Quantifying Anti-HIV Envelope-Specific Antibodies in Plasma from HIV Infected Individuals.

Quantifying HIV Envelope (Env)-specific antibodies in HIV+ plasma is useful for interpreting antibody dependent cellular cytotoxicity assay results. HIV Env, the only viral protein expressed on the surface of infected cells, has a native trimeric closed conformation on cells infected with wild-type HIV. However, CD4+ uninfected bystander cells in HIV+ cell cultures bind gp120 shed from HIV+ cells exposing CD4-induced epitopes normally hidden in native Env. We used flow-cytometry based assays to quantify antibodies in HIV+ plasma specific for native trimeric Env or gp120/CD4 conjugates using CEM.NKr.CCR5 (CEM) cells infected with HIV (iCEM) or coated with recombinant gp120 (cCEM), as a surrogate for gp120+ HIV- bystander cells. Results from both assays were compared to those of a plate-based ELISA to monomeric gp120. The levels of Env-specific antibodies to cCEM and iCEM, measured by flow cytometry, and to gp120 by ELISA were positively correlated. More antibodies in HIV+ plasma recognized the gp120 conformation exposed on cCEM than on iCEM. Comparisons of plasma from untreated progressors, treated progressors, and elite controllers revealed that antibodies to Env epitopes were the lowest in treated progressors. Plasma from elite controllers and untreated progressors had similarly high levels of Env-specific antibodies, despite elite controllers having undetectable HIV viral loads, while untreated progressors maintained high viral loads.

Glycoengineering HIV-1 Env creates 'supercharged' and 'hybrid' glycans to increase neutralizing antibody potency, breadth and saturation.

The extensive glycosylation of HIV-1 envelope (Env) glycoprotein leaves few glycan-free holes large enough to admit broadly neutralizing antibodies (bnAb). Consequently, most bnAbs must inevitably make some glycan contacts and avoid clashes with others. To investigate how Env glycan maturation regulates HIV sensitivity to bnAbs, we modified HIV-1 pseudovirus (PV) using various glycoengineering (GE) tools. Promoting the maturation of α-2,6 sialic acid (SA) glycan termini increased PV sensitivity to two bnAbs that target the V2 apex and one to the interface between Env surface gp120 and transmembrane gp41 subunits, typically by up to 30-fold. These effects were reversible by incubating PV with neuraminidase. The same bnAbs were unusually potent against PBMC-produced HIV-1, suggesting similar α-2,6 hypersialylated glycan termini may occur naturally. Overexpressing ß-galactosyltransferase during PV production replaced complex glycans with hybrid glycans, effectively 'thinning' trimer glycan coverage. This increased PV sensitivity to some bnAbs but ablated sensitivity to one bnAb that depends on complex glycans. Other bnAbs preferred small glycans or galactose termini. For some bnAbs, the effects of GE were strain-specific, suggesting that GE had context-dependent effects on glycan clashes. GE was also able to increase the percent maximum neutralization (i.e. saturation) by some bnAbs. Indeed, some bnAb-resistant strains became highly sensitive with GE-thus uncovering previously unknown bnAb breadth. As might be expected, the activities of bnAbs that recognize glycan-deficient or invariant oligomannose epitopes were largely unaffected by GE. Non-neutralizing antibodies were also unaffected by GE, suggesting that trimers remain compact. Unlike mature bnAbs, germline-reverted bnAbs avoided or were indifferent to glycans, suggesting that glycan contacts are acquired as bnAbs mature. Together, our results suggest that glycovariation can greatly impact neutralization and that knowledge of the optimal Env glycoforms recognized by bnAbs may assist rational vaccine design.

HIV gp120 in the Lungs of Antiretroviral Therapy-treated Individuals Impairs Alveolar Macrophage Responses to Pneumococci.

