Impact of heterozygosity for the chemokine receptor CCR5 32-bp-deleted allele on plasma virus load and CD4 T lymphocytes in perinatally human immunodeficiency virus-infected children at 8 years of age

The CCR5 gene encodes one of the major human immunodeficiency virus type 1 (HIV-1) coreceptors. A 32-bp deletion in this gene (delta ccr5) is associated with relative resistance to disease progression in heterozygous HIV-1-infected persons. The effect of this mutation on virologic and immunologic parameters was determined in a cohort of 45 perinatally HIV-1-infected children prospectively followed after 5 years of age. At a median age of 8.3 years, heterozygous children had significantly lower virus load than homozygous children (median, 3.3 vs. 4.1 log copies/mL, P < .009) and higher percentages of CD4 T cells (median, 26% vs. 17%, P < .07). However, there was no discernible influence of the CCR5 genotype on the percentages of CD8 T cells (P < .27) or on HIV-specific cytotoxic T lymphocyte activities (P < .65). There was a trend for lower rates of progression to AIDS (CDC stage C) in heterozygous children. These data confirm a major role for the CCR5 coreceptor in HIV-1 pathogenesis in children.     

Cultured blood dendritic cells retain HIV-1 antigen-presenting capacity for memory CTL during progressive HIV-1 infection

Dendritic cells (DC) are potent APC that may be involved in the pathogenesis of HIV-1 infection. We studied the APC function of DC from HIV-1-infected subjects that were derived from monocyte-depleted PBMC by culture in human IL-4 and human granulocyte-macrophage CSF. The cultured cells from the HIV-1-infected subjects had similar morphology and phenotype of mature DC (CD80 = 41 +/- 8%, CD86 = 77 +/- 5%, CD40 = 87 +/- 6%, CD1a = 1 +/- 1%) to DC cultured from seronegative subjects. The yield of these DC was lower than from HIV-1-seronegative subjects (4 +/- 0% vs 11 +/- 2%, p < 0.01), and the lower DC yields correlated with lower numbers of blood CD4+ T cells (r = 0.60, p < 0.01) and higher plasma viral load (r = -0.49, p < 0.01). DC from HIV-1-infected subjects were infected with recombinant vaccinia virus vectors expressing Gag, Pol, and Env and were able to stimulate equal or higher levels of MHC class I-restricted, anti-HIV-1 memory CTL (CTLm) than were similarly treated, autologous B lymphocyte cell lines. DC pulsed with peptides representing HIV-1 CTL epitopes stimulated higher levels of anti-HIV-1 CTLm responses than did DC infected with the vaccinia virus-HIV-1 constructs. Allogeneic, MHC class I-matched DC also stimulated anti-HIV-1 CTLm activity in cells from HIV-1-infected subjects. DC from early and late stages of HIV-1 infection had a similar ability to activate CTLm specific for targets expressing either HIV-1 genes via vaccinia virus vectors or HIV-1 immunodominant synthetic peptides. However, DC from either early or late stages of HIV-1 infection could not overcome the defect in anti-HIV-1 CTLm response in advanced infection.     

Evaluation of human immunodeficiency virus (HIV) type 1 RNA levels in cerebrospinal fluid and viral resistance to zidovudine in children with HIV encephalopathy

The amount of human immunodeficiency virus (HIV) type 1 RNA and the presence of a codon 215 mutation indicative of zidovudine resistance were evaluated in cerebrospinal fluid (CSF) and plasma obtained from HIV-1-infected children. The level of HIV-1 RNA in CSF was highest in children with severe encephalopathy (n = 25; median, 430 copies/mL; range, 0-2.2 x 10(5) copies/mL) followed by the moderately encephalopathic (n = 7; median, 330; range, 0-1130) and nonencephalopathic groups (n = 9; median, 0; range, 0-566) (P = .007). There was no correlation between CSF and plasma HIV-1 RNA levels. Five of 7 children with the codon 215 mutation in CSF had a progression of encephalopathy, while all 8 children with wild type codon 215 had improved or stable disease during zidovudine treatment (P = .007). These findings suggest that increased viral replication and emergence of drug-resistant HIV-1 variants within the central nervous system may play a role in progression of HIV encephalopathy.     

