Antonella Tripiciano

Istituto Superiore di Sanità | ISS · CNAIDS - National AIDS Center

Despite over 30 years of enormous effort and progress in the field, no preventative and/or therapeutic vaccines against human immunodeficiency virus (HIV) are available. Here, we briefly summarize the vaccine strategies and vaccine candidates that in recent years advanced to efficacy trials with mostly unsatisfactory results. Next, we discuss a nov...

Background Low-level HIV viremia originating from virus reactivation in HIV reservoirs is often present in cART treated individuals and represents a persisting source of immune stimulation associated with sub-optimal recovery of CD4⁺ T cells. The HIV-1 Tat protein is released in the extracellular milieu and activates immune cells and latent HIV, le...

Previous work has shown that the Tat protein of Human Immunodeficiency Virus (HIV)-1 is released by acutely infected cells in a biologically active form and enters dendritic cells upon the binding of its arginine-glycine-aspartic acid (RGD) domain to the α5β1, αvβ3, and αvβ5 integrins. The up-regulation/activation of these integrins occurs in endot...

Introduction: Although successful at suppressing HIV replication, combination antiretroviral therapy (cART) only partially restores immune functions and fails to reduce the latent HIV reservoir, thus requiring novel interventions for its intensification. Areas covered: Here are reviewed therapeutic vaccine candidates that are being developed to thi...

HIV-1 Tat is an essential protein in the virus life cycle, which is required for virus gene expression and replication. Most Tat that is produced during infection is released extracellularly and it plays a key role in HIV pathogenesis, including residual disease upon combination antiretroviral therapy (cART). Here, we review epidemiological and exp...

Introduction: Tat, a key HIV virulence protein, has been targeted for the development of a therapeutic vaccine aimed at cART intensification. Results from phase II clinical trials in Italy (ISS T-002) and South Africa (ISS T-003) indicated that Tat vaccination promotes increases of CD4⁺ T-cells and return to immune homeostasis while reducing the vi...

Flow-chart for the ISS T-002 and ISS T-002 EF-UP studies. One hundred sixty-eight HIV-infected cART-treated volunteers were enrolled in the ISS T-002 trial and randomly allocated to one of the four treatment groups to receive intradermal injections of biologically active HIV-1 Tat protein at the indicated doses without any adjuvant 1 month apart. A...

Anti-Tat Ab persistence by the number of anti-Tat Ab classes over 8 years of follow-up. Kaplan-Meier estimates showing the cumulative probability of anti-Tat Ab durability in ISS T-002 responders (n = 71) stratified according to the number of anti-Tat Ab classes induced by vaccination (1, 2, or 3 classes) up to 412 weeks of follow-up (median follow...

Changes of blood HIV-1 proviral DNA load over baseline in vaccinees stratified by cART regimen during follow-up. Baseline values (left panels) and annual changes (right panels) of HIV DNA levels (expressed as log10 copies/106 CD4+ T-cells) from ISS T-002 study entry in vaccinees stratified by cART regimen are shown. The number of participants teste...

Longitudinal regression analysis of HIV-1 proviral DNA decay in vaccinees stratified by vaccine regimens. Tat vaccine dose-effects on the proviral DNA decay (expressed as log10 copies/106 CD4+ T-cells) by a longitudinal analysis using a random-effects regression model is shown.

Relationship of CD4+ T-cells (A), CD8+ T-cells (B) and HIV-1 proviral DNA in vaccinees during follow-up. Relationships between changes of HIV proviral DNA levels from baseline (log10 copies/106 CD4+ T-cells) and the changes of CD4+ T-cells (A) or CD8+ T-cells (B) from baseline are shown. A generalized estimating equation with adjustment for repeate...

Changes over baseline of CD4+ T-cells stratified by CD4+ T-cell nadir during 8 years of follow-up. Baseline values (left panels) and annual changes over baseline (right panels) from ISS T-002 study entry of CD4+ T cells stratified by CD4+ T-cell nadir are shown. Vaccinees with CD4+ T-cell nadir ≤ 250 cells/μL: n = 20, >250 cells/μL: n = 72. Data ar...

