Coreceptor usage of human immunodeficiency virus type 2 primary isolates and biological clones is broad and does not correlate with their syncytium-inducing capacities

Entry of human immunodeficiency virus type 1 (HIV-1) into target cells is mediated by binding of the surface envelope glycoprotein to the CD4 molecule. Interaction of the resulting CD4-glycoprotein complex with alpha- or beta-chemokine receptors, depending on the biological phenotype of the virus, then initiates the fusion process. Here, we show that primary HIV-2 isolates and biological clones, in contrast to those of HIV-1, may use a broad range of coreceptors, including CCR-1, CCR-3, CCR-5, and CXCR-4. The syncytium-inducing capacity of these viruses did not correlate with the ability to infect via CXCR-4 or any other coreceptor. One cell-free passage of the intermediate isolates in mitogen-stimulated, CD8+ cell-depleted peripheral blood mononuclear cells resulted in the outgrowth of variants with CCR-5 only, whereas the coreceptor usage of late and early isolates did not change. Since HIV-2 is less pathogenic in vivo than HIV-1, these data suggest that HIV pathogenicity in vivo is not directly related to the spectrum of coreceptors used in in vitro systems.     

Dynamics of viral replication in infants with vertically acquired human immunodeficiency virus type 1 infection

About one-third of vertically HIV-1 infected infants develop AIDS within the first months of life; the remainder show slower disease progression. We investigated the relationship between the pattern of HIV-1 replication early in life and disease outcome in eleven infected infants sequentially studied from birth. Viral load in cells and plasma was measured by highly sensitive competitive PCR-based methods. Although all infants showed an increase in the indices of viral replication within their first weeks of life, three distinct patterns emerged: (a) a rapid increase in plasma viral RNA and cell-associated proviral DNA during the first 4-6 wk, reaching high steady state levels (> 1,000 HIV-1 copies/10(5) PBMC and > 1,000,000 RNA copies/ml plasma) within 2-3 mo of age; (b) a similar initial rapid increase in viral load, followed by a 2.5-50-fold decline in viral levels; (c) a significantly lower (> 10-fold) viral increase during the first 4-6 wk of age. All infants displaying the first pattern developed early AIDS, while infants with slower clinical progression exhibited the second or third pattern. These findings demonstrate that the pattern of viral replication and clearance in the first 2-3 mo of life is strictly correlated with, and predictive of disease evolution in vertically infected infants.     

Inhibition of plating of human T cell leukemia virus type I and syncytium-inducing types of human immunodeficiency virus type 1 by polycations

We examined the effects of polycations, namely, diethylaminoethyl-dextran (DEAE-dextran) and hexadimethrine bromide (Polybrene), on infection with the retroviruses human T cell leukemia virus types I and II (HTLV-I and HTLV-II) and human immunodeficiency virus type 1 (HIV-1). The plating of vesicular stomatitis virus (VSV) pseudotype bearing envelope antigens of HTLV-I [VSV(HTLV-I)] was inhibited about 2- and 10-fold by treatment with DEAE-dextran and Polybrene, respectively. The formation of HTLV-I viral DNA detected 1 day after infection was also inhibited by these polycations. In contrast, polycations enhanced the plating of the VSV (HTLV-II) pseudotype two- to threefold. The polycations did not affect the plating efficiency of HTLV-I or HTLV-II when added after virus adsorption. Infection of human T cell lines, peripheral blood lymphocytes (PBLs), or brain-derived cells with syncytium-inducing (SI) types of HIV-1 strains (GUN1 and IIIB) was inhibited 3- to 20-fold by polycations. However, infection of PBLs or monocyte-derived macrophages with the macrophage-tropic Ba-L or SF162 strain was enhanced 1.5- to twofold by polycations. On the other hand, syncytium formation in coculture induced by HTLV-I, HTLV-II, or HIV-1 was enhanced two- to threefold unanimously by DEAE-dextran or Polybrene. Although polycations have been used to potentiate human retrovirus adsorption, they inhibited infection of cell-free HTLV-I or SI-type HIV-1 strains.     

