Analysis of the adult thymus in reconstitution of T lymphocytes in HIV-1 infection.
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A key question in understanding the status of the immune system in HIV-1 infection is whether the adult thymus contributes to reconstitution of peripheral T lymphocytes. We analyzed the thymus in adult patients who died of HIV-1 infection. In addition, we studied the clinical course of HIV-1 infection in three patients thymectomized for myasthenia gravis and determined the effect of antiretroviral therapy on CD4(+) T cells. We found that five of seven patients had thymus tissue at autopsy and that all thymuses identified had inflammatory infiltrates surrounding lymphodepleted thymic epithelium. Two of seven patients also had areas of thymopoiesis; one of these patients had peripheral blood CD4(+) T-cell levels of <50/mm3 for 51 months prior to death. Of three thymectomized patients, one rapidly progressed to AIDS, one progressed to AIDS over seven years (normal progressor), whereas the third remains asymptomatic at least seven years after seroconversion. Both latter patients had rises in peripheral blood CD4(+) T cells after antiretroviral therapy. Most patients who died of complications of HIV-1 infection did not have functional thymus tissue, and when present, thymopoiesis did not prevent prolonged lymphopenia. Thymectomy before HIV-1 infection did not preclude either peripheral CD4(+) T-cell rises or clinical responses after antiretroviral therapy. (+info)
Structural basis for the specificity of the initiation of HIV-1 reverse transcription.
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Initiation of human immunodeficiency virus type 1 (HIV-1) reverse transcription requires specific recognition of the viral genome, tRNA3Lys, which acts as primer, and reverse transcriptase (RT). The specificity of this ternary complex is mediated by intricate interactions between HIV-1 RNA and tRNA3Lys, but remains poorly understood at the three-dimensional level. We used chemical probing to gain insight into the three-dimensional structure of the viral RNA-tRNA3Lys complex, and enzymatic footprinting to delineate regions interacting with RT. These and previous experimental data were used to derive a three-dimensional model of the initiation complex. The viral RNA and tRNA3Lys form a compact structure in which the two RNAs fold into distinct structural domains. The extended interactions between these molecules are not directly recognized by RT. Rather, they favor RT binding by preventing steric clashes between the nucleic acids and the polymerase and inducing a viral RNA-tRNA3Lys conformation which fits perfectly into the nucleic acid binding cleft of RT. Recognition of the 3' end of tRNA3Lys and of the first template nucleotides by RT is favored by a kink in the template strand promoted by the short junctions present in the previously established secondary structure. (+info)
High level inhibition of HIV replication with combination RNA decoys expressed from an HIV-Tat inducible vector.
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Intracellular immunization, an antiviral gene therapy approach based on the introduction of DNA into cells to stably express molecules for the inhibition of viral gene expression and replication, has been suggested for inhibition of HIV infection. Since the Tat and Rev proteins play a critical role in HIV regulation, RNA decoys and ribozymes of these sequences have potential as therapeutic molecular inhibitors. In the present study, we have generated several anti-HIV molecules; a tat-ribozyme, RRE, RWZ6 and TAR decoys and combinations of decoys, and tested them for inhibition of HIV-1 replication in vitro. We used T cell specific CD2 gene elements and regulatory the HIV inducible promoter to direct high level expression and a 3' UTR sequence for mRNA stabilization. We show that HIV replication was most strongly inhibited with the combination TAR + RRE decoy when compared with the single decoys or the tat-ribozyme. We also show that the Tat-inducible HIV promoter directs a higher level of steady-state transcription of decoys and inhibitors and that higher levels of expression directly relate to increased levels of inhibition of HIV infection. Furthermore, a stabilization of the 3' end of TAR + RRE inhibitor transcripts using a beta-globin 3' UTR sequence leads to an additional 15-fold increase in steady-state RNA levels. This cassette when used to express the best combination decoy inhibitor TAR + RRE, yields high level HIV inhibition for greater than 3 weeks. Taken together, both optimization for high level expression of molecular inhibitors and use of combinations of inhibitors suggest better therapeutic application in limiting the spread of HIV. (+info)
Pregnancy, body weight and human immunodeficiency virus infection in African women: a prospective cohort study in Kigali (Rwanda), 1992-1994. Pregnancy and HIV Study Group (EGE).
