Increased plasma levels of the C-C chemokine RANTES in patients with primary HIV-1 infection

To investigate the role played by chemokines in the natural history of human immunodeficiency virus (HIV) infection, we measured the plasma levels of RANTES. MIP-1 alpha and MIP-1 beta in a cohort of patients with primary HIV-1 infection (PHI) followed longitudinally. The cohort included 17 patients with well-documented history of acute HIV syndrome within two months of the first observation. The mean plasma concentration of RANTES, but not that of MIP-1 alpha or MIP-1 beta, was significantly higher in patients with PHI (192.3 ng/ml) than in five HIV-seronegative controls (8.0 ng/ml) studied during the same time period. Treatment of blood with a cocktail of drugs preventing platelet activation, followed by high-speed centrifugation, reduced the levels of RANTES by approximately 2 logs both in patients and in controls, indicating that the bulk of RANTES was released by platelets, which are known to store this chemokine in their alpha-granules, in the immediate aftermath of blood drawing. No correlation was seen between the levels of RANTES and the number of HIV genome equivalents in plasma. These data suggest that large amounts of pre-formed RANTES are stored in platelets and, possibly, in other blood cells during the early phases of HIV infection. The possible role of this HIV-suppressive chemokine in the control of viral replication during PHI remains to be established.     

False-positive HIV-1 test results in a low-risk screening setting of voluntary blood donation. Retrovirus Epidemiology Donor Study

CONTEXT: Persons at risk of human immunodeficiency virus 1 (HIV-1) infection, have been classified incorrectly as HIV infected because of Western blot results, but the frequency of false-positive Western blot results is unknown. OBJECTIVES: To determine the frequency of false-positive HIV-1 Western blot results in US blood donors and to make projections to other screened populations. Secondarily, to validate an algorithm for evaluating possible false-positive cases. DESIGN: A retrospective cohort study of HIV-1 enzyme immunoassay (EIA) and Western blot results from large blood donor screening programs in which donors with suspected false-positive Western blot results underwent HIV-1 RNA polymerase chain reaction (PCR) testing and follow-up HIV-1 serology. SETTING: Five US blood centers participating in the Retrovirus Epidemiology Donor Study. PARTICIPANTS: More than 5 million allogeneic and autologous blood donors who successfully donated blood at 1 of the 5 participating centers from 1991 through 1995. MAIN OUTCOME MEASURES: Rate of false positivity by Western blot and true HIV-1 infection status as determined by HIV-1 RNA PCR and by serologic follow-up of blood donors more than 5 weeks after donation. RESULTS: Of 421 donors who were positive for HIV-1 by Western blot, 39 (9.3%) met the criteria of possible false positivity because they lacked reactivity to p31. Of these, 20 (51.3%) were proven by PCR not to be infected with HIV-1. The false-positive prevalence was 4.8% of Western blot-positive donors and 0.0004% (1 in 251000) of all donors (95% confidence interval, 1 in 173000 to 1 in 379000 donors). CONCLUSIONS: A false diagnosis of HIV-1 infection can result from the combination of EIA and Western blot testing in blood donor and other HIV-1 screening programs. Individuals with a positive Western blot result lacking the p31 band should be counseled that, although they may be HIV infected, there is uncertainty about this conclusion. These individuals should be further evaluated by RNA PCR testing (if feasible) and HIV serologic analysis on a follow-up sample.     

Comparison of NucliSens and Amplicor monitor assays for quantification of human immunodeficiency virus type 1 (HIV-1) RNA in plasma of persons with HIV-1 subtype A infection in Abidjan, C?te d'Ivoire

