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

Neuropathies and HIV infection

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Restricted replication of simian immunodeficiency virus strain 239 in macrophages is determined by env but is not due to restricted entry

Virus derived from the infectious, pathogenic, molecular clone of simian immunodeficiency virus (SIV) called SIVmac239 replicates poorly in primary rhesus monkey alveolar macrophage cultures. Variants with three to nine amino acid changes in the envelope replicate 100 to 1,000 times more efficiently in these macrophage cultures than parental SIVmac239. Early events, including virus entry into cells, were analyzed by measuring the amounts of newly synthesized viral DNA 14 to 16 h after infection of macrophages by using a quantitative polymerase chain reaction method. SIVmac239 ws found to enter macrophages with an efficiency similar to that of the macrophage-tropic derivatives. The assay indeed measured newly synthesized viral DNA since detection was inhibited by the reverse transcriptase inhibitors azidothymidine and foscarnet and by heat inactivation of the virus stock prior to infection. Furthermore, entry of SIVmac239 and macrophage-tropic variant into macrophages was inhibited by monoclonal antibody against CD4. Analysis of the time course of viral DNA accumulation showed that although initial entry of SIVmac239 into cells occurred normally, subsequent logarithmic increases in the amounts of viral DNA associated with spread of virus through the macrophage cultures was blocked. Increasing the amount of SIVmac239 incubated with macrophages increased the amount of virus entering the cell, but this could not overcome the block to replication. Thus, restricted replication of SIVmac239 in macrophages is determined by the envelope, but surprisingly it is not due to restricted virus entry.

CSF follow-up in HIV-1 infection: intrathecal production of HIV-specific and unspecific IGG, and beta-2-microglobulin increase with duration of HIV-1 infection

Ninety-nine sequential cerebrospinal fluid (CSF) samples from 28 human immunodeficiency virus-1 (HIV-1)-infected patients were analyzed during the follow-up of 9 months to 4 years. Intrathecal synthesis of HIV-antibodies and IgG (p < 0.01), and the levels of beta-2-microglobulin (beta 2m) in the CSF (p < 0.05) and serum (p < 0.01) increased with duration of HIV-1 infection. No effect of duration of HIV-1 infection was observed on the individual CSF white cell counts and the levels of blood-brain-barrier (BBB) permeability. In 13 patients with HIV-1-associated central nervous system (CNS) disease, the effect of duration was seen as an increase of the individual beta 2m levels in serum (p < 0.01). Moreover, 7 of 9 patients who developed neurological disease or showed its progression during the study increased the level of beta 2m in the CSF. All of them increased the level of beta 2m in serum. In 15 neurologically healthy subjects, the effect of duration was expressed as an increase of the level of individual beta 2m in CSF (p < 0.05) and intrathecal IgG synthesis (p < 0.01). In the AIDS group, the level of beta 2m in the CSF increased, but in less severe stages the dependency of the individual CSF parameters on disease duration was not found. Our results indicate that elevated levels of beta 2m in CSF and serum appear to predict progression of neurological and systemic diseases, respectively. Elevated beta 2m in the CSF of clinically intact individuals may indicate subclinical neurological disease caused by HIV-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Human immunodeficiency virus type 1 infection of the nervous system: pathogenetic mechanisms

Human immunodeficiency virus type 1 (HIV-1) infection of the central nervous system is associated with characteristic virological, clinical, and neuropathological findings in adults and children. Productive infection in the brain and spinal cord occurs in blood-derived macrophages, resident microglia, and multinucleated giant cells. Previous work implicated indirect mechanisms for neurotoxicity by HIV-1 gene products or by factors secreted from HIV-1--infected macrophages. However, this cannot explain the paradox between the small numbers of infected cells and the widespread tissue pathology. Based on recent studies from our laboratories, we suggest that HIV-1--infected macrophages can initiate neurotoxicity, which is then amplified through cell-to-cell interactions with astrocytes. Macrophage-astrocyte interactions produce cytokines tumor necrosis factor-alpha and interleukin-1 beta and arachidonic metabolites that cause astroglial proliferation and neuronal injury. Inevitably, the astrogliosis serves to amplify these cellular processes while brain infection maintains itself in macrophage and microglia and possibly in astrocytes (by restricted infection). These findings, taken together, provide fresh insights into how low numbers of productively infected cells could elicit progressive and devastating neurological impairment during HIV-1 disease, and suggest therapeutic strategies to interrupt the pathological process.

