Isolation of HTLV-III from cerebrospinal fluid and neural tissues of patients with neurologic syndromes related to the acquired immunodeficiency syndrome

Oral lesions of iatrogenic and undefined etiology and neurologic disorders associated with HIV infection

A review of a miscellaneous group of oral mucosal disorders in the setting of infection with the human immunodeficiency virus is presented. Included is a discussion of oral lesions of iatrogenic and undefined etiology and neurologic disorders. Mechanisms of pathogenesis, including possible common pathways and relationships to underlying immunosuppression, are emphasized.

Human immunodeficiency virus type 1 envelope gene structure and diversity in vivo and after cocultivation in vitro

Nested-primer polymerase chain reaction (PCR) has been applied to the molecular cloning of 4.6-kb half-genome fragments of human immunodeficiency virus type 1 (HIV-1) taken directly from the peripheral blood mononuclear cells (PBMC) of an individual with neurological symptoms of HIV-1 infection. In a similar manner, gp120-coding portions of the envelope gene were cloned after PBMC from the same blood sample were cocultivated with uninfected PBMC for 28 days. The complete 1.6-kb nucleotide sequence of the gp120 gene was determined from each of 35 clones examined. Two of 13 (15%) PBMC-derived gp120 genes and 3 of 22 (14%) coculture-derived gp120 genes were defective as a result of frameshifts and an in-frame stop codon(s). Mean diversity between individual gp120-coding sequences in PBMC was fivefold greater (3.24%) than after coculture (0.65%). A predominant sequence of "strain" was found after coculture that was distinct from the diverse viral genotypes detected in vivo and therefore was selectively amplified during in vitro propagation. Multiple distinct third variable (V3) regions encoding the principal neutralizing domain of the envelope protein were detected in PBMC-derived genes, suggesting the presence of immunologic diversity of HIV env genes in vivo not reflected in the cocultured virus sample. The large size of the HIV fragments generated in this study will permit analysis of the diversity of immunologic reactivity, gene function, and pathogenicity of HIV genomes present within infected individuals, including the functional significance of the loss of diversity that occurs upon coculture.

Meningoencephalitis in a neonate congenitally infected with human immunodeficiency virus type 1

A newborn infant born to a mother infected with human immunodeficiency virus type 1 had acute meningoencephalitis on the second day of life. Human immunodeficiency virus type 1 was isolated from the plasma, cerebrospinal fluid, and peripheral blood mononuclear cells. Specific IgM for human immunodeficiency virus type 1 was detected by an enzyme-linked immunosorbent assay antibody-capture technique in cord blood and in serum obtained 3 weeks later. We believe that the meningoencephalitis was caused by human immunodeficiency virus type 1 acquired in utero.

Use of immunoreactive synthetic HTLV-1 peptides in the search for antibody reactivity in multiple sclerosis

The possible association between multiple sclerosis (MS) and antibodies to human T-cell lymphotropic virus type 1 (HTLV-1) was studied. Five synthetic and highly immunoreactive HTLV-1 peptides, four from the envelope (env) region and one from the core (gag) region, were used in an indirect enzyme-linked immunosorbent assay (ELISA). Presence of HTLV-1-specific antibodies in paired serum and cerebrospinal fluid (CSF) samples from 41 MS patients were investigated. No antibody reactivity was demonstrable in samples from 40 of them, whereas one reacted in one serum sample against the gag-peptide. Serum and CSF specimens from 15 with other neurologic diseases (OND), and negative control specimens, i.e. serum and CSF from 9 non-neurologic controls and CSF from 9 healthy controls, did not demonstrate any reactivity in the peptide-ELISAs. Our results do not support involvement of HTLV-1 infection in the etiology of MS.

Mononuclear phagocytes as targets, tissue reservoirs, and immunoregulatory cells in human immunodeficiency virus disease

We have presented evidence in this review for the following: 1. Macrophages are likely the first cell infected by HIV. Studies document recovery of HIV into macrophages in the early stages of infection in which virus isolation in T cells is unsuccessful and detectable levels of antibodies against HIV are absent. 2. Macrophages are major tissue reservoirs for HIV during all stages of infection. Unlike the lytic infection of T cells, many HIV-infected macrophages show little or no virus-induced cytopathic effects. HIV-infected macrophages persist in tissue for extended periods of time (months) with large numbers of infectious particles contained within intracytoplasmic vacuoles. 3. Macrophages are a vector for the spread of infection to different tissues within the patient and between individuals. Several studies suggest a "Trojan horse" role for HIV-infected macrophages in dissemination of infectious particles. The predominant cell in most bodily fluids (alveolar fluid, colostrum, semen, vaginal secretions) is the macrophage. In semen, for example, the numbers of macrophages exceed those of lymphocytes by more than 20-fold (Wolf and Anderson 1988). 4. Macrophages are major regulatory cells that control the pace and intensity of disease progression in HIV infection. Macrophage secretory products are implicated in the pathogenesis of CNS disease and in control of viral latency in HIV-infected T cells. This litany of events in which macrophages participate in HIV infection in man parallels similar observations in such animal lentivirus infections as visna-maedi or caprine arthritis-encephalitis viruses. HIV interacts with monocytes differently than with T cells. Understanding this interaction may more clearly define both the pathogenesis of HIV disease and strategies for therapeutic intervention.

