Pierre-Alexandre Bart

An HIV-1 clade C DNA prime, NYVAC boost vaccine regimen induces reliable, polyfunctional, and long-lasting T cell responses

The EuroVacc 02 phase I trial has evaluated the safety and immunogenicity of a prime-boost regimen comprising recombinant DNA and the poxvirus vector NYVAC, both expressing a common immunogen consisting of Env, Gag, Pol, and Nef polypeptide domain from human immunodeficiency virus (HIV)-1 clade C isolate, CN54. 40 volunteers were randomized to receive DNA C or nothing on day 0 and at week 4, followed by NYVAC C at weeks 20 and 24. The primary immunogenicity endpoints were measured at weeks 26 and 28 by the quantification of T cell responses using the interferon γ enzyme-linked immunospot assay. Our results indicate that the DNA C plus NYVAC C vaccine regimen was highly immunogenic, as indicated by the detection of T cell responses in 90% of vaccinees and was superior to responses induced by NYVAC C alone (33% of responders). The vaccine-induced T cell responses were (a) vigorous in the case of the env response (mean 480 spot-forming units/106 mononuclear cells at weeks 26/28), (b) polyfunctional for both CD4 and CD8 T cell responses, (c) broad (the average number of epitopes was 4.2 per responder), and (d) durable (T cell responses were present in 70% of vaccinees at week 72). The vaccine-induced T cell responses were strongest and most frequently directed against Env (91% of vaccines), but smaller responses against Gag-Pol-Nef were also observed in 48% of vaccinees. These results support the development of the poxvirus platform in the HIV vaccine field and the further clinical development of the DNA C plus NYVAC C vaccine regimen.

Dominant TNF-α + Mycobacterium tuberculosis –specific CD4 + T cell responses discriminate between latent infection and active disease

Rapid diagnosis of active Mycobacterium tuberculosis (Mtb) infection remains a clinical and laboratory challenge. We have analyzed the cytokine profile (interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2)) of Mtb-specific T cells by polychromatic flow cytometry. We studied Mtb-specific CD4+ T cell responses in subjects with latent Mtb infection and active tuberculosis disease. The results showed substantial increase in the proportion of single-positive TNF-α Mtb-specific CD4+ T cells in subjects with active disease, and this parameter was the strongest predictor of diagnosis of active disease versus latent infection. We validated the use of this parameter in a cohort of 101 subjects with tuberculosis diagnosis unknown to the investigator. The sensitivity and specificity of the flow cytometry–based assay were 67% and 92%, respectively, the positive predictive value was 80% and the negative predictive value was 92.4%. Therefore, the proportion of single-positive TNF-α Mtb-specific CD4+ T cells is a new tool for the rapid diagnosis of active tuberculosis disease.

Functional signatures of protective antiviral T-cell immunity in human virus infections.

Summary:  The most common human viruses have different abilities to establish persistent chronic infection. Virus‐specific T‐cell responses are critical in the control of virus replication and in the prevention of disease in chronic infection. A large number of phenotypic markers and a series of functions have been used to characterize virus‐specific CD4+ and CD8+ T‐cell responses, and these studies have shown great phenotypic and functional heterogeneity of the T‐cell responses against different viruses. The heterogeneity of the T‐cell response has been proposed to be specific to each virus. However, over the past 2 years, several studies have provided evidence that the phenotypic and functional heterogeneity of CD4+ and CD8+ T‐cell responses is predominantly regulated by the levels of antigen load. The levels of antigen load modulate the phenotypic and functional patterns of the T‐cell response within the same virus infection. Furthermore, the functional characterization of virus‐specific CD4+ and CD8+ T‐cell responses has identified signatures of protective antiviral immunity. Polyfunctional, i.e. interleukin‐2 and interferon‐γ (IFN‐γ) secretion and proliferation, and not monofunctional, i.e. IFN‐γ secretion, CD4+ and CD8+ T‐cell responses represent correlates of protective antiviral immunity in chronic virus infections.

