Biomedical subjects

Genoveffa Franchini

Publications and source records attributed to Genoveffa Franchini.

52 records · Page 3Linked to original sources

PubMed2003

High frequency of virus-specific CD8+ T cells in the central nervous system of macaques chronically infected with simian immunodeficiency virus SIVmac251.

Infection with human immunodeficiency virus or simian immunodeficiency virus (SIV) induces virus-specific CD8(+) T cells that traffic to lymphoid and nonlymphoid tissues. In this study, we used Gag-specific tetramer staining to investigate the frequency of CD8(+) T cells in peripheral blood and the central nervous system of Mamu-A*01-positive SIV-infected rhesus macaques. Most of these infected macaques were vaccinated prior to SIVmac251 exposure. The frequency of Gag(181-189) CM9 tetramer-positive cells was consistently higher in the cerebrospinal fluid and the brain than in the blood of all animals studied and did not correlate with either plasma viremia or CD4(+)-T-cell level. Little or no infection in the brain was documented for most animals by nucleic acid sequence-based amplification or in situ hybridization. These data suggest that this Gag-specific response may contribute to the containment of viral replication in this locale.

Animals↗

PubMed2002

Human immunodeficiency virus type-1 Tat/co-activator acetyltransferase interactions inhibit p53Lys-320 acetylation and p53-responsive transcription.

Patients with AIDS are at increased risk for developing various neoplasms, including Hodgkin's and non-Hodgkin's lymphomas, Kaposi's sarcomas, and anal-rectal carcinomas, suggestive that human immunodeficiency virus type-1 infection might promote establishment of AIDS-related cancers. Tat, the viral trans-activator, can be endocytosed by uninfected cells and has been shown to inhibit p53 functions, providing a candidate mechanism through which the human immunodeficiency virus type-1 might contribute to malignant transformation. Because Tat has been shown to interact with histone acetyltransferase domains of p300/cAMP-responsive element-binding protein (CREB)-binding protein and p300/CREB-binding protein-associated factor, we have investigated whether Tat might alter p53 acetylation and tumor suppressor-responsive transcription. Here, we demonstrate that both Tat and p53 co-localize with p300/CREB-binding protein-associated factor and p300 in nuclei of IMR-32 human neuroblastoma cells and in PC-12 pheochromocytoma cells. Further, p53 trans-activation of the 14-3-3varsigma promoter was markedly repressed by Tat-histone acetyltransferase interactions, and p53 acetylation by p300/CREB-binding protein-associated factor on residue Lys(320) was diminished as a result of Tat-histone acetyltransferase binding in vivo and in vitro. Tat also inhibited p53 acetylation by p300 in a dosage-dependent manner in vitro. Finally, HIV-1-infected Molt-4 cells displayed reduced p53 acetylation on lysines 320 and 373 in response to UV irradiation. Our results allude to a mechanism whereby the human immunodeficiency virus type-1 trans-activator might impair tumor suppressor functions in immune/neuronal-derived cells, thus favoring the establishment of neoplasia during AIDS.

Acetylation↗

PubMed2002

Immune intervention strategies for HIV-1 infection of humans in the SIV macaque model.

Studies in the SIVmac macaque model have demonstrated that the extent of virus-specific CD4+ and CD8+ T-cell responses induced by vaccination prior to virus-challenge exposure correlate with viremia containment following establishment of infection. These findings led to the hypothesis that active immunization with vaccines able to induce virus-specific T-cell responses following the establishment of infection could also ameliorate the virological outcome. Here, we will review the relative effect of ART and vaccination during primary SIVmac infection of macaques.

Animals↗

PubMed2002

Equivalent immunogenicity of the highly attenuated poxvirus-based ALVAC-SIV and NYVAC-SIV vaccine candidates in SIVmac251-infected macaques.