RATIONALE: People living with HIV are at significantly increased risk of invasive pneumococcal disease, despite long-term antiretroviral therapy (ART). The mechanism explaining this observation remains undefined. OBJECTIVES: To determine if apoptosis-associated microbicidal mechanisms, required to clear intracellular pneumococci that survive initial phagolysosomal killing, are perturbed. METHODS: Alveolar macrophages (AM) were obtained by BAL from healthy donors or HIV-1-seropositive donors on long-term ART with undetectable plasma viral load. Monocyte-derived macrophages (MDM) were obtained from healthy donors and infected with HIV-1BaL or treated with gp120. Macrophages were challenged with opsonized serotype 2 Streptococcus pneumoniae and assessed for apoptosis, bactericidal activity, protein expression, and mitochondrial reactive oxygen species (mROS). AM phenotyping, ultrasensitive HIV-1 RNA quantification, and gp120 measurement were also performed in BAL. MEASUREMENTS AND MAIN RESULTS: HIV-1BaL infection impaired apoptosis, induction of mROS, and pneumococcal killing by MDM. Apoptosis-associated pneumococcal killing was also reduced in AM from ART-treated HIV-1-seropositive donors. BAL fluid from these individuals demonstrated persistent lung CD8+ T lymphocytosis, and gp120 or HIV-1 RNA was also detected. Despite this, transcriptional activity in AM freshly isolated from people living with HIV was broadly similar to healthy volunteers. Instead, gp120 phenocopied the defect in pneumococcal killing in healthy MDM through post-translational modification of Mcl-1, preventing apoptosis induction, caspase activation, and increased mROS generation. Moreover, gp120 also inhibited mROS-dependent pneumococcal killing in MDM. CONCLUSIONS: Despite ART, HIV-1, via gp120, drives persisting innate immune defects in AM microbicidal mechanisms, enhancing susceptibility to pneumococcal disease.

Evaluation of Different Parameters of Humoral and Cellular Immune Responses in HIV Serodiscordant Heterosexual Couples: Humoral Response Potentially Implicated in Modulating Transmission Rates.

As the HIV/AIDS pandemic still progresses, understanding the mechanisms governing viral transmission as well as protection from HIV acquisition is fundamental. In this context, cohorts of HIV serodiscordant heterosexual couples (SDC) represent a unique tool. The present study was aimed to evaluate specific parameters of innate, cellular and humoral immune responses in SDC. Specifically, plasma levels of cytokines and chemokines, HIV-specific T-cell responses, gp120-specific IgG and IgA antibodies, and HIV-specific antibody-dependent cellular cytotoxicity (ADCC) activity were assessed in nine HIV-exposed seronegative individuals (ESN) and their corresponding HIV seropositive partners (HIV+-P), in eighteen chronically infected HIV subjects (C), nine chronically infected subjects known to be HIV transmitters (CT) and ten healthy HIV- donors (HD). Very low magnitude HIV-specific cellular responses were found in two out of six ESN. Interestingly, HIV+-P had the highest ADCC magnitude, the lowest IgA levels and the highest IgG/IgA ratio, all compared to CT. Positive correlations between CD4+ T-cell counts and both IgG/IgA ratios and %ADCC killing uniquely distinguished HIV+-P. Additionally, evidence of IgA interference with ADCC responses from HIV+-P and CT is provided. These data suggest for the first time a potential role of ADCC and/or gp120-specific IgG/IgA balance in modulating heterosexual transmission. In sum, this study provides key information to understand the host factors that influence viral transmission, which should be considered in both the development of prophylactic vaccines and novel immunotherapies for HIV-1 infection.

Accurate predictions of population-level changes in sequence and structural properties of HIV-1 Env using a volatility-controlled diffusion model.

The envelope glycoproteins (Envs) of HIV-1 continuously evolve in the host by random mutations and recombination events. The resulting diversity of Env variants circulating in the population and their continuing diversification process limit the efficacy of AIDS vaccines. We examined the historic changes in Env sequence and structural features (measured by integrity of epitopes on the Env trimer) in a geographically defined population in the United States. As expected, many Env features were relatively conserved during the 1980s. From this state, some features diversified whereas others remained conserved across the years. We sought to identify "clues" to predict the observed historic diversification patterns. Comparison of viruses that cocirculate in patients at any given time revealed that each feature of Env (sequence or structural) exists at a defined level of variance. The in-host variance of each feature is highly conserved among individuals but can vary between different HIV-1 clades. We designate this property "volatility" and apply it to model evolution of features as a linear diffusion process that progresses with increasing genetic distance. Volatilities of different features are highly correlated with their divergence in longitudinally monitored patients. Volatilities of features also correlate highly with their population-level diversification. Using volatility indices measured from a small number of patient samples, we accurately predict the population diversity that developed for each feature over the course of 30 years. Amino acid variants that evolved at key antigenic sites are also predicted well. Therefore, small "fluctuations" in feature values measured in isolated patient samples accurately describe their potential for population-level diversification. These tools will likely contribute to the design of population-targeted AIDS vaccines by effectively capturing the diversity of currently circulating strains and addressing properties of variants expected to appear in the future.

HIV-2 viral tropism influences CD4+ T cell count regardless of viral load.

