An elevated level of interleukin-17A in a Senegalese malaria cohort is associated with rs8193038 IL-17A genetic variant

Malaria infection is a multifactorial disease partly modulated by host immuno-genetic factors. Recent evidence has demonstrated the importance of Interleukin-17 family proinflammatory cytokines and their genetic variants in host immunity. However, limited knowledge exists about their role in parasitic infections such as malaria. We aimed to investigate IL-17A serum levels in patients with severe and uncomplicated malaria and gene polymorphism's influence on the IL-17A serum levels. In this research, 125 severe (SM) and uncomplicated (UM) malaria patients and 48 free malaria controls were enrolled. IL-17A serum levels were measured with ELISA. PCR and DNA sequencing were used to assess host genetic polymorphisms in IL-17A. We performed a multivariate regression to estimate the impact of human IL-17A variants on IL-17A serum levels and malaria outcomes. Elevated serum IL-17A levels accompanied by increased parasitemia were found in SM patients compared to UM and controls (P < 0.0001). Also, the IL-17A levels were lower in SM patients who were deceased than in those who survived. In addition, the minor allele frequencies (MAF) of two IL-17A polymorphisms (rs3819024 and rs3748067) were more prevalent in SM patients than UM patients, indicating an essential role in SM. Interestingly, the heterozygous rs8193038 AG genotype was significantly associated with higher levels of IL-17A than the homozygous wild type (AA). According to our results, it can be concluded that the IL-17A gene rs8193038 polymorphism significantly affects IL-17A gene expression. Our results fill a gap in the implication of IL-17A gene polymorphisms on the cytokine level in a malaria cohort. IL-17A gene polymorphisms also may influence cytokine production in response to Plasmodium infections and may contribute to the hyperinflammatory responses during severe malaria outcomes.

ALDsuite: Dense marker MALD using principal components of ancestral linkage disequilibrium

Background

Mapping by admixture linkage disequilibrium (MALD) is a whole genome gene mapping method that uses LD from extended blocks of ancestry inherited from parental populations among admixed individuals to map associations for diseases, that vary in prevalence among human populations. The extended LD queried for marker association with ancestry results in a greatly reduced number of comparisons compared to standard genome wide association studies. As ancestral population LD tends to confound the analysis of admixture LD, the earliest algorithms for MALD required marker sets sufficiently sparse to lack significant ancestral LD between markers. However current genotyping technologies routinely provide dense SNP data, which convey more information than sparse sets, if this information can be efficiently used. There are currently no software solutions that offer both local ancestry inference using dense marker data and disease association statistics.

Results

We present here an R package, ALDsuite, which accounts for local LD using principal components of haplotypes from surrogate ancestral population data, and includes tools for quality control of data, MALD, downstream analysis of results and visualization graphics.

Conclusions

ALDsuite offers a fast, accurate estimation of global and local ancestry and comes bundled with the tools needed for MALD, from data quality control through mapping of and visualization of disease genes.

A general approach for haplotype phasing across the full spectrum of relatedness

Many existing cohorts contain a range of relatedness between genotyped individuals, either by design or by chance. Haplotype estimation in such cohorts is a central step in many downstream analyses. Using genotypes from six cohorts from isolated populations and two cohorts from non-isolated populations, we have investigated the performance of different phasing methods designed for nominally 'unrelated' individuals. We find that SHAPEIT2 produces much lower switch error rates in all cohorts compared to other methods, including those designed specifically for isolated populations. In particular, when large amounts of IBD sharing is present, SHAPEIT2 infers close to perfect haplotypes. Based on these results we have developed a general strategy for phasing cohorts with any level of implicit or explicit relatedness between individuals. First SHAPEIT2 is run ignoring all explicit family information. We then apply a novel HMM method (duoHMM) to combine the SHAPEIT2 haplotypes with any family information to infer the inheritance pattern of each meiosis at all sites across each chromosome. This allows the correction of switch errors, detection of recombination events and genotyping errors. We show that the method detects numbers of recombination events that align very well with expectations based on genetic maps, and that it infers far fewer spurious recombination events than Merlin. The method can also detect genotyping errors and infer recombination events in otherwise uninformative families, such as trios and duos. The detected recombination events can be used in association scans for recombination phenotypes. The method provides a simple and unified approach to haplotype estimation, that will be of interest to researchers in the fields of human, animal and plant genetics.

DRAM triggers lysosomal membrane permeabilization and cell death in CD4(+) T cells infected with HIV

Productive HIV infection of CD4⁺ T cells leads to a caspase-independent cell death pathway associated with lysosomal membrane permeabilization (LMP) and cathepsin release, resulting in mitochondrial outer membrane permeabilization (MOMP). Herein, we demonstrate that HIV infection induces damage-regulated autophagy modulator (DRAM) expression in a p53-dependent manner. Knocking down the expression of DRAM and p53 genes with specific siRNAs inhibited autophagy and LMP. However, inhibition of Atg5 and Beclin genes that prevents autophagy had a minor effect on LMP and cell death. The knock down of DRAM gene inhibited cytochrome C release, MOMP and cell death. However, knocking down DRAM, we increased viral infection and production. Our study shows for the first time the involvement of DRAM in host-pathogen interactions, which may represent a mechanism of defense via the elimination of infected cells.

Lysosomes are acidic organelles capable of digesting macromolecules and regulating autophagy. In the context of host-pathogen interactions, productive viral infections are associated with lysosome membrane permeabilization (LMP) and programmed cell death (PCD). At a molecular level, the tumor suppressor protein 53 (p53), which is a key player in the detection of DNA damage, acts also as a sensor of pathogen replication. Activation of p53 has been considered to be an altruistic cell suicide mechanism that limits viral infection. Here, we provide new evidence that damage-regulated autophagy modulator (DRAM), a p53 target gene, regulates both LMP and PCD of HIV-infected CD4 T cells. Whereas the inhibition of DRAM or p53 prevents autophagy in infected cells, the inhibition of the autophagy machinery has a minor role in this context. As a consequence, the silencing of DRAM leads to increased HIV viral infection. This is the first report describing the role of DRAM in the context of host-pathogen interaction. Whereas it is to the advantage of the pathogens to preserve their hosts and thus facilitate their multiplication and dissemination, hosts have developed altruistic cellular processes to defend themself and limit the spread of the infectious agent in multicellular organisms. We propose that the ancestral DRAM protein represents a mechanism of self-defense, inducing elimination of infected cells through LMP.