Longitudinal regression analysis of CD4+ T-cells stratified by Tat vaccine regimens. Tat vaccine dose-effects on the increase of CD4+ T cells by days. A longitudinal analysis using a random-effects regression model was performed.

Variations upon time of CD4+ T-cell number stratified according to baseline CD4+ T-cell quartiles. Linear regression mixed effect model for variations upon time of CD4+ T-cell number stratified by baseline CD4+ T-cell quartiles. CD4+ T-cell quartiles at baseline: Q1 <493 (n = 23), Q2 493–600 (n = 24), Q3 601–734 (n = 22) and Q4 >734 (n = 22). Y-axi...

Variations upon time of HIV-1 proviral DNA stratified according to baseline HIV-1 proviral DNA quartiles. Linear regression mixed effect model for variations upon time of HIV-1 proviral DNA (log10 copies/106 CD4+ T-cells) stratified by baseline HIV-1 proviral DNA quartiles. HIV-1 proviral DNA quartiles at baseline: Q1 <2.86 (n = 22), Q2 2.86–3.10 (...

Introduction: In spite of its success at suppressing HIV replication, combination antiretroviral therapy (cART) only partially reduces immune dysregulation and loss of immune functions. These cART-unmet needs appear to be due to persistent virus replication and cell-to-cell transmission in reservoirs, and are causes of increased patients’ morbidity...

Background Although combined antiretroviral therapy (cART) has saved millions of lives, it is incapable of full immune reconstitution and virus eradication. The transactivator of transcription (Tat) protein is a key human immunodeficiency virus (HIV) virulence factor required for virus replication and transmission. Tat is expressed and released ext...

Introduction: Classical approaches aimed at targeting the HIV-1 envelope as well as other structural viral proteins have largely failed. The HIV-1 transactivator of transcription (Tat) is a key HIV virulence factor, which plays pivotal roles in virus gene expression, replication, transmission and disease progression. Notably, anti-Tat Abs are unco...

Background: The phase II multicenter, randomized, open label, therapeutic trial (ISS T-002, Clinicaltrials.gov NCT00751595) was aimed at evaluating the immunogenicity and the safety of the biologically active HIV-1 Tat protein administered at 7.5 or 30 μg, given 3 or 5 times monthly, and at exploring immunological and virological disease biomarker...

Background: The therapeutic management of psoriasis includes conventional treatments as well as the new generation of highly effective TNF-α inhibitors. However, psoriasis has proven to be a complex therapeutic challenge and treatment failures are not uncommon. Thus, laboratory biomarkers of disease progression/therapeutic efficacy may greatly hel...

Objective: The identification of still unrevealed mechanisms affecting the anti-HIV CD8 T-cell response in HIV-1 infection. Design: Starting from the observation that anti-Tat immunization is associated with improved CD8 T-cell immunity, we developed both in-vitro and ex-vivo assays to characterize the effects of extra-cellular Tat on the adapti...

Background Tat is a key HIV-1 virulence factor, which plays pivotal roles in virus gene expression, replication, transmission and disease progression. After release, extracellular Tat accumulates in tissues and exerts effects on both the virus and the immune system, promoting immune activation and virus spreading while disabling the host immune def...

Use of Env in HIV vaccine development has been disappointing. Here we show that, in the presence of a biologically active Tat subunit vaccine, a trimeric Env protein prevents in monkeys virus spread from the portal of entry to regional lymph nodes. This appears to be due to specific interactions between Tat and Env spikes that form a novel virus en...

Entry of wt Tat in MDDCs in the presence of different Env molecules and block by anti-integrins antibodies. Clade B trimeric wt Env (twt Env), trimeric ΔV2 Env (tΔV2 Env), monomeric wt Env (mwt Env), or monomeric ΔV2 Env (mΔV2 Env) molecules or buffer were incubated with Tat and added to MDDCs pre-treated with anti-integrin mAbs or a control isotyp...

