Paola D'Aloja - Academia.edu (original) (raw)

Papers by Paola D'Aloja

BMC biotechnology, 2006

The availability of cell lines releasing fluorescent viral particles can significantly support a ... more The availability of cell lines releasing fluorescent viral particles can significantly support a variety of investigations, including the study of virus-cell interaction and the screening of antiviral compounds. Regarding HIV-1, the recovery of such biologic reagents represents a very hard challenge due to the intrinsic cytotoxicity of many HIV-1 products. We sought to overcome such a limitation by using a cell line releasing HIV-1 particles in an inducible way, and by exploiting the ability of a HIV-1 Nef mutant to be incorporated in virions at quite high levels. Here, we report the isolation and characterization of a HIV-1 packaging cell line, termed 18-4s, able to release valuable amounts of fluorescent HIV-1 based Virus-Like Particles (VLPs) in an inducible way. 18-4s cells were recovered by constitutively expressing the HIV-1 NefG3C mutant fused with the enhanced-green fluorescent protein (NefG3C-GFP) in a previously isolated inducible HIV-1 packaging cell line. The G3C mutatio...

Nature medicine, 2001

A highly conserved signaling property of Nef proteins encoded by human or simian immunodeficiency... more A highly conserved signaling property of Nef proteins encoded by human or simian immunodeficiency virus is the binding and activation of a PAK kinase whose function is unclear. Here we show that Nef-mediated p21-activated kinase (PAK) activation involves phosphatidylinositol 3-kinase, which acts upstream of PAK and is bound and activated by Nef similar to the manner of Polyoma virus middle T antigen. The Nef-associated phosphatidylinositol-3-PAK complex phosphorylated the pro-apoptotic Bad protein without involving the protein kinase B-Akt kinase, which is generally believed to inactivate Bad by serine phosphorylation. Consequently, Nef, but not a Nef mutant incapable of activating PAK, blocked apoptosis in T cells induced by serum starvation or HIV replication. Nef anti-apoptotic effects are likely a crucial mechanism for viral replication in the host and thus in AIDS pathogenesis.

The Journal of general virology, 2001

The primary human immunodeficiency virus type 1 (HIV-1) Nef mutant F12-HIVNef is characterized by... more The primary human immunodeficiency virus type 1 (HIV-1) Nef mutant F12-HIVNef is characterized by three rare amino acid substitutions, G(140)E, V(153)L and E(177)G. It was reported previously that the expression of F12-HIVNef in the context of the highly productive NL4-3 HIV-1 strain blocks virus replication at the level of virus assembly and/or release by a mechanism depending on the presence of the CD4 intracytoplasmic tail. Here, it is reported that NL4-3 HIV-1 strains expressing F12-HIVnef alleles that were back-mutated in each amino acid substitution readily replicated in CD4(+) cells. Attempting to correlate possible functional alterations with antiviral effects, both F12-HIVNef and its back mutants were tested in terms of well-characterized markers of Nef expression. Both F12-HIVNef and its G(177)E back mutant did not down-regulate CD4 as the consequence of a greatly reduced rate of CD4 internalization. On the other hand, F12-HIVNef as well as the E(140)G and L(153)V back mut...

The Journal of general virology, 2000

Increasing interest has been devoted to the role that monocyte-macrophages play in the pathogenes... more Increasing interest has been devoted to the role that monocyte-macrophages play in the pathogenesis of AIDS. The hypothesis of an involvement in AIDS pathogenesis of human/simian immunodeficiency virus (HIV/SIV) Nef also is currently under evaluation by many investigators. The original basis of this hypothesis came from evidence that monkeys infected with a nef-deleted SIV strain failed to develop simian AIDS. Here, we show that treatment of human monocyte-derived macrophages (MDM) with recombinant HIV-1 Nef protein (rNef) induces a strong inhibition of the replication of either macrophage (M-) or dual-tropic HIV-1 strains. Through cytofluorimetric analyses, we detected internalization of FITC-conjugated rNef in MDM as early as 6 h after treatment. Confocal microscope observations demonstrated that the intracellular distribution of internalized rNef was identical to that of endogenously produced Nef. Down-regulation of the CD4 HIV receptor detected upon rNef treatment of MDM suggest...