EV02: A Phase I trial to compare the safety and immunogenicity of HIV DNA-C prime-NYVAC-C boost to NYVAC-C alone

The aim of this randomised controlled trial was to see if the addition of 4 mg/ml DNA-C priming given by the intramuscular route at weeks 0 and 4 to NYVAC-C at weeks 20 and 24, safely increased the proportion of participants with HIV-specific T-cell responses measured by the interferon (IFN)-gamma ELISpot assay at weeks 26 and/or 28 compared to NYVAC-C alone. Although 2 individuals discontinued after the first DNA-C due to adverse events (1 vaso-vagal; 1 transient, asymptomatic elevation in alanine transaminase), the vaccines were well tolerated. Three others failed to complete the regimen (1 changed her mind; 2 lost to follow-up). Of the 35 that completed the regimen 90% (18/20) in the DNA-C group had ELISpot responses compared to 33% (5/15) that received NYVAC-C alone (p=0.001). Responses were to envelope in the majority (21/23). Of the 9 individuals with responses to envelope and other peptides, 8 were in the DNA-C group. These promising results suggest that DNA-C was an effective priming agent, that merits further investigation.

Humoral Response to the Influenza A H1N1/09 Monovalent AS03-Adjuvanted Vaccine in Immunocompromised Patients

BACKGROUND Few data are available regarding the immunogenicity and safety of the pandemic influenza vaccine in immunocompromised patients. We evaluated the humoral response to the influenza A H1N1/09 vaccine in solid-organ transplant (SOT) recipients, in patients with human immunodeficiency virus (HIV) infection, and in healthy individuals. METHODS Patients scheduled to receive the pandemic influenza vaccine were invited to participate. All participants received the influenza A H1N1/09 AS03-adjuvanted vaccine containing 3.75 μg of hemagglutinin. SOT recipients and HIV-infected patients received 2 doses at 3-week intervals, whereas control subjects received 1 dose. Blood samples were taken at day 0, day 21, and day 49 after vaccination. Antibody responses were measured with the hemagglutination inhibition assay (HIA) and a microneutralization assay. RESULTS Twenty-nine SOT recipients, 30 HIV-infected patients, and 30 healthy individuals were included in the study. Seroconversion measured by HIA was observed in 15 (52%) of 29 SOT recipients both at day 21 and day 49; in 23 (77%) of 30 at day 21 and 26 (87%) of 30 at day 49 in HIV-infected patients, and in 20 (67%) of 30 at day 21 and in 23 (77%) of 30 at day 49 in control subjects (P = .12 at day 21 and P = .009 at day 49, between groups). Geometric means of antibody titers were not significantly different between groups at day 21 or at day 49. CONCLUSIONS Influenza A H1N1/09 vaccine elicited a similar antibody response in HIV-infected individuals and in control subjects, whereas SOT recipients had an overall lower response. A second dose of the vaccine only moderately improved vaccine immunogenicity in HIV-infected patients.

Distribution and functional analysis of memory antiviral CD8 T cell responses in HIV-1 and cytomegalovirus infections.

In the present study, we have investigated the anatomic distribution and the function of different populations of HIV‐1‐ and cytomegalovirus (CMV)‐specific memory CD8 T cells. The different populations of virus‐specific memory CD8 T cells were distinguished on the basis of the expression of CD45RA and CCR7, and the composition of HIV‐1‐ and CMV‐specific memory CD8 T cell pools were compared in subjects with chronic HIV‐1 and CMV co‐infection. The distribution of HIV‐1‐specific CD8 T cells was similar between blood and lymph node. However, CMV‐specific CD8 T cells were accumulated predominantly in the blood away from the lymphoid tissue. The majority (>70%) of HIV‐1‐ and CMV‐specific CD8 T cells in both blood and lymph node had a phenotype, e.g. CCR7–, typical of effector T cells. HIV‐1‐specific memory CD8 T cells were mostly (>80%) pre‐terminally differentiated cells, e.g. CD45RA–CCR7–, in both blood and lymph node while 30–50% of CMV‐specific CD8 T cells were terminally differentiated, e.g. CD45RA+CCR7–. Therefore, consistently with studies in mice, antigen‐specific effector memory CD8 T cells accumulate predominantly in the target organ of the pathogen in humans, and the differences in the composition of HIV‐1‐ and CMV‐specific CD8 T cell pools were also present in the lymphoid tissue. A substantial proportion (30–40%) of virus‐specific CD8+CCR7+ T cells produced IFN‐γ. Thus, indicating that the expression of CCR7 does not provide a clear‐cut separation of memory CD8 T cells with distinct functional capacities. Taken together, these results provide further advances in the characterization of human memory CD8 T cells.