Structural model of the ΔV1-2 Env/Tat binary complex. Color code: Env: dark blue; Env V3-loop: light blue; Tat: yellow; Tat cysteine-rich region: orange; and Tat RGD segment: red. (A) panels: surface representation; (B) panels: cartoon representation. See experimental procedures for details. (TIF)

Blockade of Tat/Env complex entry into MDDCs by anti-Tat antibodies. Trimeric ΔV2 Env was incubated with PBS, a pool of sera from six HIV uninfected healthy donors, the same pool of sera plus the anti-Tat 2A4.1 mAb, Tat, or Tat plus 2A4.1 mAb, and added to cells. Cells were then stained for intracellular Env and analyzed by flow cytometry. The perc...

Blockade of Tat/Env complex binding in PBL by anti-CD4 antibodies. PBLs were pre-incubated with buffer or an anti-CD4 mAb and then incubated with twt Env or with twt Env which had been pre-incubated with the indicated amounts of Tat. PBLs were then stained with an anti-gp120 mAb and analyzed by flow cytometry. The percentage of Env-binding cells is...

Wt Tat, but not cys22 Tat, transactivates HIV-1 LTR in TZM-bl cells. RLU in HIV-1 LTR expressing TZM-bl cells cultured in the presence of buffer, or 0.1, 1, 10 µM wt Tat or cys22 Tat. (TIF)

Block of trimeric ΔV2 Env or Tat/ΔV2 Env entry in MDDCs by anti-DC-SIGN and anti-integrins antibodies. (A) MDDCs from two different donors were pre-incubated with different concentration of an anti-DC-SIGN mAb (20 or 50 µg/mL) or with a control isotype mAb and then 70 nM (donor 1) or 35 nM (donor 2) trimeric ΔV2 Env (SF162) were added for 10 min pr...

Env and Tat interacting residues according to modeling docking analyses. Upper panel: Env interacting residues in the five lowest energy solutions. Residues involved in interactions are indicated by boxes. Different box colors correspond to different solutions. Secondary structure elements are colored as follows: the ΔV1-2 gp120 inner domain of Env...

Vaccine protocol design and schedule of immunization of cynomolgus monkeys. (DOCX)

Structures used as templates to model the structures of Tat and Env. (DOC)

Parameters used to perform MD simulations on the V3 loop of the Env protein. (DOC)

Parameters used to perform docking calculations. (DOC)

Parameters used to perform docking calculations. (DOC)

Structural Model of the ΔV1-2 Env/Tat/Integrin αvβ3 Ternary Complex. Color code: ΔV1-2 Env: violet; Tat: yellow; integrin αvβ3: cyan. (TIF)

CD4+ T cell counts, plasma viral load and proviral DNA load in blood, inguinal lymph nodes and rectal mucosal tissues at 4 week after intrarectal challenge with 70 MID50 of SHIVSF162P4cy.

Delineation of the immune correlates of protection in natural infection or after vaccination is a mandatory step for vaccine development. Although the most recent techniques allow a sensitive and specific detection of the cellular immune response, a consensus on the best strategy to assess their magnitude and breadth is yet to be reached. Within th...

We have previously demonstrated that in Ova-immunized mice the increase in intra-macrophage thiol pool induced by pro-GSH molecules modulates the Th1/Th2 balance in favour of a Th1-type immune response. We show now that the same molecules can support a Th1-type over Th2-type immunity against Tat, which is an early HIV-1 regulatory protein and a Th1...

Expression of activation markers on CD8+ and CD4+ T cells in subjects of ISS OBS T-002. Changes from baseline of CD8+ T cells (gating on CD8+ cells) expressing (A, B) CD38, (C, D) HLA-DR, or (E, F) both CD38 and HLA-DR in the Total Subjects (A, C, E) and in the Reference Group (B, D, F), respectively. Data are presented as the mean % changes (±stan...

Cellular immune responses against Tat, Env or recall antigens in the Reference Group of ISS OBS T-002. Percentage of responders at baseline (green bar) and up to week 48 (orange bar). (A) Percentage of subjects (n = 31) showing IFN-γ, IL-2 and IL-4 production against Tat, and (B) percentage of subjects (n = 26) showing anti-Tat CD4+ or CD8+ lymphop...