BACKGROUND: HIV-2 infection is characterized by low plasma viraemia and slower progression to AIDS in comparison with HIV-1 infection. However, antiretroviral therapy in patients with HIV-2 is less effective and often fails to provide optimal CD4 recovery. METHODS: We examined viral tropism in persons with HIV-2 infection enrolled in the HIV-2 Spanish cohort. Viral tropism was estimated based on V3 sequences obtained from plasma RNA and/or proviral DNA. RESULTS: From a total of 279 individuals with HIV-2 infection recorded in the Spanish national register, 58 V3 sequences belonging to 42 individuals were evaluated. X4 viruses were recognized in 14 patients (33%). Patients with X4 viruses had lower median CD4+ cell counts than patients with R5 viruses [130 (17-210) versus 359 (180-470) cells/mm(3); P = 0.007]. This was true even considering only the subset of 19 patients on antiretroviral therapy [94 (16-147) versus 184 (43-368) cells/mm(3); P = 0.041]. In multivariate analysis, significant differences in CD4+ cell counts between patients with X4 and R5 viruses remained after adjusting for age, gender, antiretroviral therapy and viral load. CONCLUSIONS: The presence of X4-tropic viruses in HIV-2 infection is associated with low CD4+ cell counts, regardless of antiretroviral treatment. Along with CD4+ cell counts, viral tropism testing may assist decisions about when to initiate antiretroviral therapy in HIV-2-infected individuals.

Design and expression of a short peptide as an HIV detection probe.

To explore a low-cost novel probe for HIV detection, we designed and prepared a 50-amino acid-length short fusion peptide (FP-50) via Escherichia coli in vivo expression. It was employed as a novel probe to detect HIV-1 gp120 protein. The detectable level of gp120 protein using the FP-50 peptide was approximately 20-200 times lower than previously published methods that used a pair of monoclonal antibodies. Thus, this short peptide is a very promising component for detection of gp120 protein during early stages of HIV infection.

Human plasmacytoid dendritic cells efficiently capture HIV-1 envelope glycoproteins via CD4 for antigen presentation.

Advances in HIV-1 vaccine clinical trials and preclinical research indicate that the virus envelope glycoproteins (Env) are likely to be an essential component of a prophylactic vaccine. Efficient Ag uptake and presentation by dendritic cells (DCs) is important for strong CD4(+) Th cell responses and the development of effective humoral immune responses. In this study, we examined the capacity of distinct primary human DC subsets to internalize and present recombinant Env to CD4(+) T cells. Consistent with their specific receptor expression, skin DCs bound and internalized Env via C-type lectin receptors, whereas blood DC subsets, including CD1c(+) myeloid DCs, CD123(+) plasmacytoid DCs (PDCs), and CD141(+) DCs exhibited a restricted repertoire of C-type lectin receptors and relied on CD4 for uptake of Env. Despite a generally poor capacity for Ag uptake compared with myeloid DCs, the high expression of CD4 on PDCs allowed them to bind and internalize Env very efficiently. CD4-mediated uptake delivered Env to EEA1(+) endosomes that progressed to Lamp1(+) and MHC class II(+) lysosomes where internalized Env was degraded rapidly. Finally, all three blood DC subsets were able to internalize an Env-CMV pp65 fusion protein via CD4 and stimulate pp65-specific CD4(+) T cells. Thus, in the in vitro systems described in this paper, CD4-mediated uptake of Env is a functional pathway leading to Ag presentation, and this may therefore be a mechanism used by blood DCs, including PDCs, for generating immune responses to Env-based vaccines.

Derivation of non-infectious envelope proteins from virions isolated from plasma negative for HIV antibodies.

Natural membrane-bound HIV-1 envelope proteins (mHIVenv) could be used to produce an effective subunit vaccine against HIV infection, akin to effective vaccination against HBV infection using the hepatitis B surface antigen. The quaternary structure of mHIVenv is postulated to elicit broadly neutralizing antibodies protective against HIV-1 transmission. The founder virus transmitted to infected individuals during acute HIV-1 infection is genetically homogeneous and restricted to CCR5-tropic phenotype. Therefore, isolates of plasma-derived HIV-1 (PHIV) from infected blood donors while negative for antibodies to HIV proteins were selected for expansion in primary lymphocytes as an optimized cell substrate (OCS). Virions in the culture supernatants were purified by removing contaminating microvesicles using immunomagnetic beads coated with anti-CD45. Membrane cholesterol was extracted from purified virions with beta-cyclodextrin to permeabilize them and expel p24, RT and viral RNA, and permit protease-free Benzonase to hydrolyze the residual viral/host DNA/RNA without loss of gp120. The resultant mHIVenv, containing gp120 bound to native gp41 in immunoreactive form, was free from infectivity in vitro in co-cultures with OCS and in vivo after inoculating SCID-hu Thy/Liv mice. These data should help development of mHIVenv as a virally safe immunogen and enable preparation of polyclonal hyper-immune globulins for immunoprophylaxis against HIV-1 infection.