We compared the sensitivity and accuracy of the NucliSens assay and those of both the standard and modified (addition of a new primer set, primer mix 1, supplied by Roche) Amplicor HIV Monitor assays to quantify human immunodeficiency virus type 1 (HIV-1) RNA in persons infected with HIV-1 subtype A in Abidjan, C?te d'Ivoire. Seventy-one plasma samples from HIV-1-seropositive persons at different stages of HIV infection and 15 samples from HIV antibody-negative persons were analyzed. The HIV-1 genetic subtype was determined either by DNA sequencing or by a restriction fragment length polymorphism assay. Of the 71 samples, 70 (98%) were subtype A and 1 was subtype G. Of the 70 subtype A samples, the proportion of RNA-positive plasma samples and mean HIV-1 RNA levels were significantly higher by the modified HIV Monitor assay (n = 67 [96%]; mean RNA levels, 5.2 log10 HIV-1 RNA copies/ml) than the NucliSens assay (n = 56 [80%]; 4.3 log10 HIV-1 RNA copies/ml) or the standard HIV Monitor assay (n = 44 [63%]; mean RNA levels, 3.8 log10 HIV-1 RNA copies/ml) (all P values were <0.05). The HIV-1 RNA levels by the modified HIV Monitor assay correlated significantly with those by the NucliSens assay (r = 0.76; P < 0.001) and the standard HIV Monitor assay (r = 0.57; P < 0.001), as did the RNA levels by the NucliSens and the standard HIV Monitor assays (r = 0.60; P < 0. 001). Lower CD4 cell counts were significantly correlated with higher HIV-1 RNA levels by all three assays (r = -0.47 for the NucliSens assay, -0.45 for the standard HIV Monitor assay, and -0.62 for the modified HIV Monitor assay). These results indicate that the modified HIV Monitor assay has the highest sensitivity and efficiency at quantifying the levels of RNA in persons infected with HIV-1 subtype A and thus constitutes a valuable tool for the monitoring of RNA levels in areas of Africa were HIV-1 subtype A is predominant.     

HIV-1 survival kinetics in peritoneal dialysis effluent

Viable and potentially infectious HIV-1 has been recovered from the peritoneal dialysis effluent (PDE) of patients with end-stage renal disease (ESRD) who are infected with the human immunodeficiency virus (HIV). No information had previously been available as to how long HIV-1 could survive in this environment, and no data were available as to how long HIV-1 could survive on peritoneal dialysis exchange tubing (PDET). Therefore, this study was designed to answer these questions. HIV-1 Mn was added to PDE and allowed to incubate at room temperature for 0 to 14 days. Following centrifugation, the cellular component of the PDE mixture was placed in co-culture with peripheral blood mononuclear cells (PBMC) from HIV negative donors. Aliquots from the co-cultures were removed after 14 days and assayed for the HIV-1-P24 antigen. High levels of HIV P24 antigen were recovered up to and including seven days of room temperature incubation. HIV could not be recovered from PDE that had been incubated at room temperature for 10 to 14 days. Ten milliters of HIV-PDE mixture was placed within PDET and incubated at room temperature for 10 minutes. The solution was then removed by gravity drainage. After drying times of 0 to 168 hours, the tubing was flushed with HIV culture medium and placed in co-culture with PBMCs from HIV negative donors. The culture supernatant was assayed for the HIV-1 P24 antigen as a marker of viral replication. High levels of HIV-1 P24 antigen were recovered from the PDET wash for up to and including 48 hours of drying time. No viable virus could be detected for drying times of between 72 and 168 hours. To determine if common disinfectants found in the dialysis unit could inactivate HIV, dilutions of Amukin 50% and household bleach were prepared at final concentrations ranging from 1:32 to 1:2048. These disinfectant solutions were incubated with PDE containing HIV for 10 minutes. The cellular fraction of the PDE was isolated by centrifugation, washed, and placed in co-cultures with peripheral blood mononuclear cells. HIV P24 antigen levels were assayed every three days for 28 days. Amukin 50% and a 10% household bleach solution were effective in killing HIV in PDE at dilutions up to and including 1:512. These results indicate that HIV can survive in PDE at room temperature for up to seven days. HIV can survive on peritoneal dialysis exchange tubing for up to 48 hours. Final dilutions of 1:512 Amukin 50% and 10% household bleach, after 10 minutes of exposure, are effective viricidal agents in disinfecting PDE.     

Plasma levels of soluble CD30, tumour necrosis factor (TNF)-alpha and TNF receptors during primary HIV-1 infection: correlation with HIV-1 RNA and the clinical outcome

