Insights into Minor Group Rhinovirus Uncoating: The X-ray Structure of the HRV2 Empty Capsid

Upon attachment to their respective receptor, human rhinoviruses (HRVs) are internalized into the host cell via different pathways but undergo similar structural changes. This ultimately results in the delivery of the viral RNA into the cytoplasm for replication. To improve our understanding of the conformational modifications associated with the release of the viral genome, we have determined the X-ray structure at 3.0 Å resolution of the end-stage of HRV2 uncoating, the empty capsid. The structure shows important conformational changes in the capsid protomer. In particular, a hinge movement around the hydrophobic pocket of VP1 allows a coordinated shift of VP2 and VP3. This overall displacement forces a reorganization of the inter-protomer interfaces, resulting in a particle expansion and in the opening of new channels in the capsid core. These new breaches in the capsid, opening one at the base of the canyon and the second at the particle two-fold axes, might act as gates for the externalization of the VP1 N-terminus and the extrusion of the viral RNA, respectively. The structural comparison between native and empty HRV2 particles unveils a number of pH-sensitive amino acid residues, conserved in rhinoviruses, which participate in the structural rearrangements involved in the uncoating process

A Middleware Layer for Flexible and Cost-Efficient Multi-tenant Applications

Part 7: Security and InteroperabilityInternational audienceApplication-level multi-tenancy is an architectural design principle for Software-as-a-Service applications to enable the hosting of multiple customers (or tenants) by a single application instance. Despite the operational cost and maintenance benefits of application-level multi-tenancy, the current middleware component models for multi-tenant application design are inflexible with respect to providing different software variations to different customers.In this paper we show that this limitation can be solved by a multi-tenancy support layer that combines dependency injection with middleware support for tenant data isolation. Dependency injection enables injecting different software variations on a per tenant basis, while dedicated middleware support facilitates the separation of data and configuration metadata between tenants. We implemented a prototype on top of Google App Engine and we evaluated by means of a case study that the improved flexibility of our approach has little impact on operational costs and upfront application engineering costs

Joosen: Managing concern interactions in middleware

Abstract. In this paper, we define a conceptual model that describes the relevant information about interactions between concerns that needs to be captured. We have developed a prototype system that, starting from this model, can automatically generate a set of rules that enables software developers to improve their understanding of concerns in middleware and their interactions. This rule-base is the basis for an expert system that can be queried about particular concern interactions and a software engineering tool to support an application development team.

An Integrated Approach for Software Design Checking Using Design Rationale

Abstract. Design Rationale (DR), the reasons behind decisions made while designing, offers a richer view of both the product and the decision-making process by providing the designers intent behind the decisions. DR is also valuable for checking to ensure that the intent was adhered to throughout the design, as well as pointing out any unresolved (or undocumented) issues that remain open. While there is little doubt of the value of DR, it is typically not captured during design. SEURAT (Software Engineering Using RATionale) is a system we have developed to explore uses of design rationale. It supports both the display of and inferencing over the rationale to point out any unresolved issues or inconsistencies. SEURAT is tightly integrated with a software development environment so that rationale capture and use can become integrated into the software development process. 1