Individual prognoses of long-term responses to antiretroviral treatment based on virological, immunological and pharmacological parameters measured during the first week under therapy

OBJECTIVE: To predict long-term (12 weeks or longer) virological responses to antiretroviral treatment from measurements made during the first few days on therapy. METHODS: Forty-one HIV-1-infected children were treated with ritonavir for 12 weeks followed by triple drug combination treatment, and the kinetics of virus decay in plasma, ritonavir concentration and CD4 cell counts were measured. A robust multivariate pattern recognition method was used for prediction of the longterm virological responses. RESULTS: The virus decay rate constants calculated from measurements of plasma viral RNA concentrations on the first, second, third, fourth and seventh day on therapy, the drug concentrations in the plasma on day seven, and the pretreatment levels of viral RNA and CD4 cell counts, correlated with long-term levels of plasma HIV-1 RNA. The combination of these parameters contained sufficient information for correct and robust prediction of the long-term response in 88% of the treated children. The predictions of individual responses were stable as demonstrated by a cross-validation analysis, which was highly statistically significant (r=0.87) and specific. CONCLUSION: These results demonstrate that multiple parameters determine the response to antiretroviral therapy and offer a very early measure of individual long-term responses, suggesting that treatment could be optimized after few days of therapy.     

Hepatitis G virus infection in human immunodeficiency virus type 1-infected mothers and their children

Hepatitis G virus (HGV) RNA and anti-E2 glycoprotein antibody (E2Ab) seroprevalence was studied in 58 human immunodeficiency virus type 1 (HIV-1)-infected mothers (34 injecting drug users [IDUs] and 24 with risky sexual behavior [RSB]) and their children (median age, 5 days; range, 1-27). Twelve women (20.6%) were RNA- and 20 (34.4%) E2Ab-positive. Seroprevalence was similar in the IDU and RSB groups and high in RSB partners of IDU men. Five (41.6%) children of RNA-positive mothers were HGV-infected, at a median age of 5 days (range, 1-27), independent of maternal CD4 T lymphocyte numbers, mode of delivery, and HIV-1 transmission; no other child at risk became RNA-positive subsequently. No HGV-infected child (follow-up, 16 months; range, 12-52) showed increased liver enzyme levels; 3 children cleared RNA and E2Ab-seroconverted after 10-48 months. Thus, in HIV-1-infected women, HGV infection is common and also sexually transmitted, and clearance may be impaired. Mother-to-child transmission is frequent and occurs antenatally; children remain long infected without evident disease.     

Increased cerebrospinal fluid ganglioside GD3 concentrations as a marker of microglial activation in HIV type 1 infection

Human immunodeficiency virus type 1 (HIV-1) invades the central nervous system (CNS) early in the infectious course. The predominant, productively infected cell type within the CNS is the microglial cell. We have analyzed the cerebrospinal fluid (CSF) levels of the ganglioside GD3, a microglia/macrophage and astrocyte marker, in 22 HIV-1-infected individuals at different stages of the disease, and in 44 age-matched HIV-negative, healthy controls. To distinguish between microglial/macrophage and astroglial involvement, the GD3 levels were compared with CSF levels of the glial fibrillary acidic protein (GFAp), which is expressed exclusively in astrocytes. A significantly higher mean CSF concentration of GD3 was found in HIV-1-infected patients compared to controls (56.7 and 40.1 nmol/L, respectively, p < 0.001). Seven of 22 HIV-1-infected patients had increased CSF levels of GD3 (above mean + 2 SD in controls), all but one of these had normal levels of GFAp, indicating a microglial activation or proliferation as the major source of the increased GD3 levels.     

Choriodecidual inflammation: a potentially preventable cause of perinatal HIV-1 transmission?

The obstetric risk factors for perinatal transmission of HIV-1 include preterm birth, prolonged rupture of the chorioamniotic membranes, and clinical and histological bacterial chorioamnionitis. A chronic chorioamnionitis precedes many cases of preterm labour and spontaneous rupture of membranes, whereas an acute chorioamnionitis is more common after rupture of the membranes at term. Amniotic fluid cytokines are raised in the presence of term and preterm intrauterine bacterial infections, and various cytokines seem able to attract HIV-1-infected leucocytes into the amniotic cavity and to increase replication of HIV-1. We postulate that the association of preterm birth and prolonged rupture of membranes with perinatal transmission of HIV-1 may result from an associated chronic or acute bacterial chorioamnionitis marked by the migration of HIV-1-infected maternal leucocytes into the amniotic cavity. Antibiotic treatment could prevent this sequence of events.     