CT and MRI: prognostic tools in patients with AIDS and neurological deficits

To determine the prognostic value of CT and MRI in AIDS we studied the survival of patients with neurological involvement, in relation to the initial imaging results. Twenty-six initial CT and 15 MRI examinations of 41 patients were reviewed for the presence of cerebral atrophy and/or focal lesions. The mean survival time of patients with initially normal imaging was longer (700 +/- 89 days) than that of patients with isolated cerebral atrophy (326 +/- 65) or isolated focal lesions (202 +/- 97). The shortest survival (78 +/- 44 days) was found in patients with both cerebral atrophy and focal lesions. The risk of death in patients with atrophy alone was 3.6 times higher, that in patients with focal lesions alone 6.4 times higher, and in patients with both changes 19.3 times higher than in patients with initially normal imaging. Cerebral imaging with CT and/or MRI thus allows identification of AIDS-related cerebral changes and may contribute to assessment of prognosis.

Increased occurrence of free immunoglobulin light chains in cerebrospinal fluid and serum in human immunodeficiency virus-1 infection

The presence of free immunoglobulin light chains (FLCs) in the cerebrospinal fluid (CSF) and sera of patients with human immunodeficiency virus-1 (HIV-1) infection, multiple sclerosis (MS), and neurologically healthy control individuals was investigated by paying special attention to ensure that only truly free light chains would be detected. The FLCs were extracted by specifically binding them to Sepharose-coupled anti-FLC monoclonal antibodies, and thereafter they were electrophoresed and immunoblotted with monoclonal antibodies to both light chain (LC) isotypes. A frequent occurrence of kappa and lambda FLCs was found in both CSF and sera of HIV-1 infected patients. In HIV-1 infection and in MS, the frequency of FLCs of the CSF was equal. In healthy controls, only occasional weak FLCs were observed in either CSF or serum. FLC bands of the CSF from patients with HIV-1 infection tended to be more intensive than those of the appropriately diluted sera. Both intrathecal synthesis of FLCs and their transudation from sera through the impaired blood-brain barrier (BBB) may contribute to this. Increasing severity of general HIV-1 infection was accompanied by an increase of FLC intensity in sera. A qualitative demonstration of FLC in the CSF may be meaningful only in the absence of altered BBB function.

Identification of human immunodeficiency virus envelope gene sequences influencing viral entry into CD4-positive HeLa cells, T-leukemia cells, and macrophages

Infectious recombinant viruses were constructed from three molecularly cloned human immunodeficiency virus (HIV) strains varying in cell tropism. All recombinants showed a high infectivity titer on phytohemagglutinin-stimulated normal T lymphocytes. However, a 120-bp region of the envelope gene including the area of the V3 hypervariable loop was found to influence infectivity titer on both clone 1022 CD4-positive HeLa cells and CD4-positive CEM leukemia cells. Infectivity for macrophages was more complex. All viruses replicated in macrophages to a low level, but viral sequences both inside and outside the V3 loop region influenced the efficiency of replication. Two experiments showed that the mechanism of restriction of infection of 1022 cells by HIV strain JR-CSF was related to lack of virus entry. First, productive virus infection occurred after transfection of 1022 cells with viral plasmid DNA. Second, the nonpermissive HIV strain JR-CSF could infect 1022 cells when pseudotyped with the envelope of other retroviruses, including human T-cell leukemia virus type I (HTLV-I), HTLV-II, and amphotropic murine leukemia virus. These results demonstrate the possibility that unexpected cell types might be infected with HIV in human patients coinfected with HIV and HTLV-I or HTLV-II.

Neurophysiological markers of central and peripheral involvement of the nervous system in HIV-infection

Peroneal motor and sural sensory conduction velocities (MNCVs/SNCVs), somatosensory evoked potentials to median nerve stimulation (MN-SEPs) and motor evoked potentials (MEPs) to transcranial stimulation were examined in 138 HIV-infected patients (in the different stages of the disease), 20 seronegative intravenous drug abusers (IVDAs), and 20 healthy subjects. Findings of peroneal MNCV slowing in patients ranged from 16% (asymptomatic HIV patients) to 63% (AIDS) and of sural SNCV slowing from 13% to 40%. Altered MN-SEPs ranged from 10% to 30%, and MEPs ranged from 44% to 72%, mostly due to a prolongation of the central motor conduction time (CMCT). All seronegative IVDAs showed patterns within the normal range. Electrophysiological techniques were helpful in demonstrating early and subclinical alterations in HIV patients.

Persistent inapparent HIV-1 infection of human neuroblastoma cells

We have studied human immunodeficiency virus type 1 (HIV-1) infection in three different human neuroblastoma cell lines; SK-N-MC, IMR-32 and SH-SY5Y. In all of these cell lines the infection became productive. However, the virus expression was different as determined by the p24 antigen capture assays from culture supernatants and immunochemical (APAAP) staining of cells. The medium of SK-N-MC cells contained approximately 300 pg p24 antigen per 10(6) cells, 0.1-1% of the cells were p24 antigen-positive and characteristic genomic and subgenomic HIV mRNA species were seen in Northern blotting. In infected IMR-32 and SH-SY5Y cell cultures, the HIV-1 production was below the level of detection. However, infectious virus was found by inoculating cultures of the lymphoid cell C8166 with the cell-free supernatant fluid from the neuroblastoma cultures. The lymphoid cells became positive within one week. Moreover, phytohemagglutinin-stimulated normal human lymphocytes produced virus, if cocultured with any of the three infected neuroblastoma cell lines. The infection was persistent and has been followed, using the above techniques, for 4 months in the case of SK-N-MC and IMR-32 cells and 6 months in the case of SH-SY5Y cells. During this period, no alterations in cell morphology, viability, or proliferative capacity were seen. All three neuroblastoma lines were negative for the CD4 receptor mRNA according to Northern hybridization and RNase protection assays. We conclude that HIV-1 produces persistent and inapparent infection in human neuroblastoma cells, using a CD 4-independent mechanism of entry to the cells.