OBJECTIVES: The immunological and virological events associated with primary HIV-1 infection have a major impact on the course of HIV-1 disease, and the identification of early predictors during primary HIV infection is critical for the therapeutic strategy. DESIGN AND METHODS: Eighteen consecutive patients with primary HIV infection were followed for a median of 398 days. Clinical status, CD4+ T-cell counts, and plasma samples were obtained weekly from enrollment until week 6, then at weeks 12, 24 and 52, and every 6 months thereafter. Seroconversion was assessed by anti-HIV-1/2 antibodies and Western blot analysis. HIV-1 RNA in plasma was quantified by Amplicor HIV Monitor test. Samples were assayed for immune complex-dissociated p24 antigen, tumour necrosis factor (TNF)-alpha, soluble TNF receptor (sTNFR)-1, sTNFR-II, sCD30 and sCD8 by enzyme immunoassays. Outcome was defined as entering clinical category B or C according to the Centers for Disease Control and Prevention criteria. As a control group, we included 23 HIV-1-negative healthy blood donors. RESULTS: Plasma levels of sCD30, TNF-alpha and sTNFR were significantly higher in HIV-1-infected patients than in controls, and were positively correlated with each other and with values of HIV-1 RNA. Patients who developed an outcome (n = 4) had significantly higher levels of sCD30, TNF-alpha and sTNFR compared with those who did not. Multivariate logistic regression analysis showed that sCD30 and TNF-alpha were the best predictors of outcome independently of CD4+ T-cell counts. CONCLUSIONS: During primary HIV infection, a persistent immune activation may be associated with a poor clinical outcome. The identification of sCD30 and TNF-alpha levels in plasma as early predictors of outcome in primary HIV infection, may direct the implementation of early therapeutic strategies in patients with elevated risk of disease progression.     

Virus burden in lymph nodes and blood of subjects with primary human immunodeficiency virus type 1 infection on bitherapy

At present, it is not known whether undetectable plasma viremia corresponds to an absence of human immunodeficiency virus type 1 (HIV-1) replication in lymphoid tissues. This issue has been explored in 11 subjects with primary HIV-1 infection treated with zidovudine plus didanosine by evaluating virologic markers in blood and lymphoid tissues 9-18 months after initiation of treatment. These markers include plasma viremia, measured with a sensitive assay with a detection limit of 20 HIV-1 RNA copies/mL, infectious virus titers and proviral DNA in lymph node mononuclear cells, and HIV-1 RNA in lymphoid tissue. Five subjects had plasma viremia <20 copies/mL and showed no evidence of viral replication in lymphoid tissue. Six subjects had both detectable plasma viremia and evidence of HIV-1 RNA in lymphoid tissue. The results indicate that absence of detectable HIV RNA in lymphoid tissue is associated with viremia levels of HIV-1 RNA <20 copies/mL.     

Infection of baboons with a simian immunodeficiency virus/HIV-1 chimeric virus constructed with an HIV-1 Thai subtype E envelope

OBJECTIVE: To construct an infectious chimeric simian immunodeficiency virus/HIV-1 (SHIV) with the envelope of a Thai subtype E HIV-1 strain for use in a non-human primate model. METHODS: A novel SHIV genome was derived using the sequences of the ectodomain of the envelope gene from the Thai subtype E strain, HIV-1(9466). This SHIV (SHIV9466.33) was recovered by cocultivation from human peripheral blood mononuclear cells (PBMC) after transfection of human rhabdosarcoma cells. Rhesus macaque and baboon PBMC were screened in vitro for susceptibility to infection with SHIV9466.33. After successful infection of baboon PBMC, four animals were inoculated intravenously with SHIV9466.33 and monitored for plasma viral RNA, virus isolation from the PBMC, seroconversion, T-cell subsets, and signs of disease. RESULTS: SHIV9466.33 was able to infect PBMC from 12 out of 14 baboons. All four of the baboons selected for in vivo inoculation became infected. Peak plasma viral RNA levels of 8000 to 700,000 RNA copies/ml were measured at 2 weeks post-inoculation. Virus was isolated from the PBMC of all four baboons during acute infection, and all seroconverted. Although transient declines in CD4+ T-cells were observed during early infection, CD4+ levels remained within normal ranges thereafter. In contrast, in vitro cultures of PBMC of four rhesus macaques were not susceptible to infection with SHIV9466.33. CONCLUSION: SHIV9466.33 containing an HIV-1 subtype E envelope displayed tropism for baboon PBMC but not for rhesus macaque PBMC. This chimeric virus established infection and induced antiviral antibodies in baboons inoculated by the intravenous route with cell-free virus. Thus, infection of baboons with SHIV9466.33 will serve as an important animal model for future studies of HIV-1 vaccine efficacy.     

