HIV versus cytotoxic T lymphocytes--the war being lost

Optimization of a multi-gene HIV-1 recombinant subtype CRF02_AG DNA vaccine for expression of multiple immunogenic forms

We developed an AIDS vaccine for Western and West-Central Africa based on a DNA plasmid vector expressing HIV-1 recombinant subtype CRF02_AG gag, pol, and env genes. To optimize the production of noninfectious HIV-like particles (VLPs) and potentially improve the effectiveness of the vaccine, we generated four potential vaccine constructs: the parental (IC2) and three modifications (IC25, IC48, and IC90) containing mutations within the HIV protease. While the parental construct IC2 expressed aggregates of Gag proteins, the IC25 construct resulted in the production of immature VLPs (the core comprises unprocessed Pr(55Gag)). The remaining two constructs (IC48 and IC90) produced mature VLPs (the core comprises processed capsid p24) in addition to immature VLPs and aggregates of Gag proteins. VLPs incorporated significant levels of mature gp120 envelope glycoprotein. Importantly, the mature VLPs were fusion competent and entered coreceptor-specific target cells. The production of multiple antigenic forms, including fusion-competent VLPs, by candidate DNA vaccine constructs may provide immunologic advantages for induction of protective cellular and humoral responses against HIV-1 proteins.

Cytokine responses to human immunodeficiency virus type 1 (HIV-1) induced by immunization with live recombinant canarypox virus vaccine expressing HIV-1 genes boosted by HIV-1(SF-2) recombinant GP120

Vaccine-induced T-cell memory for human immunodeficiency virus type 1 (HIV-1) was assessed by measuring HIV-1 antigen-stimulated cytokine secretion in 72 HIV-1-uninfected subjects, of whom 52 received live recombinant canarypox virus vaccine expressing HIV-1 env, gag, and protease gene products (vCP205) with or without HIV-1(SF-2) recombinant gp120 (SF-2 rgp120) subunit vaccine, and 20 the control. The vCP205 vaccine induced secretion of the Th1 cytokine, interferon-gamma, by peripheral blood mononuclear cells (PBMC) after in vitro stimulation with HIV-1 p24 and envelope glycoprotein. Immunization schedules with both vCP205 and SF-2 rgp120 subunit vaccines induced secretion of Th1 and Th2 cytokines by PBMC to HIV-1 envelope glycoprotein. Hence, vCP205 and SF-2 rgp120 subunit vaccines given together and in a prime-boost sequence appeared to induce a broader cytokine response pattern than vCP205 vaccine given alone.

Can Langerhans cell UV injury and dendritic cell infection by immunodepressive viruses induce immunologic tolerance? Second part: immunologic tolerance in AIDS

In the first part of the present editorial [1], we recalled experimental and clinical data demonstrating that 1) UV, via their effects on Langerhans cells, and 2) some so-called immunodepressive viruses, such as measles, lymphocytic choriomeningitis agents, and some animal retroviruses, via their action on dendritic cells, can induce tolerance in some conditions concerning immunologic parameters and/or the antigen(s). We present in this second part of the editorial a commentary on patients treated at the AIDS phase of HIV-1 infection for 3.5 to 8 years. Among them, one has been submitted before and at the beginning of our treatment, for a psoriasis, to a PUVA irradiation, at the dose of 214.5 J (spectrum 230-320). We were present at the end of this irradiation to see the disappearance of his blood CD4 and of his suppressor T cells. Comparing his data with those of other patients of the cohort similarly treated, we have found arguments to consider that this UV-victim patient has presented for the 6 years of his clinically excellent survival and still presents manifestations of immunologic tolerance towards a fraction of his HIV-1 population.

Positive and negative aspects of the human immunodeficiency virus protease: development of inhibitors versus its role in AIDS pathogenesis

In this review we summarize multiple aspects of the human immunodeficiency virus (HIV) protease from both structural and functional viewpoints. After an introductory overview, we provide an up-to-date status report on protease inhibitors (PI). This proceeds from a discussion of PI structural design, to how PI are optimally utilized in highly active antiretroviral triple therapy (one PI along with two reverse transcriptase inhibitors), the emergence of PI resistance, and the natural role of secretory leukocyte PI. Then we switch to another focus: the interaction of HIV protease with other genes in acute and persistent infection, which in turn may have an effect on AIDS pathogenesis. We conclude with a discussion on future directions in HIV treatment, involving multiple-target anti-HIV therapy, vaccine development, and novel reactivation-inhibitory reagents.

