Evaluator services for optimised service placement in distributed heterogeneous cloud infrastructures

Optimal placement of demanding real-time interactive applications in a distributed heterogeneous cloud very quickly results in a complex tradeoff between the application constraints and resource capabilities. This requires very detailed information of the various requirements and capabilities of the applications and available resources. In this paper, we present a mathematical model for the service optimization problem and study the concept of evaluator services as a flexible and efficient solution for this complex problem. An evaluator service is a service probe that is deployed in particular runtime environments to assess the feasibility and cost-effectiveness of deploying a specific application in such environment. We discuss how this concept can be incorporated in a general framework such as the FUSION architecture and discuss the key benefits and tradeoffs for doing evaluator-based optimal service placement in widely distributed heterogeneous cloud environments

Service-centric networking for distributed heterogeneous clouds

Optimal placement and selection of service instances in a distributed heterogeneous cloud is a complex trade-off between application requirements and resource capabilities that requires detailed information on the service, infrastructure constraints, and the underlying IP network. In this article we first posit that from an analysis of a snapshot of today's centralized and regional data center infrastructure, there is a sufficient number of candidate sites for deploying many services while meeting latency and bandwidth constraints. We then provide quantitative arguments why both network and hardware performance needs to be taken into account when selecting candidate sites to deploy a given service. Finally, we propose a novel architectural solution for service-centric networking. The resulting system exploits the availability of fine-grained execution nodes across the Internet and uses knowledge of available computational and network resources for deploying, replicating and selecting instances to optimize quality of experience for a wide range of services

Using conventional HIV tests on oral fluid36499

There is need for more evaluations of non-invasive tests in order to broaden the reach of testing programs and to perform large scale epidemiological studies. In this study, three different human immunodeficiency virus (HIV) enzyme linked immunosorbent assays (ELISAs) and one line immunoassay were evaluated to detect HIV antibodies in oral fluid samples. Specimens were collected, after informed consent was obtained, with the Oracol (MMD, Worcester, England) device. A total IgG quantitation test was performed to demonstrate the quality of the sample. Assessment of a modified protocol of the Vironostika(R) HIV Ag/Ab, Enzygnost(R) Anti-HIV 1/2 Plus Genscreen HIV-1/2 Version 2 and a line immune confirmatory assay the INNO-LIA HIV I/II score was done, using oral fluid specimens of 325 HIV positive and negative individuals. For the ELISAs, the addition of an extra internal oral fluid control was evaluated as well as different cut-offs, time between sampling and testing and the effect of drinking water just before sampling. Finally, the confirmatory test and some testing algorithms and combination of tests were discussed. The results obtained from the oral fluid specimens were compared with the gold standard on paired serum specimens. Firstly, there was no significant difference observed between the use of the kit controls and the oral fluid controls. New protocols and calculation of cut-offs were defined for two of the three ELISAs. High sensitivities and specificities were obtained with all three ELISAs without any statistical difference between the three tests. Secondly, no statistically significant difference was observed when samples were stored for different time periods between sampling and testing, meaning that a period of seven days at room temperature before testing is still acceptable. Thirdly, drinking water before sample collection did not interfere with the testing, although lower optical densities were observed. None of the positive samples were missed. In addition, the line immunoassay INNO-LIA HIV I/II score test is a promising test for confirmation of reactive oral fluid specimen, but more samples need to be validated in order to adapt the interpretation rules specifically for oral fluid specimens. Different choices/algorithms adapted for the purpose of testing can be proposed. In conclusion, it can be said that the commercial ELISAs with adapted protocol and cut-off values are suitable tools for making HIV test performance accessible to people. With this non-invasive sampling method, more eligible individuals can and will be selected for further HIV test on blood</p

Production of human immunodeficiency virus type 1 (HIV-1) pseudoviruses using linear HIV-1 envelope expression cassettes