Immune activation markers and T-regs at baseline in subjects of ISS OBS T-002. (0.04 MB DOC)

Cellular immune responses against Env in subjects of ISS OBS T-002. (0.04 MB DOC)

CD25 and FOXP3 expression on CD4+ T cells in Total Subjects of ISS OBS T-002. (A) Changes from baseline of CD4+ lymphocytes expressing CD25 are shown for Total Subjects (n = 34 at week 12; n = 10 at week 24; n = 8 at week 36 and n = 8 at week 48). (B) Changes from baseline of the percentage of CD4+CD25+ lymphocytes expressing FOXP3+ in Total Subjec...

CD25 and FOXP3 expression on CD4+ T cells in subjects of the Reference Group of ISS OBS T-002 study. (A) Changes from baseline of CD4+ lymphocytes expressing CD25 are shown in subjects of the Reference Group (n = 20 at week 12; n = 8 at week 24; n = 4 at week 36 and n = 4 at week 48). (B) Changes from baseline of the percentage of CD4+CD25+ lymphoc...

Characterization of naïve, central and effector memory CD4+ and CD8+ T cells in Total Subjects and in the Reference Group of ISS OBS T-002. Percentage of naïve (CD45RA+/CD62L+), effector RA+ (CD45RA+/CD62L-, Temra) or RA- (CD45RA-/CD62L-, Temro) and central memory (CD45RA-/CD62L+, Tcm) CD4+ (A) or CD8+ (B) T cells for total OBS subjects at baseline...

Cellular immune responses against Tat, Env or recall antigens in Total Subjects of ISS OBS T-002. Percentage of responders at baseline (green bar) and up to week 48 (orange bar). (A) Percentage of subjects (n = 87) showing anti-Tat production of IFN-γ, IL-2 and IL-4, and (B) percentage of subjects (n = 67) showing anti-Tat CD4+ or CD8+ lymphoprolif...

Cellular immune responses against CEF in subjects of ISS OBS T-002. (0.04 MB DOC)

ISS OBS T-002 Protocol. (0.15 MB PDF)

Flow diagram of ISS OBS T-002 study participants. One hundred and twenty-seven subjects were recruited in the observational study ISS OBS T-002. Among them, 25 individuals were anti-Tat Ab positive and 91 anti-Tat Ab negative, respectively. Evaluable subjects were constituted by 88 anti-Tat Ab negative (Total OBS Subjects) and 32 Reference Group su...

Production of β2-microglobulin, neopterin and total Ig in subjects of the Reference Group of ISS OBS T-002. Changes from baseline of (A) β2-microglobulin serum levels (mg/L), (B) Neopterin (nmol/L), Total (C) IgM, (D) IgG and (E) IgA serum levels (mg/dL), respectively. Data are presented as the mean changes (± standard error) at 12, 24 and 36 weeks...

Baseline characteristics of study participants in ISS OBS T-002 for the Total Subjects and the Reference Group. (0.04 MB DOC)

Cellular immune responses against Candida in subjects of ISS OBS T-002. (0.04 MB DOC)

Trial Protocol. (0.89 MB PDF)

Evaluation of PBMC viability, CD4+ T cell and B cell counts in subjects of ISS OBS. Changes from baseline of in vitro PBMC viability in Total Subjects (A) and the Reference Group (B); n = 88 at week 12; n = 62 at week 24; n = 46 at week 36 and n = 30 at week 48 for the Total Subjects; n = 32 at week 12; n = 20 at week 24; n = 11 at week 36 and n =...

Evaluation of the percentage of CD4+, CD8+, NK and B cells in subjects of ISS OBS T-002 prior or after stratification by HAART regimen. Changes from baseline of CD4+, CD8+, NK and B cells (percentage) for Total Subjects (A) and Reference Group subjects (B); n = 73 at week 12; n = 20 at week 24; n = 10 at week 36 for Total Subjects; n = 27 at week 1...

Tat-specific cellular immune responses in subjects of ISS OBS T-002. (0.04 MB DOC)

CONSORT Checklist. (0.23 MB DOC)

Although HAART suppresses HIV replication, it is often unable to restore immune homeostasis. Consequently, non-AIDS-defining diseases are increasingly seen in treated individuals. This is attributed to persistent virus expression in reservoirs and to cell activation. Of note, in CD4+ T cells and monocyte-macrophages of virologically-suppressed indi...