Molecular characterization of human immunodeficiency virus type 1 cloned directly from uncultured human brain tissue: identification of replication-competent and -defective viral genomes

All presently available replication-competent proviral clones of human immunodeficiency virus type 1 (HIV-1) are derived from cell culture-amplified virus. Since tissue culture is highly selective for viral strains with an in vitro growth advantage, such clones may not be representative of the biologically relevant virus present in vivo. In this study, we report the molecular cloning and genotypic characterization of 10 HIV-1 genomes directly from uncultured brain tissue of a patient with AIDS dementia complex. Targeting unintegrated circular HIV-1 molecules for recombinant lambda phage cloning, we obtained four full-length genomes with one or two long terminal repeats (LTRs), three defective genomes with internal deletions, two rearranged genomes with inverted LTR sequences, and one integrated proviral half with flanking cellular sequences. Nucleotide sequence analysis of these clones demonstrated chromosomal integration, circle formation, genomic inversion, and LTR-mediated autointegration of HIV-1 genomes in vivo. Comparison of a 510-bp hypervariable envelope region among 8 lambda phage-derived and 12 polymerase chain reaction-derived clones from the same brain specimen identified a predominant viral form as well as genetically divergent variants. Variability among 19 of 20 clones ranged between 0.2 and 1.2%. One clone exhibited 8.2% nucleotide sequence differences consisting almost exclusively of G-to-A changes. Transfection of the four full-length HIV-1 genomes identified one clone (YU-2) as replication competent and exhibiting growth characteristics similar to those of tissue culture-derived macrophage tropic strains of HIV-1. These results demonstrate, for the first time, that replication-competent HIV-1 genomes, complex mixtures of defective viral forms, and chromosomally integrated provirus persist in vivo. In addition, the brain-derived viral clones are expected to prove valuable for future studies of macrophage and neurotropism as well as for the analysis of other viral properties that are subject to in vitro selection pressures.

Ocular motor abnormalities in human immunodeficiency virus infection

We studied ocular motor performance in 47 subjects with human immunodeficiency virus (HIV) infection and 25 normal control subjects. Saccade accuracy was the most sensitive measure, being significantly poorer for all four HIV-positive groups (asymptomatic, acquired immunodeficiency syndrome [AIDS] without dementia, and AIDS with dementia, and AIDS-related complex) than for control subjects. While saccade duration and peak velocity were not significantly different across groups, the scatter of saccade duration was increased in all HIV-positive groups. Saccade latency was not significantly affected. In both simple and complex antisaccade tasks, the asymptomatic, AIDS, and AIDS dementia groups made significantly fewer correct-way antisaccades than did control subjects. Latencies of correct-way antisaccades were increased for AIDS and AIDS dementia groups in the simple antisaccade trials, and for all HIV-positive groups in the complex trials. Fixation stability was significantly worse in the AIDS dementia group than in control subjects. Smooth pursuit gain was decreased in the asymptomatic, AIDS, and AIDS dementia groups for the least demanding trial. One or more ocular motor abnormalities were present in 15 (88%) asymptomatic subjects, 11 (69%) with AIDS-related complex, and 14 (100%) AIDS patients without or with dementia.

EEG in early HIV-1 infection is characterized by anterior dysrhythmicity of low maximal amplitude

We analyzed the EEGs of 67 HIV-1-infected patients at various stages of the disease and of 35 HIV-1-seronegative controls. The most common EEG abnormality in HIV-1 infection was an increased amount of generalized episodic or persistent, predominantly anterior slow activity, associated with a low level of maximal amplitude. When compared to the controls, a lower maximal amplitude of dominant background activity (p less than 0.001), and more marked generalized (p less than 0.01) and anterior (p less than 0.001) disturbances were already seen in early stages of HIV-1 infection. EEG abnormalities were more severe in patients with advanced HIV-1 infection than in those at early infection (p less than 0.001 to p less than 0.05). The presence of a more marked, posteriorly (p less than 0.01) accentuated, generalized slow activity (p = 0.02) was found more often in patients with T-helper cell counts lower than 0.4 x 10(9) (p = 0.05) than in those with higher numbers of T-helper cells. No clear associations were found between the severity of EEG abnormalities and the duration of HIV-1 infection. Our results suggest that EEG is a sensitive method in detecting subclinical functional cerebral disturbances caused by HIV-1.

Review of the central nervous system cytopathology in human immunodeficiency virus infection

The human immunodeficiency virus (HIV) is a neurotropic retrovirus capable of producing a wide spectrum of central nervous system changes. Nearly 40% of HIV-infected patients demonstrate neuropathy ranging from dementia to the opportunistic infections and neoplasia seen in the acquired immunodeficiency syndrome (AIDS). Dramatic increases in the numbers of AIDS cases have allowed for the cytotechnologist and cytopathologist to become acquainted with the various pathologic manifestations of HIV infection. In this review, we are reporting the HIV-related diseases in the central nervous system and the role of diagnostic cytology.

Neocortical damage during HIV infection

Clinical and pathological evidence of subcortical central nervous system (CNS) damage is observed commonly in patients with human immunodeficiency virus (HIV) encephalitis. Whether other CNS regions are also affected has not been well studied. We report neocortical damage in patients with HIV encephalitis. Using quantitative techniques, we demonstrate statistically significant thinning of the neocortex, with a loss of large cortical neurons. Qualitative and quantitative assessments of neocortical neuropil reveal a loss of synaptic density and vacuolation of dendritic processes. Failure to demonstrate an association of these changes with the presence of HIV antigens suggests that neocortical damage may be an indirect effect of HIV infection of the CNS.