Effects of malaria infection in human immunodeficiency virus type 1-infected Ugandan children

BACKGROUND: Malaria causes severe morbidity and mortality in many areas of Africa where HIV-1 infection is also prevalent. Immunosuppression is associated with both diseases but most reports do not find significant interactions between them. METHODS: A collaborative study of HIV-1 infection in Ugandan women and their infants was established between the Ministry of Health, Makerere University, Kampala, and Case Western Reserve University in 1988. Four hundred fifty-eight infants, including 77 HIV-1-infected, 232 seroreverter and 125 control children born to HIV-1-negative mothers and 24 of indeterminate status were followed closely from birth for 4 years. Data on these infants were reviewed with respect to episodes of general illness and infections, suspected and confirmed episodes of malaria, onset and frequency of malaria, use of chloroquine and occurrence of selected illnesses after episodes of febrile illnesses. Thick and thin blood smears for malaria were obtained from children with fever. RESULTS: There was no association between occurrence of febrile illnesses and childrens' HIV-1 category. The relative rates of occurrence were 1.0 (95% confidence interval (CI), 0.8 to 1.2) and 1.1 (95% CI 0.9 to 1.4) for the HIV seroreverter and control children compared with the HIV-infected children. Although there was no association (P = 0.83) between HIV-1 status and a smear being taken during a febrile episode, there was an increase in smears positive for malaria parasitemia among seroreverter (risk ratio, 1.5; 95% CI 1.1 to 1.9) and control infants (risk ratio, 1.6; 95% CI 1.2 to 2.2) compared with HIV-1-infected infants. The level of parasitemia was similar in each group. A greater proportion of malaria episodes among the HIV-infected group than among the control groups resulted in hospitalizations (P = 0.001) and blood transfusions (P = 0.02). There was a positive association between time to clinical AIDS and absence of malaria (adjusted for follow-up age) in infected children (P = 0.02). Use of chloroquine was similarly high in each HIV-1 category (80%). CONCLUSIONS: In this group of HIV-infected children there was no significant increase in malarial episodes as compared with their HIV-negative controls. The results suggest a possibility that malaria may offer some protection against HIV-1 progression or that chloroquine used to treat malaria may have a direct effect against the HIV-1 virus.     

Reduction of Th1 cell activity in the peripheral circulation of patients with rheumatoid arthritis after treatment with a non-depleting humanized monoclonal antibody to CD4

Differences in early events during entry and integration of HIV-1 into peripheral blood mononuclear cells (PBMC) might contribute to the absence of AIDS-like disease in chimpanzees as compared to humans. To address this question, we first tested the in vitro susceptibility of human and chimpanzee PBMC for infection with the two HIV-1 isolates III B and RF. The results of these studies revealed that chimpanzee PBMC had a slightly lower capability to support the growth of HIV-1 as compared to human PBMC. This was accompanied by a delayed accumulation of proviral HIV-1 DNA in cultures of HIV-1-infected chimpanzee PBMC. However, no differences between cells of the two species were observed when very early events of HIV-1 infection were studied. Shortly (20 h) after infection chimpanzee and human cells harbored similar amounts of proviral HIV-1 DNA and PBMC of both species behaved comparably with respect to pre-integration latency (i.e. the ability to activate extrachromosomal HIV-1 intermediates in HIV-1 infected quiescent cells at various times after infection). These results strongly suggest that the absence of AIDS-like disease in chimpanzees cannot be correlated with defects in early events of the HIV-1 replicative cycle.     

Tryptophan depletion and HIV infection: a metabolic link to pathogenesis

HIV-1-infected patients have low circulating tryptophan concentrations despite evidence of adequate dietary intake of this essential amino acid. A chronic increase in inducible tryptophan oxidation is the basis of HIV-1-associated tryptophan depletion. This metabolic process results in the irretrievable loss of tryptophan molecules from the available pool. Such sustained disruption of normal tryptophan metabolism over time disturbs the many metabolic processes involving this amino acid, and has been implicated in some features of AIDS pathogenesis. Normal T-cell function is adversely affected by tryptophan depletion, but the extent of the effect in HIV-1-infected patients is still unclear. Attempting to directly supplement tryptophan is not advised given the potential increase in circulating concentrations of neurotoxic intermediates. Although only preliminary data are available, evidence suggests that antiretroviral and nicotinamide treatments can boost plasma tryptophan concentrations in HIV-1-infected patients and impact the secondary effects of tryptophan depletion. Additional study of this metabolism could lead to improved treatment strategies for patients with HIV infection. In this review I focus on the potential links between disturbed tryptophan metabolism and pathogenesis.     