Therapeutic immunization of HIV-1-infected individuals may induce and/or enhance HIV-1-specific immune responses and decrease the dependency on antiretroviral drug treatment. However, repeated immunizations with live-recombinant vectors may induce vector-specific immune responses that interfere with the elicitation of vigorous immune responses to the desired antigen. Therefore, the use of mixed-modality vaccinations may be necessary to induce sustained virus-specific immune responses in HIV-1-infected individuals treated with antiretroviral therapy (ART). Thus, the relative immunogenicity of various vaccine modalities needs to be assessed. Here we compared the immunogenicity of two vaccine candidates, the canarypox-based ALVAC-SIV-gag-pol-env (ALVAC-SIV-gpe) and the vaccinia-based NYVAC-SIV-gag-pol-env (NYVAC-SIV-gpe), in rhesus macaques infected with SIVmac251 and treated with ART by 2 weeks postinfection. Both ALVAC-SIV-gpe and NYVAC-SIV-gpe vaccine candidates induced and/or enhanced a virus-specific CD8+ T cell response to a similar extent, as demonstrated by tetramer staining of Gag-specific CD8+ T cells. Similarly, both vaccines elicited comparable lymphoproliferative responses (LPRs) to the SIV p27 Gag and gp120 Env proteins. Thus, both these vaccine modalities alone or in combination may be suitable candidate vaccines for immune therapy of HIV-1-infected individuals.

Animals↗

PubMed2002

Containment of simian immunodeficiency virus infection in vaccinated macaques: correlation with the magnitude of virus-specific pre- and postchallenge CD4+ and CD8+ T cell responses.

Macaques infected with the SIV strain SIVmac251 develop a disease closely resembling human AIDS characterized by high viremia, progressive loss of CD4(+) T cells, occurrence of opportunistic infection, cachexia, and lymphomas. We report in this study that vaccination with the genetically attenuated poxvirus vector expressing the structural Ags of SIVmac (NYVAC-SIV-gag, pol, env) in combination with priming with DNA-SIV-gag, env resulted in significant suppression of viremia within 2 mo after mucosal exposure to the highly pathogenic SIVmac251 in the majority of vaccinated macaques. The control of viremia in these macaques was long lasting and inversely correlated to the level of both pre- and postchallenge Gag-specific lymphoproliferative responses, as well as to the level of total SIV-specific CD4(+) T lymphocyte responses at the peak of acute viremia as detected by intracellular cytokine-staining assay. Viremia containment also correlated with the frequency of the immunodominant Gag(181-189)CM9 epitope-specific CD8(+) T cells present before the challenge or expanded during acute infection. These data indicate, for the first time, the importance of vaccine-induced CD4(+) Th cell responses as an immune correlate of viremia containment. The results presented in this work also further demonstrate the potential of a DNA-prime/attenuated poxvirus-boost vaccine regimen in an animal model that well mirrors human AIDS.

Acute Disease↗

PubMed2002

Vaccination of macaques with long-standing SIVmac251 infection lowers the viral set point after cessation of antiretroviral therapy.

A cohort of rhesus macaques with long-standing SIVmac251 infection (> or =5 mo) was treated with continuous antiretroviral therapy (ART). A group of eight macaques was vaccinated with or without simultaneous administration of low dose IL-2 with the highly attenuated poxvirus vector (NYVAC) vaccine candidate expressing the SIVmac structural gag-pol-env (gpe) genes and a novel chimeric fusion protein derived from the rev-tat-nef (rtn) regulatory genes. Control groups consisted of mock-vaccinated macaques or animals treated only with IL-2. Vaccination significantly expanded both virus-specific CD4(+) and CD8(+) T cell responses, and IL-2 further increased the vaccine-induced response to an immunodominant Gag epitope. Following antiretroviral treatment interruption, the viral set point was significantly lower in vaccinated than in control macaques for at least 4 consecutive mo, and viral containment was inversely correlated with vaccine-induced, virus-specific CD4(+) and CD8(+) T cell responses. These data provide the proof of concept that therapeutic vaccination before cessation of ART may be a feasible approach in the clinical management of HIV-1 infection.

Animals↗

PubMed2002

IL-7 therapy dramatically alters peripheral T-cell homeostasis in normal and SIV-infected nonhuman primates.