Function of human immunodeficiency virus type 1 nef gene product in virus replication

We comparatively analyzed the replication kinetics of wild-type (wt) and nef mutant human immunodeficiency virus type 1 (HIV-1) in several CD4-positive cell lines, in order to clarify the molecular function of Nef protein. The delayed growth of nef mutant virus was observed at the initial stage of replication in all cell lines examined. This phenomenon was greatly amplified in the absence of vpu gene. In order to determine the infection stage in viral replication cycle which is specifically affected on virus replication rate in the presence of the Nef protein, we first examined the difference between wt and nef mutant viruses in the virus production rate from transfected cells, and found that the both viruses were produced with equal efficiency. This result showed that Nef protein could be dispensable for virion production. Therefore, early infection stages were focused by single-round infection assay, and the nef mutant virus was found to be much less infectious than wt virus. This indicated that the effect of Nef protein was exhibited in the early phase of a virus replication cycle, during viral adsorption to integration. By entry assay using wt and nef mutant virions, it was revealed that the Nef protein was required for efficient viral entry. These data suggest that the Nef protein might play a role in efficient incorporation of the Env protein into the virions, leading to enhanced viral infectivity.     

Neuronal apoptosis in the course of human immunodeficiency virus infection

Apart from the unique changes characteristic of "HIV encephalitis", the productive infection of central nervous system by HIV, which involves predominantly the white matter and basal ganglia, evidence is accumulating that the cerebral cortex may also be affected in AIDS patients. Neuronal loss, suspected at microscopical examination, has been demonstrated by a number of morphometric studies. However, the cause and mechanism of neuronal damage in HIV infection, are still unclear. In an attempt to look for an apoptotic process at the origin of neuronal loss in AIDS, we examined samples of frontal cortex, temporal cortex and basal ganglia from 12 patients who died from AIDS and 4 HIV-positive asymptomatic cases using in situ end labelling to demonstrate characteristic DNA fragmentation. These were compared with 5 seronegative asymptomatic controls, and 2 seronegative patients with Alzheimer's disease. We demonstrated neuronal apoptosis in all the AIDS cases and in the Alzheimer's cases. Positive in situ end labelling was usually associated with morphological changes suggestive of neuronal apoptosis. Semiquantitative appreciation of the density of apoptotic neurons showed that neuronal apoptosis was more severe in atrophic brains. In contrast, no correlation was found between the density of apoptotic neurons and the presence of HIV encephalitis or a history of cognitive disorder. Only occasional apoptotic neurons were found in one asymptomatic, HIV-positive case. Apoptosis was never observed in asymptomatic seronegative cases. Experimental studies tend to support our in vivo findings. Infection by HIV of primary cultures of human embryonic central nervous system induced frequent apoptosis of neurons. No apoptotic cell was identified in non infected control cultures.     

Inhibition of human immunodeficiency virus type 1 replication by a Tat-activated, transduced interferon gene: targeted expression to human immunodeficiency virus type 1-infected cells