Journal of virology, 1998

We previously demonstrated that expression of the nonproducer F12-human immunodeficiency virus ty... more We previously demonstrated that expression of the nonproducer F12-human immunodeficiency virus type 1 (HIV-1) variant induces a block in the replication of superinfecting HIV that does not depend on the down-regulation of CD4 HIV receptors. In order to individuate the gene(s) involved in F12-HIV-induced interference, vectors expressing each of the nine F12-HIV proteins were transfected in HIV-susceptible HeLa CD4 cells. Pools of cell clones stably producing each viral protein were infected with HIV-1, and virus release was measured in terms of reverse transcriptase activity in supernatants. We hereby demonstrate that HeLa CD4 cells expressing the F12-HIV gag, vif, or nef gene were resistant, to different degrees, to infection with T-cell-line-adapted HIV-1 strains. Conversely, expression of either the tat, rev, or vpu F12-HIV gene increased the rate of HIV release, and no apparent effects on HIV replication were observed in cells expressing either the F12-HIV vpr, pol, or env gene. ...

Blood, Jan 15, 1997

Recent findings have shown that the expression of the seven trans-membrane G-protein-coupled CXCR... more Recent findings have shown that the expression of the seven trans-membrane G-protein-coupled CXCR4 (the receptor for the stromal cell-derived factor [SDF]-1 chemokine) is necessary for the entry of T-lymphotropic human immunodeficiency virus (HIV) strains, acting as a coreceptor of the CD4 molecule. In the human system, the role of CXCR4 in HIV infection has been determined through env-mediated cell fusion assays and confirmed by blocking viral entry in CD4+/CXCR4+ cells by SDF-1 pretreatment. We observed that the human megakaryoblastic CD4+ UT-7 cell line fails to express CXCR4 RNA and is fully resistant to HIV entry. Transfection of an expression vector containing the CXCR4 c-DNA rendered UT-7 cells readily infectable by different T-lymphotropic syncytium-inducing HIV-1 and HIV-2 isolates. Interestingly, HIV-1 infection of CXCR4 expressing UT-7 cells (named UT-7/fus) induces the formation of polynucleated cells through a process highly reminiscent of megakaryocytic differentiation...

Virology, 1995

An Hut-78 cell clone (F12) harboring a nonproducer human immunodeficiency virus-1 (HIV) variant, ... more An Hut-78 cell clone (F12) harboring a nonproducer human immunodeficiency virus-1 (HIV) variant, and showing a complete resistance to HIV-1 or HIV-2 superinfection, was previously characterized. We demonstrated that the replication of the superinfecting HIVs is blocked at the retrotranecription step, despite the CD4 down-regulation, since HIVe are able to cross the Hut-78/F12 cell membrane. In order to establish if the expression of the HIV-1 variant (F12/HIV) could be per se sufficient to induce the homologous viral interference shown in the F12 cells, the whole F12/HIV provirus was cloned and transfected in He-La CD4+ cells. In F12/HIV expressing He-La CD4+ clones, both the viral proteins expressed and the HIV nonproducer phenotype remain unmodified compared to F12 cells. Furthermore, despite the full expression of CD4 HIV receptors, the life cycle of the superinfecting HIV could be either strongly inl-]ibited or totally abolished, depending on the cell clone considered. The inhibition of the euperinfecting HIV was also reproduced when an HIV infectious molecular clone was transfected in F12/HIV He-La CD4+ clones, thus indicating that a post-cDNA synthesis block may operate against the superinfecting HIV. These data demonstrate that HIV susceptibility could be abrogated in cells expressing the F12/HIV genome, even in absence of any CD4 down-regulation.

Journal of Virology, 2000

F12 human immunodeficiency virus type 1 (HIV-1) nef is a naturally occurring nef mutant cloned fr... more F12 human immunodeficiency virus type 1 (HIV-1) nef is a naturally occurring nef mutant cloned from the provirus of a nonproductive, nondefective, and interfering HIV-1 variant (F12-HIV). We have already shown that cells stably transfected with a vector expressing the F12-HIV nef allele do not downregulate CD4 receptors and, more peculiarly, become resistant to the replication of wild type (wt) HIV. In order to investigate the mechanism of action of such an HIV inhibition, the F12-HIV nef gene was expressed in the context of the NL4-3 HIV-1 infectious molecular clone by replacing the wt nef gene (NL4-3/chi). Through this experimental approach we established the following. First, NL4-3/chi and nef-defective (⌬nef) NL4-3 viral particles behave very similarly in terms of viral entry and HIV protein production during the first replicative cycle. Second, no viral particles were produced from cells infected with NL4-3/chi virions, whatever the multiplicity of infection used.