Cognitive-behavioral stress management intervention effects on anxiety, 24-hr urinary norepinephrine output, and T-cytotoxic/suppressor cells over time among symptomatic HIV-infected gay men

The present study tested the effects of a multimodal cognitive-behavioral stress management (CBSM) intervention on anxious mood, perceived stress, 24-hr urinary catecholamine levels, and changes in T-lymphocyte subpopulations over time in symptomatic HIV+ gay men. Seventy-three men were randomized to either a group-based CBSM intervention (n = 47) or a wait-list control (WLC) condition (n = 26). Men assigned to CBSM showed significantly lower posttreatment levels of self-reported anxiety, anger, total mood disturbance, and perceived stress and less norepinephrine (NE) output as compared with men in the WLC group. At the individual level, anxiety decreases paralleled NE reductions. Significantly greater numbers of T-cytotoxic/suppressor (CD3+CD8+) lymphocytes were found 6 to 12 months later in those assigned to CBSM. Moreover, greater decreases in NE output and a greater frequency of relaxation home practice during the 10-week CBSM intervention period predicted higher CD3+CD8+ cell counts at follow-up.

Vaccine-induced cytotoxic T lymphocytes against human immunodeficiency virus type 1 using two complementary in vitro stimulation strategies

CD8+ cytotoxic T lymphocytes (CTL) against human immunodeficiency virus type 1 (HIV-1) induced by candidate HIV-1 vaccines may be a mechanism of immune protection against HIV-1 infection. We measured in vitro inducible CD8+ and CD4+ CTL using two in vitro effector cell stimulation strategies. Peripheral blood mononuclear cells (PBMC) for CTL assay were obtained after the third and/or fourth immunization timepoints from 23 healthy, uninfected adult volunteers, of whom 19 received a canarypox virus vaccine expressing HIV-1 env, gag, pol, nef and protease gene products (vCP300) with or without injections of HIV-1(SF-2) rgp120 subunit vaccine and four subjects received only control injections. CD8+ CTL activity was detected employing the two in vitro stimulation strategies against one or more HIV-1 antigens in 15 (79%) of 19 HIV-1 vaccine recipients on at least one occasion and repeatedly against the same antigen in 8 (42%). Canarypox virus-based HIV-1 vaccines represent a step forward in HIV-1 vaccine development.

Characterization of a multi-lipopeptides mixture used as an HIV-1 vaccine candidate

A multi-component vaccine has been defined, which contains six different synthetic 24- to 32-amino acid lipopeptides derived from the sequence of HIV-1 proteins. The physicochemical properties of the lipopeptide components were compatible with multi-dimensional analysis, using RP-HPLC, Edman sequencing, electrospray mass spectrometry, and 2D-NMR. Detailed analysis of the impurity profiles led to the detection and evaluation of the relative proportions of most by-products: several contaminants resulted from the formation of acetylated fragments, transpeptidation reactions with succinimide or piperidide formation, or methionine and/or tryptophan mono-oxidations. The first batch to be produced underwent extensive pharmacotoxicological testings to confirm its safety; this vaccine candidate has now been used in phase I clinical trials. Despite the complexity of such multi-lipopeptide vaccines, our findings suggest the possibility of preparing a clear and precise assignment of by-products to toxicologically qualified impurities in the eventuality of a future production of several successive batches.

Drug Monitoring of Antiretroviral Therapy for HIV-1 Infection: Method Validation and Results of a Pilot Study

Background: Antiretroviral therapy for HIV-1 infection has become increasingly complex. The availability of new and potent drugs and progress in understanding the pathogenesis of HIV-1 infection have led to the establishment of new treatment paradigms. The varying dosing regimens, associated toxicities, and the potential for drug-drug and food-drug interactions further complicate treatment. This complexity contributes to patient nonadherence. Because clinicians have no tools to monitor adherence or drug-drug interactions and because response requires that therapy exceed the known inhibiting concentration, serum monitoring of antiretroviral therapy may play a role in improving treatment of HIV-1 infection. We report methods to quantify serum concentrations of antiretroviral drugs used to treat HIV-1 infection, precision and interference studies of these methods, and results observed in a pilot evaluation of blood serum concentrations from 12 human subjects.

Methods: HPLC offers adequate sensitivity to measure peak or trough serum concentrations of delavirdine, lamivudine, nevirapine, indinavir, nelfinavir, ritonavir, and saquinavir and peak serum concentrations of stavudine, zidovudine, and didanosine with reasonable precision.

Results: Peak indinavir serum concentrations in most patients were in the range of 1–10 mg/L, and trough concentrations were in the range of 0.1–0.5 mg/L. Peak stavudine concentrations were in the range of 0.3–1.3 mg/L, and trough concentrations were in the range of 0.1–0.5 mg/L. Peak zidovudine concentrations were in the range of 0.1–1.1 mg/L.