Exhaustive genotyping of the interleukin-1 family genes and associations with AIDS progression in a French cohort

Interleukin (IL)-1 family members are key players in inflammatory processes but have been the subject of few studies of acquired immunodeficiency syndrome (AIDS). To better evaluate the impact of the IL-1 family on AIDS development, we genotyped the IL1 alpha , IL1 beta , IL1Ra, and IL1R1 genes in 245 slow progressor (SP) and 82 rapid progressor (RP) human immunodeficiency virus type 1-seropositive patients as well as in 446 control subjects, all of whom were of white ethnicity. One hundred sixteen frequent polymorphisms were identified, of which 23 were newly characterized by our study. Many putative associations were found between single-nucleotide polymorphism (SNP) or haplotype alleles and the extreme profiles of progression. Most of them corresponded to weak associations (.01<P<.05); however, the SNP IL1Ra_2134 exhibited a consistent association, found at the level of the SNP, haplotypes, and haploblocks, when the SP and control populations were compared (P=.0002). The IL-1-dependent inflammatory response is, thus, likely to play a role in AIDS progression via the regulation of IL-1Ra expression. This association will need to be confirmed in other AIDS cohorts, and experiments will also have to be performed to unravel the biological mechanisms at work. The data presented here will be useful for future genomic studies of the IL-1 family members in other infectious and chronic inflammatory diseases.

Genomic studies in AIDS: problems and answers. Development of a statistical model integrating both longitudinal cohort studies and transversal observations of extreme cases

Genomic studies developed to understand HIV-1 infection and pathogenesis have often lead to conflicting results. This is linked to various factors, including differences in cohort design and selection, the numbers of patients involved, the influence of population substructure, the ethnic origins of the participants, and phenotypic definition. These difficulties in the interpretation of results are examined through published studies on the role of polymorphisms in HLA and the chemokine receptors genes in AIDS. Our analysis suggests that the use of haplotypes will strengthen the results obtained in a given cohort, and meta-analysis including multiple cohorts to gather large-enough numbers of patients should also allow clarification of the genetic associations observed. A P-value of 0.001 appears to be a good compromise for significance on candidate genes in a genetic study. Due to the generally limited size of available cohorts, results will have to be validated in other cohorts. We developed a model to fit transversal case studies (extreme case-control studies) with longitudinal cohorts (all-stages patients) for observations on two gene polymorphisms of CCR5 and NQO1. Interestingly, we observe a protective effect for the CCR5-Delta32 mutant allele in 95% of the simulations based on that model when using a population of 600 subjects; however, when using populations of 250 subjects we find a significant protection in only 59% of the simulations. Our model gives thus an explanation for the discrepancies observed in the various genomic studies published in AIDS on CCR5-Delta32 and other gene polymorphisms: they result from statistical fluctuations due to a lack of power. The sizes of most seroconverter cohorts presently available seem thus insufficient since they include less than a few hundred subjects. This result underlines the power and usefulness of the transversal studies involving extreme patients and their complementarity to longitudinal studies involving seroconverter cohorts. The transposition approach of extreme case-control data into longitudinal analysis should prove useful not only in AIDS but also in other diseases induced by chronic exposure to a foreign agent or with chronic clinical manifestations.

Outcome of simian-human immunodeficiency virus strain 89.6p challenge following vaccination of rhesus macaques with human immunodeficiency virus Tat protein

The regulatory proteins Nef, Rev, and Tat of human immunodeficiency virus type 1 (HIV-1) are attractive targets for vaccine development, since induction of effective immune responses targeting these early proteins may best control virus replication. Here we investigated whether vaccination with biologically active Tat or inactive Tat toxoid derived from HIV-1(IIIB) and simian-human immunodeficiency virus (SHIV) strain 89.6p would induce protective immunity in rhesus macaques. Vaccination induced high titers of anti-Tat immunoglobulin G in all immunized animals by week 7, but titers were somewhat lower in the 89.6p Tat group. Dominant B-cell epitopes mapped to the amino terminus, the basic domain, and the carboxy-terminal region. Tat-specific T-helper responses were detected in 50% of immunized animals. T-cell epitopes appeared to map within amino acids (aa) 1 to 24 and aa 37 to 66. In addition, Tat-specific gamma interferon responses were detected in CD4+ and/or CD8+ T lymphocytes in 11 of 16 immunized animals on the day of challenge. However, all animals became infected upon intravenous challenge with 30 50% minimal infective doses of SHIV 89.6p, and there were no significant differences in viral loads or CD4+ T-cell counts between immunized and control animals. Thus, vaccination with HIV-1(IIIB) or SHIV 89.6p Tat or with Tat toxoid preparations failed to confer protection against SHIV 89.6p infection despite robust Tat-specific humoral and cellular immune responses in some animals. Given its apparent immunogenicity, Tat may be more effective as a component of a cocktail vaccine in combination with other regulatory and/or structural proteins of HIV-1.

Selective activation of cervical microvascular endothelial cells by human papillomavirus 16-e7 oncoprotein

BACKGROUND

Human papillomavirus type 16 (HPV16) is strongly implicated in the etiology of cervical cancer, with the expression of HPV16-encoded E7 oncoprotein in infected epithelial cells contributing to their malignant transformation. Although nuclear E7 interacts with several nuclear targets, we have previously shown that extracellular E7 can cause suppression of immune cell function. Moreover, cervical microvascular endothelial (CrMVEn) cells treated with E7 increase their expression of adhesion molecules. High levels of some cytokines in serum and in cervicovaginal secretions are associated with the progression of cervical cancer. In this study, we investigated the effects of extracellular E7 on cytokine production and on cytoskeleton structure of CrMVEn cells and vascular endothelial cells from different organs.

METHODS

Immunocytochemical staining and flow cytometry techniques were used to detect E7 in endothelial cells incubated with purified E7 protein. Laser scanning confocal microscopy was used to study the E7-induced modification of the endothelial cytoskeleton. An enzyme-linked immunosorbent assay was performed to measure the production of two cytokines, interleukin 6 (IL-6) and interleukin 8 (IL-8), by E7-treated endothelial cells. All statistical tests were two-sided.

RESULTS

Extracellular E7 was taken up by CrMVEn cells and localized to the cytoplasm. CrMVEn cells showed a statistically significant (P<.02) increase in the production of IL-6 and IL-8 after treatment with E7 compared with the controls. CrMVEn cells also produced higher levels of these cytokines than did the other endothelial cells (P<.01). E7 also induced marked alterations in the endothelial cytoskeleton of CrMVEn cells as a result of actin fiber polymerization.

CONCLUSION

These findings suggest a novel mechanism by which E7, as an extracellular factor, can play a role in the progression and dissemination of cervical cancer via its selective effects on endothelial cells.

Effects of CCR5-Delta32, CCR2-64I, and SDF-1 3'A alleles on HIV-1 disease progression: An international meta-analysis of individual-patient data

BACKGROUND

Studies relating certain chemokine and chemokine receptor gene alleles with the outcome of HIV-1 infection have yielded inconsistent results.

OBJECTIVE

To examine postulated associations of genetic alleles with HIV-1 disease progression.

DESIGN

Meta-analysis of individual-patient data.

SETTING

19 prospective cohort studies and case-control studies from the United States, Europe, and Australia.

PATIENTS

Patients with HIV-1 infection who were of European or African descent.

MEASUREMENTS

Time to AIDS, death, and death after AIDS and HIV-1 RNA level at study entry or soon after seroconversion. Data were combined with fixed-effects and random-effects models.