The native HIV-1 Tat protein was chosen as vaccine candidate for phase I clinical trials based on its role in the natural infection and AIDS pathogenesis, on the association of Tat-specific immune response with the asymptomatic stage as well as on its sequence conservation among HIV clades. A randomized, double blind, placebo-controlled phase I stu...

The native HIV-1 Tat protein was chosen as vaccine candidate for phase I clinical trials in both uninfected (ClinicalTrials.gov identifier: NCT00529698) and infected volunteers (ClinicalTrials.gov identifier: NCT00505401). The rationale was based on the role of Tat in the natural infection and AIDS pathogenesis, on the association of Tat-specific i...

Strategies to improve vaccine efficacy are still required, especially in the case of chronic infections, including human immunodeficiency virus (HIV). DNA vaccines have potential advantages over conventional vaccines; however, low immunological efficacy has been demonstrated in many experiments involving large animals and in clinical trials. To imp...

We previously reported that cynomolgus monkeys vaccinated with the human immunodeficiency virus (HIV)-1 Tat protein controlled infection after challenge with the simian human immunodeficiency virus (SHIV) 89.6P(cy243) for up to 2 y of follow-up. To evaluate the breadth of the protective immunity elicited by the Tat protein, the vaccines along with...

Tat is an early regulatory protein that plays a major role in human HIV-1 replication and AIDS pathogenesis, and therefore, it represents a key target for the host immune response. In natural infection, however, Abs against Tat are produced only by a small fraction (approximately 20%) of asymptomatic individuals and are rarely seen in progressors,...

A randomized, double blind, placebo-controlled phase I vaccine trial based on the native Tat protein was conducted in HIV-infected asymptomatic individuals. The vaccine was administered five times subcute with alum or intradermally without adjuvant at 7.5microg, 15microg or 30microg doses, respectively. The Tat vaccine was well tolerated both local...

The HIV epidemic continues to represent one of the major problems worldwide, particularly in the Asia and Sub-Saharan regions of the world, with social and economical devastating effects. Although antiretroviral drugs have had a dramatically beneficial impact on HIV-infected individuals that have access to treatment, it has had a negligible impact...

According to recent estimates, 39.5 million people have been infected with HIV and 2.9 million have already died. The effect of HIV infection on individuals and communities is socially and economically devastating. Although antiretroviral drugs have had a dramatically beneficial impact on HIV-infected individuals who have access to treatment, it ha...

The contractile activity of peritubular tissue is responsible for the propulsion of spermatozoa along the lumen of seminiferous tubules toward the hilum of the testis. This function is performed by specialized contractile cells [peritubular smooth muscle cells (PSMC)] in response to the locally produced agonist, endothelin (ET). Here, we review cur...

The human immunodeficiency virus (HIV) type 1 Tat protein plays a key role in the life cycle of the virus and in pathogenesis and is highly conserved among HIV subtypes. On the basis of this and of safety, immunogenicity, and efficacy findings in monkeys, Tat is being tested as a vaccine in phase 1 trials. Here, we evaluated the incidence and risk...

Vaccination with a biologically active Tat protein or tat DNA contained infection with the highly pathogenic SHIV89.6P virus, preventing CD4 T-cell decline and disease onset. Here we show that protection was prolonged, since neither CD4 T-cell decline nor active virus replication was observed in all vaccinated animals that controlled virus replicat...

We determined immune cross-recognition and the degree of Tat conservation in patients infected by local human immunodeficiency virus (HIV) type 1 strains. The data indicated a similar prevalence of total and epitope-specific anti–Tat IgG in 578 serum samples from HIV-infected Italian (n=302), Ugandan (n=139), and South African (n=137) subjects, usi...

Human immunodeficiency virus (HIV)-1 Tat protein induces protection in non-human primates upon systemic vaccination. In view of the design of mucosal vaccines against HIV-1 we studied the immune response to native Tat (aa 1-86) in mice following intranasal delivery of the protein with two mucosal adjuvants, Escherichia coli heat-labile enterotoxin...

