Rev Proteins of Human and Simian Immunodeficiency Virus Enhance RNA Encapsidation

The main function attributed to the Rev proteins of immunodeficiency viruses is the shuttling of viral RNAs containing the Rev responsive element (RRE) via the CRM-1 export pathway from the nucleus to the cytoplasm. This restricts expression of structural proteins to the late phase of the lentiviral replication cycle. Using Rev-independent gag-pol expression plasmids of HIV-1 and simian immunodeficiency virus and lentiviral vector constructs, we have observed that HIV-1 and simian immunodeficiency virus Rev enhanced RNA encapsidation 20- to 70-fold, correlating well with the effect of Rev on vector titers. In contrast, cytoplasmic vector RNA levels were only marginally affected by Rev. Binding of Rev to the RRE or to a heterologous RNA element was required for Rev-mediated enhancement of RNA encapsidation. In addition to specific interactions of nucleocapsid with the packaging signal at the 5′ end of the genome, the Rev/RRE system provides a second mechanism contributing to preferential encapsidation of genomic lentiviral RNA

Analisis Faktor-Faktor yang Memengaruhi Tingkat Kepatuhan Wajib Pajak Orang Pribadi di Lingkungan Kantor Pelayanan Pajak Pratama, Tigaraksa Tangerang

Tax collection is not an easy matter. Active participation from the tax authorities also requires the willingness of the taxpayer. A public reaction can be seen from the taxpayer\u27s willingness to pay taxes. Willingness and awareness to pay taxes represent a value contributed by someone (which has been determined by regulation). Tax is used to finance public expenditures without any direct benefit. Taxpayer\u27s awareness about taxation functions as state funding is needed to improve tax compliance and to determine the level of tax compliance in implementing their tax obligations. Limitation of the scope of this study is the effect of the level of awareness of paying taxes, taxpayer\u27s understanding about tax benefits, tax penalties, and understanding of service quality to the tax authorities of individual taxpayer compliance in the fulfillment of tax obligations, as well as restricted to data obtained through questionnaires received and filled by the individual taxpayer of Tigaraksa Pratama Tax Office area. Data were obtained through questionnaire and processed and analyzed using parametric statistical tests and multiple linear regression with 4 independent variables and one dependent variable resulted in the conclusion that the factors that most influence taxpayer compliance in carrying out its tax liability is the use of sanctions against taxpayers who do not carry out its obligations under applicable legislation

Targeting Antibody Responses to the Membrane Proximal External Region of the Envelope Glycoprotein of Human Immunodeficiency Virus

Although human immunodeficiency type 1 (HIV-1) infection induces strong antibody responses to the viral envelope glycoprotein (Env) only a few of these antibodies possess the capacity to neutralize a broad range of strains. The induction of such antibodies represents an important goal in the development of a preventive vaccine against the infection. Among the broadly neutralizing monoclonal antibodies discovered so far, three (2F5, Z13 and 4E10) target the short and hidden membrane proximal external region (MPER) of the gp41 transmembrane protein. Antibody responses to MPER are rarely observed in HIV-infected individuals or after immunization with Env immunogens. To initiate antibody responses to MPER in its membrane-embedded native conformation, we generated expression plasmids encoding the membrane-anchored ectodomain of gp41 with N-terminal deletions of various sizes. Following transfection of these plasmids, the MPER domains are displayed on the cell surface and incorporated into HIV virus like particles (VLP). Transfected cells displaying MPER mutants bound as efficiently to both 2F5 and 4E10 as cells transfected with a plasmid encoding full-length Env. Mice immunized with VLPs containing the MPER mutants produced MPER-specific antibodies, the levels of which could be increased by the trimerization of the displayed proteins as well as by a DNA prime-VLP boost immunization strategy. Although 2F5 competed for binding to MPER with antibodies in sera of some of the immunized mice, neutralizing activity could not be detected. Whether this is due to inefficient binding of the induced antibodies to MPER in the context of wild type Env or whether the overall MPER-specific antibody response induced by the MPER display mutants is too low to reveal neutralizing activity, remains to be determined

Influence of HIV-1 Rev and Gag on the post-transcriptional fate of the viral genomic RNA

Die viralen Proteine Rev und Gag sind essentiell für die Vermehrung des humanen Immundefizienz Virus HIV-1. In dieser Arbeit wurde untersucht welche Einflüsse Rev und Gag auf die post-transkriptionale Regulation der viralen genomischen RNA von HIV-1 haben. Die Anwesenheit von Rev war in der Lage die Menge der genomischen RNA im Zytoplasma effektiv zu erhöhen und ermöglichte anschließend ihre Translation. Im Gegensatz dazu war Gag, in der Abwesenheit von Rev, nicht in der Lage die zytoplasmatischen Level der genomischen RNA zu erhöhen und vermittelte auch nicht ihre Translation oder ihre Verpackung in virale Partikel. Die zuvor publizierte Eigenschaft von Gag, zwischen Zellkern und Zytoplasma hin und her transportiert zu werden, konnte nicht bestätigt werden. Für die Bildung infektiöser HIV-1 Partikel muss die virale genomische RNA dementsprechend durch Rev aus dem Zellkern ins Zytoplasma exportiert werden, wo sie anschließend durch Gag erkannt und verpackt wird