RESULTS

Both the CCR5-Delta32 and CCR2-64I alleles were associated with a decreased risk for progression to AIDS (relative hazard among seroconverters, 0.74 and 0.76, respectively; P = 0.01 for both), a decreased risk for death (relative hazard among seroconverters, 0.64 and 0.74; P < 0.05 for both), and lower HIV-1 RNA levels after seroconversion (difference, -0.18 log(10) copies/mL and -0.14 log(10) copies/mL; P < 0.05 for both). Having the CCR5-Delta32 or CCR2-64I allele had no clear protective effect on the risk for death after development of AIDS. The results were consistent between seroconverters and seroprevalent patients. In contrast, SDF-1 3'A homozygotes showed no decreased risk for AIDS (relative hazard for seroconverters and seroprevalent patients, 0.99 and 1.03, respectively), death (relative hazard, 0.97 and 1.00), or death after development of AIDS (relative hazard, 0.81 and 0.97; P > 0.5 for all).

CONCLUSIONS

The CCR5-Delta32 and CCR2-64I alleles had a strong protective effect on progression of HIV-1 infection, but SDF-1 3'A homozygosity carried no such protection.

A common stromal cell-derived factor-1 chemokine gene variant is associated with the early onset of type 1 diabetes

Type 1 diabetes results from the autoimmune destruction of pancreatic beta-cells. Although the disease shows a strong association with HLA class II alleles, other genes may influence the initiation or the rate of progression of the autoimmune process. The recruitment of mononuclear cells within the islets of Langerhans is a critical step in the pathogenesis of the disease. Because chemokines are cytokines that promote migration of mononuclear cells, we hypothesized that polymorphisms in chemokine receptor or chemokine genes, CCR5 and SDF1, may be involved in susceptibility to or clinical expression of type 1 diabetes. The frequencies of the CCR5-delta32 and SDF1-3'A (801G-->A in the 3' untranslated region) variants were similar in 208 unrelated Caucasian patients with type 1 diabetes and in 120 Caucasian control subjects. They were not modified after stratification for the predisposing HLA-DR3 and -DR4 haplotypes. However, the SDF1-3'A variant was strongly associated with early onset (< 15 years) of the disease (odds ratio 2.6, P = 0.0019). On average, the presence of the SDF1-3'A allele was associated with a 5-year reduction in the age at onset of diabetes (P = 0.0067). Our results suggest that stromal cell-derived factor-1 may be implicated in the aggressiveness of the autoimmune process leading to type 1 diabetes. These preliminary data require replication in other populations.

Validation of genetic case-control studies in AIDS and application to the CX3CR1 polymorphism

New polymorphisms have been recently identified in CX3CR1, a coreceptor for some HIV-1 strains, one of which was associated with a strong acceleration of HIV disease progression. This effect was observed both by a case-control study involving 63 nonprogressors (NP) from the asymptomatic long-term (ALT) cohort and Kaplan-Meier analysis of 426 French seroconverters (SEROCO cohort). These results prompted us to analyze these polymorphisms in 244 nonprogressors (NPs) and 80 rapid progressors (RPs) from the largest case-control cohort known to date, the GRIV cohort. Surprisingly, the genetic frequencies found were identical for both groups under all genetic models (p >.8). The discrepancy with the previous work stemmed only from the difference between GRIV NPs versus ALT NPs. We hypothesized this might be due to the limited number of NPs in ALT (n = 63) and in this line we reanalyzed the data previously collected on GRIV for over 100 different genetic polymorphisms: we effectively observed that the genetic frequencies of some polymorphisms could vary by as much as 10% (absolute percentage) when computing them on the first 50 NP subjects enrolled, on the first 100, or on all the NPs tested (240 study subjects). This observation emphasizes the need for caution in case-control studies involving small numbers of subjects: p values should be low or other control groups should be used.However, the association of the CX3CR1 polymorphism with progression seems quite significant in the Kaplan-Meier analysis of the SEROCO cohort (426 individuals), and the difference observed with GRIV might be explained by a delayed effect of the polymorphism on disease. Further studies on other seroconverter cohorts are needed to confirm the reported association with disease progression.

Human papillomavirus-16-E7 oncoprotein enhances the expression of adhesion molecules in cervical endothelial cells but not in human umbilical vein endothelial cells

OBJECTIVES

E7 is one of the oncoproteins encoded by human papillomavirus-16 (HPV-16), the major etiologic factor responsible for cervical cancer. Human papillomavirus-16-E7 expressed by human uterine cervix carcinoma cells is also released in the extracellular compartment where it induces immune suppression. We investigated whether E7 was also responsible for the enhanced endothelial adhesiveness required in cancer progression.

STUDY DESIGN/METHODS

We treated cervical microvascular endothelial cells (CrMVEn) and human umbilical vein endothelial cells (HUVEC) with E7, tumor necrosis factor-alpha (TNF-alpha), and hydrogen peroxide (H2O2) and measured the expression of E-selectin, intercellular adhesion molecule-1 (ICAM-1), and vascular cell adhesion molecule-1 (VCAM-1) by fluorescent-activated cell sorter analysis.

RESULTS

E7 strongly induced the expression of E-selectin, ICAM-1, and VCAM-1 in CrMVEn, but not in HUVEC. Tumor necrosis factor-alpha further increased the endothelial expression of adhesion molecules in CrMVEn. Hydrogen peroxide pre-treatment resulted in an enhanced ICAM-1 and a decreased E-selectin and VCAM-1 expression. We also show indirect effects when endothelial cells were stimulated with the supernatant of E7-pretreated macrophages.

CONCLUSIONS

These results show that HPV-16-E7 oncoprotein strongly induces adhesion molecules expression in organ-specific endothelial cells.

Autoantibodies to TNFalpha in HIV-1 infection: prospects for anti-cytokine vaccine therapy

Tumor necrosis factor alpha (TNFalpha) is a proinflammatory cytokine principally involved in the activation of lymphocytes in response to viral infection. TNFalpha also stimulates the production of other cytokines, activates NK cells and potentiates cell death and/or lysis in certain models of viral infection. Although TNFalpha might be expected to be a protective component of an antiviral immune response, several lines of evidence suggest that TNFalpha and other virally-induced cytokines actually may contribute to the pathogenesis of HIV infection. Based on the activation of HIV replication in response to TNFalpha, HIV appears to have evolved to take advantage of host cytokine activation pathways. Antibodies to TNFalpha are present in the serum of normal individuals as well as in certain autoimmune disorders, and may modulate disease progression in the setting of HIV infection. We examined TNFalpha-specific antibodies in HIV-infected non-progressors and healthy seronegatives; anti-TNFalpha antibody levels are significantly higher in GRIV seropositive slow/non-progressors (N = 120, mean = 0.24), compared to seronegative controls (N= 12, mean = 0.11). TNFalpha antibodies correlated positively with viral load, (P = 0.013, r = 0.282), and CD8+ cell count (P = 0.03, r = 0.258), and inversely with CD4+ cell count (P = 0.003, r = - 0.246), percent CD4+ cells (P = 0.008, r = -0.306), and CD4 :CD8 ratio (P = 0.033, r = - 0.251). TNFalpha antibodies also correlated positively with antibodies to peptides corresponding to the CD4 binding site of gp160 (P = 0.001, r = 0.384), the CD4 identity region (P = 0.016, r = 0.29), the V3 loop (P = 0.005, r = 0.34), and the amino terminus of Tat (P = 0.001, r = 0.395); TNFalpha antibodies also correlated positively with antibodies to Nef protein (P = 0.008, r = 0.302). The production of anti-TNFalpha antibodies appears to be an adaptive response to HIV infection and suggests the potential utility of modified cytokine vaccines in the treatment of HIV infections as well as AIDS-related and unrelated autoimmune and CNS disorders.

