Functional analysis of the EsaB component of the<i> Staphylococcus aureus</i> Type VII secretion system

This study was supported by the Wellcome Trust (through Investigator Award 10183/Z/15/Z to TP and through Clinical PhD studentship support to CPH through grant 104241/z/14/z), the Biotechnology and Biological Sciences Research Council and the Medical Research Council (through grants BB/H007571/1 and MR/M011224/1, respectively).Type VII secretion systems (T7SS) are found in many bacteria and secrete proteins involved in virulence and bacterial competition. In Staphylococcus aureus the small ubiquitin-like EsaB protein has been previously implicated as having a regulatory role in the production of the EsxC substrate. Here we show that in the S. aureus RN6390 strain, EsaB does not genetically regulate production of any T7 substrates or components, but is indispensable for secretion activity. Consistent with EsaB being an essential component of the T7SS, loss of either EsaB or EssC are associated with upregulation of a common set of iron acquisition genes. However, a further subset of genes were dysregulated only in the absence of EsaB. Quantitative western blotting indicates that EsaB is present at very low levels in cells. Substitution of a highly conserved threonine for alanine or arginine resulted in a loss of EsaB activity and destabilisation of the protein. Taken together our findings show that EsaB is essential for T7SS activity in RN6390.Publisher PDFPeer reviewe

Haem-iron plays a key role in the regulation of the Ess/Type VII secretion system of <i>Staphylococcus aureus</i> RN6390

This study was supported by the Wellcome Trust (through Investigator Award 10183/Z/15/Z to T. P. and through Clinical PhD studentship support to C. P. H. through grant 104241/z/14/z), the Biotechnology and Biological Sciences Research Council and the Medical Research Council (through grants BB/H007571/1 and MR/M011224/1, respectively).The Staphylococcus aureus type VII protein secretion system (T7SS) plays important roles in virulence and intra-species competition. Here we show that the T7SS in strain RN6390 is activated by supplementing the growth medium with haemoglobin, and its cofactor haemin (haem B). Transcript analysis and secretion assays suggest that activation by haemin occurs at a transcriptional and a post-translational level. Loss of T7 secretion activity by deletion of essC results in upregulation of genes required for iron acquisition. Taken together these findings suggest that the T7SS plays a role in iron homeostasis in at least some S. aureus strains.Publisher PDFPeer reviewe

Tuberculosis transmission patterns among Spanish-born and foreign-born populations in the city of Barcelona

AbstractDuring a 2-year period (2003–2004), tuberculosis (TB) transmission in Barcelona and the factors related to transmission among the Spanish- and foreign-born populations were studied by molecular epidemiology. Data were obtained from TB cases and Conventional Contact Tracing registries and genotyping was performed using restriction fragment length polymorphism (RFLP)-IS6110 and MIRU12 as a secondary typing method. Of the 892 TB cases reported, 583 (65.3%) corresponded to Spanish-born and 309 (34.6%) to foreign-born. Six hundred and eighty-seven cases (77%) were confirmed by culture. RFLP typing of 463/687 (67.4%) isolates was performed, revealing 280 (60.5%) unique and 183 (39.5%) shared patterns, which were grouped into 65 clusters. Spanish-born individuals were significantly more clustered than foreign-born individuals (44.6% vs. 28.8%; p 0.016). Clustering in foreign-born individuals was associated with HIV (p 0.051, odds ratio = 3.1, 95% confidence interval 1–10.9) and alcohol abuse (p 0.022), whereas, in the Spanish-born individuals, clustering was associated with age in the range 21–50 years, (p 0.024). Of the total clusters, 36/65 (55.3%) included only Spanish-born patients, whereas 22/65 (33.8%) included individuals from both populations. In mixed clusters, the index case was Spanish-born in 53% and foreign-born in 47%. Among the foreign-born, 2.8% were ill on arrival, 30% developed TB within the first year and 50.3% developed TB within the first 2 years; 58.3% were from South America. In conclusion, half of the foreign-born TB patients developed the disease during the first 2 years after arrival, which, in most cases, was the result of endogenous reactivation. Recent TB transmission among Spanish-born and foreign-born populations, as well as bidirectional transmission between communities, contributed significantly to the burden of TB in Barcelona, suggesting the need to improve Public Health interventions in both populations

CD4 cell count and the risk of AIDS or death in HIV-Infected adults on combination antiretroviral therapy with a suppressed viral load: a longitudinal cohort study from COHERE.