Evidence of brain methyltransferase inhibition and early brain involvement in HIV-positive patients

The myelopathy associated with human immunodeficiency virus (HIV) infection closely resembles that in subacute combined degeneration, a disorder of vitamin B12 metabolism. To investigate whether the disorders share a pathogenetic mechanism, S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) were measured in the cerebrospinal fluid (CSF) of 20 HIV-seropositive patients and 30 HIV-negative patients who were undergoing lumbar puncture for other medical reasons. The HIV-seropositive patients had significantly lower CSF concentrations of SAM (mean 77 [SD 25] vs 131 [35] nmol/l; p less than 0.001) and significantly higher concentrations of SAH (30.5 [6.8] vs 19.0 [7.1] nmol/l; p less than 0.001) than the controls. There was therefore a significant difference between the groups in the SAM/SAH (methylation) ratio (HIV 2.7 [1.0] vs control 7.6 [3.4]; p less than 0.001). There were no correlations between SAM or SAH concentrations or methylation ratio and age or sex in both groups, or serum B12 and folate concentrations, CSF folate, serum or CSF methylmalonic acid, risk factors, body mass index, specific drug treatment received, or disease stage in the HIV group. This finding suggests that HIV affects the brain from a very early stage of the infection. We suggest that, as in the pig, the CSF methylation ratio closely reflects that in the brain. In HIV-infected patients a reduced brain methylation ratio would inhibit methyltransferase enzymes, which would lead to hypomethylation in the central nervous system and ultimately to neurological lesions. In a pig model of subacute combined degeneration and in vitamin-B12-deficient human beings, the primary cause of the low methylation ratio is impaired recycling of SAH back to SAM, a process which requires vitamin-B12-dependent methionine synthase. The HIV patients in this study were vitamin B12 and folate replete, which suggests a different cause for the low methylation ratio.

Transient high levels of viremia in patients with primary human immunodeficiency virus type 1 infection

BACKGROUND

The rapidly evolving clinical picture of primary infection with the human immunodeficiency virus type 1 (HIV-1) suggests that a better understanding of the kinetics of viral replication in vivo during the short period before seroconversion may provide insight into the pathogenesis of the acquired immunodeficiency syndrome (AIDS).

METHODS AND RESULTS

Titers of infectious HIV-1 were determined by end-point-dilution culture in sequential samples of plasma and peripheral-blood mononuclear cells from four patients with primary infection, with peak titers of 1000 to 10,000 tissue-culture-infective doses per milliliter of plasma and 100 to 10,000 infective doses per 10(6) peripheral-blood mononuclear cells. The high viral burden in mononuclear cells was confirmed by quantitative studies using a polymerase-chain-reaction method. In as little as 10 days, the high HIV-1 load in both plasma and cells decreased spontaneously and precipitously, at least 100-fold, in all four patients.

CONCLUSIONS

Although p24 core antigenemia and viral isolation have previously been described during primary HIV-1 infection, this report documents the large viral burden during the acute phase of infection. The rapid and spontaneous decline in the viral load suggests an effective immune response in the host that, if understood, may be used to combat AIDS.

Virucidal efficacy of various lens cleaning and disinfecting solutions on HIV-I contaminated contact lenses

The virucidal efficacy of various commercially available contact lens care cleaning regimens on human immunodeficiency virus (HIV-1) contaminated contact lenses using either cursory or meticulous cleaning with a rubber policeman was evaluated. Levels of infectious HIV-1 remaining on individual contact lenses were determined by cultivating the lenses with target HUT-78 cells and subsequently analyzing the cultures for the production of HIV-1 p24 by antigen capture and for HIV-1 gag gene DNA content by the polymerase chain reaction. The data indicate that most of the lens care regimens tested, when coupled with meticulous rubbing, were capable of safely decontaminating the contact lenses, that is, they reduce the amount of infectious HIV-1 on the lenses by greater than a 10 log concentration (10(-10], relative to standard controls. Most tested lens care regimens, if properly followed, would virtually eliminate any chance of the lens serving as a vector for HIV.

Immunopathogenesis of HIV encephalitis

HIV infection leads to severe immunosuppression and in a sub-population of patients, encephalitis. Whether systemic immunosuppression is required for CNS infection is still unclear. However, latent infection of monocytes/macrophages is an important mechanism by which HIV escapes immune surveillance and enters the CNS. Unlike other viral encephalitides, HIV predominantly infects macrophages/microglia and not neurons and glia. These cells produce retroviral proteins and cytokines which may be neurotoxic. Despite significant MHC expression within the CNS, there is a limited infiltration of immune cells, possibly due to a defect in systemic immunity. Anti-retroviral therapy by decreasing viral replication and reversing immunosuppression, may arrest nervous system damage.

HIV encephalopathy: incidence, definition and pathogenesis. Results of a Swiss collaborative study

The incidence of HIV encephalopathies was determined in an ongoing consecutive autopsy study. Among 345 patients who died from AIDS in Switzerland during 1981-1990, 68 (19%) showed morphological evidence of HIV encephalopathy. Two major histopathological manifestations were observed. Progressive diffuse leukoencephalopathy (PDL) was present in 33 cases and is characterized by a diffuse loss of myelin staining in the deep white matter of the cerebral and cerebellar hemispheres, with scattered multinucleated giant cells but little or no inflammatory reaction. Multinucleated giant cell encephalitis (MGCE) was diagnosed in 32 cases; it's hallmarks are accumulations of multinucleated giant cells with prominent inflammatory reaction and focal necroses. In 3 patients both types of lesions overlapped. Brain tissue from 27 patients was analyzed for the presence of HIV gag sequences using the polymerase chain reaction (PCR) with primers encoding a 109 base pair segment of the viral gene. Amplification succeeded in all patients with clinical and histopathological evidence for HIV encephalopathy but was absent in AIDS patients with opportunistic bacterial, parasitic and/or viral infections. Potential mechanisms by which HIV exerts it's adverse effects on the human CNS are discussed.