We have examined the feasibility of using interferon (IFN) gene transfer as a novel approach to anti-human immunodeficiency virus type 1 (HIV-1) therapy in this study. To limit expression of a transduced HIV-1 long terminal repeat (LTR)-IFNA2 (the new approved nomenclature for IFN genes is used throughout this article) hybrid gene to the HIV-1-infected cells, HIV-1 LTR was modified. Deletion of the NF-kappa B elements of the HIV-1 LTR significantly inhibited Tat-mediated transactivation in T-cell lines, as well as in a monocyte line, U937. Replacement of the NF-kappa B elements in the HIV-1 LTR by a DNA fragment derived from the 5'-flanking region of IFN-stimulated gene 15 (ISG15), containing the IFN-stimulated response element, partially restored Tat-mediated activation of LTR in T cells as well as in monocytes. Insertion of this chimeric promoter (ISG15 LTR) upstream of the human IFNA2 gene directed high levels of IFN synthesis in Tat-expressing cells, while this promoter was not responsive to tumor necrosis factor alpha-mediated activation. ISG15-LTR-IFN hybrid gene inserted into the retrovirus vector was transduced into Jurkat and U937 cells. Selected transfected clones produced low levels of IFN A (IFNA) constitutively, and their abilities to express interleukin-2 and interleukin-2 receptor upon stimulation with phytohemagglutinin and phorbol myristate acetate were retained. Enhancement of IFNA synthesis observed upon HIV-1 infection resulted in significant inhibition of HIV-1 replication for a period of at least 30 days. Virus isolated from IFNA-producing cells was able to replicate in the U937 cells but did not replicate efficiently in U937 cells transduced with the IFNA gene. These results suggest that targeting IFN synthesis to HIV-1-infected cells is an attainable goal and that autocrine IFN synthesis results in a long-lasting and permanent suppression of HIV-1 replication.     

Clinical course of human immunodeficiency virus type 1 associated pulmonary tuberculosis during short-course antituberculosis therapy

PURPOSE: It was reported that Matrigel improved hatching of mouse blastocysts produced in vitro from F1 hybrid-derived zygotes. We investigated whether Matrigel would be similarly beneficial with outbred strain-derived embryos, which exhibit a "two-cell" block similar to the developmental blocks of other species. METHODS: Mouse embryo development was assessed with or without Matrigel in KSOM medium, which supports the development of blocking strain zygotes in vitro, and in human tubal fluid (HTF) medium, which normally does not but which is used for human IVF. RESULTS: Matrigel severely inhibited the development of zygotes to blastocysts in KSOM and did not improve culture in HTF. There was no effect on development from the two-cell stage. We were not able to replicate the previous finding of Matrigel's beneficial effect on hatching of F1-derived zygotes. CONCLUSIONS: Matrigel may be a deleterious addition to embryo culture or coculture systems.     

Increased mortality associated with vitamin A deficiency during human immunodeficiency virus type 1 infection

OBJECTIVE: To determine whether plasma vitamin A levels are associated with immunologic status and clinical outcome during human immunodeficiency virus type 1 (HIV-1) infection. PATIENTS AND METHODS: Analysis of vitamin A levels, CD4 T cells, complete blood cell count, and serologic markers for liver disease in a random subsample of 179 subjects from a cohort of more than 2000 intravenous drug users with longitudinal follow-up to determine survival. RESULTS: Mean (+/- SE) follow-up time was 22.8 +/- 1.1 months, and 15 subjects died during follow-up. More than 15% of the HIV-1-seropositive individuals had plasma vitamin A levels less than 1.05 mumol/L, a level consistent with vitamin A deficiency. The HIV-1-seropositive individuals had lower mean plasma vitamin A levels than HIV-1-seronegative individuals (P < .001). Vitamin A deficiency was associated with lower CD4 levels among both seronegative individuals (P < .05) and seropositive individuals (P < .05). In the HIV-seropositive participants, vitamin A deficiency was associated with increased mortality (relative risk = 6.3; 95% confidence interval, 2.1 to 18.6). CONCLUSION: Vitamin A deficiency may be common during HIV-1 infection, and vitamin A deficiency is associated with decreased circulating CD4 T cells and increased mortality. Vitamin A is an essential micronutrient for normal immune function, and vitamin A deficiency seems to be an important risk factor for disease progression during HIV-1 infection.     

