Superior efficacy of a human immunodeficiency virus vaccine combined with antiretroviral prevention in simian-human immunodeficiency virus-challenged nonhuman primates

International audienc

Therapeutic DNA vaccination of vertically HIV-infected children: Report of the first pediatric randomised trial (PEDVAC)

Subjects: Twenty vertically HIV-infected children, 6–16 years of age, with stable viral load control and CD4+ values above 400 cells/mm³. Intervention: Ten subjects continued their ongoing antiretroviral treatment (ART, Group A) and 10 were immunized with a HIV-DNA vaccine in addition to their previous therapy (ART and vaccine, Group B). The genetic vaccine represented HIV-1 subtypes A, B and C, encoded Env, Rev, Gag and RT and had no additional adjuvant. Immunizations took place at weeks 0, 4 and 12, with a boosting dose at week 36. Monitoring was performed until week 60 and extended to week 96. Results: Safety data showed good tolerance of the vaccine. Adherence to ART remained high and persistent during the study and did not differ significantly between controls and vaccinees. Neither group experienced either virological failure or a decline of CD4+ counts from baseline. Higher HIV-specific cellular immune responses were noted transiently to Gag but not to other components of the vaccine. Lymphoproliferative responses to a virion antigen HIV-1 MN were higher in the vaccinees than in the controls (p = 0.047), whereas differences in reactivity to clade-specific Gag p24, RT or Env did not reach significance. Compared to baseline, the percentage of HIV-specific CD8+ lymphocytes releasing perforin in the Group B was higher after the vaccination schedule had been completed (p = 0.031). No increased CD8+ perforin levels were observed in control Group A. Conclusions: The present study demonstrates the feasibility, safety and moderate immunogenicity of genetic vaccination in vertically HIV-infected children, paving the way for amplified immunotherapeutic approaches in the pediatric population. Trial registration: clinicaltrialsregister.eu 2007-002359-18; 2007-002359-18/I

International Network for Comparison of HIV Neutralization Assays: The NeutNet Report

BACKGROUND: Neutralizing antibody assessments play a central role in human immunodeficiency virus type-1 (HIV-1) vaccine development but it is unclear which assay, or combination of assays, will provide reliable measures of correlates of protection. To address this, an international collaboration (NeutNet) involving 18 independent participants was organized to compare different assays. METHODS: Each laboratory evaluated four neutralizing reagents (TriMab, 447-52D, 4E10, sCD4) at a given range of concentrations against a panel of 11 viruses representing a wide range of genetic subtypes and phenotypes. A total of 16 different assays were compared. The assays utilized either uncloned virus produced in peripheral blood mononuclear cells (PBMCs) (virus infectivity assays, VI assays), or their Env-pseudotyped (gp160) derivatives produced in 293T cells (PSV assays) from molecular clones or uncloned virus. Target cells included PBMC and genetically-engineered cell lines in either a single- or multiple-cycle infection format. Infection was quantified by using a range of assay read-outs that included extracellular or intracellular p24 antigen detection, RNA quantification and luciferase and beta-galactosidase reporter gene expression. FINDINGS: PSV assays were generally more sensitive than VI assays, but there were important differences according to the virus and inhibitor used. For example, for TriMab, the mean IC50 was always lower in PSV than in VI assays. However, with 4E10 or sCD4 some viruses were neutralized with a lower IC50 in VI assays than in the PSV assays. Inter-laboratory concordance was slightly better for PSV than for VI assays with some viruses, but for other viruses agreement between laboratories was limited and depended on both the virus and the neutralizing reagent. CONCLUSIONS: The NeutNet project demonstrated clear differences in assay sensitivity that were dependent on both the neutralizing reagent and the virus. No single assay was capable of detecting the entire spectrum of neutralizing activities. Since it is not known which in vitro assay correlates with in vivo protection, a range of neutralization assays is recommended for vaccine evaluation

HIV-1 isolation from infected peripheral blood mononuclear cells

Human immunodeficiency virus 1 (HIV-1) isolation from peripheral blood mononuclear cells (PBMCs) allows retrieval of replication-competent viral variants. In order to impose the smallest possible selective pressure on the viral isolates, isolation must be carried out in primary cultures of cells and not in tumor derived cell lines. The procedure involves culture of PBMCs from an infected patient with phytohemagglutinin (PHA)-stimulated PBMC from seronegative donors, which provide susceptible target cells for HIV replication. HIV can be isolated from the bulk population of PBMCs or after cloning of the cells to obtain viral biological clones. Viral production is determined with p24 antigen (Ag) detection assays or with reverse transcriptase (RT) activity assay. Once isolated, HIV-1 can be propagated by infecting PHA-stimulated PBMCs from healthy donors. Aliquots from culture with a high production of virus are stored for later us