HIV-1 pseudoviruses constitute an important tool in HIV-1 vaccine and entry inhibitor research. Single-cycle pseudoviruses carrying functional envelopes are generated by co-transfecting HEK293T cells with pNL4-3.LucR(-)E(-) and Env expression plasmids. However, cloning of Env genes is time consuming and single Env clones are not representative of the diversity of HIV-1 in a patient's blood sample. A new method to construct Env expression cassettes is proposed which can be used for the rapid generation of heterogeneous HIV-1 pseudoviruses without a cloning step. The linear Env expression cassettes are constructed by ligating PCR amplified Env genes between a 5' CMV promoter and 3' SV40 polyadenylation element. The resulting cassettes generate pseudoviruses carrying heterogeneous Env variants of a primary HIV-1 isolate derived from viral RNA or proviral DNA. The influence of cis-acting sequences upstream of the Env gene on infectivity was compared between pseudoviruses generated from plasmids and linear expression cassettes. The results suggest that the presence of these upstream sequences tends to result in higher infectivity of pseudoviruses when present in heterogeneous Env expression cassettes, but they do not enhance infectivity of pseudoviruses generated with homogeneous Env expression constructs. Using linear expression cassettes allows for the rapid production of heterogeneous patient-derived functional Env genes

Neutralization kinetics of sensitive and resistant subtype B primary human immunodeficiency virus type 1 isolates

The aim of the study was to determine if sensitive and resistant human immunodeficiency virus type 1 (HIV-1) subtype B primary isolates have different neutralization kinetics. Neutralization assays were undertaken where either the time allowed for virus to react with antibodies or the subsequent period of this mixture's exposure to target cells were varied. The relative neutralization sensitivity/resistance is a reproducible property of the isolates. In a minority of combinations, the titre falls exponentially for as long as the free virions are exposed to antibody. In the remainder, neutralization kinetics shows deviations which may be attributed to events occurring after the virus-antibody mixture is added to the target cells: significant neutralization with minimal exposure of the free virions to antibody; a plot where reduction in virus titre is parallel to the duration of the incubation phase of the assay. Neutralization rate constants are similar for primary HIV-1 SF33, HIV-1 SF162, and HIV-1 89.6, reaching 5 x 10(5)-1 x 10(6)/M sec for the monoclonal antibody IgG1 b12. However, although increased antibody levels produced greater reductions in virus titre the rate of neutralization was not proportional to the antibody concentration. Neutralization of either the free virion or cell-associated virus does not correlate with the resistance/sensitivity of primary subtype B isolates. The target cells play an active role, so that in designing neutralization assays with primary isolates of HIV-1, events following the virus-antibody complex binding to the cell surface have to be taken into consideration

Antiviral compounds show enhanced activity in HIV-1 single cycle pseudovirus assays as compared to classical PBMC assays

HIV-1 Env pseudotyped viruses (PV) are an attractive tool for studying the antiviral activities of compounds interfering with virus entry into a target cell. To investigate whether results obtained in PV assays are relevant biologically, the antiviral activity of 6 reference compounds was compared on 5 virus isolates of different clades using three assays: (1) replicating virus in peripheral blood mononuclear cells (PBMCs), (2) PV in CD4 and CCR5- or CXCR4 co-receptor expressing Ghost cells, and (3) PV in PBMCs. A significant linear relationship was found between both single-cycle PV assays (P<0.0001, R2=0.75). Moreover, both assays showed enhanced sensitivity to the antiretrovirals tested (P=0.013 and 0.015, respectively) as compared to the PBMC assay with replication-competent virus. Most importantly, results from the latter assay could be predicted significantly from both PV assays, in which either Ghost target cells (P<0.0001, R2=0.61) or PBMCs (P<0.0001, R2=0.55) were used. The usefulness of the PV assay was demonstrated further by investigating the impact of the HIV-1 Env subtype on the antiviral activity of five new compounds derived from the entry inhibitor BMS806

Inhibition of replication of primary HIV-1 isolates in huPBL-NOD/Scid mice by antibodies from HIV-1 infected patients

Although a limited number of HIV-infected patients have broadly neutralizing antibodies, it has not been examined whether these antibodies can protect against infection with primary virus in vivo. Here we screened the plasma of 23 HIV-1-infected patients for broadly neutralizing antibodies. Purified antibodies from subjects with broad and more narrow responses were administered to huPBL-NOD/Scid mice that were subsequently challenged with primary viruses of clade A, B and CRF01_AE. Although we observed a lack of correlation between the data from the in vitro neutralization assay and the results from the passive immunization experiments, we report for the first time that antibodies from HIV-infected persons can inhibit replication of primary virus isolates in an animal model