We isolated a human cDNA by expression cloning and characterized its gene product as a new human protein that enables entry and infection of herpes simplex virus (HSV). The gene, designated hfl-B5, encodes a type II cell surface membrane protein, B5, that is broadly expressed in human primary tissue and cell lines. It contains a high-scoring heptad repeat at the extracellular C terminus that is predicted to form an ␣-helix for coiled coils like those in cellular SNAREs or in some viral fusion proteins. A synthetic 30-mer peptide that has the same sequence as the heptad repeat ␣-helix blocks HSV infection of B5-expressing porcine cells and human HEp-2 cells. Transient expression of human B5 in HEp-2 cells results in increased polykarocyte formation even in the absence of viral proteins. The B5 protein fulfills all criteria as a receptor or coreceptor for HSV entry. Use by HSV of a human cellular receptor, such as B5, that contains putative membrane fusion domains provides an example where a pathogenic virus with broad tropism has usurped a widely expressed cellular protein to function in infection at events that lead to membrane fusion.Herpes simplex virus type 1 (HSV-1) and HSV-2 are prevalent human pathogens that infect a broad range of animal cells. They establish lifelong latency in human neurons from which reactivation to lytic replication leads to recurrent herpes lesions. Entry into cells involves attachments of viral glycoproteins to multiple alternative cellular receptors (2,10,30). However, the molecular mechanisms of entry have not yet been defined.The human proteins identified as receptors for HSV include heparan sulfate (HS) proteoglycans and several integral membrane proteins that are members of well-characterized families (30). Herpesvirus entry mediator HVEM (HveA) is a member of the tumor necrosis factor receptor family (20). Nectin 2 (HveB) and nectin 1 (HveC) or herpes immunoglobulin-like receptor are adhesion molecules in the immunoglobulin superfamily (7,12,35). D-Glucosaminyl 3-O-sulfotransferase (3-OS) modifies specific sites in cellular HS to generate binding sites for the essential HSV attachment glycoprotein D (gD) (27). Nectin 1, which was originally isolated as poliovirus receptorrelated protein, allows entry of most HSV-1 and HSV-2 strains and is broadly expressed on a range of human tissues. HVEM and nectin 2 are more limited by either tissue distribution or strain specificity for transfer of HSV susceptibility. HVEM does not support entry of mutant virus HSV-1(Rid-1) that has a point mutation in gD (20). Nectin 2 is reported to allow entry of HSV-2 strains and HSV-1(Rid-1), but not most HSV-1 strains (35). Isolation of animal homologs for nectin 1 and HVEM raises the possibility that they may engage HSV during infection of animal cells.With the exception of HS, HSV gD is a viral ligand for these receptors. Some regions of gD involved in receptor interactions have been defined (3,8). How the cellular proteins interact with other viral proteins (each other or other cellular proteins) ...
Power consumption is a key point of WSN (Wireless Sensor Network) lifespan. Because of difference among monitoring objects and complex signal channel condition, the power consumption of each node in farmland WSN is uneven, which makes the network performing as multi-level energy heterogeneous. LEACH and its improving algorithms average the power consumption between nodes by clustering and cluster-head switching. But the cluster-head voting brings a lot extra power consumption. To solve this problem, this paper proposes EACHS (Energy Approximation Cluster-Head Selection), an optimized cluster-head selection mechanism that approximates the energy of cluster-head targeting the lowest energy level in the network. When approaching the target, the current cluster-head collects the energy status of all nodes and determines which one becoming the new cluster-head. The simulation results show that, EACHS can balance the network power consumption and reduce most protocol cost, prolong the overall network lifespan.
SCADA (Supervisory Control and Data Acquisition) is an important concern about national security of our country and its security professionals. During those early days, a so called "security by obscurity" helped provide a palpable layer of cyber security and defense and a general feeling of immunity kinds of security problems that have started emerging networks to emerge in the mid 1980's, starting with the known Morris Worm. However, with the global standardization of TCP/IP protocol, and for the past 20 years, with the migration of autonomous systems SCADA interconnected power grids, security risks have increased exponentially. The security officials can no longer rely on the isolated nature of these systems to provide protection. Unfortunately, the security of SCADA systems has not kept pace with advances in computer technology. According to a 2003 report by Sandia National Laboratories, the SCADA security is generally five to ten years behind compared to typical systems of information technology. As threat, the contradictory range has expanded to include not only domestic but foreign terrorists, disgruntled internal, organized crime and even international competitors. This volatile convergence of global computer network and critical weaknesses in the operating system and application software system are well understood by opponents. Although a catastrophic failure is unlikely, these risks could be very problematic and cause disruptions in essential services and billions of euros in losses. This study includes a description of the state of the art of attacks against these systems and the reasons for the vulnerability of these systems. [1, 2, 3]
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