in the two other groups (21% and 16%). Influenza genotyping revealed strains that were similar to the ones circulating elsewhere in the world.Conclusion In African children with febrile illness, the prevalence of respiratory viruses, especially influenza A and B, is high particularly in the presence of respiratory symptoms, but also, although less so, in those with unspecified etiology or other infectious diseases. This highlights that these viruses are commonly circulating in Tanzanian children.

Cross-neutralization of four paramyxoviruses by a human monoclonal antibody.

Broadly neutralizing antibodies reactive against most and even all variants of the same viral species have been described for influenza and HIV-1 (ref. 1). However, whether a neutralizing antibody could have the breadth of range to target different viral species was unknown. Human respiratory syncytial virus (HRSV) and human metapneumovirus (HMPV) are common pathogens that cause severe disease in premature newborns, hospitalized children and immune-compromised patients, and play a role in asthma exacerbations. Although antisera generated against either HRSV or HMPV are not cross-neutralizing, we speculated that, because of the repeated exposure to these viruses, cross-neutralizing antibodies may be selected in some individuals. Here we describe a human monoclonal antibody (MPE8) that potently cross-neutralizes HRSV and HMPV as well as two animal paramyxoviruses: bovine RSV (BRSV) and pneumonia virus of mice (PVM). In its germline configuration, MPE8 is HRSV-specific and its breadth is achieved by somatic mutations in the light chain variable region. MPE8 did not result in the selection of viral escape mutants that evaded antibody targeting and showed potent prophylactic efficacy in animal models of HRSV and HMPV infection, as well as prophylactic and therapeutic efficacy in the more relevant model of lethal PVM infection. The core epitope of MPE8 was mapped on two highly conserved anti-parallel β-strands on the pre-fusion viral F protein, which are rearranged in the post-fusion F protein conformation. Twenty-six out of the thirty HRSV-specific neutralizing antibodies isolated were also found to be specific for the pre-fusion F protein. Taken together, these results indicate that MPE8 might be used for the prophylaxis and therapy of severe HRSV and HMPV infections and identify the pre-fusion F protein as a candidate HRSV vaccine.

Kanainfluenssa

Summary: Avian influenza

Revue de la littérature 2013--les neuropathies inflammatoires [2013: what's new in inflammatory neuropathies].

Several high-quality publications were published in 2013 and some major trials studies were started. In Guillain-Barré syndrome, events included the launch of IGOS and a better understanding of diagnostic limits, the effect of influenza vaccination, and better care, but uncertainty remains about analgesics. A new mouse model was also described. In chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), diagnostic pitfalls can be recalled. Our knowledge of underlying pathophysiological processes has improved, and the value of monitoring with function and deficit scores has been demonstrated. IVIG can sometimes be effective longer than expected, but CIDP remains sensitive to corticosteroids, particularly with the long-term beneficial effects of megadose dexamethasone. The impact of fingolimod remains to be demonstrated in an ongoing trial. Advances concerning multifocal motor neuropathy, inflammatory plexopathy, and neuropathy with anti -MAG activity are discussed but treatments already recognized as effective should not be changed. Imaging of peripheral nerve progresses.

Socioeconomics status and quality of care in a population-based sample of swiss diabetic patients