Broad cross-neutralizing activity in serum is associated with slow progression and low risk of transmission in primate lentivirus infections

Sera from human immunodeficiency virus type 1 and type 2 (HIV-1 and HIV-2)-infected humans were tested with autologous (from the same individual) and heterologous (from other individuals) virus isolates in a neutralization assay. Similarly, sera from experimentally simian immunodeficiency virus (SIVsm from sooty mangabey) or HIV-2SBL6669-infected cynomolgus macaques were tested for neutralizing activity against autologous and heterologous reisolates. In the neutralization assay, the virus dose ranged between 10-75 50% infectious dose (ID50), sera were used in five 2- or 4-fold dilutions, beginning with 1:20, and human peripheral blood mononuclear cells (PBMCs) served as target cells. The readout of the 7-day assay was a HIV-1 or HIV-2 antigen enzyme-linked immunosorbent assay (ELISA). Our results show that SIVsm-inoculated monkeys who develop early immunodeficiency lack serum neutralizing activity or develop a neutralizing antibody response with narrow specificity. Long survival is associated with the ability to neutralize several autologous and heterologous SIVsm reisolates. Infection of macaques with HIV-2SBL6669 did not cause disease within the 5 years observation time and elicited a broadly cross-reactive neutralizing antibody response, including neutralization of other, independently obtained, HIV-2 isolates. In HIV-1-infected humans, neutralizing antibodies can only be detected in up to 50% of cases. Neutralizing activity, whenever present, may show a broad specificity, that is, neutralization may occur across genetic subtypes. Presence of broadly cross-reactive neutralizing antibodies is associated with a lower risk of HIV-1 (subtype B) transmission both from mother to child and sexually from male to female. Unlike HIV-1 infection, serum neutralizing activity is regularly present in HIV-2 infection. In view of the differences between HIV-1 and HIV-2 pathogenesis, we suggest that an effective neutralizing antibody response may contribute to a delay in disease progression and to a decrease in risk of transmission.     

What is the effect of adjusting epirubicin doses for body surface area?

A broad antibody panel was used for immunophenotyping of human immunodeficiency virus type 1 (HIV-1)-infected patients who were long-term nonprogressors (LTNP). The LTNP were compared with patients in the early phase of infection and patients who had progressed to advanced immunodeficiency. Changes in CD8(+) subset distribution were observed mainly at acquisition of HIV-1 infection, whereas CD4(+) subset changes appeared during progression of HIV-1 infection. The decreasing levels of CD4(+) cells were characterized by an increasing frequency of cells expressing the activation markers HLA-Dr and CD45RO but not the CD28 surface antigen. The LTNP exhibited significant changes compared to HIV-negative patients in almost all markers. Compared to patients in the early phase of infection, the only difference was a relatively lower frequency of CD4(+) cells expressing CD26 among the LTNP. The results show that HIV-1-infected persons who have no signs of immunodeficiency despite many years of infection have an immunophenotypic pattern that is substantially different from that of noninfected persons. Despite the long duration of infection, the LTNP exhibit a pattern similar to that of newly infected persons, with the exception of lower expression of CD26 on CD4(+) cells.     

Effect of antiretroviral treatment on early electroencephalographic and otoneurologic manifestations in HIV infection and prognostic importance of verified perturbations

Electrophysiologic tests may be abnormal in asymptomatic HIV-1-infected individuals. Our study was aimed at determining whether these findings have a prognostic value and could be corrected by antiviral treatment. In 18 patients, followed for 34 or 43 months, these findings were not progressive. Only one patient developed Aids dementia complex (ADC). Three have died (one with normal, two with abnormal tests at baseline). To study the effect of antiviral treatment, another group of seven asymptomatic patients was included into a cross-over double-blind study with either eight weeks zidovudine or eight weeks placebo, separated by eight more weeks without treatment. Electrophysiological evaluation was also performed in a group of 15 patients before antiviral therapy with zidovudine or didanosine was started and again after a mean of three and 13 months treatment. Results did not suggest that treatment reverses early electroencephalographic and otoneurological changes seen in HIV-1 infection.     

Genetic characterization of viral quasispecies in blood and cervical secretions of HIV-1- and HIV-2-infected women

We evaluated cervical samples from 11 HIV-1- and 25 HIV-2-infected individuals. The rate of viral shedding was 36.4% for HIV-1 and 16% for HIV-2, after repeat PCRs. We sequenced multiple clones of the C2-C3 env region from cervical secretions and PBMC samples from three HIV-2-infected individuals, and the C2-V3 env region from four HIV-1-infected individuals. In most cases, phylogenetic analysis showed that the viral sequences from blood and genital secretions were intermingled and subclusters did not segregate according to sample site. In rare cases, however, tissue-specific sequences were observed, suggesting a complex relationship between quasispecies in the two sites where preferential transmission of HIV variants may be due to multiple factors.     