Journal of Virology, 2001

Human immunodeficiency virus type 1 F12 (HIV-1 F12 ) interferes with the replication of other str... more Human immunodeficiency virus type 1 F12 (HIV-1 F12 ) interferes with the replication of other strains of HIV. Its accessory protein, Nef, is sufficient for this phenotype, where the production and infectivity of HIV are impaired significantly. The analysis of three rare mutations in this Nef protein revealed that these effects could be separated genetically. Moreover, the defect in virus production correlated with the lack of processing of the p55 Gag precursor in the presence of Nef from HIV-1 F12 . Importantly, the introduction of one of these mutations (E177G) into Nef from HIV-1 NL4-3 also created a dominant-negative Nef protein. Effects of Nef from HIV-1 F12 on virus production and Gag processing correlated with its altered subcellular distribution. Moreover, the association with two new cellular proteins with molecular masses of 74 and 75 kDa, which do not interact with other Nef proteins, correlated with the decreased virion infectivity. The identification of a dominant-negative protein for the production and infectivity of HIV suggests that Nef plays an active role at this stage of the viral replicative cycle.

Journal of General Virology, 1996

Fertility and Sterility, 2014

To compare mature human oocytes cryopreservation with slow freezing (SF) and vitrification (VT) i... more To compare mature human oocytes cryopreservation with slow freezing (SF) and vitrification (VT) in infertile couples. Retrospective study of national Italian data submitted during the period 2007-2011. National ART registry. Infertile patients with supernumerary oocytes. Thawing or warming of cryopreserved oocytes and ICSI. oocyte survival, fertilization, implantation and clinical pregnancy rate between SF and VT. A total of 14,328 cycles with 11,599 transfers, 1,850 pregnancies, 1,168 deliveries and 1,342 babies born were analyzed from 146 reporting centers (range of cycles 1-1,255 per center). The SF oocytes&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39; survival rate was lower than in VT (51.1% vs. 63.1%). Fertilization rate was significantly higher in SF than in VT (SF 71.6% vs. VT 70.1%). VT showed a significantly higher pregnancy rate, both per started cycle (14.4% vs. 12.0%) and per transfer (18.0% vs. 14.8%), and implantation rate (9.5% vs. 8.1%) than SF. However, the range and median pregnancy rate per started cycle were, respectively, 0%-50% and 7.7% in SF and 0%-100% and 6.7% in VT. VT showed a statistically significant higher performance than SF. As with other ART procedures, the results are not homogeneous among clinics and protocols, but the confirm the clinical value of oocyte cryopreservation in infertile patients.

Current Biology, 2001

Some nef alleles like IIIB and BH8 fail to support viral required for high viral loads and thus d... more Some nef alleles like IIIB and BH8 fail to support viral required for high viral loads and thus disease progression [1-3]. Recent evidence indicates that replication in primary cells in vitro . In some cases, such as with NP003, this correlates with the lack of disease

Cell Host & Microbe, 2009

Acta Haematologica, 1996

A Hut-78 cell clone (F12) harboring a nonproducer human immunodeficiency virus (HIV-1) variant sh... more A Hut-78 cell clone (F12) harboring a nonproducer human immunodeficiency virus (HIV-1) variant shows complete resistance to HIV-1 or HIV-2 superinfection. The F12-HIV provirus produces an altered HIV-1 protein pattern and cannot generate even immature viral particles. We demonstrated that HeLa CD4+ cells transfected with the F12-HIV genome resist HIV superinfection through a CD4-independent mechanism. As F12-HIV appears to be a useful system to induce anti-HIV intracellular immunization, we constructed various retroviral vectors containing the F12-HIV genome, modified by elimination of the F12 3'LTR and part of its nef gene, inserted 'antisense' with respect to the Moloney murine leukemia virus 5' LTR. Here we show that recombinant retroviral particles carrying the N2/F12-HIV nef- (as) construct can stably transduce both CEMss human cells and primary human peripheral blood lymphocytes, inducing the expression of the F12-HIV genome. These results could open the way to an anti-AIDS gene therapy strategy based on F12-HIV-induced intracellular immunization.

La prospettiva di una mancata fertilità è molto remota nei vissuti e nella progettualità dei giov... more La prospettiva di una mancata fertilità è molto remota nei vissuti e nella progettualità dei giovani e rende la prevenzione della salute riproduttiva una sfida particolarmente ardua e di complessa realizzazione. L'obiettivo del volume è riflettere su possibili percorsi di sensibilizzazione dei giovani verso quella che abbiamo chiamato cultura riproduttiva, un insieme di conoscenze, consapevolezze e sensibilità sui temi della procreazione e della salute riproduttiva che riguardano vissuti, scelte e desideri sia nostri che altrui. Una cultura che nel nostro paese si mostra di una complessità sconcertante, tanto è caratterizzata da contraddizioni e ambivalenze, a volte da veri e propri paradossi che attraversano le immagini e i desideri di famiglia e di genitorialità ma coinvolgono anche altri importanti aspetti della nostra vita. Il volume si interroga sulle criticità di una comunicazione sulla salute riproduttiva in Italia, che attraversa i media tradizionali di massa e i nuovi l...