Comparative pharmacokinetics of two prodrugs of zidovudine in rabbits: enhanced levels of zidovudine in brain tissue

The pharmacokinetics of two prodrugs of zidovudine (AZT), 1,4-dihydro-1-methyl-3-[(pyridylcarbonyl)oxy] ester and isoleucinyl ester (DPAZT and IAZT, respectively), were investigated in a rabbit model to determine their potential utility as drugs against human immunodeficiency virus. Drugs were administered by intravenous infusion over 5 min at doses equal to 10 mg of AZT per kg of body weight. The levels of the prodrugs and of released AZT in plasma, cerebrospinal fluid (CSF), and brain were determined by high-performance liquid chromatography analysis. DPAZT disappeared rapidly from plasma, whereas IAZT maintained a sustained level in plasma for up to 4 h. The levels in plasma of AZT released from DPAZT were consistently lower than the levels of AZT released from IAZT or AZT itself. At 75 min after infusion of AZT, DPAZT, and IAZT, the CSF plasma AZT ratios were 0.23, 0.30, and 0.25, while the brain/CSF AZT ratios were 0.32, 0.63, and 0.64, respectively. These results indicate that the administration of each of the prodrugs produced a higher concentration of AZT in the brain than did the direct administration of AZT. Both prodrugs therefore may be superior to AZT itself with respect to achieving anti-human immunodeficiency virus concentrations within the central nervous system.

AIDS-myelopathy. A neuropathological study

Vacuolar myelopathy belongs to the AIDS-associated diseases. It is characterized by vacuolation and infiltration of the long tracts of the spinal cord by macrophages. The clinical and morphological findings of 8 AIDS-patients with vacuolar myelopathy are reported here. The syndrome developed during the final stages of AIDS and was associated with HIV-encephalopathy in 5 cases. The vacuoles were mainly due to intramyelinic swelling and vacuolation. Vacuolated macrophages and axons contributed only to a minor degree. In one case only, HIV-antigens were detected immunohistochemically. The results are discussed in the light of modern pathogenetical concepts of HIV-related diseases.

Pediatric HIV infection: a neuropsychological and educational challenge

Pediatric acquired immunodeficiency syndrome (AIDS) and human immunodeficiency virus (HIV) infection will soon be the primary infectious cause of perinatally acquired developmental disabilities in the United States. HIV encephalopathy and a variety of opportunistic infections, neoplasms, and vascular changes associated with pediatric HIV infection create a high probability of neuropsychological impairment among preschool and school-age children infected perinatally. Although the use of antiretrovirals may moderate some of the functional difficulties faced by these children, specific neuropathological and neuropsychological deficits are likely to remain. Treatments that prevent the central nervous system (CNS) effects of HIV have yet to be identified. As the epidemic progresses among women of child-bearing age, well-controlled developmental studies are needed to further clarify the relationship between HIV and child development, and to aid professionals in developing appropriate, school-based educational plans.

Facial nerve paralysis related to HIV disease. Case report and dental considerations

Neurologic manifestations of human immunodeficiency virus disease have been well documented and include peripheral neuropathy of the facial nerve. HIV-related peripheral facial nerve paralysis may be of predictive value in endemic populations, and it may be associated with acute HIV infection. It may herald the onset of seroconversion, and it is more common in the later stages of HIV disease. Treatment is palliative in nature and, although self-limiting, the condition may be of an extended duration and result in increased patient morbidity. The nutritional impact of HIV-related peripheral facial nerve paralysis on the patient and associated exacerbation of oral manifestations of HIV disease resulting from the presence of oral dryness are addressed. Early dental intervention is essential to reduce patient morbidity.