Long-latency event-related potentials in asymptomatic human immunodeficiency virus type 1 infection

An ideal technique for following the development of the vertebrate nervous system would allow cells to be followed at the resolution of light microscopy at depths of several millimeters into the tissue. This would permit critical events to be followed at cellular or sub-cellular resolution even deep within the developing organism. To date, no technique has emerged with all of the needed properties. Light microscopy can follow a cell and its descendants after they have been labeled by either the infection of embryonic cells with a recombinant retrovirus or the microinjection of individual precursor cells with enzymes or fluorescent dyes. However, light microscopy cannot image events deeper than a few hundred micrometers within an embryo due to light scattering and aberrations in the objective lenses and other optics. Magnetic resonance imaging (MRI) does not suffer from these limitations, routinely being used to image in 3 dimensions through specimens as large as adult humans. However, it is relatively slow and, as implemented to date, it cannot routinely achieve cellular resolution. Here, we present our attempts to meet the technical challenges posed by in vivo MRI microscopy. As an example of both the progress and the future challenges, we present images of cells within the developing frog embryo over a several day time course.     

Adaptive evolution of human immunodeficiency virus-type 1 during the natural course of infection

The rate of progression to disease varies considerably among individuals infected with human immunodeficiency virus-type 1 (HIV-1). Analyses of semiannual blood samples obtained from six infected men showed that a rapid rate of CD4 T cell loss was associated with relative evolutionary stasis of the HIV-1 quasispecies virus population. More moderate rates of CD4 T cell loss correlated with genetic evolution within three of four subjects. Consistent with selection by the immune constraints of these subjects, amino acid changes were apparent within the appropriate epitopes of human leukocyte antigen class I-restricted cytotoxic T lymphocytes. Thus, the evolutionary dynamics exhibited by the HIV-1 quasispecies virus populations under natural selection are compatible with adaptive evolution.     

Importance of ribosomal frameshifting for human immunodeficiency virus type 1 particle assembly and replication

The recent development and use of protease inhibitors have demonstrated the essential role that combination therapy will play in the treatment of individuals infected with the human immunodeficiency virus type 1 (HIV-1). Past clinical experience suggests that due to the appearance of resistant HIV-1 variants, additional therapeutics will be required in the future. To identify new options for combination therapy, it is of paramount importance to pursue novel targets for drug development. Ribosomal frameshifting is one potential target that has not been fully explored. Data presented here demonstrate that small molecules can stimulate frameshifting, leading to an imbalance in the ratio of Gag to Gag-Pol and inhibiting HIV-1 replication at what appears to be the point of viral particle assembly. Thus, we propose that frameshifting represents a new target for the identification of novel anti-HIV-1 therapeutics.     

Primary infection by type 1 human immunodeficiency virus: diagnosis and prognosis

Primary infection by type 1 human immunodeficiency virus (HIV) is symptomatic in about 70% of cases. The acute illness is a mononucleosis-like syndrome with characteristics such as mucosal ulcerations. The duration and severity of the symptoms appear to be related to the prognosis. After reviewing the most frequent signs and symptoms of primary HIV infection, we report different prognostic studies which examined the association between the acute illness and the progression of HIV disease.     

Macrophages and CD4+ T lymphocytes from two multiply exposed, uninfected individuals resist infection with primary non-syncytium-inducing isolates of human immunodeficiency virus type 1

Despite multiple, high-risk sexual exposures, some individuals remain uninfected with human immunodeficiency virus type 1 (HIV-1). CD4+ lymphocytes from these individuals are less susceptible to infection in vitro with some strains of HIV-1, suggesting that the phenotype of the virus may influence its ability to interact with certain CD4+ cells. In the present study, we examined the susceptibility of CD4+ T lymphocytes and macrophages from two exposed uninfected individuals (EU2 and EU3) to infection with a panel of biologically cloned isolates of HIV-1 having either a non-syncytium-inducing (NSI) or a syncytium-inducing (SI) phenotype. Our results indicate that CD4+ T lymphocytes from EU2 and EU3 are resistant to infection with NSI isolates of HIV-1 but are susceptible to infection with primary SI isolates. In addition, we found that macrophages from EU2 and EU3 are resistant to infection with both NSI and SI isolates. The latter finding was confirmed by using several uncloned NSI and SI isolates obtained from patients during acute HIV-1 infection. In further experiments, env clones encoding glycoproteins characteristic of NSI or SI viruses were used in single-cycle infectivity assays to evaluate infection of CD4+ lymphocytes and macrophages from EU2 and EU3. Consistent with our previous results, we found that macrophages from these individuals are resistant to infection with NSI and SI env-pseudotyped viruses, while CD4+ T lymphocytes are resistant to NSI, but not SI, pseudotyped viruses. Overall, our results demonstrate that CD4+ cells from two exposed uninfected individuals resist infection in vitro with primary, macrophage-tropic, NSI isolates of HIV-1, which is the predominant viral phenotype found following HIV-1 transmission. Furthermore, infection with NSI isolates was blocked in both CD4+ T lymphocytes and macrophages from these individuals, suggesting that there may be a common mechanism for resistance in both cell types.     