Detection of HIV gp120 in plasma during early HIV infection is associated with increased proinflammatory and immunoregulatory cytokines.

Events that occur during acute HIV infection likely contribute to the immune dysfunction common in HIV-infected individuals. During this early stage, there is high-level viral replication, loss in CD4(+) T cell number and function, and an up-regulation of proinflammatory and immunoregulatory cytokines. The mechanisms responsible for this are not completely understood. We hypothesize that the HIV envelope glycoprotein, gp120, contributes to immune dysfunction during early HIV infection. Using a cohort of subjects enrolled during acute and early HIV infection, we determined the amount of gp120, TNF-α, IL-6, IL-10, IFN-α, and IFN-γ in plasma at baseline and 6 months. At matched time points, we also measured CD4(+) T cell proliferation, T cell activation, and apoptosis. Plasma from 109 subjects was screened for gp120. Thirty-six subjects (33%) had detectable gp120 (0.5-15.6 ng/ml). Subjects with greater than 1 ng/ml of gp120 at baseline had similar levels at all time points tested, even when viral replication was undetectable due to therapy. Subjects with detectable gp120 had higher levels of plasma IL-6, IL-10, and TNF-α. There was no difference in the level of T cell activation, proliferation, or apoptosis in subjects with gp120 compared to those without. We conclude that persistent expression of gp120 occurs in a subset of individuals. Furthermore, the presence of gp120 is associated with higher levels of plasma IL-6, IL-10, and TNF-α, which may contribute to immune dysfunction during early HIV infection.

Structure and function of HIV-1 CRF01_AE envelope proteins from blood and genital fluid isolates.

The recombinant envelope protein (gp120) of the human immunodeficiency virus type 1 (HIV-1) CRF01_AE env gene isolated from the corresponding blood (rgp120-F36PC) and genital fluid (rgp120-F36VC) specimens obtained from HIV infected individuals was successfully produced in both prokaryote and eukaryote cells. The yields of HIV-1 recombinant envelope proteins rgp120-F36PC and rgp120-F36VC produced in E. coli and in mammalian cells were 1.0 and 1.2, and 0.3 and 0.5 mg/ml, respectively. Antibody responses in mice immunized with rgp120-F36VC protein were not significantly higher than those with rgp120-F36PC protein. The level of antibody response in mice immunized with V3 deleted recombinant gp120 proteins from rgp120-F36VC and rgp120-F36PC was not significantly different from wild type rgp120 proteins. beta-strands at the tip of the V3 loop of the HIV-1 envelope protein were predicted for the wild type genital fluid isolate but not for the wild type blood isolate. The replication capacity of both F36PC and F36VC was quite efficient. The infectivity assay of the epithelial cell line for pNL4-3/gp120F36VC was better than for pNL4-3/gp120F36PC. The extra beta-strands in the V3 loop may be involved in cell tropism.

HIV-1 envelope protein gp120 is present at high concentrations in secondary lymphoid organs of individuals with chronic HIV-1 infection.

The envelope protein of human immunodeficiency virus type 1 (HIV-1)--glycoprotein 120 (gp120)--has been demonstrated to dysregulate T cell function in vitro. We obtained autopsy tissues from individuals with chronic HIV-1 infection to determine whether there was enough gp120 in lymphoid tissues and/or blood to elicit these effects. We found that gp120 was present in high concentrations (>300 pg/mL) in the spleen and lymph nodes of some of these individuals. In contrast, very low amounts of gp120 and p24 were detected in all serum samples tested. These findings underpin the clinical relevance of nonentry functions of gp120 and the chronic nature of human immunodeficiency virus (HIV)-induced immune dysregulation.

Lessons from a multisite international trial in the Caribbean and South America of an HIV-1 Canarypox vaccine (ALVAC-HIV vCP1452) with or without boosting with MN rgp120.