Mechanisms of human immunodeficiency virus Type 1 (HIV-1) neutralization: irreversible inactivation of infectivity by anti-HIV-1 antibody

An assay for the neutralization of human immunodeficiency virus type 1 (HIV-1) is described in which the reduction in infectious titer of HIV-1 after preincubation at 37 degrees C with antibody-positive serum is the measure of neutralization. The assay format and its controls allow several experimental manipulations that, taken together, indicate an effect of antibody on HIV-1 infectivity that occurs before or independently of HIV-1 attachment. The direct inactivation of HIV-1 infectivity by antibody is irreversible and temperature dependent, requires a bivalent antibody directed against accessible envelope determinants, and does not require a heat-labile or (Ca2+)- or (Mg2+)-dependent cofactor. The mechanism of inactivation cannot be explained by agglutination of virus, nor is it associated with disruption or dissociation of envelope protein from virions. Rather, the antibody is likely to perturb some metastable property of the envelope that is required for entry. Laboratory-adapted HIV-1 isolates were more sensitive to the inactivating effects of sera than were primary patient isolates. The latter were particularly resistant to inactivation by contemporary autologous sera, a feature not explained by blocking antibodies. Additional studies showed a weak relationship between disease course and serum inactivation of the reference LAI laboratory strain of HIV-1. Heteroduplex analysis and autologous inactivation assays of sequential specimens from individual patients indicate that over time, the viral quasispecies that emerge and dominate are resistant to the inactivating effects of earlier sera.     

Psoralen-mediated photodecontamination of platelet concentrates: inactivation of cell-free and cell-associated forms of human immunodeficiency virus and assessment of platelet function in vivo

BACKGROUND: Treatment of platelet concentrates (PCs) with psoralens and broad-band ultraviolet A (UVA) radiation is being examined for the elimination of pathogens that might be present in donated blood. Previous studies have demonstrated the inactivation of cell-free viruses and the maintenance of platelet integrity with common in vitro assays. STUDY DESIGN AND METHODS: Human immunodeficiency virus (HIV) in three forms-cell-free, activity replicating, and latently infected cell lines-was added to PCs and treated with 50-microgram per mL of 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT), 0.35 mM rutin, and broad- and narrow-band UVA light (320-400 nm and 360-370 nm [UVA1], respectively). The inactivation of added HIV was assessed in tissue culture; platelet hemostatic activity was assessed in thrombocytopenic rabbits. RESULTS: Each form of HIV was inactivated completely (> or = 10(5) infectious units) on treatment with 30 J per cm2 of UVA1 light. Similar results were obtained on treatment of 2.5 mL of PCs in test tubes or intact PC units (50 mL) in blood bags. Latently infected cell lines were substantially more sensitive than cell-free HIV or HIV that was actively replicating. Human platelets treated with 40 J per cm2 of UVA1 light had a fully corrected bleeding time shortly after treatment or after 5 days' storage, as assessed in thrombocytopenic rabbits. Platelet hemostatic function began to decrease with 81 J per cm2 of UVA1 light and was abolished with 113 J per cm2. At similar fluences, broad-band UVA light was more injurious to platelets than was UVA1 light. CONCLUSION: HIV transmission might be eliminated by PCs after treatment with AMT and UVA1 light and without a reduction in platelet hemostatic function.     

Elevated cerebrospinal fluid levels of monocyte chemotactic protein-1 correlate with HIV-1 encephalitis and local viral replication

OBJECTIVE: To investigate whether the CC-chemokine monocyte chemotactic protein (MCP)-1 could play a role in the pathogenesis of HIV infection of the central nervous system. This hypothesis was suggested by previous observations, including our finding of elevated cerebrospinal fluid (CSF) levels of this chemokine in patients with cytomegalovirus (CMV) encephalitis. DESIGN AND METHODS: CSF levels of MCP-1 were determined in 37 HIV-infected patients with neurological symptoms, and were compared with both the presence and severity of HIV-1 encephalitis at post-mortem examination and CSF HIV RNA levels. MCP-1 production by monocyte-derived macrophages was tested after in vitro infection of these cells by HIV. RESULTS: CSF MCP-1 levels were significantly higher in patients with (median, 4.99 ng/ml) than in those without (median, 1.72 ng/ml) HIV encephalitis. Elevated CSF MCP-1 concentrations were also found in patients with CMV encephalitis and with concomitant HIV and CMV encephalitis (median, 3.14 and 4.23 ng/ml, respectively). HIV encephalitis was strongly associated with high CSF MCP-1 levels (P = 0.002), which were also correlated to high HIV-1 RNA levels in the CSF (P = 0.007), but not to plasma viraemia. In vitro, productive HIV-1 infection of monocyte-derived macrophages upregulated the secretion of MCP-1. CONCLUSIONS: Taken together, these in vivo and in vitro findings support a model whereby HIV encephalitis is sustained by virus replication in microglial cells, a process amplified by recruitment of mononuclear cells via HIV-induced MCP-1.     