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OBJECTIVE: To study the relationship between human immunodeficiency virus (HIV) infection and body weight in African women during and after pregnancy. METHODS: A prospective cohort study was initiated at the Centre Hospitalier de Kigali in July 1992. Every woman seen at the antenatal clinic and with a gestational age of <28 weeks was offered HIV-1 antibody testing. Comparable numbers of HIV-infected (HIV+) and uninfected (HIV-) women were recruited. At inclusion, socio-demographic characteristics and self-reported pre-pregnancy weight were recorded; height and weight were measured. Each woman enrolled had a monthly follow-up until 9 months after delivery, with a clinical examination including weighing. Three anthropometric indices were used to answer the study objectives: weight, body mass index (BMI), and pregnancy balance. RESULTS: As of April 1994, 101 HIV+ and 106 HIV- women were followed until 5 months after delivery. Weight and BMI during pregnancy were lower in HIV+ women than in HIV- women. After delivery, weight and BMI gains were significantly lower in HIV+ women. Until 5 months after delivery, the mean weight variation was -2.2 kg (standard deviation [SD] = 5.9 kg) in HIV+ women and +0.2 kg (SD = 6.6 kg) in HIV- women (P = 0.007) in comparison to pre-pregnancy weight. Comparisons of the slopes of the weight curves did not show statistical differences throughout the pregnancy, but it did during the post-partum period (P = 0.02). CONCLUSIONS: Our study suggests that HIV infection could impair nutritional status in pregnant women, especially during the post-partum period. Family planning and maternal and child health services including HIV testing and counselling, should consider a nutritional assessment and intervention programme targeted to HIV+ pregnant women. (+info)
Dysregulated production of interleukin-8 in individuals infected with human immunodeficiency virus type 1 and Mycobacterium tuberculosis.
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Interleukin-8 (IL-8) production in vivo was monitored in four study groups: normal blood donors, patients with pulmonary tuberculosis (TB), patients with human immunodeficiency virus type 1 (HIV-1) infection, and dually infected (HIV/TB) patients. We show that whereas there was evidence of detectable levels of cell-associated IL-8 (mRNA and protein) in peripheral cells of healthy individuals, this was largely lost in the disease states studied. Coupled with this finding was significantly increased circulating levels of IL-8 in HIV-1-infected individuals with or without concomitant pulmonary TB (P < 0.001). On the other hand, the capacity of peripheral mononuclear cells to produce IL-8 spontaneously ex vivo was enhanced in HIV-1 and TB patients (P < 0.05) and many of the HIV/TB group, but their corresponding capacities to respond to various stimuli, in particular phytohemagglutinin, were significantly diminished compared to those of normal donors (P < 0.05). Circulating levels of IL-8 in a group of HIV/TB patients were significantly positively correlated with the percentage of polymorphonuclear leukocytes (PMN) in the peripheral circulation (r = 0.65; P = 0.01), the proportions of IL-8 receptor A (IL-8RA)-expressing (r = 0.86; P < 0.01) and IL-8RB-expressing (r = 0.77; P < 0.01) PMN, and the capacity of PMN to migrate in response to IL-8 as chemoattractant (r = 0.68; P < 0. 01). IL-8RB fluorescence intensity, however, was negatively correlated with plasma IL-8 levels (r = -0.73; P < 0.01). Our results suggest that altered regulation of IL-8 in HIV-1 may have important implications for antimicrobial defenses and for normal immune processes. (+info)
Biophysical characterization of the structure of the amino-terminal region of gp41 of HIV-1. Implications on viral fusion mechanism.