Conclusions: Because this was a blood serum concentration-seeking pilot study to evaluate analytic performance, we do not report on the correlation of drug response to blood concentration. However, the concentrations observed in patients are generally consistent with blood concentrations reported from studies of monotherapy.

Accumulation of specific amino acid substitutions in HLA-B35-restricted human immunodeficiency virus type 1 cytotoxic T lymphocyte epitopes

HLA is one of the genetic factors that influence the clinical course of HIV-1 infection, and patients with HLA-B35 are prone to rapid disease progression. Nine viral epitopes that are recognized by cytotoxic T lymphocytes (CTLs) in an HLA-B35-restricted manner were determined. To examine how HIV-1 sequences are selected by CTLs in vivo, we sequenced the nine CTL epitopes of the virus in patient plasma. Here we show that certain amino acid substitutions at three epitopes were observed with significantly higher frequency in HLA-B35-positive patients than in HLA-B35-negative patients. By performing experiments with CTL clones established from the HLA-B35-positive patients, it was determined that one of the three substitutions was probably an escape mutation. However, concerning the other two epitopes, representative CTL clones killed target cells pulsed with mutant peptides as efficiently as those pulsed with wild-type peptides, suggesting that CTLs that can be established in vitro are not functioning properly in vivo. Amino acid sequence drift in all HLA-B35-restricted epitopes was rare during the observation period (1 year). Our results may have relevance in understanding the rapid clinical progression in HLA-B35-positive patients.

The Susceptibility to X4 and R5 Human Immunodeficiency Virus-1 Strains of Dendritic Cells Derived In Vitro From CD34+ Hematopoietic Progenitor Cells Is Primarily Determined by Their Maturation Stage

Dendritic cells (DC) were sorted on day 8 from cultures of CD34+ cells with stem cell factor/Flt-3 ligand/ granulocyte-macrophage colony-stimulating factor (GM-CSF)/tumor necrosis factor- (TNF-)/interleukin-4 (IL-4). Exposing immature CCR5+CXCR4lo/− DC to CCR5-dependent human immunodeficiency virus (HIV)-1Ba-L led to productive and cytopathic infection, whereas only low virus production occurred in CXCR4-dependent HIV-1LAI–exposed DC. PCR analysis of the DC 48 hours postinfection showed efficient entry of HIV-1Ba-L but not of HIV-1LAI. CD40 ligand- or monocyte-conditioned medium-induced maturation of HIV-1Ba-L–infected DC reduced virus production by about 1 Log, while cells became CCR5−. However, HIV-1Ba-L–exposed mature DC harbored 15-fold more viral DNA than their immature counterparts, ruling out inhibition of virus entry. Simultaneously, CXCR4 upregulation by mature DC coincided with highly efficient entry of HIV-1LAI which, nonetheless, replicated at the same low level in mature as in immature DC. In line with these findings, coculture of HIV-1Ba-L–infected immature DC with CD3 monoclonal antibody–activated autologous CD4+ T lymphocytes in the presence of AZT decreased virus production by the DC. Finally, whether they originated from CD1a+CD14− or CD1a−CD14+ precursors, DC did not differ as regards permissivity to HIV, although CD1a+CD14− precursor-derived immature DC could produce higher HIV-1Ba-L amounts than their CD1a−CD14+ counterparts. Thus, both DC permissivity to, and capacity to support replication of, HIV is primarily determined by their maturation stage.

The Susceptibility to X4 and R5 Human Immunodeficiency Virus-1 Strains of Dendritic Cells Derived In Vitro From CD34+ Hematopoietic Progenitor Cells Is Primarily Determined by Their Maturation Stage

Dendritic cells (DC) were sorted on day 8 from cultures of CD34+ cells with stem cell factor/Flt-3 ligand/ granulocyte-macrophage colony-stimulating factor (GM-CSF)/tumor necrosis factor- (TNF-)/interleukin-4 (IL-4). Exposing immature CCR5+CXCR4lo/− DC to CCR5-dependent human immunodeficiency virus (HIV)-1Ba-L led to productive and cytopathic infection, whereas only low virus production occurred in CXCR4-dependent HIV-1LAI–exposed DC. PCR analysis of the DC 48 hours postinfection showed efficient entry of HIV-1Ba-L but not of HIV-1LAI. CD40 ligand- or monocyte-conditioned medium-induced maturation of HIV-1Ba-L–infected DC reduced virus production by about 1 Log, while cells became CCR5−. However, HIV-1Ba-L–exposed mature DC harbored 15-fold more viral DNA than their immature counterparts, ruling out inhibition of virus entry. Simultaneously, CXCR4 upregulation by mature DC coincided with highly efficient entry of HIV-1LAI which, nonetheless, replicated at the same low level in mature as in immature DC. In line with these findings, coculture of HIV-1Ba-L–infected immature DC with CD3 monoclonal antibody–activated autologous CD4+ T lymphocytes in the presence of AZT decreased virus production by the DC. Finally, whether they originated from CD1a+CD14− or CD1a−CD14+ precursors, DC did not differ as regards permissivity to HIV, although CD1a+CD14− precursor-derived immature DC could produce higher HIV-1Ba-L amounts than their CD1a−CD14+ counterparts. Thus, both DC permissivity to, and capacity to support replication of, HIV is primarily determined by their maturation stage.