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.     

Slower evolution of human immunodeficiency virus type 1 quasispecies during progression to AIDS

The evolution of human immunodeficiency virus type 1 (HIV-1) quasispecies at the envelope gene was studied from the time of infection in 11 men who experienced different rates of CD4+ cell count decline and 6 men with unknown dates of infection by using DNA heteroduplex mobility assays. Quasispecies were genetically homogeneous near the time of seroconversion. Subsequently, slower proviral genetic diversification and higher plasma viremia correlated with rapid CD4+ cell count decline. Except for the fastest progressors to AIDS, highly diverse quasispecies developed in all subjects within 3 to 4 years. High quasispecies diversity was then maintained for years until again becoming more homogeneous in a subset of late-stage AIDS patients. Individuals who maintained high CD4+ cell counts showed continuous genetic turnover of their complex proviral quasispecies, while more closely related sets of variants were found in longitudinal samples of severely immunocompromised patients. The limited number of variants that grew out in short-term PBMC cocultures were rare in the uncultured proviral quasispecies of healthy, long-term infected individuals but more common in vivo in patients with low CD4+ cell counts. The slower evolution of HIV-1 observed during rapid progression to AIDS and in advanced patients may reflect ineffective host-mediated selection pressures on replicating quasispecies.     

Parvovirus B19 quiescence during the course of human immunodeficiency virus infection in persons with hemophilia

One hundred and seventy patients with major lower limb amputation (MLLA) presenting to The National Prosthetic-Orthotic Centre (NPOC) in Khartoum over a 1-year period were studied. There were 141 males and 29 females giving a M:F ratio of 4.9: 1.0, with mean age of 37 years (range 5-72 years). Forty-one patients (24%) underwent amputation of diabetic septic foot, 30 patients (17.6%) underwent amputation as a result of trauma from road traffic accidents and Madura foot, and war injuries accounted for 29 amputations (17%). One hundred and eleven patients had below knee amputation (BKA), 52 had above knee amputation (AKA) and seven patients had Syme's amputation. Diabetic amputees had higher rate of revisional surgery compared with others because of sepsis and/or flap necrosis. Stump pain was reported by amputees with excessive scarring of the stump and those with undue prominence of bony ends. There are two types of prostheses provided by the NPOC for both BKA and AKA: the peg leg and the conventional prostheses. The Syme's amputees were fitted with either simple hoof or articulated prostheses with solid ankle cushion heel (SACH). The peg leg consists of a leather lined side bearing metal socket connected to a rocker base by side steels. It is used by the country natives as it suits different weather and job conditions, particularly farming, and it can be repaired locally. The urban population use the conventional prostheses which is lighter in weight, can be put on and taken off easily and is cosmetically acceptable. However, these prostheses are more expensive and require frequent repair or replacement. The functional outcome of patient's rehabilitation with the prostheses was significantly affected by the level and indication of amputation. Those with BKA and those amputated because of trauma or Madura foot experienced better functional outcome compared with the diabetics, independent of age. 50% of patients with the AKA and 19% of those with BKA reported poor functional outcome. Surgeons should be more involved with the long-term evaluation of functional outcome in such patients, to offer help if feasible and to modify their technique for future procedures.