Analysis of telomere length and thymic output in fast and slow/non-progressors with HIV infection

There are two models for CD4+ T-cell depletion leading to AIDS: a kinetic model and an immune suppression model. In the kinetic model, direct cell killing due to viral replication results in a continuous demand for CD4+ T-cells, which eventually exhausts their capacity for renewal by proliferative mechanisms. In the immune suppression model, CD4+ T-cell decline is due to an indirect global inhibitory effect of the virus on uninfected immune cell function. In order to address differences in the two models, we investigated proliferative history and thymic output in PBMC from the GRIV cohort of fast (FP) and slow/non-progressors (S/NP), and uninfected controls. Proliferative history and thymic output were assessed by measurement of mean telomeric restriction fragment (TRF) length and T-cell receptor Rearrangement Excision Circles (TREC) levels, respectively. Mean TRF lengths were significantly shorter in S/NP (n = 93, 7.59 +/- 0.11 kb) and FP (n = 42, 7.25 +/- 0.15 kb) compared to controls (n = 35, 9.17 +/- 0.19 kb). Mean TRF length in PBMC (n = 9, 7.32 +/- 0.31 kb) and CD4+ enriched fractions (n = 9, 7.41 +/- 0.30 kb) from a subset of non-GRIV HIV-1 infected samples were also significantly smaller than PBMC (n = 8, 9.77 +/- 0.33 kb) and CD4+ fractions (n = 8, 9.41 +/- 0.32 kb) from uninfected controls. Rates of telomeric shortening, however, were similar among S/NP (n = 93, -45 +/- 20 bp/yr), FP (n = 42, -41 +/- 14 bp/yr) and controls (-29 +/- 17 bp/yr). Paralleling differences observed in mean TRF length, TREC levels were significantly reduced in S/NP (n = 10, 3,433 +/- 843 mol/mu and FP (n = 8, 1,193 +/- 413) compared to controls (n = 15, 22,706 +/- 5,089), indicative of a defect in thymopoiesis in HIV-1 infection. When evaluated in the context of reduced thymopoiesis, the difference in mean TRF length between S/NP and controls (1.58 +/- 0.30 kb) is similar to that observed between memory and naïve T-cells (1.4 +/- 0.1 kb), and may reflect perturbations in the peripheral T-cell population due to a decline in thymic output of naïve T-cells rather than increased turnover. Based on the different clinical criteria used to select S/NP and FP, the sight difference in TREC between these two groups suggests the threshold for pathogenesis as a result of naïve T-cell depletion may be quite low, and incremental increases in thymic output may yield substantial clinical results. Future studies regarding therapeutic vaccination, specifically with HIV-1 Tat targeted anti-immunosuppressive vaccines, should address the defect in thymic output in HIV-1 infection by using TREC analysis as a rapid method for biological evaluation.

HPV-16 E7 but not E6 oncogenic protein triggers both cellular immunosuppression and angiogenic processes

HPV-16 E6 and E7 oncoproteins impair the cell cycle in human uterine cervix carcinoma cells (HUCC) by acting on p53 and retinoblastoma proteins, respectively. We recently reported that E7 related into the extracellular compartment by HUCC SiHa cells could inhibit immune T-cell response to recall and alloantigens by a mechanism involving an overproduction of the immunosuppressive IFN alpha by antigen presenting cells (APCs). In this study, we found that besides E7, E6 protein and the vascular endothelium growth factor (VEGF) were released into the SiHa cell supernatants, and we further showed that extracellular E7 but not E6 oncoprotein 1) inhibits the immune cell response to recall and alloantigens, and 2) enhances the release of angiogenic cytokines, including TNF alpha, IL-1 beta and IL-6 by macrophages and/or dendritic cells. VEGF unexpectedly released by cancer cells could also contribute to angiogenesis. Thus in HUCC the same E7 oncoprotein which contributes to controlling the cancer cell cycle has the means in its extracellular configuration to contribute to microenvironmental immunosuppressive and angiogenic processes. Neutralizing anti-E7 antibodies either passively administered or induced by active immunization could represent a new immunotherapeutic endeavour to combat the immunosuppression and/or neoangiogenesis effects of extracellular E7 protein.

Induction of cellular immunosuppression by the human papillomavirus type 16 E7 oncogenic protein

The human papillomavirus type 16 (HPV-16) E7 oncogenic protein is found in the culture supernatant of SiHa cells, a cervical carcinoma cell line. Extracellular E7 protein, acting as a viral toxin in human immune cells, induces the overproduction of the immune suppressive IFN alpha cytokine by APCs, and inhibits the T-cell response to recall and allogenic antigens. These effects should be taken into account for the design of anti-human cervical carcinoma vaccines.

New class I and II HLA alleles strongly associated with opposite patterns of progression to AIDS

The genetics of resistance to infection by HIV-1 cohort consists of 200 slow and 75 rapid progressors to AIDS corresponding to the extremes of HIV disease outcome of 20,000 Caucasians of European descent. A comprehensive analysis of HLA class I and class II genes in this highly informative cohort has identified HLA alleles associated with fast or slow progression, including several not described previously. A quantitative analysis shows an overall HLA influence independent of and equal in magnitude (for the protective effect) to the effect of the CCR5-Delta32 mutation. Among HLA class I genes, A29 (p = 0.001) and B22 (p < 0.0001) are significantly associated with rapid progression, whereas B14 (p = 0.001) and C8 (p = 0.004) are significantly associated with nonprogression. The class I alleles B27, B57, C14 (protective), and C16, as well as B35 (susceptible), are also influential, but their effects are less robust. Influence of class II alleles was only observed for DR11. These results confirm the influence of the immune system on disease progression and may have implications on peptide-based vaccine development.

Tat toxoid as a component of a preventive vaccine in seronegative subjects

Because administration of Tat protein, the HIV-1 toxin that induces immunosuppression and apoptosis, may be deleterious to the host immune system, a chemically inactivated but nonetheless immunogenic Tat preparation, Tat toxoid, was used to immunize seronegative individuals against Tat. In an open, controlled, phase I clinical trial, Tat toxoid turned out to be safe, well tolerated, and able to trigger a specific immune reaction. In particular, a threefold to more than 10-fold increase of circulating antibodies directed against the native Tat was observed after immunization in all of 5 immunized study subjects, together with a positive reaction to delayed-type hypersensitivity (DTH) skin test with Tat toxoid in vivo and increased lymphoproliferative response to native Tat in vitro. Persistent (> or =1 year) high levels of circulating anti-Tat antibodies could prevent the Tat-induced immune suppression and, following HIV-1 exposure, allow the anti-HIV-1 cellular immune response, with its early release of protective beta-chemokines, to occur leading to an increase of host resistance, that is, protection.

