Construction of a linkage map of the Rennell Island Tall coconut type (Cocos nucifera L.) and QTL analysis for yield characters

Des marqueurs AFLP et microsatellites ont été employés afin de produire une carte génétique du cocotier (Cocos nucifera L.; 2n = 32) de type " Rennel Island Tall " (RIT). Au total, 227 marqueurs ont été assemblés en 16 groupes de linkage. La longueur totale de la carte RIT totalisait 1971 cM et le nombre de marqueurs par groupe de linkage variait entre 5 et 23. Une analyse QTL de caractères contribuant au rendement, tel que mesuré lors de deux périodes d'échantillonnage, a permis d'identifier neuf locus. Trois et deux locus ont été identifiés pour le nombre de régimes tandis qu'un et trois locus ont été identifiés pour le nombre de noix. La corrélation entre les valeurs phénotypiques pour ces caractères et les périodes d'échantillonnage est partiellement reflétée par l'identification de QTL communs. Ces QTL représentent des caractères qui sont importants en amélioration génétique du cocotier. La co-ségrégation de marqueurs avec ces QTL rend possible la sélection assistée dans le cadre de programmes d'amélioration génétique du cocotier

HIV-1 epitope-specific CD8+ T cell responses strongly associated with delayed disease progression cross-recognize epitope variants efficiently.

The ability of HIV-1-specific CD8(+) T cell responses to recognize epitope variants resulting from viral sequence variation in vivo may affect the ease with which HIV-1 can escape T cell control and impact on the rate of disease progression in HIV-1-infected humans. Here, we studied the functional cross-reactivity of CD8 responses to HIV-1 epitopes restricted by HLA class I alleles associated with differential prognosis of infection. We show that the epitope-specific responses exhibiting the most efficient cross-recognition of amino acid-substituted variants were those strongly associated with delayed progression to disease. Not all epitopes restricted by the same HLA class I allele showed similar variant cross-recognition efficiency, consistent with the hypothesis that the reported associations between particular HLA class I alleles and rate of disease progression may be due to the quality of responses to certain "critical" epitopes. Irrespective of their efficiency of functional cross-recognition, CD8(+) T cells of all HIV-1 epitope specificities examined showed focused TCR usage. Furthermore, interpatient variability in variant cross-reactivity correlated well with use of different dominant TCR Vbeta families, suggesting that flexibility is not conferred by the overall clonal breadth of the response but instead by properties of the dominant TCR(s) used for epitope recognition. A better understanding of the features of T cell responses associated with long-term control of viral replication should facilitate rational vaccine design

Safety, tolerance, and efficacy of atevirdine in asymptomatic human immunodeficiency virus-infected individuals

Atevirdine is a nonnucleoside reverse transcriptase inhibitor of human immunodeficiency virus type 1 (HIV-1). In this study we investigated the effect of atevirdine in asymptomatic antiretroviral naive HIV-infected patients with CD4(+) cell counts of between 200 and 750 cells per mm(3). Patients were randomized to receive 600 mg of atevirdine (n = 15) or a placebo (n = 15) three times a day for 12 weeks. There was no statistically significant effect of atevirdine on viral loads (HIV p24 antigen and HIV-1 RNA levels by PCR) or CD4(+) cell counts. The data do not support the use of atevirdine as a monotherapy in the treatment of HIV-infected patients

Kinetics of expansion of epitope-specific T cell responses during primary HIV-1 infection.

Multiple lines of evidence support a role for CD8(+) T cells in control of acute/early HIV replication; however, features of the primary HIV-specific CD8(+) T cell response that may impact on the efficiency of containment of early viral replication remain poorly defined. In this study, we performed a novel, comprehensive analysis of the kinetics of expansion of components of the HIV-specific CD8(+) T cell response in 21 acutely infected individuals. Epitope-specific T cell responses expanded asynchronously during primary infection in all subjects. The most rapidly expanded responses peaked as early as 5 days following symptomatic presentation and were typically of very limited epitope breadth. Responses of additional specificities expanded and contracted in subsequent waves, resulting in successive shifts in the epitope immunodominance hierarchy over time. Sequence variation and escape were temporally associated with the decline in magnitude of only a subset of T cell responses, suggesting that other factors such as Ag load and T cell exhaustion may play a role in driving the contraction of HIV-specific T cell responses. These observations document the preferential expansion of CD8(+) T cells recognizing a subset of epitopes during the viral burst in acute HIV-1 infection and suggest that the nature of the initial, very rapidly expanded T cell response may influence the efficiency with which viral replication is contained in acute/early HIV infection

Circulating levels of cobalt and chromium from metal-on-metal hip replacement are associated with CD8+ T-cell lymphopenia

We carried out a cross-sectional study with analysis of the demographic, clinical and laboratory characteristics of patients with metal-on-metal hip resurfacing, ceramic-on-ceramic and metal-on-polyethylene hip replacements. Our aim was to evaluate the relationship between metal-on-metal replacements, the levels of cobalt and chromium ions in whole blood and the absolute numbers of circulating lymphocytes. We recruited 164 patients (101 men and 63 women) with hip replacements, 106 with metal-on-metal hips and 58 with non-metal-on-metal hips, aged < 65 years, with a pre-operative diagnosis of osteoarthritis and no pre-existing immunological disorders. Laboratory-defined T-cell lymphopenia was present in13 patients (15%) (CD8+ lymphopenia) and 11 patients (13%) (CD3+ lymphopenia) with unilateral metal-on-metal hips. There were significant differences in the absolute CD8+ lymphocyte subset counts for the metal-on-metal groups compared with each control group (p-values ranging between 0.024 and 0.046). Statistical modelling with analysis of covariance using age, gender, type of hip replacement, smoking and circulating metal ion levels, showed that circulating levels of metal ions, especially cobalt, explained the variation in absolute lymphocyte counts for almost all lymphocyte subsets