Combinations of four virostatics applied in rotational sequences induce an exponential VL regression curve, the first part of which is rapidly decreasing to a PCR-undetectable level, while the last part is insensitive to the model. Indications for virostatic and immunotherapeutic reinforcements?

Between 1992 and 1995, we have had five virostatics available: zidovudine (AZT), didanosine (ddI), zalcitabine (ddC) (as retrotranscriptase nucleosidic antagonists, RTNA), acriflavine (ACF), and hydroxy-methyl-ellipticine (HEL), as respectively a DNA synthesis and structure antagonist, and a topoisomerase II inhibitor. Between 1995 and now, we have had ten virostatics the same, plus lamivudine (3TC), stavudine (d4T) as RTNA, and indinavir (IDV), ritonavir (RTV) and saquinavir (SQV) as protease inhibitors. We first conducted a phase I-like study concerning the ratios of the drug numbers in combinations over the numbers available. The optimal model for the study was that of four virostatics selected out of the ten. The four virostatic combinations were applied in short (3 week) sequences, differing each others by drug rotation. The patients were, before treatment, nine at the phase of AIDS, one at the A3 stage. They presented a very rapid decrease of viral load (VL) which became undetectable at PCR, being first below 200 RNA copies/mL, then below 20. We call this condition 'minimum residual disease' as HIV1 persistence is revealed by virus rebounds, reversible, and probably induced by cofactors. The frequency of the latter selection is due to the very frequent (each 3 weeks) VL evaluations. The last part of the VL exponential curve which the minimum residual disease represents, is almost horizontal and quasi insensitive to the powerful virostatic model described above, though no resistance has appeared at the combination or sequence levels. Thus we propose to add phases of: a) reinforcements by virostatics, adding two more ones to the four of the model; and b) treatment complement by active immunotherapy phases: the most adapted immunomodulator is the combination of the peptidic cytokine, tuftsine, and of its antipeptidase, bestatine If they are not available, another interleukine, able to help restoring the AIDS disturbed immunologic system, interleukin 2, could be tried, as it has induced beneficial effects at very small doses by subcutaneous injections.

Combinations of three or four HIV virostatics applied in short sequences which differ from each other by drug rotation. Preliminary results of the viral loads and CD4 numbers

This paper presents the evolution during its follow-up of a virostatic combination study of the type I-II trial conducted on ten AIDS-related complex (ARC) or acquired immunodeficiency syndrome (AIDS) patients [1, 9, respectively]. Its concept is based on the following original notions: a) it is not the number of the virostatics applied to each patient at any phase which determines their effect; it is the number of affected virus targets which determines the effect. Thus, the so called "tritherapies", imposed by the "AIDS Command" to thousands of patients selected at random, to be compared to the same number of subjects receiving only "bi" or "monotherapies", might be beginning to face failure because they attack only two targets: retro-transcriptase and HIV1 protease. Having discovered, owing to our experimental screening, original HIV1 virostatics, acriflavine (ACF) and several ellipticine analogues among which we have used methyl-hydroxy-ellipticine (MHE), we are able to attack two virus targets unaffected by classical virostatics: ACF attacks DNA, from its integrated double branched stage to the provirus one, and MHE inhibits topoisomerase II. We experimentally combined these two agents with AZT, which inhibits retro-transcriptase, thus we realized a combination affecting three targets. This three agent combination was able to eradicate Friend's virus from infected mice. Clinically, combinations of three drugs affecting four targets (as they are selected among the ten virostatics available today) give a stronger result than three drug combinations affecting only three targets, because they were selected from the five virostatics which were the only ones available at the beginning of the present study. Five patients out of five who received the combinations of four virostatics chosen among the ten currently available (thus affecting four targets) from the beginning of their treatment to the present have all reduced their viral load (VL) and maintained it below the detectable level (< 200 RNA copies/mL then 20 copies/mL); b) as the toxicities of virostatics and as HIV1 resistances may happen as soon as 12 weeks of treatment, the combinations have been, in our study, applied in shorter (3 week) sequences, differing from each other due to drug rotation; c) neither toxicity nor resistance occurred; d) curiously, the CD4 numbers, even when they increased rapidly, has never attained their normal count, and their curve may be a Gombertzian one. This CD4 restoration limitation can be due to persisting virus, as indicated in some patients by small peaks which may appear on some VL plateaus, though they disappear without treatment change.