AIDS dementia complex complicated by cytomegalovirus encephalopathy

We have studied longitudinally ten patients with AIDS encephalopathy with respect to pathogenetic roles of human immunodeficiency virus (HIV) and cytomegalovirus (CMV). Three patients manifested typical AIDS dementia complex (ADC) (initially without retinitis and with slowly progressive cognitive, motor and behavioral abnormalities which were zidovudine-responsive, and relatively preserved CD4+ T cells), and seven patients presented with AIDS dementia complex complicated by CMV encephalopathy (ACE) (with CMV retinitis, peripheral neuropathy, altered sensorium, and rapidly declining clinical and immunological status). Whereas only HIV antibody was elevated in the spinal fluid of patients with ADC, both virus infections were active in the central nervous system of patients with ACE as shown by HIV p24 antigenemia and antigenrrhachia, elevated HIV and CMV antibody in the spinal fluid, disseminated CMV infection with retinitis, and basilar ventriculoencephalitis with multinucleated cytomegalic cells containing CMV and HIV proteins and CMV DNA. The recognition of ADC and ACE is important, since some patients with ACE may respond to ganciclovir or foscarnet.

The neurologic complications of human immunodeficiency virus infection

The physician caring for HIV-1-infected patients must have a good working knowledge of the broad spectrum of neurologic diseases that occur in association with this infection. As with any other neurologic disorder, the site of the neuraxis that is affected must be properly identified. In HIV-1-infected persons, more than one site may be involved simultaneously, such as the coexistence of myelopathy and peripheral neuropathy, often resulting in a confusing array of neurologic signs and symptoms. The frequent occurrence of two or more diseases affecting the neuraxis, such as progressive multifocal leukoencephalopathy and toxoplasmosis, further complicates the picture. With the AIDS patient, the physician cannot rely on the clinical adage that all attempts should be made to ascribe the patient's problems to one disease. Often, it is not the case. As with other illnesses, the approach to the HIV-1-infected person with neurologic disease needs to be thorough and fluid. After rendering a diagnosis and embarking on therapy, the physician needs to be open minded about the possibility of an incorrect or additional diagnosis not previously considered. Lastly, despite all the knowledge that has been accumulated in the first decade of the AIDS epidemic, new illnesses occurring with HIV-1 infection are recognized with regularity. The physician must always bear in mind that the illness with which he or she is confronted may be one that has not been previously described.

Pathogenesis of virus-induced demyelination

Demyelination is a component of several viral diseases of humans. The best known of these are subacute sclerosing panencephalitis (SSPE) and progressive multifocal leukoencephalopathy (PML). There are a number of naturally occurring virus infections of animals that involve demyelination and many of these serve as instructive models for human demyelinating diseases. In addition to the naturally occurring diseases, many viruses have been shown to be capable of producing demyelination in experimental situations. In discussing virus-associated demyelinating disease, the chapter reviews the architecture and functional organization of the CNS and considers what is known of the interaction of viruses with CNS cells. It also discusses the immunology of the CNS that differs in several important aspects from that of the rest of the body. Experimental models of viral-induced demyelination have also been considered. Viruses capable of producing demyelinating disease have no common taxonomic features; they include both DNA and RNA viruses, enveloped and nonenveloped viruses. The chapter attempts to summarize the important factors influencing viral demyelination, their common features, and possible mechanisms.

Potent gp120-like neurotoxic activity in the cerebrospinal fluid of HIV-infected individuals is blocked by peptide T

The envelope protein of the human immunodeficiency virus (gp120) causes neuronal death in developing murine hippocampal cultures or rat retinal ganglion cells. In HIV-infected individuals, gp120 released from HIV-infected macrophages or other cells in the brain has been proposed as the etiology for the pathophysiology of AIDS central nervous system (CNS) disease by diffusing to act at a distance to cause damage and/or death to neighboring neurons. In this study, 28 cerebrospinal fluid (CSF) samples from HIV-infected individuals (79% were WR stage 1 and 2) and neurological disease controls were tested, blind to the investigator, for the presence of in vitro neuronal killing activity. Neurotoxic activity was detected with peak effects at a 1:10(5) dilution in CSF from 9/18 HIV-infected individuals and 1/10 neurological disease controls. Thus half of CSF from early stages of HIV disease are characterized by the presence of neurotoxic activity which is not present in control CSF (Fischers exact test, P < 0.05). The neuronal toxicity by patient CSF could be prevented by peptide T (1 nM). A monoclonal antibody to mouse CD4, RL.172, also attenuated or prevented CSF-induced neuronal killing in all four CSF samples tested. In addition, an antiserum to peptide T previously shown to bind gp120 and neutralize both infectively and direct gp120 neurotoxicity, neutralized the CSF factor. gp120, or a modified small fragment, is suggested to be the responsible toxic molecular entity. These results may be relevant to the pathophysiology of HIV-related CNS disease and the mechanism by which peptide T causes improvements.