Interleukin-7 (IL-7) is important for thymopoiesis in mice and humans because IL-7 receptor alpha (IL-7Ralpha) mutations result in a severe combined immunodeficiency phenotype with severe thymic hypoplasia. Recent evidence has indicated that IL-7 also plays an important role as a regulator of T-cell homeostasis. Here we report the immunologic effects of recombinant human IL-7 (rhIL-7) therapy in normal and simian immunodeficiency virus (SIV)-infected nonhuman primates. Cynomolgus monkeys receiving 10 days of rhIL-7 showed substantial, reversible increases in T-cell numbers involving a dramatic expansion of both naive and nonnaive phenotype CD4(+) and CD8(+) subsets. Although IL-7 is known to have thymopoietic effects in mice, we observed marked declines in the frequency and absolute number of T-cell receptor excision circle-positive (TREC(+)) cells in the peripheral blood and dramatic increases in the percentage of cycling T cells in the peripheral blood as measured by Ki-67 expression (baseline less than 5% to approximately 50% after 6 days of therapy) and ex vivo bromodeoxyuridine (BrdU) incorporation. Similarly, moderately CD4- depleted SIV-infected macaques treated with rhIL-7 also had significant increases in peripheral blood CD4(+) and CD8(+) T cells following rhIL-7 therapy. Thus, rhIL-7 induces dramatic alterations in peripheral T-cell homeostasis in both T-cell-replete and T-cell-depleted nonhuman primates. These results further implicate IL-7 as a promising immunorestorative agent but illustrate that a major component of its immunorestorative capacity reflects effects on mature cells. These results also raise the possibility that IL-7 therapy could be used to temporarily modulate T-cell cycling in vivo in the context of immunotherapies such as vaccination.

Animals↗

PubMed2002

A novel chimeric Rev, Tat, and Nef (Retanef) antigen as a component of an SIV/HIV vaccine.

The human immunodeficiency virus type 1 (HIV-1) regulatory proteins Rev, Tat, and Nef are expressed at early time post-infection and represent attractive targets to be included in a vaccine candidate for AIDS. However, the putative immunosuppressive activities of some of these proteins may limit their immunogenicity. To circumvent these issues, a novel chimeric polyprotein vaccine candidate (Retanef), comprising genetically modified and re-assorted rev, tat, and nef open reading frames of simian immunodeficiency virus (SIV), was constructed and optimized for its expression in mammalian cells. Retanef encodes a protein of approximately 55 kDa localized primarily in the cytoplasm of transfected cells. The Retanef gene expressed in context of an eucaryotic expression vector (DNA-SIV-Retanef) or cloned into a highly attenuated poxvirus-based NYVAC vector (NYVAC-SIV-Retanef) was used to immunize either naive rhesus macaques or macaques chronically infected with SIVmac251 undergoing anti-retroviral therapy (ART). Three immunizations of naive macaques with DNA-SIV-Retanef followed by a single NYVAC-SIV-Retanef boost induced a response to the Mamu-A(*)01-restricted Tat epitope (Tat_SL8, TTPESANL) demonstrated by staining with a specific tetramer and by direct cytolytic activity assays, as well as responses to Rev, Tat and Nef proteins demonstrated by ELISPOT assays using overlapping peptide pools encompassing the entire proteins. Immunization of infected macaques with either DNA-SIV-Retanef or NYVAC-SIV-Retanef expanded the frequency of Tat-specific tetramer-staining cells by two- to seven-fold. No adverse effects were observed in either naive or SIV-infected rhesus macaques. Thus, an analogous HIV-1-based chimeric vaccine may represent useful component of an HIV-1 vaccine.

AIDS Vaccines↗

PubMed2002

Recombinant canarypox vaccine-elicited CTL specific for dominant and subdominant simian immunodeficiency virus epitopes in rhesus monkeys.