Unintegrated circular HIV-1 DNA in the peripheral mononuclear cells of HIV-1-infected subjects: association with high levels of plasma HIV-1 RNA, rapid decline in CD4 count, and clinical progression to AIDS

We observed 36 HIV-infected patients to evaluate whether the presence of tandem 2-long terminal repeat circular unintegrated HIV-1 DNA (2-LTR) in peripheral blood mononuclear cells (PBMC) at baseline was associated with acceleration of HIV disease. Detection of 2-LTR at baseline correlated with high plasma HIV-1 RNA levels (p < .01), recovery of culturable HIV-1 from plasma (p = .02), and progression to AIDS during follow-up (p = .01). More patients with 2-LTR (68%) than without 2-LTR (31%) had a decline in CD4 levels of >50 cells/mm3 over the first 18 months of follow-up (p = .04), and the average annual CD4 decline was 35% in patients with 2-LTR compared with 16% in those without 2-LTR (p = 0.06). Detection of 2-LTR in PBMC at baseline was an independent predictor of high plasma HIV-1 RNA levels and subsequent CD4 cell decline in this cohort of patients with predominantly nonsyncytium-inducing (NSI) isolates at baseline. The presence of 2-LTR in PBMC appears to be reflective of ongoing HIV-1 replication, as measured by plasma HIV-1 RNA levels, and identifies persons at risk for immunologic and clinical decline.     

Comparison of the Amplicor HIV-1 monitor test and the nucleic acid sequence-based amplification assay for quantitation of human immunodeficiency virus RNA in plasma, serum, and plasma subjected to freeze-thaw cycles

The Amplicor HIV-1 Monitor test was compared to the nucleic acid sequence-based amplification (Nasba) assay system for the quantitation of human immunodeficiency virus (HIV) RNA in three different types of clinical samples: plasma, serum, and plasma subjected to freeze-and-thaw cycles. Each assay detected HIV RNA in the same 73 (90%) of 81 samples tested, and the quantitative results obtained with the two assays were significantly correlated. Both assays detected higher RNA levels in patients with CD4+ cell counts lower than 200 cells/mm3 than in patients with CD4+ cell counts higher than 200 cells/mm3. In addition, RNA levels in plasma higher than 5 logs predicted higher numbers of clinical events than did RNA levels in plasma lower than 5 logs. Quantitation of HIV RNA in paired plasma and serum samples showed lower HIV RNA content in serum than in the paired plasma sample, with mean differences between HIV RNA contents of plasma and serum of 0.54 and 0.28 log RNA copy/ml by the Nasba assay and the Amplicor HIV-1 Monitor assay, respectively. No significant loss of HIV RNA was detected with either assay in plasma samples subjected to multiple freeze-and-thaw cycles. These studies demonstrate that the Nasba and Amplicor assays perform similarly with plasma and serum samples. Further, the results indicate that freeze-and-thaw cycles do not result in significant loss of detectable HIV RNA.     