Introduction: Low socioeconomic status (SES) is associated with higher prevalence of diabetes and worse outcomes; it has also been shown to be associated with worse quality of care. We aimed to explore the relationship between SES and quality of care in the Swiss context. Methods: We used data from a population-based survey including 519 adult diabetic patients living in the canton of Vaud. Self-reported data on patients' and diabetes characteristics, indicators of process and outcomes of care and quality of life were collected. Dependent variables included 6 processes of care (PoC) received during the last 12 months (HbA1C, lipid, microalbuminuria, fundoscopy, feet examination and influenza vaccination) and selected clinical outcomes (blood pressure, LDL, HbA1C, diabetes-specific (ADDQoL) and generic quality of life (SF-12)). Regression analyses were performed to assess the relationship between education and income, respectively, and quality of care as measured by PoC and clinical outcomes. Adjustment was made for age, gender and comorbidities. Results: Mean age was 64.5 years, 40% were women; 19%, 56% and 25% of the patients reported primary (I), secondary (II) and tertiary (III) education. Fundoscopy was the only PoC significantly associated with education, with III education patients more likely to get the exam than those with primary education (adjOR 1.8, 95% CI 1.0-3.3). Use of composite indicators of PoC showed that compared to patients with primary education, patients with III education were more likely to receive ≥5/6 PoC (adjOR 1.9, 95% CI 1.1-3.4), and that those with II or III education were more likely to receive 4/4 PoC (adjOR 1.9, 95% CI 1.0-3.3; adjOR 2.1, 95% CI 1.1-4.1, respectively). Quality of life was the only clinical outcome significantly associated with education, with II and III education patients reporting better quality of life compared to primary education patients, as measured by the ADDQoL (β 0.6, 95% CI 0.3-1.0, β 0.6, 95% CI 0.2-1.0, respectively) and the physical component score of the SF-12 (β 2.5, 95% CI 0.2-4.8, β 3.6, 95% CI 0.9-6.4, respectively). No associations were found between income and quality of care. Conclusion: Social inequalities have been demonstrated in Switzerland for global health indicators. Our results suggest that similar associations are found when considering quality of care measures in individuals with diabetes, but only for a few indicators.

Functional glycosylation of dystroglycan is crucial for thymocyte development in the mouse.

BACKGROUND: Alpha-dystroglycan (alpha-DG) is a cell surface receptor providing a molecular link between the extracellular matrix (ECM) and the actin-based cytoskeleton. During its biosynthesis, alpha-DG undergoes specific and unusual O-glycosylation crucial for its function as a high-affinity cellular receptor for ECM proteins. METHODOLOGY/PRINCIPAL FINDINGS: We report that expression of functionally glycosylated alpha-DG during thymic development is tightly regulated in developing T cells and largely confined to CD4(-)CD8(-) double negative (DN) thymocytes. Ablation of DG in T cells had no effect on proliferation, migration or effector function but did reduce the size of the thymus due to a significant loss in absolute numbers of thymocytes. While numbers of DN thymocytes appeared normal, a marked reduction in CD4(+)CD8(+) double positive (DP) thymocytes occurred. In the periphery mature naïve T cells deficient in DG showed both normal proliferation in response to allogeneic cells and normal migration, effector and memory T cell function when tested in acute infection of mice with either lymphocytic choriomeningitis virus (LCMV) or influenza virus. CONCLUSIONS/SIGNIFICANCE: Our study demonstrates that DG function is modulated by glycosylation during T cell development in vivo and that DG is essential for normal development and differentiation of T cells.

Diabetic patients who report receiving processes of diabetic care do not express a better quality of life

Background: Chronic disease management initiatives emphasize patient-centered care, and quality of life (QoL) is increasingly considered a representative outcome in that context. In this study we evaluated the association between receipt of processes of diabetic care and QoL. Methods: This cross-sectional population-based study (2011) used self-reported data from non-institutionalized, adult diabetics, recruited from randomly selected community pharmacies in Vaud. Outcomes included the physical and mental composites of the SF-36 (PCS, MCS) and the disease-specific Audit of Diabetes-Dependent QoL (ADDQoL). Main exposure variables were receipt of six diabetes processes-of care in the past 12 months. We also evaluated whether the association between care received and QoL was congruent with the chronic care model, when assessed by the Patient Assessment of Chronic Illness Care (PACIC). We used linear regressions to examine the association between process measures and the three composites of health-related QoL. Analyses were adjusted for age, gender, socioeconomic status, living companion, BMI, alcohol, smoking, physical activity, co-morbidities and diabetes mellitus (DM) characteristics (type, insulin use, complications, duration). Results: Mean age of the 519 diabetic patients was 64.4 years (SD 11.3), 60% were male and 73% had a living companion; 87% reported type 2 DM, half of respondents required insulin treatment, 48% had at least one DM complication, and 48% had DM over 10 years. Crude overall mean QoL scores were PCS: 43.4 (SD 10.5), MCS: 47.0 (SD 11.2) and ADDQoL: -1.56 (SD 1.6). In bivariate analyses, patients who received the influenza vaccine versus those who did not, had lower ADDQoL and PCS scores; there were no other indicator differences. In adjusted models including all processes, receipt of influenza vaccine was associated with lower ADDQoL (β= - 0.41, p=.01); there were no other associations between process indicators and QoL composites. There was no process association even when these were reported as combined measures of processes of care. PACIC score was associated only with the MCS (β= 1.57, p=.004). Conclusions: Process indicators for diabetes care did not show an association with QoL. This may represent an effect lag time between time of process received and quality of life; or that treatment may be related with inconvenience and patient worry. Further research is needed to explore these unexpected findings.