Pneumococcal vaccination in HIV-1-infected adults in Uganda: humoral response and two vaccine failures

OBJECTIVES: To assess the feasibility of establishing a pneumococcal vaccine trial among HIV-1-infected adults in Uganda and to characterize their responses to 23-valent pneumococcal polysaccharide vaccine. DESIGN: An open-label pilot trial to assess recruitment and compliance of HIV-1-infected adults in Uganda to vaccination and to determine the immunogenicity of the vaccine. SETTING: A community clinic for HIV-1-infected adults in Entebbe, Uganda. METHODS: Levels of capsule-specific IgG to four common vaccine capsular serotypes were measured before vaccination and 1 month after vaccination. Subsequent rates of disease episodes and deaths, and immunologic responses in two vaccine failures, were followed. RESULTS: One month after-vaccination, both HIV-1-infected (n = 77) and seronegative control subjects (n = 10) demonstrated a significant rise in capsule-specific immunoglobulin G (IgG) for three of four serotypes tested, but levels were significantly lower among HIV-1-infected patients. In 149 patient-years of follow-up, two (2.6%) developed pneumococcal pneumonia, one bacteremic with serotype 1 and one non-bacteremic with serotype 13, a non-vaccine serotype; both patients showed inadequate killing of the organism in vitro. In this same follow-up period, 29 (38%) patients died. CONCLUSION: HIV-1-infected adults in Uganda are at high risk of pneumococcal disease and show a significant but suboptimal response to pneumococcal vaccine. Although reliable recruitment and follow-up of vaccinees is feasible, evaluation of vaccine efficacy may be compromised by limited responses to common vaccine serotypes, an unknown incidence of disease with non-vaccine serotypes, and a high rate of mortality unrelated to Streptococcus pneumoniae infection.     

Preclinical characterization of an anti-tat ribozyme for therapeutic application

A hammerhead ribozyme retroviral construct, denoted RRz2, targeting the coding region of the human immunodeficiency virus type 1 (HIV-1) tat gene, has shown itself to be effective in a range of test systems. Inhibition of the replication of HIV-1 IIIB and primary drug-resistant strains in pooled transduced CEMT4 cells was consistently found to be more than 80% compared with the control-vector transduced cells, whereas a mutant RRz2 gave approximately 45% inhibition. A multiple HIV-1 passage assay showed the absence of emergence of mutations within the specific viral RNA ribozyme target sequences. This lack of generation of ribozyme "escape mutants" occurred despite the almost complete disappearance of a HIV-1 quasi-species in the testing virus. When RRz2 was tested in peripheral blood lymphocytes (PBLs) from HIV-1-infected patients, paired analysis showed that cell viability in the ribozyme-transduced HIV-1-infected PBLs was significantly higher than that in the vector-transduced cells. This difference in viability (vector versus RRz2) was not observed in PBLs from non-HIV-1-infected donors. Taken together, these results indicate that the transfer of an anti-HIV-1 ribozyme gene into human T lymphocytes could have major impact on viral replication and T cell viability in the HIV-1-infected individual.     

Evaluation of human immunodeficiency virus type 1 (HIV-1)-specific cytotoxic T-lymphocyte responses utilizing B-lymphoblastoid cell lines transduced with the CD4 gene and infected with HIV-1