Stressful events, pessimism, natural killer cell cytotoxicity, and cytotoxic/suppressor T cells in HIV+ black women at risk for cervical cancer

OBJECTIVE

This study examines whether stressful negative life events and pessimism were associated with lower natural killer cell cytotoxicity (NKCC) and T cytotoxic/suppressor cell (CD8+CD3+) percentage in black women co-infected with human immunodeficiency virus Type 1 (HIV-1) and human papillomavirus (HPV), a viral initiator of cervical cancer.

METHOD

Psychosocial interviews, immunological evaluations, and cervical swabs for HPV detection and subtyping were conducted on 36 HIV+ African-American, Haitian, and Caribbean women.

RESULTS

Greater pessimism was related to lower NKCC and cytotoxic/suppressor cells after controlling for presence/absence of HPV Types 16 or 18, behavioral/lifestyle factors, and subjective impact of negative life events.

CONCLUSIONS

A pessimistic attitude may be associated with immune decrements, and possibly poorer control over HPV infection and increased risk for future promotion of cervical dysplasia to invasive cervical cancer in HIV+ minority women co-infected with HPV.

Evidence for an underlying CD4 helper and CD8 T-cell defect in B-cell-deficient mice: failure to clear persistent virus infection after adoptive immunotherapy with virus-specific memory cells from muMT/muMT mice

Adoptive transfer of virus-specific memory lymphocytes can be used to identify factors and mechanisms involved in the clearance of persistent virus infections. To analyze the role of B cells in clearing persistent infection with lymphocytic choriomeningitis virus (LCMV), we used B-cell-deficient muMT/muMT (B-/-) mice. B-/- mice controlled an acute LCMV infection with the same kinetics and efficiency as B-cell-competent (B+/+) mice via virus-specific, major histocompatibility complex (MHC) class I-restricted CD8(+) cytotoxic T lymphocytes (CTL). CTL from B-/- and B+/+ mice were equivalent in affinity to known LCMV CTL epitopes and had similar CTL precursor frequencies (pCTL). Adoptive transfer of memory cells from B+/+ mice led to virus clearance from persistently infected B+/+ recipients even after in vitro depletion of B cells, indicating that B cells or immunoglobulins are not required in the transfer population. In contrast, transfer of memory splenocytes from B-/- mice failed to clear virus. Control of virus was restored neither by transferring higher numbers of pCTL nor by supplementing B-/- memory splenocytes with LCMV-immune B cells or immune sera. Instead, B-/- mice were found to have a profound CD4 helper defect. Furthermore, compared to cultured splenocytes from B+/+ mice, those from B-/- mice secreted less gamma interferon (IFN-gamma) and interleukin 2, with differences most pronounced for CD8 T cells. While emphasizing the importance of CD4 T-cell help and IFN-gamma in the control of persistent infections, the CD4 T-helper and CD8 T-cell defects in B-/- mice suggest that B cells contribute to the induction of competent T effector cells.

Cytotoxic T-lymphocyte escape viral variants: how important are they in viral evasion of immune clearance in vivo?

Although viral variants which are not recognized by epitope-specific cytotoxic T lymphocytes (CTL) have been shown to arise during a number of persistent virus infections, in many cases their significance remains controversial: it has been argued that the immune response is sufficiently plastic to contain their replication. In this review, we describe the mechanisms by which amino acid changes in viral proteins may affect epitope recognition by virus-specific CTL, and discuss the viral and immunological basis for the emergence of viral variants bearing such amino acid changes during infection. We then consider the impact that viral variation may have on the host CTL response and its ability to contain virus replication. We argue that the emergence of a viral variant demonstrates that it must have an in vivo replicative advantage, and that as such, the variant must tip the balance between virus replication and immune control somewhat in favor of the virus. Further, we suggest that although the immune response can evolve to recognize new viral epitopes, the CTL generated following such evolution frequently have a reduced ability to contain virus replication. We conclude that this escape mechanism likely does make a significant contribution to persistence/pathogenesis during a number of different virus infections.