Clastogenic factors in plasma of HIV-1 infected patients

The objective of this study was to investigate the clastogenic activity of plasma ultrafiltrates from HIV-1 infected patients. Clastogenic factors are chromosome-damaging agents with low molecular weight (< 10,000 daltons) which cause chromosome aberrations, sister chromatid exchanges, DNA strand breakage, and gene mutation. They have first been described in the plasma of irradiated persons, but they are also found in hereditary breakage syndromes and chronic inflammatory diseases with autoimmune reactions. Their formation and their clastogenic effects are modulated by superoxide anion radicals. We analyzed a total of 22 HIV-1 positive patients in comparison to 20 reference plasma samples from healthy HIV negative blood donors of similar age. The plasma ultrafiltrates (filter cutoff 10,000 daltons) from patients induced a statistically significant increase in chromosomal breakage in the cytogenetic test system (20.5 +/- 6.8 aberrations per 100 cells), while no increase was observed in test cultures exposed to plasma ultrafiltrates from healthy blood donors (6.3 +/- 2.9 aberrations per 100 cells). The breakage values were slightly, but not significantly, lower in the 10 patients with more than 200 T-helper cells/ml (18 +/- 4 aberrations per 100 cells), than in the 12 patients with less than 200 T-helper cells/ml (22.3 +/- 7.9 aberrations per 100 cells). HIV patients with high clastogenic activity (induction of more than 20 aberrations per 100 cells, range 20 to 39) showed higher plasma levels for malondialdehyde than those with lower clastogenic activity (less than 20 aberrations per 100 cells, range 12 to 18). However, the difference was statistically not significant. Another lipid peroxidation product, 4-hydroxynonenal, was increased equally in both groups. There were no significant differences in water- and lipid-soluble plasma antioxidants between the low- and high-breakage group. In agreement with previous findings, the clastogenic effects of plasma ultrafiltrates in the test cultures were reduced by the antioxidant enzyme superoxide dismutase. The presence of clastogenic factors in the plasma of HIV patients is further evidence for a prooxidant state in these persons. Since clastogenic factor formation appears to occur at an early stage of the disease, it may be significant for virus release or activation, because of the superoxide anion stimulating effects of clastogenic factors. From a practical standpoint, clastogenic factors may be useful for evaluation of promising drugs.     

Co-packaging of sense and antisense RNAs: a novel strategy for blocking HIV-1 replication

Retroviral vectors were engineered to express either sense (MoTiN-TRPsie+) or sense and antisense (MoTN-TRPsie+/-) RNAs containing the human immunodeficiency virus type-1 (HIV-1) trans -activation response (TAR) element and the extended packaging (Psie) signal. The Psie signal includes the dimer linkage structure (DLS) and the Rev response element (RRE). Amphotropic vector particles were used to transduce a human CD4+ T-lymphoid (MT4) cell line. Stable transductants were then tested for sense and antisense RNA production and susceptibility to HIV-1 infection. HIV-1 production was significantly decreased in cells transduced with MoTiN-TRPsie+ and MoTN-TRPsie+/-vectors. Efficient packaging of sense and most remarkably of antisense RNA was observed within the virus progeny. Infectivity of this virus was significantly decreased in both cases, suggesting that the interfering RNAs were co-packaged with HIV-1 RNA. Vector transduction was not expected to occur and was not observed. Inhibition of HIV-1 replication was also demonstrated in human peripheral blood lymphocytes transduced with retroviral vectors expressing antisense RNA. These results suggest that (i) both sense and antisense RNAs were co-packaged with HIV-1 RNA, (ii) the co-packaged sense and antisense RNAs inhibited virus infectivity and (iii) the co-packaged sense and antisense RNAs were not transduced. Sense and antisense RNA-based strategies may also be used to co-package other interfering RNAs (e.g. ribozymes) to cleave HIV-1 virion RNA.     

Levels of HIV-infected peripheral blood cells remain stable throughout the natural history of HIV-1 infection. Swiss HIV Cohort Study

OBJECTIVE: To clarify the relationship between the number of provirus-bearing peripheral blood mononuclear cells (PBMC) and HIV-1 disease progression during the natural history of infection. DESIGN: Twenty-four HIV-1-infected subjects with known seroconversion dates and long-term follow-up were retrospectively identified using the Swiss HIV Cohort Database. PBMC specimens from this cohort were retrieved from storage for analysis. METHODS: Infected PBMC equivalents were determined by HIV-1 DNA quantitative competitive (QC)-PCR. The results were analysed with respect to HIV-1 disease stage and compared with a mathematical model of long-term HIV-1 disease progression. RESULTS: PBMC HIV-1 DNA did not correlate with major indices of disease progression, including time following primary infection, time before reaching a CD4 cell count less than 200 x 10(6)/l, and time before death. The number of PBMC harbouring HIV-1 provirus was relatively constant throughout the clinical stages of HIV-1 infection, consistent with simulated data from a mathematical model of long-term HIV-1 infection. We also showed that a biased interpretation of the QC-PCR data may arise when the values are expressed as HIV-1 DNA copies per PBMC or per CD4 cell. CONCLUSIONS: This analysis suggests that levels of provirus-bearing PBMC remain constant during the natural course of HIV-1 infection, whereas plasma virus load typically increases logarithmically during the same period. The hypothesis that plasma virus levels are directly related to the number of infected cells may deserve reconsideration.     

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.