Nuclear RNA Export and Packaging Functions of HIV-1 Rev Revisited▿

Although the viral Rev protein is necessary for HIV replication, its main function in the viral replication cycle has been controversial. Reinvestigating the effect of Rev on the HIV-1 RNA distribution in various cell lines and primary cells revealed that Rev enhanced cytoplasmic levels of the unspliced HIV-1 RNA, mostly 3- to 12-fold, while encapsidation of the RNA and viral infectivity could be stimulated >1,000-fold. Although this clearly questions the general notion that the nuclear export of viral RNAs is the major function of Rev, mechanistically encapsidation seems to be linked to nuclear export, since the tethering of the nuclear export factor TAP to the HIV-1 RNA also enhanced encapsidation. Interference with the formation of an inhibitory ribonucleoprotein complex in the nucleus could lead to enhanced accessibility of the cytoplasmic HIV-1 RNA for translation and encapsidation. This might explain why Rev and tethered TAP exert the same pattern of pleiotropic effects

The HIV-1 Rev protein enhances encapsidation of unspliced and spliced, RRE-containing lentiviral vector RNA.

BACKGROUND: During the RNA encapsidation process of human immunodeficiency virus (HIV) viral genomic, unspliced RNA (gRNA) is preferentially incorporated into assembling virions. However, a certain amount of spliced viral transcripts can also be detected in viral particles. Recently, we observed that nuclear export of HIV and lentiviral vector gRNA by Rev is required for efficient encapsidation. Since singly-spliced HIV transcripts also contain the Rev-response element (RRE), we investigated if the encapsidation efficiency of RRE-containing spliced HIV-vector transcripts is also increased by the viral Rev protein. FINDINGS: Starting with a lentiviral vector imitating the splicing pattern of HIV, we constructed vectors that express an unspliced transcript either identical in sequence to the singly-spliced or the fully-spliced RNA of the parental construct. After transfection of the different lentiviral vectors cytoplasmic and virion-associated RNA levels and vector titers were determined in the presence and absence of Rev. Rev enhanced the infectious titer of vectors containing an RRE 6 to 37-fold. Furthermore, Rev strongly increased encapsidation efficiencies of all RRE-containing transcripts up to 200-fold. However, a good correlation between encapsidation efficiency and lentiviral vector titer could only be observed for the gRNA. The infectious titer of the vector encoding the fully-spliced RNA without RRE as well as the encapsidation efficiency of all transcripts lacking the RRE was not influenced by Rev. Interestingly, the splicing process itself did not seem to interfere with packaging, since the encapsidation efficiencies of the same RNA expressed either by splicing or as an unspliced transcript did not differ significantly. CONCLUSIONS: Rev-mediated nuclear export enhances the encapsidation efficiency of RRE-containing lentiviral vector RNAs independently of whether they have been spliced or not

Comparison of Various Aircraft Routing Strategies Using the Air Traffic Simulation Model AirTraf 2.0

A climate-optimized routing is expected as an operational measure to reduce the climate impact of aviation, whereas this routing causes extra aircraft operating costs. This study performs some air traffic simulations of nine aircraft routing strategies which include the climate-optimized routing, and examines characteristics of those routings. A total of 103 trans-Atlantic flights of an Airbus A330 is simulated for five weather types in winter and for three types in summer over the North Atlantic by using the chemistry-climate model EMAC with the air traffic simulation submodel AirTraf. For every weather type, the climate-optimized routing shows the minimum climate impact, whereas a trade-off exists between the costs and the climate impact. The cost-optimized routing lies between time- and fuel-optimized routings, and minimizes the costs. The aircraft routing for minimum contrail formation shows the second-lowest climate impact, whereas this routing also causes extra costs

Comparison of various aircraft routing strategies using the air traffic simulation model airtraf 2.0

A climate-optimized routing is expected as an operational measure to reduce the climate impact of aviation, whereas this routing causes extra aircraft operating costs. This study performs some air traffic simulations of nine aircraft routing strategies which include the climate-optimized routing, and examines characteristics of those routings. A total of 103 trans-Atlantic flights of an Airbus A330 is simulated for five weather types in winter and for three types in summer over the North Atlantic by using the chemistry-climate model EMAC with the air traffic simulation submodel AirTraf. For every weather type, the climate-optimized routing shows the minimum climate impact, whereas a trade-off exists between the costs and the climate impact. The cost-optimized routing lies between time- and fuel-optimized routings, and minimizes the costs. The aircraft routing for minimum contrail formation shows the second-lowest climate impact, whereas this routing also causes extra costs