Perspectives on the Trypanosoma cruzi-host cell receptor interaction

Chagas disease is caused by the parasite Trypanosoma cruzi. The critical initial event is the interaction of the trypomastigote form of the parasite with host receptors. This review highlights recent observations concerning these interactions. Some of the key receptors considered are those for thromboxane, bradykinin, and for the nerve growth factor TrKA. Other important receptors such as galectin-3, thrombospondin, and laminin are also discussed. Investigation into the molecular biology and cell biology of host receptors for T. cruzi may provide novel therapeutic targets

Histone H2A and H2B Are Monoubiquitinated at AID-Targeted Loci

Background: Somatic hypermutation introduces base substitutions into the rearranged and expressed immunoglobulin (Ig) variable regions to promote immunity. This pathway requires and is initiated by the Activation Induced Deaminase (AID) protein, which deaminates cytidine to produce uracils and UG mismatches at the Ig genes. Subsequent processing of uracil by mismatch repair and base excision repair factors contributes to mutagenesis. While selective for certain genomic targets, the chromatin modifications which distinguish hypermutating from non-hypermutating loci are not defined. Methodology/Principal Findings: Here, we show that AID-targeted loci in mammalian B cells contain ubiquitinated chromatin. Chromatin immunoprecipitation (ChIP) analysis of a constitutively hypermutating Burkitt\u27s B cell line, Ramos, revealed the presence of monoubiquitinated forms of both histone H2A and H2B at two AID-associated loci, but not at control loci which are expressed but not hypermutated. Similar analysis using LPS activated primary murine splenocytes showed enrichment of the expressed V(H) and S gamma 3 switch regions upon ChIP with antibody specific to AID and to monoubiquitinated H2A and H2B. In the mechanism of mammalian hypermutation, AID may interact with ubiquitinated chromatin because confocal immunofluorescence microscopy visualized AID colocalized with monoubiquitinated H2B within discrete nuclear foci. Conclusions/Significance: Our results indicate that monoubiquitinated histones accompany active somatic hypermutation, revealing part of the histone code marking AID-targeted loci. This expands the current view of the chromatin state during hypermutation by identifying a specific nucleosome architecture associated with somatic hypermutation

Reviewing the evidence on effectiveness and cost-effectiveness of HIV prevention strategies in Thailand

<p>Abstract</p> <p>Background</p> <p>Following universal access to antiretroviral therapy in Thailand, evidence from National AIDS Spending Assessment indicates a decreasing proportion of expenditure on prevention interventions. To prompt policymakers to revitalize HIV prevention, this study identifies a comprehensive list of HIV/AIDs preventive interventions that are likely to be effective and cost-effective in Thailand.</p> <p>Methods</p> <p>A systematic review of the national and international literature on HIV prevention strategies from 1997 to 2008 was undertaken. The outcomes used to consider the effectiveness of HIV prevention interventions were changes in HIV risk behaviour and HIV incidence. Economic evaluations that presented their results in terms of cost per HIV infection averted or cost per quality-adjusted life year (QALY) gained were also included. All studies were assessed against quality criteria.</p> <p>Results</p> <p>The findings demonstrated that school based-sex education plus life-skill programs, voluntary and routine HIV counselling and testing, male condoms, street outreach programs, needle and syringe programs, programs for the prevention of mother-to-child HIV transmission, male circumcision, screening blood products and donated organs for HIV, and increased alcohol tax were all effective in reducing HIV infection among target populations in a cost-effective manner.</p> <p>Conclusion</p> <p>We found very limited local evidence regarding the effectiveness of HIV interventions amongst specific high risk populations. This underlines the urgent need to prioritise health research resources to assess the effectiveness and cost-effectiveness of HIV interventions aimed at reducing HIV infection among high risk groups in Thailand.</p