Distinct Profiles of Cytotoxic Granules in Memory CD8 T Cells Correlate with Function, Differentiation Stage, and Antigen Exposure

ABSTRACT Cytotoxic CD8 T cells exert their antiviral and antitumor activity primarily through the secretion of cytotoxic granules. Degranulation activity and cytotoxic granules (perforin plus granzymes) generally define CD8 T cells with cytotoxic function. In this study, we have investigated the expression of granzyme K (GrmK) in comparison to that of GrmA, GrmB, and perforin. The expression of the cytotoxic granules was assessed in virus-specific CD8 T cells specific to influenza virus, Epstein-Barr virus (EBV), cytomegalovirus (CMV), or human immunodeficiency virus type 1 (HIV-1). We observed a dichotomy between GrmK and perforin expression in virus-specific CD8 T cells. The profile in influenza virus-specific CD8 T cells was perforin− GrmB− GrmA+/− GrmK+; in CMV-specific cells, it was perforin+ GrmB+ GrmA+ GrmK−/+; and in EBV- and HIV-1-specific cells, it was perforin−/+ GrmB+ GrmA+ GrmK+. On the basis of the delineation of memory and effector CD8 T cells with CD45RA and CD127, the GrmK+ profile was associated with early-stage memory CD8 T-cell differentiation, the perforin+ GrmB+ GrmA+ profile with advanced-stage differentiation, and the GrmB+ GrmA+ Grmk+ profile with intermediate-stage differentiation. Furthermore, perforin and GrmB but not GrmA and GrmK correlated with cytotoxic activity. Finally, changes in antigen exposure in vitro and in vivo during primary HIV-1 infection and vaccination modulated cytotoxic granule profiles. These results advance our understanding of the relationship between distinct profiles of cytotoxic granules in memory CD8 T cells and function, differentiation stage, and antigen exposure.

EV01: a phase I trial in healthy HIV negative volunteers to evaluate a clade C HIV vaccine, NYVAC-C undertaken by the EuroVacc Consortium

NYVAC-C (vP2010), a recombinant vector expressing HIV subtype C gag, pol, env and nef antigens, was tested in a phase I study in healthy, HIV negative volunteers in London and Lausanne. Twenty-four participants were randomised to receive NYVAC-C (20) or matching placebo (4) at weeks 0 and 4, and assessed for safety and immunogenicity over 48 weeks. There were no serious adverse events, and no clinical or laboratory abnormalities or other events that led to withdrawal, interruption or dose reduction of the NYVAC-C/placebo. Half of the 10 assessed responded in the ELISpot assay under stringent criteria, which informed the sample size for a DNA-NYVAC-C comparison to NYVAC-C alone.

Methadone blood concentrations are decreased by the administration of Abacavir plus amprenavir

Abacavir and amprenavir, a nucleoside reverse transcription inhibitor and a protease inhibitor, respectively, are new drugs used for the treatment of HIV. Methadone blood concentrations were measured in five addict patients receiving methadone maintenance therapy before and after introduction of abacavir plus amprenavir. The administration of these two drugs for a median period of 14 days resulted in a significant reduction (P = 0.043) of methadone concentration, with a median decrease to 35% of the original concentration (range 28–87%). Two patients reported on several occasions nausea in the morning before the intake of the daily methadone dose, which is compatible with withdrawal reaction to opioids. Because amprenavir is a cytochrome P4503A4 substrate and is involved in the metabolism of methadone, reduction of methadone concentrations could be explained by an induction of cytochrome P4503A4.

Exhaustion of bacteria-specific CD4 T cells and microbial translocation in common variable immunodeficiency disorders.

Common variable immunodeficiency (CVID) is characterized by abnormally low levels of antibodies in the blood and dysfunctional immune cells called CD4+ T cells. Perreau et al. now show evidence that bacteria-fighting CD4+ T cells in these patients are in a state of exhaustion due to a constant leakage of normal gut bacteria into the bloodstream, possibly due to insufficient antibody levels.