Anti-IFN alpha immunization raises the IFN alpha-neutralizing capacity of serum--an adjuvant to antiretroviral tritherapy

HAART (highly active antiretroviral therapy) suppresses but does not eradicate HIV-1 infection. However, since the antiretroviral agents used in HAART may also be toxic in the long-term, immunotherapies which correct HIV-1 immunosuppression or the cytokine dysregulation associated with it may be beneficial. In this respect, a double blind multicentric placebo-controlled phase II/III anti-IFN alpha vaccine trial has been carried out on 242 HIV-1 patients, the majority of whom were undergoing HAART treatment. In vaccinated patients (vaccinees) who responded to immunization by increased levels of IFN alpha Abs (whether under HAART or not) when compared to placebo or non-responder vaccinees, a strong correlation was found between an increased IFN alpha neutralizing capacity and the reduction of clinical manifestations.

A prophylactic and therapeutic AIDS vaccine containing as a component the innocuous Tat toxoid

Extracellular Tat can act as a viral toxin on uninfected cells of different tissues, including the CNS and the immune system, thus in order to immunize humans against Tat we have prepared a biologically inactivated but immunogenic Tat (Tat Toxoid). Tat Toxoid is not toxic in mice even at high doses. It triggers high levels of specific Tat Abs in the mouse and rabbit. Furthermore, in humans Tat Toxoid immunization was safe and induced in seronegatives persistent high levels of Tat Abs and in immunodeficient patients a significant rise of these specific Abs. Facing acute HIV-1 infection, the presence of high level of circulating Tat Abs promoted by Tat Toxoid vaccine should prevent Tat-induced immunosuppression and allow anti-HIV-1 cellular response to develop. As a consequence, early release of beta-chemokines could enhance host resistance towards HIV-1, and, in infected people, inhibit viral replication and evolution towards AIDS.

Binding of HIV-1 to RBCs involves the Duffy antigen receptors for chemokines (DARC)

The Duffy Antigen Receptor for Chemokines (DARC) belongs to a family of erythrocyte chemokine receptors that bind C-X-C and C-C chemokines such as interleukin 8 (IL-8), monocyte chemoattractant protein 1 (MCP-1) and regulated-on-activation, normal T cell-expressed and -secreted (RANTES), but not macrophage inflammatory protein 1 alpha (MIP-1 alpha) or MIP-1 beta. DARC has also been identified to a receptor for malaria parasites Plasmodium vivax and Plasmodium knowlesi. In the present study, we show that HIV-1 binds to RBCs from Caucasian individuals via DARC making RBCs able to transmit HIV to peripheral blood mononuclear cells (PBMCs). Furthermore, binding of HIV-1 particles to RBCs is inhibited by treating these cells with recombinant RANTES, but not with recombinant MIP-1 alpha prior to their incubation with HIV-1. This finding suggests that RBCs may function as a reservoir for HIV-1 or as a receptor for the entry of HIV-1 into CD4-cell subsets as well as neurons or endothelial cells.

Distinctive effects of CCR5, CCR2, and SDF1 genetic polymorphisms in AIDS progression

The Genetics of Resistance to Infection by HIV-1 (GRIV) cohort represents 200 nonprogressor/slow-progressor (Slowprog) and 90 fast-progressor (Fastprog) HIV-1-infected patients. Using this unique assembly, we performed genetic studies on three recently discovered polymorphisms of CCR5, CCR2, and SDF1, which have been shown to slow the rate of disease progression. The increased prevalence of mutant alleles among Slowprogs from the GRIV cohort was significant for CCR5 (p < .0001) but not for CCR2 (p = .09) or SDF1 (p = . 12), emphasizing the predominant role of CCR5 as the major HIV-1 coreceptor. However, the prevalence of the CCR2 mutant allele (64I) was significantly increased among Slowprogs homozygous for wild-type CCR5 compared with Fastprogs (p = .04). The prevalence of double mutants SDF1-3'A/3'A genotypes was also increased among Slowprogs homozygous for wild-type CCR5 compared with Fastprogs (p = .05). The effects of the CCR2 and SDF1 mutations are overshadowed by the protective effects of the CCR5 deletion. Predictive biologic markers such as CD4 cell counts or viral load in the Slowprog population did not show significant differences between Slowprog groups with wild-type or mutant alleles for the three genes. Thus, our data suggest that the effects of these genes are exerted earlier in infection and no longer evident in the Slowprog of the GRIV cohort whose average duration of HIV infection is 12 years. We conclude that these genes, whose products serve as viral coreceptors or their ligands, may play a role early in infection and delay the onset of disease. However, among Slowprogs, whose duration of infection is >8 years, they are no longer influential for maintenance of their longterm nonprogression status. Other genetic determinants may be responsible for late protective effects.

Antibodies to the HIV-1 Tat protein correlated with nonprogression to AIDS: a rationale for the use of Tat toxoid as an HIV-1 vaccine

OBJECTIVES

To investigate which immune parameters, such as antibodies against HIV-1 specificities, or viral parameters, such as p24 antigenemia, are predictive of disease progression.

STUDY DESIGN

We performed studies on serum collected from individuals exhibiting two extremes of disease evolution--67 fast progressors (FP) and 182 nonprogressors (NP)--at their enrollment. After a 1- to 2-year clinical follow-up of 104 nonprogressors after their enrollment, we could determine the best serologic predictors for disease progression.

METHODS

We investigated levels of antibodies to tetanus toxoid and to HIV antigens including Env, Gag, Nef, and Tat proteins, as well as p24 antigenemia, viremia, CD4 cell count, and interferon-alpha (IFN-alpha) titers in FPs and NPs, and we correlated these data with clinical and biologic signs of progression.

RESULTS

p24 Antigenemia, a marker of viral replication, and anti-Tat antibodies were highly and inversely correlated in both groups (P < .001). Furthermore, anti-p24 antibodies and low serum IFN-alpha levels were correlated to the NP versus the FP cohort. Finally, among NPs, only antibodies to Tat and not to the other HIV specificities (Env, Nef, Gag) were significantly predictive of clinical stability during their follow-up.

CONCLUSION

Antibodies toward HIV-1 Tat, which are inversely correlated to p24 antigenemia, appear as a critical marker for a lack of disease progression. This study strongly suggests that rising anti-Tat antibodies through active immunization may be beneficial in AIDS vaccine development to control viral replication.