BACKGROUND: The first multicenter, international National Institutes of Allergy and Infectious Diseases (NIAID)-sponsored HIV vaccine trial took place in Brazil, Haiti, Peru and Trinidad. This randomized, double-blind, placebo-controlled, phase 2 trial evaluated the safety and immunogenicity of a clade B-derived, live canarypox HIV vaccine, vCP1452. vCP1452 was administered alone or with a heterologous boost of MN rgp120 glycoprotein. The trial was pivotal in deciding whether these vaccines advanced to phase 3 efficacy trials. METHODS: Forty seronegative volunteers per site were randomized to ALVAC alone, ALVAC plus MN rgp120, or placebo in a 0, 1, 3, and 6 month schedule. Immunogenicity was assayed by chromium-release cytotoxic T lymphocyte (CTL) responses; interferon-gamma (IFN-gamma) enzyme-linked immunosorbent spot assays (ELISpot); lymphocyte proliferation assays (LPA); neutralization; and enzyme-linked immunosorbent assays (ELISA). RESULTS: Enrollment and follow-up were excellent. Both vaccines were well tolerated. Neutralizing antibody to the laboratory-adapted MN strain was detected. Cellular immune responses, as measured by CTL, ELISpot, and LPA, did not differ between vaccines and placebos. CONCLUSIONS: The observation of disappointing immunogenicity in this and a parallel domestic study has informed future vaccine development. Equally important, challenges to doing an integrated trial across countries, cultures, languages, and differing at-risk populations were overcome. The identification of specific safety, ethical, logistic, and immunological issues in this trial established the foundation for current larger international studies.

HIV-1 gp120/V3-derived epitopes promote activation-induced cell death to superantigen-stimulated CD4+/CD45RO+ T cells.

The third hypervirable (V3) domain of the HIV-1 envelope glycoprotein gp120 has been implicated in HIV pathogenesis via co-receptor usage of chemokine receptors CCR5 and CXCR4. As the protagonist cell populations in the asymptomatic phase of HIV-1 infection are infected macrophages and effector/memory (CD45RO+) CD4+ T cells that express CCR5, we established an in vitro model using human primary monocyte-derived macrophages and lymphocytes to investigate the role of V3 in affecting antigen presentation. We used staphylococcal enterotoxin A (SEA) as a superantigen at a low concentration of 1ng/ml, to activate naïve CD4+ T cells. Exposure of cells to SEA and lipoV3-liposomes increased the percentage of CD4+/CD45RO+/CCR5+ T cell population as compared to cells treated with SEA and plain liposomes. A consequent decrease of the percentage of CD4+/CD45RO+/CXCR4+ subset was observed. The V3-mediated activation was competitively inhibited by soluble V3-derived peptides with higher cationic charge. V3 enhanced also apoptosis as demonstrated by flow cytometry and intracellular calcium ion assays. These results reinforce the postulation that V3 alters the antigen presentation function itself, independent of specific antigens, thus leading to an enhanced activation-induced cell death (AICD) of responding T cells.

Mathematical model of the effect of affinity hemodialysis on the T-cell depletion leading to AIDS.

HIV-derived envelope proteins appear to be intimately involved in the destruction of uninfected T cells that leads to AIDS in a process known as the 'bystander effect'. Affinity hemodialysis has been proposed as an effective means of reducing these viral toxins. Using deterministic mathematical models based on the well-known Perelson formulations, the effectiveness of affinity hemodialysis in reducing the levels of viral gp120 was analyzed. Incorporating experimental data on the function of the affinity dialysis system and data from published analyses of HIV viral dynamics, two different models of HIV and AIDS were analyzed. Both models predict a rapid and sustained reduction in gp120 levels. In the model incorporating stem cell dynamics, affinity hemodialysis treatment under several different scenarios was associated with a significant increase in T-cell levels independent of any release from lymphatic tissues. The calculations support the contention that affinity hemodialysis is a potentially useful adjunctive therapy, which can be employed to treat HIV-infected patients in conjunction with drug therapy. For those patients resistant to anti-retroviral drugs or those unable to take the drugs due to the side effects of those medications, affinity hemodialysis treatment may become a viable option.

Affinity hemodialysis for antiviral therapy. II. Removal of HIV-1 viral proteins from cell culture supernatants and whole blood.