Since virus-specific CTL play a central role in containing HIV replication, a candidate AIDS vaccine should generate virus-specific CTL responses. In this study, the ability of a recombinant canarypox virus expressing SIV Gag-Pol-Env (ALVAC/SIV gag-pol-env) was assessed for its ability to elicit both dominant and subdominant epitope-specific CTL responses in rhesus monkeys. Following a series of five immunizations, memory CTL responses specific for a dominant Gag epitope could be demonstrated in the peripheral blood of vaccinated monkeys. Memory CTL responses to a subdominant Pol epitope were undetectable in these animals. Following challenge with SIVmac251, the experimentally vaccinated animals developed high frequency CTL responses specific for the dominant Gag epitope that emerged in temporal association with the early containment of viral replication. Interestingly, the experimentally vaccinated, but not the control vaccinated animals, developed CTL responses to the subdominant Pol epitope that were detectable only after containment of early viremia. Thus, recombinant canarypox vaccination elicited low frequency, but durable memory CTL populations. The temporal association of the emergence of the dominant epitope-specific response with early viral containment following challenge suggests that this immune response played a role in the accelerated clearing of early viremia in these animals. The later emerging CTL response specific for the subdominant epitope may contribute to the control of viral replication in the setting of chronic infection.

Animals↗

PubMed2002

Genetic mutation and early onset of T-cell leukemia in pediatric patients infected at birth with HTLV-I.

T-cell leukemia/lymphoma (T-c LL) associated with prior infection with HTLV-I is rarely described in children. We present herein, the clinical, morphological, and virologic features of T-c LL, which occurred in eight pediatric cases with similar features of ATLL described in adults. There were three girls and five boys with age ranging from 2 to 18 years. Lymphoadenopathy, hepatosplenomegaly and marked skin lesions were presented in all cases. Five patients had hypercalcemia. The diagnostic criteria of T-c LL were based on both morphological and immunophenotypical analyses characterized by T-cell markers positively. Seven cases were cCD3+, CD4/CD25+, whereas CD1a and TdT were negative in all cases tested. HTLV-I antibodies were detected in all cases. HTLV-I provirus integration of at least one provirus was seen in all cases tested by molecular analysis. Mother-to-child transmission of HTLV-I was demonstrated in six cases. Interestingly, a homozygous deletion in p16 gene locus was observed in all four cases studied, while exons 7 and 8 of p53 were deleted in one child. The deletion of the p16(INK4A)/p14(ARF) or mutation of p53, key regulatory protein of cell cycle checkpoint in G1/S progression, found in five of the eight pediatric patients suggests that in these cases genetic lesions associated with HTLV-I infection may predispose for an early onset of leukemia.

Adolescent↗

PubMed2002

Retroviral proteins that target the major histocompatibility complex class I.

The human T-cell leukemia virus type 1 (HTLV-1) and human immunodeficiency virus type 1 (HIV-1) retroviruses are two evolutionary distinct human pathogens. HTLV-1 is the etiologic agent of two diverse diseases: adult T-cell leukemia/lymphoma, as well as the neurologic disorder tropical spastic paraparesis/HTLV-1-associated myelopathy. HTLV-1 is the only retrovirus known to be the etiologic agent of human cancer. HTLV-2, the other known oncovirus, is not apparently associated with human cancer. While HTLV-1 transforms T-cells in vitro, HIV kills CD4+ T-cells and is the etiological agent of human acquired immunodeficiency syndrome, characterized by a progressive loss of CD4+ cells, weakening of the immune system, and susceptibility to opportunistic infections and cancer. HTLV-1 and HIV-1 both cause lifelong infections, which suggests that they have evolved mechanism(s) to evade detection by the host's immune response; particularly to evade cytotoxic T-lymphocytes, which play a major role in cellular immunity against viruses and will be the focus of this review.

Down-Regulation↗

PubMed2002

Cervicovaginal lamina propria lymphocytes: phenotypic characterization and their importance in cytotoxic T-lymphocyte responses to simian immunodeficiency virus SIVmac251.

