The Epstein-Barr Virus Glycoprotein gp150 Forms an Immune-Evasive Glycan Shield at the Surface of Infected Cells

Contains fulltext : 171658.PDF (publisher's version ) (Open Access)Cell-mediated immunity plays a key role in host control of viral infection. This is exemplified by life-threatening reactivations of e.g. herpesviruses in individuals with impaired T-cell and/or iNKT cell responses. To allow lifelong persistence and virus production in the face of primed immunity, herpesviruses exploit immune evasion strategies. These include a reduction in viral antigen expression during latency and a number of escape mechanisms that target antigen presentation pathways. Given the plethora of foreign antigens expressed in virus-producing cells, herpesviruses are conceivably most vulnerable to elimination by cell-mediated immunity during the replicative phase of infection. Here, we show that a prototypic herpesvirus, Epstein-Barr virus (EBV), encodes a novel, broadly acting immunoevasin, gp150, that is expressed during the late phase of viral replication. In particular, EBV gp150 inhibits antigen presentation by HLA class I, HLA class II, and the non-classical, lipid-presenting CD1d molecules. The mechanism of gp150-mediated T-cell escape does not depend on degradation of the antigen-presenting molecules nor does it require gp150's cytoplasmic tail. Through its abundant glycosylation, gp150 creates a shield that impedes surface presentation of antigen. This is an unprecedented immune evasion mechanism for herpesviruses. In view of its likely broader target range, gp150 could additionally have an impact beyond escape of T cell activation. Importantly, B cells infected with a gp150-null mutant EBV displayed rescued levels of surface antigen presentation by HLA class I, HLA class II, and CD1d, supporting an important role for iNKT cells next to classical T cells in fighting EBV infection. At the same time, our results indicate that EBV gp150 prolongs the timespan for producing viral offspring at the most vulnerable stage of the viral life cycle

Multiple Scan Chains for Power Minimization during Test Application in Sequential Circuits

This paper presents a new technique for power minimization during test application in sequential circuits using multiple scan chains. The technique is based on a new design for test architecture and a novel test application strategy which reduces spurious transitions in the circuit under test. To facilitate the reduction of spurious transitions, the proposed design for test architecture is based on classifying scan latches into compatible, incompatible and independent scan latches. Based on their classification, the scan latches are partitioned into multiple scan chains and a single extra test vector associated with each scan chain is computed. A new test application strategy which applies the extra test vector to primary inputs while shifting out test responses for each scan chain, minimizes power dissipation by eliminating the spurious transitions which occur in the combinational part of the circuit. The newly introduced multiple scan chain-based technique does not introduce performance degradation and minimizes clock tree power dissipation with minimal impact on both test area and test data overhead. Unlike previous approaches which are test set dependent and, hence, are not able to handle large circuits due to the complexity of the design space, this paper shows that with low test area and test data overhead substantial savings in power dissipation during test application are achieved in very low computational time for both small and large test sets. For example, in the case of the benchmark circuit s15850 it takes <600s in computational time and <1 percent in test area and test data overhead to achieve over 80 percent savings in power dissipation

The impact of general and carbon-related environmental knowledge on attitudes and behaviour of US consumers

Global warming and carbon emissions have gained international attention. However, it would appear that consumers are still unclear about what it encompasses and how it relates to their individual behaviour. Using the Theory of Reasoned Action (TRA) as a guiding framework, this study presents a structural equation model that tests the relationships between carbon and environmental knowledge, environmental attitude and behaviour using a sample of US consumers. The findings of the research suggest that a positive relationship was found between general and carbon-specific knowledge, attitude towards the environment, and general and carbon-specific behaviours. Therefore, general and carbon-specific environmental behaviours are related and may be driven by general attitudes and knowledge (i.e. both carbon-specific and general environmental knowledge). The implications of the study would suggest that marketers, working in tandem with government policymakers, need to focus efforts on developing consumers' knowledge about specific sub-issues, such as global warming. However, additional research needs to be undertaken to develop marketing communication that accurately reflects the environmental impact of consumption behaviour, thereby allowing for considered consumption