Expression directed from HIV long terminal repeats in the central nervous system of transgenic mice

Infection with the human immunodeficiency virus (HIV) is frequently accompanied by the AIDS (acquired immunodeficiency syndrome) dementia complex. The role of specific HIV genetic elements in the pathogenesis of central nervous system (CNS) disease is not clear. Transgenic mice were constructed that contained the long terminal repeats (LTRs) of two CNS-derived strains and a T cell tropic strain of HIV-1. Only mice generated with CNS-derived LTRs directed expression in the CNS, particularly in neurons. Thus, some strains of HIV-1 have a selective advantage for gene expression in the brain, and neurons can supply the cellular factors necessary for their transcription.

Cytokines and arachidonic metabolites produced during human immunodeficiency virus (HIV)-infected macrophage-astroglia interactions: implications for the neuropathogenesis of HIV disease

Human immunodeficiency virus (HIV) infection of brain macrophages and astroglial proliferation are central features of HIV-induced central nervous system (CNS) disorders. These observations suggest that glial cellular interactions participate in disease. In an experimental system to examine this process, we found that cocultures of HIV-infected monocytes and astroglia release high levels of cytokines and arachidonate metabolites leading to neuronotoxicity. HIV-1ADA-infected monocytes cocultured with human glia (astrocytoma, neuroglia, and primary human astrocytes) synthesized tumor necrosis factor (TNF-alpha) and interleukin 1 beta (IL-1 beta) as assayed by coupled reverse transcription-polymerase chain reaction, enzyme-linked immunosorbent assay, and biological activity. The cytokine induction was selective, cell specific, and associated with induction of arachidonic acid metabolites. TNF-beta, IL-1 alpha, IL-6, interferon alpha (IFN-alpha), and IFN-gamma were not produced. Leukotriene B4, leukotriene D4, lipoxin A4, and platelet-activating factor were detected in large amounts after high-performance liquid chromatography separation and correlated with cytokine activity. Specific inhibitors of the arachidonic cascade markedly diminished the cytokine response suggesting regulatory relationships between these factors. Cocultures of HIV-infected monocytes and neuroblastoma or endothelial cells, or HIV-infected monocyte fluids, sucrose gradient-concentrated viral particles, and paraformaldehyde-fixed or freeze-thawed HIV-infected monocytes placed onto astroglia failed to induce cytokines and neuronotoxins. This demonstrated that viable monocyte-astroglia interactions were required for the cell reactions. The addition of actinomycin D or cycloheximide to the HIV-infected monocytes before coculture reduced, > 2.5-fold, the levels of TNF-alpha. These results, taken together, suggest that the neuronotoxicity associated with HIV central nervous system disorders is mediated, in part, through cytokines and arachidonic acid metabolites, produced during cell-to-cell interactions between HIV-infected brain macrophages and astrocytes.

Electrophysiologic study of HIV-1 + patients without signs of peripheral neuropathy

HIV-1 seropositive patients have a high frequency of nervous system diseases, and asymptomatic abnormalities are frequently detected. We studied 124 neurologically asymptomatic HIV-1 seropositive subjects and 23 normal control subjects by nerve conduction studies. No alterations were detectable in the asymptomatic stages of infection (CDC groups II and III), while subclinical peripheral nervous system (PNS) impairment was detected in symptomatic HIV-1 stages (CDC group IV). Specifically, in CDC group IV we observed a reduction in the motor conduction velocity of the deep peroneal nerve and the median nerve, and a similar reduction of the sensory conduction velocity of the sural nerve. There were no differences of the amplitude and area of the muscular response or of the sensory nerve action potential. As our patients did not present clinical or laboratory evidence for a toxic-dismetabolic etiology, our data indicate a progressive myelin damage more directly related to HIV-1 infection. This subclinical finding may have importance for the progression of the disease in the PNS.