BACKGROUND: HIV-1 gp120 may play a role in the progression from HIV infection to AIDS. AIMS: We investigated affinity hemodialysis for removing gp120 from cell culture and whole blood. METHODS: Anti-gp120 antibodies covalently coupled to agarose beads were packed into columns or hollow-fiber hemodialysis cartridges. Supernatants from HIV-infected HL2/3 cells or gp120 containing whole blood were pumped over the columns and gp120 measured by ELISA. RESULTS: Anti-gp120 agarose removed approximately 90% of HIV-1 gp120 from HL2/3 cultures in 30-60 min. Capture was antibody-dependent (F105 > IDX 1121 > ABI 13-108). Affinity hemodialysis also efficiently captured gp120 from buffer in a first-order, flow-rate-dependent fashion (t((1/2)) = 13 min at 0.9 ml/min). Clearance was faster than calculated diffusion (t((1/2)) approximately 2.5 h) suggesting significant convective transport. gp120 removal from blood was slower (t((1/2)) = 1.4 h). CONCLUSION: Affinity hemodialysis efficiently clears gp120 from cell culture fluids and blood and may be useful in slowing the progression to AIDS.

Significant differences between plasma HIV-1 RNA assays in HIV-1 subtype E infected patients treated with antiretroviral therapy.

UNLABELLED: A total of 72 HIV-1 infected Thai patients treated with didanosine (ddI) or stavudine (d4T) plus ddI at the time of interim analysis were analyzed. Sixty patients (83%) carried subtype E documented by HIV-1 V3 serotyping. HIV-1 RNA levels were measured using three commercial viral load assays. At baseline (n = 57), Quantiplex 2.0 and NucliSens 2.0 showed mean log10 HIV-1 RNA of 0.7 log10 or 5 fold lower than Amplicor 1.5 (mean 4.29 versus 5.0 log10, respectively, p < 0.001). At week 20 of treatment (n = 29), HIV-1 RNA levels were detected in 55.2%, 31%, and 33.5% of subjects tested by Amplicor 1.5, Quantiplex 2.0, and NucliSens 2.0, respectively. IN CONCLUSION: plasma HIV-1 RNA analyses showed comparable values with Quantiplex 2.0 and NucliSens 2.0 assays. In contrast, Amplicor 1.5 resulted in approximately 5 folds higher HIV-1 RNA levels and a 25% higher rate of detection of plasma HIV-1 RNA as compared to the other two assays. As the current goal of therapy is to suppress plasma viral load below the detection limit of the assays, the significant differences between the assays may influence antiretroviral efficacy evaluation and management.

Impact of HIV vaccination on laboratory diagnosis: case reports.

BACKGROUND: It has not been clearly demonstrated whether HIV vaccination can complicate routine HIV testing. In this report, we describe the laboratory data of two prisoners who received rgp120 vaccine in a phase III trial underway in Thailand. These data indicate that previous vaccination may complicate the interpretation of screening HIV diagnostic tests. CASE PRESENTATION: The participants were identified from a cohort study on "Health factors related to HIV-1 and other viral infections among incarcerated people" that was approved by The Ethical Committee for Research in Human Subjects, Ministry of Public Health, Thailand. HIV diagnosis was definitively established with serial specimens using multi-screening tests, Western blot and diagnostic PCR.Anti-HIV screening tests consistently exhibited either weakly reactive or inconclusive results. The band patterns of the Western blot analysis corresponded to those found in individuals who received the rgp120 vaccination. Definite results were established using diagnostic PCR, which exhibited consistently negative results with follow-up specimens. Such problems in HIV testing are not easily resolved in the routine clinical setting in Thailand. CONCLUSIONS: These data demonstrate that HIV-1 vaccination interferes with routine diagnostic tests. Similar cases will not be uncommon in Thailand, where 2,545 people have already participated in a phase III trial.

Circulating gp120 alters the blood-brain barrier permeability in HIV-1 gp120 transgenic mice.

The mechanism underlying invasion of the central nervous system by HIV-1 is unclear. We recently demonstrated blood-brain barrier changes in a model of HIV-1 gp120 transgenic mice. To test whether this alteration was intrinsic to the brain endothelium of transgenic mice or depended on circulating gp120, we used brain endothelial cultures from gp120 transgenic and non-transgenic mice and exposed them to serum from gp120 transgenic or non-transgenic mice. We measured permeability to albumin as a marker of functional endothelial integrity. A significant increase in permeability (up to 47%) was observed in transgenic and non-transgenic cultures exposed to serum samples from transgenic but not to those from non-transgenic mice. This permeability was neutralized after immunoabsorption of sera with anti-gp120 monoclonal antibody. These findings demonstrate that the blood-brain barrier alteration in HIV-1 gp120 transgenic mice is due to circulating gp120.