Upper and lower respiratory tract viral infections and acute graft rejection in lung transplant recipients.

Background: Lung transplant recipients are frequently exposed to respiratory viruses and are particularly at risk for severe complications. The aim of this study was to assess the association among the presence of a respiratory virus detected by molecular assays in bronchoalveolar lavage (BAL) fluid, respiratory symptoms, and acute rejection in adult lung transplant recipients. Methods: Upper (nasopharyngeal swab) and lower (BAL) respiratory tract specimens from 77 lung transplant recipients enrolled in a cohort study and undergoing bronchoscopy with BAL and transbronchial biopsies were screened using 17 different polymerase chain reaction-based assays. Result: BAL fluid and biopsy specimens from 343 bronchoscopic procedures performed in 77 patients were analyzed. We also compared paired nasopharyngeal and BAL fluid specimens collected in a subgroup of 283 cases. The overall viral positivity rate was 29.3% in the upper respiratory tract specimens and 17.2% in the BAL samples (). We observed a significant association P < .001 between the presence of respiratory symptoms and positive viral detection in the lower respiratory tract (Pp. 012). Conversely, acute rejection was not associated with the presence of viral infection (odds ratio, 0.41; 95% confidence interval, 0.20-0.88). The recovery of lung function was significantly slower when acute rejection and viral infection were both present. Conclusions: A temporal relationship exists between acute respiratory symptoms and positive viral nucleic acid detection in BAL fluid from lung transplant recipients. We provide evidence suggesting that respiratory viruses are not associated with acute graft rejection during the acute phase of infection.

In vivo activation of melanoma-specific CD8(+) T cells by endogenous tumor antigen and peptide vaccines. A comparison to virus-specific T cells.

Many new types of vaccines against infectious or malignant diseases are currently being proposed. Careful characterization of the induced immune response is required in assessing their efficiency. While in most studies human tumor antigen-specific T cells are analyzed after in vitro re-stimulation, we investigated these T cells directly ex vivo using fluorescent tetramers. In peripheral blood lymphocytes from untreated melanoma patients with advanced disease, a fraction of tumor antigen (Melan-A/MART-1)-specific T cells were non-naive, thus revealing tumor-driven immune activation. After immunotherapy with synthetic peptides plus adjuvant, we detected tumor antigen-specific T cells that proliferated and differentiated to memory cells in vivo in some melanoma patients. However, these cells did not present the features of effector cells as found in cytomegalovirus specific T cells analyzed in parallel. Thus, peptide plus adjuvant vaccines can lead to activation and expansion of antigen specific CD8(+) T cells in PBL. Differentiation to protective CD8(+) effector cells may, however, require additional vaccine components that stimulate T cells more efficiently, a major challenge for the development of future immunotherapy.

CD160-Associated CD8 T-Cell Functional Impairment Is Independent of PD-1 Expression.

Expression of co-inhibitory molecules is generally associated with T-cell dysfunction in chronic viral infections such as HIV or HCV. However, their relative contribution in the T-cell impairment remains unclear. In the present study, we have evaluated the impact of the expression of co-inhibitory molecules such as 2B4, PD-1 and CD160 on the functions of CD8 T-cells specific to influenza, EBV and CMV. We show that CD8 T-cell populations expressing CD160, but not PD-1, had reduced proliferation capacity and perforin expression, thus indicating that the functional impairment in CD160+ CD8 T cells may be independent of PD-1 expression. The blockade of CD160/CD160-ligand interaction restored CD8 T-cell proliferation capacity, and the extent of restoration directly correlated with the ex vivo proportion of CD160+ CD8 T cells suggesting that CD160 negatively regulates TCR-mediated signaling. Furthermore, CD160 expression was not up-regulated upon T-cell activation or proliferation as compared to PD-1. Taken together, these results provide evidence that CD160-associated CD8 T-cell functional impairment is independent of PD-1 expression.