Most human immunodeficiency virus (HIV) type 1 infections occur by the mucosal route. Thus, it is important to assess the immune responses to HIV in the vaginal, cervical, and rectal compartments. Here we quantitated the virus-specific CD8+ T-cell response and characterized the phenotype of lymphocytes in the genital tracts of naive macaques, macaques acutely or chronically infected with simian immunodeficiency virus SIVmac251, and macaques chronically infected with chimeric simian/human immunodeficiency virus SHIV(KU2.) Vaginal biopsy samples or samples obtained at the time of euthanasia were used in this analysis. The percentage of Gag-specific, tetramer-positive T cells was as high as 13 to 14% of the CD3+ CD8+ T-cell population in the vaginal and cervical laminae propriae of both SIVmac251 and SHIV(KU2) chronically infected macaques. In most cases, the frequency of this response in the cervicovaginal compartment far exceeded the frequency in the blood or the draining iliac lymph node. Vaginal laminae propriae of naive macaques contained 55 to 65% CD3+ CD8+ cells and 28 to 34% CD3+ CD4+ cells, while the majority of intraepithelial cells were CD8+ T cells (75 to 85%). For the same cells, the surface expression of CD62L was low whereas that of alphaEbeta7 was high. No difference in the expression of CD45RA on CD8+ T cells was observed in the chronic stage of SIVmac251 infection. Although no decrease in the percentage of CD4+ cells in the genital tract was observed within the first 12 days of infection, by 6 weeks from SIVmac251 infection and thereafter the percentage of CD4+ T cells was decreased in the laminae propriae of the vagina and cervix. Expression of CD45RA did not differ in naive and acutely SIVmac251 infected macaques. Information on the quality and quantity of local immune responses may help in the design of vaccine strategies aimed at containing viral replication at the site of viral encounter.

Animals↗

PubMed2002

Dominance of CD8 responses specific for epitopes bound by a single major histocompatibility complex class I molecule during the acute phase of viral infection.

Cytotoxic T-lymphocyte (CTL) responses are thought to control human immunodeficiency virus replication during the acute phase of infection. Understanding the CD8(+) T-cell immune responses early after infection may, therefore, be important to vaccine design. Analyzing these responses in humans is difficult since few patients are diagnosed during early infection. Additionally, patients are infected by a variety of viral subtypes, making it hard to design reagents to measure their acute-phase immune responses. Given the complexities in evaluating acute-phase CD8(+) responses in humans, we analyzed these important immune responses in rhesus macaques expressing a common rhesus macaque major histocompatibility complex class I molecule (Mamu-A*01) for which we had developed a variety of immunological assays. We infected eight Mamu-A*01-positive macaques and five Mamu-A*01-negative macaques with the molecularly cloned virus SIV(mac)239 and determined all of the simian immunodeficiency virus-specific CD8(+) T-cell responses against overlapping peptides spanning the entire virus. We also monitored the evolution of particular CD8(+) T-cell responses by tetramer staining of peripheral lymphocytes as well as lymph node cells in situ. In this first analysis of the entire CD8(+) immune response to autologous virus we show that between 2 and 12 responses are detected during the acute phase in each animal. CTL against the early proteins (Tat, Rev, and Nef) and against regulatory proteins Vif and Vpr dominated the acute phase. Interestingly, CD8(+) responses against Mamu-A*01-restricted epitopes Tat(28-35)SL8 and Gag(181-189)CM9 were immunodominant in the acute phase. After the acute phase, however, this pattern of reactivity changed, and the Mamu-A*01-restricted response against the Gag(181-189)CM9 epitope became dominant. In most of the Mamu-A*01-positive macaques tested, CTL responses against epitopes bound by Mamu-A*01 dominated the CD8(+) cellular immune response.

Acute Disease↗

PubMed2002

Both mucosal and systemic routes of immunization with the live, attenuated NYVAC/simian immunodeficiency virus SIV(gpe) recombinant vaccine result in gag-specific CD8(+) T-cell responses in mucosal tissues of macaques.