Analysis of major histocompatibility complex-restricted cytotoxic T lymphocytes (CTL) capable of killing human immunodeficiency virus type 1 (HIV-1)-infected targets is essential for elucidating the basis for HIV-1 disease progression and the potential efficacy of candidate vaccines. The use of primary CD4+ T cells with variable infectivity as targets for such studies has significant limitations, and immortal autologous cells with high levels of CD4 expression that can be consistently infected with HIV-1 would be of much greater utility. Therefore, we transduced Epstein-Barr-virus-transformed B-lymphoblastoid cell lines (LCL) with a retroviral vector, LT4SN, containing the human CD4 gene. Stable LCL in which more than 95% of cells expressed membrane CD4 were obtained. Aliquots were infected with HIV-1, and, after 4 to 7 days, nearly all of the cells contained cytoplasmic gag and produced high levels of p24 antigen. The ability of major histocompatibility complex-restricted CD8+ CTL to lyse such HIV-1-infected CD4-transduced LCL (LCL-CD4HIV-1) was evaluated. These autologous targets were lysed by CTL generated from an HIV-1-uninfected vaccinee over a broad range of effector-to-target ratios. Similarly, the LCL-CD4HIV-1 were efficiently lysed by fresh circulating CTL from HIV-1-infected individuals, as well as by CTL activated by in vitro stimulation. Both HIV-1 env- and gag-specific CTL effectors lysed LCL-CD4HIV-1, consistent with the cellular expression of both HIV-1 genes. The LCL-CD4HIV also functioned as stimulator cells, and thus are capable of amplifying CTL against multiple HIV-1 gene products in HIV-1-infected individuals. The ability to produce HIV-1-susceptible autologous immortalized cell lines that can be employed as target cells should enable a more detailed evaluation of vaccine-induced CTL against both homologous and disparate HIV-1 strains. Furthermore, the use of LCL-CD4HIV-1 should facilitate the analysis of the range of HIV-1 gene products recognized by CTL in seropositive persons.     

Testing cord blood human chorionic gonadotropin as a surrogate marker for early identification of human immunodeficiency virus-1 infection in children

We measured human chorionic gonadotropin (hCG) in cord sera of 22 infants born to women infected with the human immunodeficiency virus-1 (HIV-1). hCG was also determined in cord sera from 173 infants born at a suburban hospital to HIV-1-seronegative women. The findings indicate that 16 (9%) of 173 HIV-1-seronegative samples had hCG levels greater than 90 IU/L (values were distributed as a Poisson curve). In contrast, 8 (36%) of the 22 infants born to HIV-1-infected women had hCG levels in excess of 90 IU/L, and 7 (88%) of these were shown to be HIV-infected. The remaining 14 infants born to HIV-1-infected women had low hCG levels, and 3 (21%) of the 14 had HIV infection. Mean follow-up time for HIV-uninfected infants was 17.5 months (range 9 months to 3 years). A statistically significant association between maternal-fetal HIV-1 transmission and hCG levels > or = 90 IU/L in cord sera was observed (p = 0.02). The difference between CD4 counts among mothers who transmitted HIV and those who did not was also statistically significant (p = 0.025). On the basis of this study's findings, we propose that cord blood hCG may serve as a surrogate marker for HIV-1 infection. Testing hCG levels in cord sera is an inexpensive and readily available screening test for early identification of infants at increased risk for getting HIV-1 from their mothers.     

Chronic human immunodeficiency virus type 1 infection of myeloid cells disrupts the autoregulatory control of the NF-kappaB/Rel pathway via enhanced IkappaBalpha degradation

Productive human immunodeficiency virus type 1 (HIV-1) infection causes sustained NF-kappaB DNA-binding activity in chronically infected monocytic cells. A direct temporal correlation exists between HIV infection and the appearance of NF-kappaB DNA-binding activity in myelomonoblastic PLB-985 cells. To examine the molecular basis of constitutive NF-kappaB DNA-binding activity in HIV1 -infected cells, we analyzed the phosphorylation and turnover of IkappaBalpha protein, the activity of the double-stranded RNA-dependent protein kinase (PKR) and the intracellular levels of NF-kappaB subunits in the PLB-985 and U937 myeloid cell models. HIV-1 infection resulted in constitutive, low-level expression of type 1 interferon (IFN) at the mRNA level. Constitutive PKR activity was also detected in HIV-1-infected cells as a result of low-level IFN production, since the addition of anti-IFN-alpha/beta antibody to the cells decreased PKR expression. Furthermore, the analysis of IkappaBalpha turnover demonstrated an increased degradation of IkappaBalpha in HIV-1-infected cells that may account for the constitutive DNA binding activity. A dramatic increase in the intracellular levels of NF-kappaB subunits c-Rel and NF-kappaB2 p100 and a moderate increase in NF-kappaB2 p52 and RelA(p65) were detected in HIV-1-infected cells, whereas NF-kappaB1 p105/p50 levels were not altered relative to the levels in uninfected cells. We suggest that HIV-1 infection of myeloid cells induces IFN production and PKR activity, which in turn contribute to enhanced IkappaBalpha phosphorylation and subsequent degradation. Nuclear translocation of NF-kappaB subunits may ultimately increase the intracellular pool of NF-kappaB/IkappaBalpha by an autoregulatory mechanism. Enhanced turnover of IkappaBalpha and the accumulation of NF-kappaB/Rel proteins may contribute to the chronically activated state of HIV-1-infected cells.