Detection of proviral sequences in saliva of patients infected with human immunodeficiency virus type 1

Single samples of saliva collected from 20 human immunodeficiency virus type I (HIV-1) seropositive patients were tested by the polymerase chain reaction for HIV-1 proviral sequences using primers from the long terminal repeat (LTR), gag, and env regions of the virus. Proviral sequences were detected in the saliva of 50% of the patients. Sequential samples of saliva, collected at four different times, from each of six additional patients led to the detection of proviral sequences in 100% of the patients. Since, however, the detection of HIV-1 required not only the highly sensitive polymerase chain reaction, but also multiple samples, it appears that under ordinary circumstances infected cells are present in saliva in low numbers. Although this may explain the lack of transmission of HIV-1 by casual contact through the salivary route to household members and health-care workers, the presence of infected cells in the saliva of a high percentage of patients argues for avoidance of sexually intimate situations involving prolonged and repeated contact with saliva.

Heme inhibits human immunodeficiency virus 1 replication in cell cultures and enhances the antiviral effect of zidovudine

The effects of heme alone and heme administered together with 3'-azido-3'-deoxythymidine (AZT) on human immunodeficiency virus replication in human peripheral blood lymphocytes and in the H9 cell line were studied. Heme enhanced the antiviral action of AZT against both drug-resistant and drug-sensitive viral strains; the heme effect was more pronounced against the latter. Moreover, heme alone displayed a significant ability to inhibit viral replication in concentrations markedly smaller than those required to inhibit the reverse transcriptase of Rauscher murine leukemia virus. The results of this study extend the range of pharmacological actions that metalloporphyrins exert in biological systems and suggest that further study of the interactions of the natural compound heme and human immunodeficiency virus chemotherapeutic agents such as AZT may be useful.

Tumor necrosis factor and interferon as prognostic markers in human immunodeficiency virus (HIV) infection

Peripheral blood cells were obtained from patients at different stages of their human immunodeficiency virus (HIV) infection. It was found that the capacity to generate interferon alpha was reduced already at Walter Reed stage 2 (WR) while the interferon gamma capacity remained largely unaffected until WR stage 4. Endogenous tumor necrosis factor (TNF) alpha production increased as the HIV disease progressed. The data obtained add to our knowledge on destruction of the immune system by the HIV. Moreover TNF and acid labile interferon alpha might contribute to HIV replication and disease progression. Nevertheless the tests performed are too time-consuming to be introduced into routine analysis of HIV infection or for monitoring its therapy and can so far not be used for intervention strategies. Further studies are needed.

Neuropsychological functioning of HIV-infected males

This article presents a Meta-Analysis of previous HIV-related neuropsychological research and new data from a study with methodological improvements over early investigations. In this study, the authors compared neuropsychological testing for three groups of adult male homosexuals: (a) HIV seronegative controls (n = 30), (b) HIV seropositive non-AIDS subjects (n = 27), and (c) diagnosed AIDS patients (n = 26). Groups were matched for age, education, and handedness, and subjects with other neurobehavioral risk factors were excluded. Subjects with AIDS performed worse than other groups on all tests, with 80% showing clinical impairment. HIV seropositive non-AIDS subjects differed from controls on 3 of 14 tests, with 33% showing clinical impairment. Group differences remained significant even after covarying for psychological distress, using the General Severity Index (GSI) of the Symptom Checklist-90-Revised as the covariate. These results are discussed in reference to findings from the Meta-Analysis of previous research and implications for future research.

Evidence for neurotoxic activity of tat from human immunodeficiency virus type 1

The human immunodeficiency virus (HIV) genome codes for a trans-activating regulatory protein, tat. Using chemically synthesized tat, it was found that 125I-tat and 125I-tat38-86 specifically bound to rat brain synaptosomal membranes with moderate affinity (K0.5 = 3 microM). Interaction of tat with nerve cells was also revealed by flow cytometry, which showed its binding to rat glioma and murine neuroblastoma cells, using both direct fluorescence with fluorescein isothiocyanate-labeled tat and indirect immunofluorescence assays. This interaction was investigated with electrophysiology using isolated excitable frog muscle fibers and cockroach giant interneuron synapses. tat acted on the cell membrane and induced a large depolarization, accompanied by a decrease in membrane resistance, thereby modifying cell permeability. The neurotoxicity of tat was further demonstrated in vitro, on glioma and neuroblastoma cell growth, as well as by a 51Cr release assay in both tumor cell lines. Interestingly, no hemolytic activity of tat for human erythrocytes was found even when tat was tested at its highly neurotoxic concentration. Experiments in vivo showed that synthetic tat is a potent and lethal neurotoxic agent in mice. The use of tat peptide derivatives showed that basic region from 49 to 57 is necessary and sufficient for binding to cell membranes and toxicity.

Intrathecal IgG synthesis and specificity of oligoclonal IgG in patients infected with HIV-1 do not correlate with CNS disease

The CSF/serum immune response to HIV 1 was studied in 24 patients admitted for investigation. The level of antibody to HIV-1 and specificity of oligoclonal IgG were determined in blood and cerebrospinal fluid (CSF). The majority of patients demonstrated elevated levels of intrathecal IgG synthesis, with levels of HIV-1-specific antibody frequently being significantly higher in CSF than in serum. In 16 of 21 patients the CSF/serum antibody ratio indicated active intrathecal synthesis. Oligoclonal banding was present in CSF from all 24 patients. Immunoprinting of serum and CSF demonstrated antigenic specificity (p24, gp 160, RT) of the clonal antibodies in all of 12 patients though the patterns of reactivity in CSF did not necessarily correspond with that of serum. Although a specific association of particular patterns with HIV CNS disease was not found we feel that these markers should be included in longitudinal studies of HIV-related diseases of the CNS. The specificity of oligoclonal antibodies, both in CSF and in serum was demonstrated, and this specificity may be a useful marker for longitudinal studies in HIV-1 antibody-positive asymptomatic patients.