Safety and immunogenicity of HIV-1 Tat toxoid in immunocompromised HIV-1-infected patients

OBJECTIVES

To antagonize the deleterious effects of the HIV-1 toxin extracellular Tat on uninfected immune cells, we developed a new strategy of anti-HIV-1 vaccine using an inactivated but immunogenic Tat (Tat toxoid). Tat toxoid has been assayed for safety and immunogenicity in seropositive patients.

METHOD

The phase I vaccine clinical trial testing Tat toxoid preparation in Seppic Isa 51 oil adjuvant was performed on 14 HIV-1-infected asymptomatic although biologically immunocompromised individuals (500-200 CD4+ cells/mm3).

RESULTS

Following as many as 8 injections, no clinical defects were observed. All patients exhibited an antibody (Ab) response to Tat, and some had cell-mediated immunity (CMI) as evaluated by skin test in vivo and T-cell proliferation in vitro.

CONCLUSION

These results provide initial evidence of safety and potency of Tat toxoid vaccination in HIV-1-infected individuals.

Interferon alpha and Tat involvement in the immunosuppression of uninfected T cells and C-C chemokine decline in AIDS

HIV type 1 (HIV-1) not only directly kills infected CD4(+) T cells but also induces immunosuppression of uninfected T cells. Two immunosuppressive proteins, interferon alpha (IFNalpha) and extracellular Tat, mediate this process because specific antibodies against these proteins prevent generation of suppressor cells in HIV-1-infected peripheral blood mononuclear cell cultures. Furthermore, the production of C-C chemokines in response to immune cell activation, initially enhanced by IFNalpha and Tat, ultimately is inhibited by these proteins in parallel with their induction of immunosuppression. The clinical corollary is the immunosuppression of uninfected T cells and the decline in C-C chemokine release found at advanced stages of HIV-1 infection paralleling rising levels of IFNalpha and extracellular Tat. We, therefore, suggest that IFNalpha and Tat may be critical targets for anti-AIDS strategies.

C-C chemokines, pivotal in protection against HIV type 1 infection

Exposure to HIV type 1 (HIV-1) does not usually lead to infection. Although this could be because of insufficient virus titer, there is now abundant evidence that some individuals resist infection even when directly exposed to a high titer of HIV. This protection recently has been correlated with homozygous mutations of an HIV-1 coreceptor, namely CCR5, the receptor for the beta-chemokines. Moreover, earlier results already had shown that the same chemokines markedly suppress the nonsyncitial inducing variants of HIV-1, the chief virus type transmitted from person to person. CCR5 mutation, as a unique mechanism of protection, is, however, suspect because HIV-1 variants can use other chemokine receptors as their coreceptor. Moreover, recent results have established that infection can indeed sometimes occur with such mutations. Here, we report on transient natural resistance over time of most of 128 hemophiliacs who were inoculated repeatedly with HIV-1-contaminated Factor VIII concentrate from plasma during 1980-1985 before the development of the HIV blood test. Furthermore, and remarkably, 14 subjects remain uninfected to this date, and in these subjects we found homozygous CCR5 mutations in none but in most of them overproduction of beta chemokines. In vitro experiments confirmed the potent anti-HIV suppressive effect of these chemokines.

Homeostasis of chemokines, interferon production and lymphocyte subsets: implications for AIDS pathogenesis

Certain individuals with elevated levels of macrophage inflammatory protein (MIP)1 alpha, MIP1 beta and RANTES expression appear to be resistant to human immunodeficiency virus (HIV) infection. In this work, we demonstrate that chemokines production by peripheral blood mononuclear cells (PBMCs) are homeostatic parameters varying from one individual to another, and we define optimized experimental conditions to reproducibly assess these parameters. We also studied alpha- and gamma-interferons (IFN alpha and IFN gamma, respectively) which have been implicated in the pathogenesis of acquired immunodeficiency syndrome (AIDS). The kinetics of production of all these cytokines by fresh PBMCs were determined upon stimulation with phytohemagglutinin (PHA), staphylococcus enterotoxin b (SEB) and purified protein derivative (PPD). RANTES and MIP1 alpha are produced early in response to activation, followed by MIP1 beta, (alpha-interferon, gamma-interferon, alpha IFN, gamma-IFN alpha and IFN alpha and gamma. These results suggest that using our methodology, chemokines levels can be reliably determined, permitting the performance of accurate genetic studies using PBMCs from various cohorts (siblings or AIDS related cohorts).

Absence of clinical, virological, and immunological signs of progression in HIV-1-infected patients receiving active anti-interferon-alpha immunization: a 30-month follow-up report

Twenty-seven HIV-1-infected patients, 16 at early stage of disease and without concomitant antiretroviral therapy and 11 at more advanced stage of disease receiving antiretroviral therapy, have been followed since their enrollment, November 1992 and July 1993, respectively, in phase I/II studies to evaluate safety and immunogenicity of an anti-interferon-alpha (IFN-alpha) vaccine, aimed at modulating the impaired cytokine network in AIDS patients by counteracting IFN-alpha overproduction. We compared clinical, virological, and immunological markers of disease progression, including circulating IFN-alpha levels in a 24- to 30-month follow-up period with those of 62 patients fulfilling the same enrollment criteria and comparable for sex, risk factor, and age, regularly followed at our center. Anti-IFN-alpha immunization consisted of four-six intramuscular injections 1 month apart of a water-in-oil emulsion of 500 micrograms formalin-inactivated recombinant IFN-alpha-2b (iIFN-alpha) followed by intramuscular injections of 250 micrograms iIFN-alpha adsorbed onto calcium phosphate every 3 months. Neither clinical deterioration nor a CD4+ cell count decrease from pretreatment values was observed in IFN-alpha-immunized patients in the follow-up period, whereas clinical and immunological disease progressions were observed among open-comparison patients. Furthermore, statistical analysis showed a strong association between occurrence of clinical manifestations and high circulating IFN-alpha titers, while nonprogression of IFN-alpha-immunized patients was associated with decreased levels of circulating IFN-alpha.

Repair of the in vitro HIV-1-induced immunosuppression and blockade of the generation of functional suppressive CD8 cells by anti-alpha interferon and anti-Tat antibodies

The acute human immunodeficiency virus type 1 (HIV-1) infection of activated peripheral blood mononuclear cells (PBMCs) from normal donors results in inhibition of cell proliferation and generation of functional suppressive T cells. Cultured HIV-1 infected PBMCs but not uninfected PBMCs, following irradiation, can inhibit the proliferation of antigen-activated autologous T cells in a dose-dependent way. CD8+ cell subpopulation is responsible for this inhibition. The presence of anti-alpha interferon (IFN alpha) and anti-Tat antibodies in the culture medium counteracts the HIV-1-induced immunosuppression and prevents the generation of suppressive T cells by these PBMCs. The reported data should have major implications for strategies of AIDS treatment which, in association with antiviral drugs, aim at targetting immune disorders.