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A peptide of 51 amino acids corresponding to the NH2-terminal region (5-55) of the glycoprotein gp41 of human immunodeficiency virus type 1 was synthesized to study its conformation and assembly. Nuclear magnetic resonance experiments indicated the sequence NH2-terminal to the leucine zipper-like domain of gp41 was induced into helix in the micellar solution, in agreement with circular dichroism data. Light scattering experiment showed that the peptide molecules self-assembled in water into trimeric structure on average. That the peptide molecules oligomerize in aqueous solution was supported by gel filtration and diffusion coefficient experiments. Molecular dynamics simulation based on the NMR data revealed a flexible region adjacent to the hydrophobic NH2 terminus of gp41. The biological significance of the present findings on the conformational flexibility and the propensity of oligomerization of the peptide may be envisioned by a proposed model for the interaction of gp41 with membranes during fusion process. (+info)
Maturation-induced conformational changes of HIV-1 capsid protein and identification of two high affinity sites for cyclophilins in the C-terminal domain.
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Viral incorporation of cyclophilin A (CyPA) during the assembly of human immunodeficiency virus type-1 (HIV-1) is crucial for efficient viral replication. CyPA binds to the previously identified Gly-Pro90 site of the capsid protein p24, but its role remained unclear. Here we report two new interaction sites between cyclophilins and p24. Both are located in the C-terminal domain of p24 around Gly-Pro157 and Gly-Pro224. Peptides corresponding to these regions showed higher affinities (Kd approximately 0.3 microM) for both CyPA and cyclophilin B than the best peptide derived from the Gly-Pro90 site ( approximately 8 microM) and thus revealed new sequence motifs flanking Gly-Pro that are important for tight interaction of peptide ligands with cyclophilins. Between CyPA and an immature (unprocessed) form of p24, a Kd of approximately 8 microM was measured, which corresponded with the Kd of the best of the Gly-Pro90 peptides, indicating an association via this site. Processing of immature p24 by the viral protease, yielding mature p24, elicited a conformational change in its C-terminal domain that was signaled by the covalently attached fluorescence label acrylodan. Consequently, CyPA and cyclophilin B bound with much higher affinities ( approximately 0.6 and 0.25 microM) to the new, i.e. maturation-generated sites. Since this domain is essential for p24 oligomerization and capsid cone formation, CyPA bound to the new sites might impair the regularity of the capsid cone and thus facilitate in vivo core disassembly after host infection. (+info)
HIV-associated nephropathy is a late, not early, manifestation of HIV-1 infection.
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BACKGROUND: Human immunodeficiency virus-associated nephropathy (HIVAN) can be the initial presentation of HIV-1 infection. As a result, many have assumed that HIVAN can occur at any point in the infection. This issue has important implications for appropriate therapy and, perhaps, for pathogenesis. Since the development of new case definitions for acquired immunodeficiency syndrome (AIDS) and better tools to assess infection, the relationship of HIVAN to the time of AIDS infection has not been addressed. In this study, we reassessed the stage of infection at the time of HIVAN diagnosis in 10 patients, and we reviewed all previously published cases applying the new case definitions to assess stage of infection. METHODS: HIVAN was confirmed by kidney biopsy in HIV seropositive patients with azotemia and/or proteinuria. CD4+ cell count and plasma HIV-1 RNA copy number were measured. We also reviewed all published cases of HIVAN to determine if AIDS-defining conditions, by current Centers for Disease Control definitions, were present in patients with biopsy-proven HIVAN. RESULTS: Twenty HIV-1 seropositive patients with proteinuria and an elevated creatinine concentration were biopsied. HIVAN was the single most common cause of renal disease. CD4+ cell count was below 200/mm3 in all patients with HIVAN, fulfilling Centers for Disease Control criteria for an AIDS-defining condition. HIV-1 plasma RNA was detectable in all patients with HIVAN. In reviewing previous reports, an AIDS-defining condition was present in virtually all patients with HIVAN. CONCLUSION: HIVAN develops late, not early, in the course of HIV-1 infection following the development of AIDS. This likely accounts for the poor prognosis noted in previous publications and has implications for pathogenesis. In addition, given the detectable viral RNA levels, highly active antiretroviral therapy is indicated in HIVAN. Highly active antiretroviral therapy may improve survival as well as alter the natural history of HIVAN. (+info)