Human immunodeficiency virus-infected macrophages produce soluble factors that cause histological and neurochemical alterations in cultured human brains

We wanted to establish an in vitro human model for AIDS-associated dementia and pursue the hypothesis that this disease process may be a result of soluble factors produced by HIV-infected macrophages. Human brain aggregates were prepared from nine different brain specimens, and were treated with supernatants from in vitro HIV-infected macrophages (SI), uninfected macrophages (SU), infected T cells, or macrophage-conditioned media from four AIDS patients. Seven of nine treated brains exposed to SI showed peripheral rarefaction after 1 wk of incubation that by ultrastructural analysis showed cytoplasmic vacuolation. Aggregates from two of three brain cultures treated with SI for 3 wk became smaller, an approximately 50% decrease in size. The degree of apparent toxicity in brains exposed to patient-derived macrophage supernatants paralleled the proportion of macrophages found to be expressing HIV p24. Ultrastructural abnormalities were not observed in brains treated with supernatants from HIV-infected T cells, uninfected macrophages, or LPS-activated macrophages. Levels of five neurotransmitter amino acids were decreased in comparison to the structural amino acid leucine. These findings suggest that HIV-infected macrophages, infected both in vitro as well as derived from AIDS patients' peripheral blood, produce factors that cause reproducible histochemical, ultrastructural, and functional abnormalities in human brain aggregates.

Positron emission tomography in the investigation of neuropsychiatric disorders: update and comparison with magnetic resonance imaging and computerized tomography

In many neuropsychiatric disorders, PET imaging offers functional insights unavailable from anatomic imaging alone. Functional deficits may be more extensive than structural findings would indicate, may occur before the detection of anatomic changes, or may even occur in the absence of any structural lesions. We contrast the current role of PET with that of MRI and CT in the investigation of neuropsychiatric disorders including stroke, tumor, head trauma, epilepsy, schizophrenia, movement disorders, normal aging and dementia.

Salivary detection of HIV-1 antibodies using recombinant HIV-1 peptides

Salivary antibodies may play a role in the absence of HIV-1 transmission by saliva. We evaluated the presence of salivary IgG antibodies to HIV-1 using a recombinant ELISA. Whole saliva was collected from 21 HIV-1-seropositive individuals and assayed in an ELISA, ASQ (Beckman Instruments, Brea, CA), consisting of a panel of six HIV-1 recombinant peptides. Saliva samples from 20 individuals demonstrated IgG to one or more peptides and 18 to two or more peptides. Samples from 20 seropositive individuals were reactive with the gp41 peptide, whereas only 12 were reactive with the two gp120 peptides. Nineteen of twenty salivas also had detectable IgG antibodies to HIV-1 by Western blotting. The results indicate that viral-specific IgG antibodies are present in the saliva of a high percentage of HIV-infected individuals and that a recombinant peptide ELISA for saliva might be useful for the detection of HIV-1 infection.

Secretion of neurotoxins by mononuclear phagocytes infected with HIV-1

Mononuclear phagocytes (microglia, macrophages, and macrophage-like giant cells) are the principal cellular targets for human immunodeficiency virus-1 (HIV-1) in the central nervous system (CNS). Since HIV-1 does not directly infect neurons, the causes for CNS dysfunction in acquired immunodeficiency syndrome (AIDS) remain uncertain. HIV-1-infected human monocytoid cells, but not infected human lymphoid cells, released toxic agents that destroy chick and rat neurons in culture. These neurotoxins were small, heat-stable, protease-resistant molecules that act by way of N-methyl-D-aspartate receptors. Macrophages and microglia infected with HIV-1 may produce neurologic disease through chronic secretion of neurotoxic factors.

Symptomatic polyneuropathy in human immunodeficiency virus antibody seropositive men with and without immune deficiency: a comparative electrophysiological study

Symptomatic polyneuropathy in human immunodeficiency virus (HIV) infection was studied in ten men with acquired immunodeficiency syndrome (AIDS) and in ten men without the immune deficiency. In both groups of patients electrophysiological signs of polyneuropathy of the axonal type were present in the sural, median and peroneal nerves. The AIDS patients had a greater reduction of the mean (SD) sural nerve action potential, 3.1 (2.7) microV, than in patients without AIDS, 10.2 (6.1) microV (p less than 0.01) and greater slowing of peroneal nerve conduction velocity, 42.6 (1.4) m/s in AIDS patients versus 52.6 (3.3) m/s in patients without AIDS (p less than 0.0001). These findings indicate that in most HIV infected patients the severity but not the type of neuropathy depends on whether an immune deficient state has developed. Seven patients with symptomatic polyneuropathy were treated with azidothymidine (AZT) for an average of 10 months and compared with a group of five untreated patients with similar symptoms. No effect of AZT treatment on sural or median nerve amplitude or conduction velocity or on the vibratory or temperature thresholds was observed.