[Involvement of the peripheral nervous system in HIV infection: electromyographic study and nerve conduction velocity]

Disorders of the peripheral nervous system occur at all stages of HIV1 infection. Acute and subacute inflammatory demyelinating polyneuropathies are mainly observed in otherwise asymptomatic HIV+ patients and in patients with ARC (AIDS-related complex): clinical and electrophysiological features are similar to those observed in Guillain-Barré syndrome (GBS) and chronic inflammatory demyelinating polyneuropathy (CIDP), but CSF examination usually shows pleocytosis, and an infiltration of the endoneurium and/or the epineurium is commonly seen in nerve biopsies. Mononeuropathy multiplex is a rare complication occurring in ARC-patients: electrophysiological studies are consistent with an axonopathy and nerve biopsies may show vasculitis. Distal predominantly sensory polyneuropathies are the most frequent peripheral neuropathies in HIV1 infection and are usually reported in patients with AIDS and severe immunosuppression: electrophysiological features are of an axonopathy with signs of acute denervation. Meningoradiculitis is observed at the late stages of the disease and is mainly due to a cytomegalovirus infection. On the other hand, systematic electrophysiological studies in HIV+ cases reveal a high percentage of abnormalities concerning sensory and less frequently motor nerve conduction velocities. The severity of this asymptomatic involvement of the peripheral nervous system seems to be related to the degree of the immunodeficiency. The mechanism of these peripheral neuropathies remains hypothetical in most cases.

[Study of sensory involvement and dysautonomia in HIV infected patients. A prospective study of 55 cases]

Subclinical impairment of the peripheral nervous system (PNS) is frequent during HIV infection. Nevertheless, little attention has been given to the autonomic nervous system (ANS). We undertook a prospective study of the ANS, exploring 55 HIV+ subjects with non-invasive functional tests for the cardiac ANS. We also made a quantitative study of thermic (small fibers) and vibratory (large fibers) sensibilities. The results do not show any statistically significant difference between HIV+ subjects and control subjects or between HIV+ subjects of groups I, II and III and those of group IV of the CDC classification. However, an individual analysis comparing the results of the infected subjects with those of the control group indicated the presence of functional abnormalities of the ANS (small fibers) in 34.5% of HIV+ patients with an equally frequent impairment of the thermic perception (small fibers) and of the vibratory perception (large fibers). Moreover, the signs of subclinical dysautonomia were more frequent in group IV (48.3%) than in groups I, II and III (19%) showing a progressive accentuation of the troubles during the course of the infection.

[Evoked potentials in HIV infection]

The study of the literature data on the multimodal evoked potentials in HIV infected patients shows many abnormalities as well in asymptomatic subjects without AIDS as in AIDS subjects with or without neurological signs. Visual evoked potentials (VEPs) reveal prolonged P100 wave latency in 22% of HIV asymptomatic subjects and in 26% of HIV symptomatic subjects; brainstem auditory evoked potentials (BAEPs) reveal an increase of the interpeak latency I-V in 16% of asymptomatic subjects and in 32% of symptomatic subjects; somatosensory evoked potentials (SEPs) by median nerve stimulation reveal prolonged central conduction time in 6% of asymptomatic subjects and in 11% of symptomatic subjects; somatosensory evoked potentials (SEPs) by tibial nerve stimulation reveal prolonged central conduction time in 4% of asymptomatic subjects and in 45% of symptomatic subjects; motor evoked potentials (MEPs) by magnetic stimulation reveal prolonged central motor conduction time in 46% of asymptomatic subjects.

Peripheral and central nervous system anomalies in HIV-1 infection: an electrophysiological study

This study explored the neurophysiological changes in 87 HIV1+ (20 AIDS, 24 ARC, 24 LAS and 19 AC) patients showing no clinical evidence of neurological impairment. Tracing somatosensory responses by recording SEPs from upper and lower limbs, we found a slowing of both peripheral and central nerve conduction. Peripheral alterations occurred in virtually all patients of the AIDS group. Central anomalies, confined largely to the lower spinal cord, manifested themselves only during the later stages of the disease (ARC and AIDS) and then only in about half of our sample. More marked neurotropic varieties of HIV1 may account for these differences. We feel that SEP studies can serve to reveal pre-clinical NS involvement in HIV1+ subjects and should be included among research strategies aimed at tracing the evolution of AIDS.