Continuous hiv-1 escape from autologous neutralization and development of cross-reactive antibody responses characterizes slow disease progression of children

The antibodies with different effector functions evoked by Human Immunodeficiency Virus type 1 (HIV-1) transmitted from mother to child, and their role in the pathogenesis of infected children remain unresolved. So, too, the kinetics and breadth of these responses remain to be clearly defined, compared to those developing in adults. Here, we studied the kinetics of the autologous and heterologous neutralizing antibody (Nab) responses, in addition to antibody-dependent cellular cytotoxicity (ADCC), in HIV-1 infected children with different disease progression rates followed from close after birth and five years on. Autologous and heterologous neutralization were determined by Peripheral blood mononuclear cells (PBMC)-and TZMbl-based assays, and ADCC was assessed with the GranToxiLux assay. The reactivity to an immunodominant HIV-1 gp41 epitope, and childhood vaccine antigens, was assessed by ELISA. Newborns displayed antibodies directed towards the HIV-1 gp41 epitope. However, antibodies neutralizing the transmitted virus were undetectable. Nabs directed against the transmitted virus developed usually within 12 months of age in children with slow progression, but rarely in rapid progressors. Thereafter, autologous Nabs persisted throughout the follow-up of the slow progressors and induced a continuous emergence of escape variants. Heterologous cross-Nabs were detected within two years, but their subsequent increase in potency and breadth was mainly a trait of slow progressors. Analogously, titers of antibodies mediating ADCC to gp120 BaL pulsed target cells increased in slow progressors during follow-up. The kinetics of antibody responses to the immunodominant viral antigen and the vaccine antigens were sustained and independent of disease progression. Persistent autologous Nabs triggering viral escape and an increase in the breadth and potency of cross-Nabs are exclusive to HIV-1 infected slowly progressing children

Virus phenotype variability during disease progression of HIV-1 infected children

Background HIV-1 infected children display different clinical evolution, i.e., “fast progression” (FP), “slow progression” (SP) and “long term non progression” (LTNP). One important phenotypic trait linked to disease progression is the evolution of the viral co-receptor use [1], involving a change from CCR5 to CXCR4 use [2]. However, AIDS symptoms can appear in absence of X4 viruses. Recently chimeric receptors between CCR5 and CXCR4 were developed, in which subsequent parts of CCR5 were replaced with corresponding parts of CXCR4 [3]. Their use allowed to document the biological variability of R5 isolates during the pathogenic process in adults [4]. Aim To examine the HIV biological variability in children with different modes of disease progression. Materials and methods 119 isolates from19 HIV-1 positive children were tested for their ability to infect U87.CD4+ cells expressing the wild type receptor CCR5, CXCR4, or one of the 6 chimeric CCR5/CXCR4 receptors. Results Early during infection, all the viruses isolated from 8 SP children used only wild type CCR5 (called R5narrow). In one case, this phenotype persisted during disease progression, whereas in 2 children the virus evolved and was able to use multiple chimeric receptors (called R5broad), and in additional 5 children the virus evolved to CXCR4 usage. Interestengly the FP children, carried close to birth in 2 cases R5narrow virus, in 2 cases R5broad and in one case a dualtropic R5X4 virus. Virus with R5narrow evolved to R5broad in one of the 2 children carrying such phenotype. Both children with R5broad phenotype developed CXCR4 variants during the follow-up. Evolution was observed also in the LTNP, although followed from later on in life (>8 years of age): all tested isolates from 2/6 LTNP remained R5narrow during disease progression; in one child an evolution from R5narrow to R5broad was observed whereas in another child the virus evolved from R5narrow to R5X4. The remaining two children showed R5broad phenotype during the whole followup. Conclusions Our results show that HIV-1 with broad chimeric receptor use is not hampered in transmission, and is more frequent close to birth in FP than in SP children. Viruses from LTNP show a similar phenotypic evolution though at later age

Human seminal plasma stimulates the migration of CD11c+ mononuclear phagocytes to the apical side of the colonic epithelium without altering the junctional complexes in an ex vivo human intestinal model

International audienc

Identification of CX3CR1 + mononuclear phagocyte subsets involved in HIV-1 and SIV colorectal transmission

International audienc