In vitro inhibition of HIV-1 infectivity by human salivas

Inhibitory factors to human immunodeficiency virus type 1 (HIV-1) in saliva may be responsible for the infrequent isolation of virus from saliva and also may account for the marked infrequency of salivary and/or oral transmission of HIV-1. Incubation of HIV-1 with human saliva followed by addition of the mixture to susceptible cells leads to partial or complete suppression of viral replication in vitro. We investigated the inhibitory effects of whole saliva and specific glandular salivas on HIV-1 infectivity as measured by viral-induced cytopathic effects in susceptible cells. Whole saliva contained marked inhibitory activity to HIV-1, strain HTLV-IIIB, and to virus infected cells. Submandibular saliva contained inhibitory activity, but of lesser quantity. Parotid saliva demonstrated no HIV-inhibitory activity. Whole saliva also appeared to contain filterable components that were inhibitory to lymphocyte growth. Passage through a .45 micron pore-size filter eliminated the viral inhibitory activity of submandibular saliva and some of the activity in whole saliva. All salivas except parotid incubated with HIV-1 followed by filtration were inhibitory suggesting that complexing of virus with high molecular weight, submandibular mucins may play a role in viral inhibition.

The viral envelope gene is involved in macrophage tropism of a human immunodeficiency virus type 1 strain isolated from brain tissue

Human immunodeficiency virus type 1 (HIV-1) strains isolated from the central nervous system (CNS) may represent a subgroup that displays a host cell tropism different from those isolated from peripheral blood and lymph nodes. One CNS-derived isolate, HIV-1SF128A, which can be propagated efficiently in primary macrophage culture but not in any T-cell lines, was molecularly cloned and characterized. Recombinant viruses between HIV-1SF128A and the peripheral blood isolate HIV-1SF2 were generated in order to map the viral gene(s) responsible for the macrophage tropism. The env gene sequences of the two isolates are about 91.1% homologous, with variations scattered mainly in the hypervariable regions of gp120. Recombinant viruses that have acquired the HIV-1SF128A env gene display HIV-1SF128A tropism for macrophages. Furthermore, the gp120 variable domains, V1, V2, V4, and V5, the CD4-binding domain, and the gp41 fusion domain are not directly involved in determining macrophage tropism.

Otologic pathophysiology in patients with human immunodeficiency virus

During the initial phase of clinical diagnosis and treatment of the manifestations of acquired immunodeficiency syndrome, involvement of the ear appeared minor. In the past several years, however, otologic disorders increasingly have been reported in individuals with human immunodeficiency virus (HIV), as well as in retrospective studies of such patients. The otologic data appear quite variable. Functionally, conductive hearing loss, unilateral and bilateral sudden or progressive sensorineural hearing losses, vertigo, and tinnitus have been reported. In addition, tissue responses in each division of the ear have been observed. Based on collective serologic and immunologic diagnostic assays, clinical histories, and temporal bone histopathology, otologic symptoms may not be the direct effect of HIV alone, but rather a combination of the effects of HIV infection coupled with that of opportunistic microorganisms and/or possible ototoxic effects of certain therapeutic agents. It is within this context that otologic findings in this population of subjects will be discussed.

Cerebrospinal fluid interleukin-6 activity in HIV infection and inflammatory and noninflammatory diseases of the nervous system

Interleukin-6 (IL-6) activity was measured in the cerebrospinal fluid (CSF) of patients at different stages of human immunodeficiency (HIV) virus infection and of patients with multiple sclerosis (MS) or other inflammatory (OID) and noninflammatory neurological diseases (OND). In the advanced stages of HIV infection and in OID, IL-6 was detected more frequently (80 and 75% of the cases) and at higher concentrations than in the early stages of HIV infection. MS and OND (44, 48, and 44% of cases). Analysis of CSF and paired sera indicated that IL-6 production can be compartmentalized to either of the fluids. Evidence that altered blood-brain barrier functions can, at least in part, influence the CSF IL-6 levels was found in OID patients. No association was evident between intrathecal immunoglobulin synthesis and CSF IL-6 levels. Interleukin-1 (IL-1) levels were detectable in a minority of the samples from neurological patients; one OID patient had high levels of both CSF IL-1 and IL-6.

Mild brain atrophy in early HIV infection: the lack of association with cognitive deficits and HIV-specific intrathecal immune response

Brain MRI and/or CT were performed on 72 HIV-infected patients at various stages of the disease, and on 34 controls. The neuroradiological findings were related to duration of the infection, neurological symptoms, and cognitive abnormalities as well as to immunological findings in the CSF and blood. All types of brain atrophy were more severe and more frequent in HIV-infected subjects than in controls. Patients with neurological symptoms, those with advanced HIV infection, and patients with a duration of HIV infection of more than 4 years showed the most severe and most frequent neuroradiological abnormalities, including central and cortical atrophy, brain stem atrophy, and cerebellar atrophy. Subjects with cognitive defects exhibited more severe central atrophy than cognitively intact patients. However, slight brain atrophy and/or parenchymal lesions were found in 57% of cognitively intact HIV-seropositive individuals. Patients with brain atrophy and those with radiologically normal brain, both showed increased intrathecal synthesis of total IgG, and intrathecal HIV-antibody synthesis. However, a declined general immune response and a lowered CSF leukocyte count were seen predominantly in patients with brain atrophy. The results suggest that subcortical, neurologically "silent" areas of brain white matter are an early target of HIV infection.