Contribution of cohort studies in understanding HIV pathogenesis: introduction of the GRIV cohort and preliminary results

In the present paper we review studies performed on HIV-infected patients cohorts in order to understand AIDS disease development. The interplay between diverse factors such as the HIV envelope proteins, cellular co-receptors, the immune response with chemokines and cytokines production define the viral tropism, cytopathicity and progression of HIV disease. We present the trends of the research particularly in the domain concerning host genetics. In this context, we describe the GRIV cohort of fast and slow/non-progressors, and its use for understanding basic features of the yet unknown HIV pathogenesis mechanisms.

Are CD4 and Fas peptide identities of gp120 relevant to the molecular basis of AIDS pathogenesis?

The release of virions from HIV-1-infected CD4 cells, although occurring readily as a result of immune activation, does not appear to be the only mechanism mediating T-cell loss in AIDS. Three other interacting HIV-1-induced immune disorders in association with viral release (the source of gp120 molecules) may also account for the constitutive T-cell depletion and functional immune suppression: 1. gp120-induced CD4(+) cell anergy, which can be reproduced in cultures of immune activated normal T-cells in the presence of gp120 or gp120 peptide containing the SLWDQ sequence identity to the CD4 molecule; 2. overproduction of IFNalpha and gamma, 3. activation-driven apoptosis of non infected T-cells. Apoptosis of T-cells could also be: 1. induced by effector components - particularly CTL and lymphotoxins produced by helper T-cells of the anti-Fas autoimmune reaction triggered by gp120 epitopes shared with the Fas/APO-1 molecule; 2. enhanced by IFN overproduction. These molecular mechanisms stress the importance in the progression to AIDS of both the viral load and HIV-induced cytokine dysregulation, including overproduction of IFNalpha, which should be considered as targets in the development of strategies for AIDS prophylaxis and immunotherapy.

Automat: a novel software system for the systematic search for protein (or DNA) similarities with a notable application to autoimmune diseases and AIDS

Automat is a novel program which finds exhaustively all the oligopeptide segments shared by a given protein of any size with the proteins of a whole databank. It allows the user to collect statistics on the composition of the sequence studied in reference to the databank used. We present here the rationale and the algorithm underlying this powerful software. Besides its immediate interest for identifying efficiently similarities between proteins (or DNAs), biological applications of this software have already been described in the case of HIV-1 viral proteins, and Automat should prove useful also for studying more generally autoimmune diseases.

Screening of protein sequences databanks by Automat for search of host sequences integration and/or autoimmune disorders induction by retroviruses

We have designed an efficient algorithm in order to detect systematically all the oligopeptides shared by a given protein with all the protein sequences in a databank. This software, Automat, also makes statistics on the number of shared oligopeptides. In the present study, we apply Automat on HIV-1 proteins to detect putative critical sites and to identify candidate viral antigens that may trigger autoimmune disorders. A list of pertinent similarities between HIV-1 proteins and human proteins, as detected by Automat, is reported.

Detection of CTL activity in PBMCS taken from HIV-ENV immunized individuals after in vitro viral infection

The cellular immune response to the AIDS virus in healthy individuals immunized with HIV-1 antigens has not yet been entirely understood. Unlike HIV-1 infected patients where direct measurements of anti HIV-1 CTL activities can be readily performed with fresh peripheral blood mononuclear cells, uninfected volunteers immunized against HIV-1 antigens have fewer circulating CTL necessitating an in vitro activation in order to amplify the cytotoxic signal and make it measurable. This study presents experiments where specific CTLs are successfully obtained simply by in vitro infection of PBMCs from HIV-1 Envelope immunized individuals.

Effect of purified IgGs from HIV-1-infected and non infected individuals on immune activation

The purification and analysis of IgGs from sera of HIV-1-infected and non infected individuals are reported. The effect of antibodies purified from sera of infected individuals on antigen-induced T cell proliferation was investigated in relation to their possible involvement in an autoimmune reaction in AIDS, in view of the previously unravelled striking peptide similarities between HIV-1 gp120 and the immunoregulatory CD4 and Fas molecules. However, our data do not allow definite conclusions to be drawn. The necessity of purifying antibodies against specific peptides to show their direct effect on T-cell activation is further stressed.

Cytotoxic T lymphocytes specific for HIV-1 gp160 antigen and synthetic P18IIIB peptide in an HLA-A11-immunized individual

Cytotoxic T cell determinants should be an important component of an anti-human immunodeficiency virus (HIV) vaccine. The epitopes of proteins can be defined with short synthetic peptides for class I-restricted CTLs. An immunodominant CTL epitope from the HIV-1 IIIB envelope protein gp160 comprising 15 amino acids (residues 315-329: RIQRGPGRAFVTIGK) (P18IIIB) has been identified that is recognized by class I MHC molecule H-2d-restricted murine CD8+ CTLs. We have investigated the epitope specificity of anti-HIV-1 CTLs in immunized individuals and we found that the CTL response was restricted by more than one class I MHC molecule, including HLA-A2 and HLA-A3. In the present work, we also show that the response against P18IIIB peptide is restricted by the HLA-A11 molecule in an individual immunized by vaccinia virus expressing gp160 protein. This peptide could thus be recognized in association with different HLA class I allotypes. This work has implications for vaccine strategies, using the P18 peptide.

Pathogenic disorders involved in immunosuppression and T cell depletion characterizing AIDS

Four cardinal immune disorders interacting with each other may promote the progressive T cell depletion and immunosuppression characterizing AIDS. Immune activation of HIV-1 infected T4 cells leads to virus release and premature cell death. Both virus release with its resulting viral load and dead cells are the source of gp120 stimulus. Anergy of non-infected CD4 cells, resulting in cytokine dysregulation may be promoted by impairing the CD4-MHC interaction during CD4 cell activation either directly through the SLWDQ pentapeptide identity with the CD4 molecule and the CD4 binding region or through a gp120-induced autoimmune reaction to CD4. Overproduction of IFN alpha, the known antiproliferative and cytolytic cytokine may promote in a paracrine manner to neighbouring cells the immunosuppression generated by the lack of IL2 secretion following CD4 cell anergy. Apoptosis of activated non infected T cells could be induced by effector components of the autoimmune reaction (CTL, Lymphotoxins or Abs?) directed towards the 2 consensus gp120 sequence identity/similarity (INCTR and FYCNST) shared with the APO/Fas molecule. These two sequences are known as immunodominant sites of the gp120. Furthermore, IFN alpha overproduction may also render circulating memory T cells competent to apoptosis by upregulating the cascade of metabolic events leading to programmed cell death.