A major requirement for HIV/AIDS research is the development of a mucosal vaccine that stimulates humoral and cell-mediated immune responses at systemic and mucosal levels, thereby blocking virus replication at the entry port. Thus, a vaccine prototype based on biologically active HIV-1 Tat protein as antigen and the synthetic lipopeptide, macropha...

The immunotherapeutic potential of biologically active HIV-1 Tat protein coupled to autologous red blood cells (RBCs) was evaluated in a mouse model. HIV-1 Tat expressed in Escherichia coli and purified to homogeneity was found to be active in viral trans activation and efficiently internalised by monocyte-derived dendritic cells (MDDCs). The produ...

Vaccination against human immunodeficiency virus (HIV)-1 infection requires candidate antigen(s) (Ag) capable of inducing an effective, broad, and long-lasting immune response against HIV-1 despite mutation events leading to differences in virus clades. The HIV-1 Tat protein is more conserved than envelope proteins, is essential in the virus life c...

The adsorption/release behaviour of oligodeoxynucleotides (ODNs) on double functional core-shell polymethylmethacrylate nanospheres, with a narrow size distribution, is described. The outer shell consists of alkyl or glycolic chains containing permanently-charged quaternary ammonium groups. Ion pair formation between negatively-charged ODN phosphat...

The tunica propria of seminiferous tubules contains a particular type of smooth muscle cell (myoid cells) arranged in a contractile epithelioid layer that is responsible for sperm and tubular fluid flow. Unlike other types of smooth muscle (SM) cells, highly purified populations of peritubular smooth muscle cells (PSMC) survive and maintain their c...

In the present work we have studied the variation of intracellular calcium levels induced by muscarinic agonists in chick dorsal root ganglia neurons. Muscarinic agonists such as muscarine and oxotremorine cause an increase of intracellular calcium levels in fura-2AM-loaded DRG neurons of E18 chick embryos. This increase was abolished following tre...

The potent smooth muscle agonist endothelin-1 (ET-1) is involved in the local control of seminiferous tubule contractility, which results in the forward propulsion of tubular fluid and spermatozoa, through its action on peritubular myoid cells. ET-1, known to be produced in the seminiferous epithelium by Sertoli cells, is derived from the inactive...

Prostaglandin (PG) F2alpha, a well known agonist of smooth muscle, is produced in the male gonad. We have investigated whether PG F2alpha stimulates seminiferous tubule contractility through direct action on peritubular myoid cells. Myoid cells from prepubertal rats were highly purified through Percoll density gradient and cultured in vitro. Stimul...

Testicular myoid cells surrounding the seminiferous tubule are contractile cells responsible for peritubular contractility and for the propulsion of tubular fluid and spermatozoa. We have investigated the contractile response of rat myoid cells to endothelins (ETs) in cell and organ culture and analyzed the cell signaling involved. ET-2, ET-3, and...

Seminiferous tubule contractility is fundamental for sperm progression towards the rete testis; hence its regulation represents a key point in male fertility. Endothelin-1 (ET-1), a potent stimulator of smooth muscle contractility, has recently been shown to be produced in the testis, as well as to bind to specific receptors on myoid cells and ther...

The presence of endothelin (ET), a vasoconstrictor peptide, in the testis suggests that it may regulate nonvascular target cells. We investigated binding ability, regulation of inositol phosphate metabolism, changes in cytosolic free Ca2+ concentrations ([Ca2+]i), and induction of morphological changes by ET-1 in rat primary testicular myoid cell c...

The equation for diauxic growth is derived as a linear combination of two functions describing a slow and a fast rate of cell multiplication. The growth curve displays the typical biphasic shape, containing two sigmoidal branches. The curve fits very satisfactorily experimental data describing the increase of cell number in developing sea urchin em...

One of the great merits of the extention of Thermodynamics to non-equilibrium systems achieved through the development of Irreversible Thermodynamics (1) lies in the close connection established between thermodynamic and kinetic aspects of chemical reactions.