As most human immunodeficiency virus (HIV) infection occurs via mucosal surfaces, an important goal of vaccination may be the induction of virus-specific immune responses at mucosal sites to contain viral infection early on. Here we designed a study in macaques carrying the major histocompatibility complex class I Mamu-A(*)01 molecule to assess the capacity of the highly attenuated poxvirus NYVAC/simian immunodeficiency virus (SIV) SIV(gpe) vaccine candidate administered by the intranasal, intramuscular, or intrarectal route to induce mucosal immunity. All macaques, including one naive macaque, were exposed to SIV(mac251) by the intrarectal route and sacrificed 48 h after infection. The kinetics of immune response at various time points following immunization with NYVAC/SIV(gpe) and the anamnestic response to SIV(mac251) at 48 h after challenge were assessed in blood, in serial rectal and vaginal biopsy samples, and in tissues at euthanasia with an SIV(mac) Gag-specific tetramer. In addition, at euthanasia, antigen-specific cells producing gamma interferon or tumor necrosis factor alpha from the jejunum lamina propria were quantified in all macaques. Surprisingly, antigen-specific CD8(+) T cells were found in the mucosal tissues of all immunized macaques regardless of whether the vaccine was administered by a mucosal route (intranasal or intrarectal) or systemically. In addition, following mucosal SIV(mac251) challenge, antigen-specific responses were mainly confined to mucosal tissues, again regardless of the route of immunization. We conclude that immunization with a live vector vaccine results in the appearance of CD8(+) T-cell responses at mucosal sites even when the vaccine is delivered by nonmucosal routes.

Administration, Intranasal↗

PubMed2000

Viral Disease in Hematology.

As part of the international outreach of the American Society of Hematology, this review addresses some aspects of the genetics, biology, epidemiology, and clinical relevance of viruses that cause a variety of hematopoietic disorders in human populations. The viruses described here have a different pattern of geographical distribution, and the disease manifestations may vary according to environmental and/or genetic characteristics of the host. Epstein-Barr virus, a linear double-stranded DNA virus (herpesvirus), and the human T-cell leukemia virus, a retrovirus with a single-stranded diploid RNA genome, are associated among other diseases with lymphoma and leukemia/lymphoma, respectively. Both viruses cause a lifelong infection, but only a small percentage of infected individuals develop hematopoietic neoplasms. Epidemiological data suggest that the time of infection may be important in determining disease outcome in both HTLV-I and EBV infection. The pathogenic mechanisms used by these viruses are of most interest since they may recapitulate growth dysregulation steps also occurring in other hematopoietic malignancies. In Section I Dr. Franchini reviews the biology, genetics and diseases associated with HTLV-I and HTLV-II. In Section II, Dr. Ambinder reviews the biology of EBV infection and its relationship to the pathogenesis of Hodgkin's disease and other malignancies. In Section III, Dr. Barry reviews the viral hemorrhagic fevers caused by RNA viruses such as Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae, which can lead to acute syndromes that can be fatal. However, prompt diagnosis is key for patient management as well as for limiting their spread to others. These syndromes have become the focus of public concern and represent not only a clinical challenge, since in most cases no specific antiviral treatment is available, but also a challenge for future basic research on their biology and pathogenesis since little is known at present.

Journal Article↗

PubMedDate not supplied

Do regulatory T-cells play a role in AIDS pathogenesis?

The impairment of adaptive immune responses to HIV and abnormalities in the immune regulatory function mechanisms during HIV infection have been regarded as key issues in AIDS pathogenesis since the early years of the pandemic. However, the multiple mechanisms underlying this impairment are still not fully understood. New emerging information shows that alterations in the number and/or function of regulatory T-cells may contribute to HIV pathogenesis. Thus, pharmacologic manipulation of regulatory T-cells as well as blocking the activity of other immunomodulatory molecules, such as indoleamine 2,3-dioxygenase, glucocorticoid-induced tumor necrosis factor receptor and PD1, might provide a valuable approach to redirect the immune system towards an efficient antiviral response.

Acquired Immunodeficiency Syndrome↗