Identification of CD4 and major histocompatibility complex functional peptide sites and their homology with oligopeptides from human immunodeficiency virus type 1 glycoprotein gp120: role in AIDS pathogenesis

CD4 molecules interact with class II major histocompatibility complex molecules as a critical costimulatory signal in CD4+ cell immune activation. CD4 also recognizes a specific region of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp120 forming a binding site for early stages of HIV-1 infection. We designed two software packages, AUTOMAT and CRITIC, which allowed us to identify similarities between regions of HIV-1 proteins and immunoregulatory protein sequences stored in data banks. In this report we have characterized (i) a pentapeptide, SLWDQ, found in both CD4 and HIV-1 gp120, which surprisingly had remained undetected in these two well-studied molecules until now, and (ii) an HLA sequence corresponding to the putative functional site of H2 I-A. We found that a region of gp120 (residues 254-263) known to be similar to a sequence in HLA class II beta chain overlaps this functional region. We showed experimentally that these two CD4 and HLA peptide segments inhibit CD4+ cell immune activation. There is strong inhibition (50% up to 80%) of immune activation by SLWDQ-containing gp120 segments and a lesser inhibition by the gp120 HLA-homologous segment. In addition, we found that SLWDQ induced in HIV-1-infected individuals a humoral (antibody) and cellular (cytotoxic T lymphocyte) immune reaction. We propose that these HIV-1 gp120 segments, together with the known CD4-binding region, may contribute to the HIV-1-induced immunosuppression by two mechanisms affecting CD4-HLA interaction during T-cell immune activation: autoimmune reaction toward CD4 and direct interference with the CD4-HLA costimulatory signal inducing CD4+ cell anergy with, as a consequence, generation of immunosuppression.

erbB-2/Her-2 gene amplification and overexpression in parotid gland tumors

Proto-oncogenes represent a family of normal cellular genes that were identified on the basis of their similarity to genetic sequences with known tumorigenic or transforming potential. Accumulating evidence links alterations in either the structure, copy number, or expression of one or another of these genes to neoplasia. One such gene, called erbB-2/Her-2 was found amplified in an adenocarcinoma of the human salivary gland and has also been found associated with primary human breast cancer. Patients with multiple copies of the gene have had a shorter overall survival. In the present study, 21 tumors of the parotid gland were examined by Southern and Northern blot hybridization for amplification and possible overexpression of the erbB-2/Her-2 oncogene. Normal parotid gland tissue was used as negative control. The parotid gland lesions comprised 7 pleomorphic adenomas, 5 squamous cell carcinomas, 4 cases of chronic fibrotic sialadenosis, 3 mucoepidermoid carcinomas as well as 1 lymphoma and 1 cystadenolymphoma. Gene amplification was found in 1 of the pleomorphic adenomas, with 2 tumors showing a significant overexpression of the erbB-2/Her-2 oncogene. Because 3-5% of all pleomorphic adenomas undergo malignant transformation, close follow-up of patients is currently underway.

Polymerase chain reaction amplified HTLV-I, HIV-1 and HIV-2 DNA fragments in subjects with mixed retroviral infections

Serum and peripheral blood mononuclear cells from eight patients from the Ivory Coast with positive screening test results for retroviral infections were studied by serology (ELISA, Western blot (WB), synthetic peptide test), cell co-culture, and polymerase chain reaction (PCR). Two HIV-2 infections with indeterminate interpretation on HIV-1 WB were detected, two were clear dual HIV-1/HIV-2 infections, three were ambiguous mixed HIV-1/HIV-2 infections, and one was a triple retroviral infection by HTLV-I, HIV-1 and HIV-2. Four slow/low HIV-1 strains were isolated at the expense of HTLV-I and HIV-2 strains. The ELISA tests were found to be very sensitive. Indeterminate WB interpretations were frequent (HTLV-I, four; HIV-1, three; HIV-2, two). PCR provided clear evidence of multiple retroviral infections in three cases and enabled interpretation of indeterminate WB samples in three cases. One sample presented a puzzling pattern with positive PCR results for HIV-1 and HIV-2 associated with negative or indeterminate serological results. Thus, our data emphasise the need to analyse serological as well as virological markers to gain better insight on mixed retroviral infections, especially in endemic areas such as West Africa.

Striking similarities between HIV-1 Env protein and the apoptosis mediating cell surface antigen Fas. Role in the pathogenesis of AIDS

We have designed a computer strategy in order to detect systematically peptidic sites with the potential of interfering with the immune regulatory processes. Applying this software to HIV-1 proteins has led us to unravel a few peptidic sites which could either act directly or be the targets of an auto-immune reaction during HIV-1 infection. We previously reported that the SLWDQ pentapeptide identity with a critical site of CD4 could trigger in HIV-1 infected individuals both an humoral and a cellular autoimmune reaction. In this study, we focused on surprising similitudes unravelled by our software Automat, between HIV-1/2 and another immunoregulatory molecule, the Fas protein which is also called the apoptosis-mediating cell-surface antigen.

HIV-1-induced immune suppression may result from autoimmune disorders including anti-SLWDQ autoantibodies

We have previously unravelled the striking SLWDQ pentapeptide identity between HIV-1 env gp120 and the CD4 molecule. We show here that this pentapeptide is required for the functioning of the co-stimulatory MHC-CD4 signal in T4-cell activation since it suppresses antigen-induced T-cell proliferation. Moreover, concerning the MHC class II counterpart, the LNGQEETGVVSTN sequence which strongly inhibits T-cell immune activation is likely to be part of the functional site of the molecule. Interestingly the MHC/gp120 homology described by Young overlaps this MHC region. We further report that the gp120 SLWDQ peptide triggers an immune reaction which is both humoral (anti-SLWDQ antibodies) and cellular (CTLs against autologous targets carrying the pentapeptide) in HIV-1 infected individuals. Finally, anti-SLWDQ antibodies from patients sera purified by column chromatography strongly inhibit antigen-induced immune T-cell activation. This result led us to postulate that these antibodies found in high titers in HIV-1 infected individuals could contribute to set up the progressive systemic immune T-cell suppression characterizing AIDS.

Critical sites: a semantic approach to protein sequences. Application to the HIV-1 envelope molecule

We have designed two software systems allowing the study of proteins through a comparison to those stored in data banks. The first one, "Automat", locates in a systematic manner all identities shared by a given protein and the proteins in a data bank. The second, "Critic" enables the selection of specific segments in a given molecule by comparing them with those gathered in a data bank. These sites were termed "critical" since they mostly correspond to functional sites (active sites) of the well-known proteins which were studied with the aid of this program (somatostatin, insulin, IL2, etc). Automat allowed us to reveal homologies between HIV-1 and the CD4, which have remained unsolved until now. These similitudes proved to be critical sites (according to Critic). The putative involvement of these sites in the physiopathological processes as induced by HIV-1 are worth considering since the results of our experiments are consistent with this assumption.

Immunogenicity of combined anti-HIV and anti-suppressive vaccine preparations

HIV-1 antigens generate in man both a humoral and cellular immune reaction. However, in ARC/AIDS patients, the cellular response is inhibited by HIV-1 which induces an antiproliferative (suppressive) effect on activated T cells. To overcome this inhibition and up-regulate the cellular response, we designed a new vaccine strategy directed both against HIV-1 and immunosuppression and we used an immunizing preparation composed of HIV-1 antigens combined with immunoregulatory peptides prepared in a biologically inactivated but immunogenic form. In mice, this preparation induced anti-HIV-1 antibodies and a cell-mediated cytotoxicity directed against H2 restricted cells carrying HIV-1 antigens.