Sustained increases in cerebrospinal fluid quinolinic acid concentrations in rhesus macaques (Macaca mulatta) naturally infected with simian retrovirus type-D

Sustained increases in CSF concentrations of the excitotoxin quinolinic acid (QUIN) occur in patients with AIDS and have been implicated in the pathogenesis of the AIDS dementia complex. Macaques in captivity may also develop immunodeficiency syndromes caused by retrovirus infection, including simian retrovirus type-D. In the present study, CSF QUIN concentrations were moderately increased in retrovirus type-D-positive/antibody-negative macaques (163.8 +/- 35.1 nmol/l; P less than 0.0001, n = 21) but not virus-negative/antibody-positive macaques (27.4 +/- 9.4 nmol/l, n = 8) compared to uninfected control macaques (23.0 +/- 1.6 nmol/l; n = 22). CSF QUIN concentrations in virus-positive/antibody-negative macaques tended to remain elevated over a 4-20 month period. Post-mortem studies of 9 virus-positive/antibody-negative macaques and 6 virus-negative/antibody-positive macaques revealed inflammatory responses in the brains of 6 of 9 virus-positive/antibody negative macaques, including lymphocytic infiltrates of the choroid plexus in 3 macaques, glial nodules in 3 macaques and perivascular infiltrates in 1 macaque. These lesions were not extensive and no evidence of brain atrophy was observed. No lesions were observed in the 6 antibody-positive/virus-negative macaques. Small increases in plasma L-kynurenine in virus-positive/antibody-negative macaques are consistent with activation of indoleamine-2,3-dioxygenase, the first enzyme in the kynurenine pathway. We conclude that sustained moderate increases in CSF QUIN occur in viremic simian retrovirus type-D macaques. The increases in CSF QUIN may reflect inflammatory responses within the brain or synthesis of QUIN precursors in systemic tissues, their entry into brain and subsequent conversion to QUIN. The neuropathologic significance of these increases in CSF QUIN remains to be determined.

Multimodality evoked potentials in HIV infected subjects: a longitudinal study

18 subjects with symptomless HIV infection were investigated with multimodal evoked potentials for possible CNS involvement and again after an 8-12 month interval. 13 subjects showed neuropsychological changes, which were confirmed at the second examination. The 5 subjects found normal remained so at the second examination. On WAIS assessment the only patient to earn pathological scores was the one with the greatest evoked potentials changes. Thus the evoked potentials procedure proved capable of identifying early CNS involvement by HIV infection.

Early HIV-related neuropsychological impairment: relationship to stage of viral infection

Sixty male outpatients with no past neuropsychiatric history were examined for evidence of early HIV-related neuropsychological impairment. Significant cognitive deficit, as measured by the RAVLT and WAIS-R Digit Symbol Substitution tests, and moderate correlation with indices of immune function, were observed in a group of patients with AIDS-Related Complex [ARC]. Patients with asymptomatic HIV-infection demonstrated no significant differences in performance compared to a group of HIV-seronegative controls. No significant group differences in age, education, predicted-IQ or self-rated depression and anxiety were observed. These results support the hypothesis that HIV-related cognitive disturbance occurs within the context of immunosuppression.

Multifocal vacuolar leucoencephalopathy: a distinct HIV-associated lesion of the brain

A 20-year-old male AIDS patient developed rapidly progressive dementia for more than 3 months prior to death. Autopsy showed, in addition to adrenal cytomegalovirus (CMV) infection and focal cerebral necrosis due to toxoplasmosis, multifocal subcortical white matter lesions of the brain which were strikingly similar to the histopathology of vacuolar myelopathy in AIDS. These distinct lesions contained macrophages which were rarely multinucleated and expressed HIV antigens by immunocytochemistry. The distribution of lesions mimics extrapontine myelinolysis and progressive multifocal leucoencephalopathy (PML); PML was excluded by the absence of papovaviruses by immunocytochemistry and by in situ DNA hybridization. Tissue damage in multifocal vacuolar leucoencephalopathy is different from hitherto characterized HIV-specific neuropathology such as HIV encephalitis and HIV leucoencephalopathy, and should be included in the list of conditions with damage of the brain white matter in AIDS.

Brain imaging in acquired immunodeficiency syndrome dementia complex

Human immunodeficiency virus (HIV) infections are accompanied by many different types of neurological complications. Opportunistic infections and neoplasms, particularly lymphoma, are often an underlying cause for these complications in patients with acquired immunodeficiency syndrome (AIDS). Frequently, these can be detected by cerebrospinal fluid (CSF) examination, double-dose contrast transmission computed tomography (CT), and/or magnetic resonance imaging (MRI). It has become apparent that the HIV itself is responsible for a significant percentage of neurological disease in the HIV-seropositive individual. The onset may be subtle and may occur before the onset of frank immunosuppression. Diagnosis of HIV encephalitis or AIDS dementia complex (ADC) is complicated by the frequent coexistence of opportunistic infections. Structural neuroimaging (CT or MRI) shows atrophy and in some case white matter abnormalities, but imaging-pathological correlation suggests that these modalities are relatively insensitive to the presence of HIV brain infection. Functional neuroimaging, both 18fluorodeoxyglucose positron emission tomography (PET) for evaluation of glucose metabolism and 123I iodoamphetamine or 99mTc-HMPAO single-photon emission computed tomography (SPECT) for evaluation of cerebral perfusion, can demonstrate abnormalities in the subcortical gray matter structures and the cerebral cortex in patients with ADC. These abnormalities may be observed early in the course of ADC even when MRI is negative and the patient is relatively asymptomatic. Also, PET and SPECT may be useful to follow progression of the dementia or response to therapy.

Abnormalities in cholesterol metabolism cause peripheral neuropathy and dementia in AIDS--a hypothesis

The AIDS dementia complex and peripheral neuropathy in AIDS are considered to be direct or indirect manifestations of HIV infection, yet the pathogenesis in unclear. There are parallels between AIDS and Tangier disease clinically and histopathologically and in lipid metabolism. The neurological disorders in AIDS may be caused by dysfunction of cellular cholesterol transport. Substitution of high density lipoprotein is recommended in the treatment of severe polyneuropathy and dementia in AIDS.