BACKGROUND: Most adults infected with HIV achieve viral suppression within a year of starting combination antiretroviral therapy (cART). It is important to understand the risk of AIDS events or death for patients with a suppressed viral load. METHODS AND FINDINGS: Using data from the Collaboration of Observational HIV Epidemiological Research Europe (2010 merger), we assessed the risk of a new AIDS-defining event or death in successfully treated patients. We accumulated episodes of viral suppression for each patient while on cART, each episode beginning with the second of two consecutive plasma viral load measurements 500 copies/µl, the first of two consecutive measurements between 50-500 copies/µl, cART interruption or administrative censoring. We used stratified multivariate Cox models to estimate the association between time updated CD4 cell count and a new AIDS event or death or death alone. 75,336 patients contributed 104,265 suppression episodes and were suppressed while on cART for a median 2.7 years. The mortality rate was 4.8 per 1,000 years of viral suppression. A higher CD4 cell count was always associated with a reduced risk of a new AIDS event or death; with a hazard ratio per 100 cells/µl (95% CI) of: 0.35 (0.30-0.40) for counts <200 cells/µl, 0.81 (0.71-0.92) for counts 200 to <350 cells/µl, 0.74 (0.66-0.83) for counts 350 to <500 cells/µl, and 0.96 (0.92-0.99) for counts ≥500 cells/µl. A higher CD4 cell count became even more beneficial over time for patients with CD4 cell counts <200 cells/µl. CONCLUSIONS: Despite the low mortality rate, the risk of a new AIDS event or death follows a CD4 cell count gradient in patients with viral suppression. A higher CD4 cell count was associated with the greatest benefit for patients with a CD4 cell count <200 cells/µl but still some slight benefit for those with a CD4 cell count ≥500 cells/µl

Determinants of Depressive Symptoms in People Living with HIV : Findings from a Population-Based Study with a Gender Perspective

Altres ajuts: Fundació La Marató de TV3 (239/C/2018)Depressive symptoms are common among people living with HIV (PLWH). The aim of this study was to identify the determinants of depressive symptoms in PLWH in Spain. A total of 1060 PLWH participated in this cross-sectional study and completed the Patient Health Questionnaire-9. The odds ratios for the presence of depressive symptoms were analyzed in a multivariable logistic regression model, including sociodemographic data, comorbidities, health-related behaviors, and social-environment-related variables. We found an overall prevalence of depressive symptoms of 21.42%; by subgroup, namely men, women, and transgender persons, prevalence was 18.13%, 32.81%, and 37.14%, respectively. Moreover, social isolation (OR = 1.05 [CI, 1.02-1.08]) and poor physical and mental quality of life (OR = 1.06 [CI, 1.02-1.09] and OR = 1.13 [CI, 1.09-1.17], respectively) were associated with depressive symptoms. As protective factors, we identified serodisclosure to more people (vs. none; OR = 0.39 [CI, 0.17-0.87]), satisfaction with social roles (OR = 0.86 [CI, 0.79-0.94]), better cognitive function (OR = 0.92 [CI, 0.89-0.95]), and sexualized drug use once in a lifetime (OR = 0.52 [CI, 0.29-0.93]). This study showed a high prevalence of depressive symptoms in PLWH, especially among women and transgender people. The association between psychosocial variables and depressive symptoms highlights the multidimensionality of the problem and identifies areas for intervention. This study found that the management of mental health issues is an area that needs to be improved and tailored to specific groups, with the aim of enhancing the well-being of PLWH

Risk Factors and Outcomes for Late Presentation for HIV-Positive Persons in Europe: Results from the Collaboration of Observational HIV Epidemiological Research Europe Study (COHERE).

Few studies have monitored late presentation (LP) of HIV infection over the European continent, including Eastern Europe. Study objectives were to explore the impact of LP on AIDS and mortality

Efavirenz versus boosted atazanavir-containing regimens and immunologic, virologic, and clinical outcomes: A prospective study of HIV-positive individuals

OBJECTIVE: To compare regimens consisting of either ritonavir-boosted atazanavir or efavirenz and a nucleoside reverse transcriptase inhibitor (NRTI) backbone with respect to clinical, immunologic, and virologic outcomes. DESIGN: Prospective studies of human immunodeficiency virus (HIV)-infected individuals in Europe and the United States included in the HIV-CAUSAL Collaboration. METHODS: HIV-positive, antiretroviral therapy-naive, and acquired immune deficiency syndrome (AIDS)-free individuals were followed from the time they started an atazanavir or efavirenz regimen. We estimated an analog of the "intention-to-treat" effect for efavirenz versus atazanavir regimens on clinical, immunologic, and virologic outcomes with adjustment via inverse probability weighting for time-varying covariates. RESULTS: A total of 4301 individuals started an atazanavir regimen (83 deaths, 157 AIDS-defining illnesses or deaths) and 18,786 individuals started an efavirenz regimen (389 deaths, 825 AIDS-defining illnesses or deaths). During a median follow-up of 31 months, the hazard ratios (95% confidence intervals) were 0.98 (0.77, 1.24) for death and 1.09 (0.91, 1.30) for AIDS-defining illness or death comparing efavirenz with atazanavir regimens. The 5-year survival difference was 0.1% (95% confidence interval: -0.7%, 0.8%) and the AIDS-free survival difference was -0.3% (-1.2%, 0.6%). After 12 months, the mean change in CD4 cell count was 20.8 (95% confidence interval: 13.9, 27.8) cells/mm lower and the risk of virologic failure was 20% (14%, 26%) lower in the efavirenz regimens. CONCLUSION: Our estimates are consistent with a smaller 12-month increase in CD4 cell count, and a smaller risk of virologic failure at 12 months for efavirenz compared with atazanavir regimens. No overall differences could be detected with respect to 5-year survival or AIDS-free survival