In vitro infection of human macrophages by human T-cell leukemia/lymphotropic virus type I (HTLV-I)

HTLV-I is associated with a neurological syndrome designated Tropical Spastic Paraparesis/HTLV-I associated myelopathy (TSP/HAM). To determine whether HTLV-I can replicate in human primary macrophages and thus contribute to HTLV-I dissemination in the nervous system, elutriated human macrophages were infected cell-free with the HTLV-ICR and HTLV-IBOU isolates from patients with adult T-cell leukemia and TSP/HAM, respectively. Viral production was monitored by measuring the viral p24 gag antigen in the cell culture supernatant, by electron microscopy (EM) and by polymerase chain reaction (PCR) on viral DNA and RNA. The HTLV-I p24 gag antigen was detected 21 days after infection with either isolate, and the presence of mature viral particles was demonstrated by electron microscopy one month after infection. Viral sequences were amplified by PCR analysis of the infected macrophages' DNA. Spliced mRNAs for the p40tax and p27rex proteins, as well as the p12I, and p30II proteins encoded by the pX region were readily identified by reverse transcriptase PCR. Altogether, these data indicate that HTLV-I replication occurs in vitro in primary human macrophages. Whether macrophage infection occurs also in vivo and is a crucial step in the induction of the neurological manifestations observed in TSP/HAM remains an open question.

Cytokine-mediated regulation of monocyte/macrophage cytotoxicity in human immunodeficiency virus-1 infection

Monocyte/macrophage-mediated tumor cytotoxicity was studied in patients infected with human immunodeficiency virus-1 (HIV-1) at various stages [Center for disease control (CDC) classification] of the disease. using the P-815 tumor cell line as target cells, the results demonstrated reduced monocyte/macrophage cytotoxicity early in HIV-1-related disease (CDCIII, P < 0.01). This cellular dysfunction sustained during the progression of the disease. Evidence could be presented that neither exogenous application of macrophage-stimulating cytokines (e.g. interferons) nor their endogenous induction in vitro restored monocyte/macrophage cytotoxicity. However, enhanced tumor necrosis factor (TNF)-alpha production, which parallels the observed reduced capacity to lyse P-815 tumor cells, might be the major source for monocyte/macrophage-mediated cell lysis. TNF-alpha-induced cytotoxicity can be inhibited by addition of anti-TNF-alpha. Other experimental models using TNF-sensitive tumor target cells may, therefore, mimic monocyte/macrophage-mediated lysis. Suppression of monocyte/macrophage cytotoxicity in later stages of HIV-1 infection (AIDS-related complex, AIDS) could partly be reverted by treatment with the cyclooxygenase blocker, indomethacin. The responsible arachidonic acid product mediating suppression was found to be prostaglandin E2, suggesting that in addition to the direct viral interference cellular dysfunction is at least in part a result of altered cytokine regulation.

Macrophage-tropic human immunodeficiency virus isolates from different patients exhibit unusual V3 envelope sequence homogeneity in comparison with T-cell-tropic isolates: definition of critical amino acids involved in cell tropism

Previous experiments indicate that the V3 hypervariable region of the human immunodeficiency virus (HIV) envelope protein influences cell tropism of infection; however, so far no consistent V3 sequence can account for macrophage or T-cell tropism. In these experiments, we studied infectious recombinant HIV clones constructed by using V3 region sequences of HIV isolates from 16 patients to search for sequences associated with cell tropism. Remarkable homology was seen among V3 sequences from macrophage-tropic clones from different patients, and a consensus V3 region sequence for patient-derived macrophage-tropic viruses was identified. In contrast, V3 sequences of T-cell-tropic clones from different patients were highly heterogeneous, and the results suggested that sequence diversity leading to T-cell tropism might be generated independently in each patient. Site-specific mutations identified amino acids at several positions on each side of the GPGR motif at the tip of the V3 loop as important determinants of tropism for T cells and macrophages. However, a wide variety of mutant V3 sequences induced macrophage tropism, as detected in vitro. Therefore, the homogeneity of macrophage-tropic patient isolates appeared to be the result of selection based on a biological advantage in vivo.

The neuropathology of pediatric acquired immunodeficiency syndrome

Central nervous system disease has emerged as an important manifestation of acquired immunodeficiency syndrome in both the adult and pediatric populations, with neurologic abnormalities occurring in up to 90% of pediatric patients in some series. Neuropathologic studies, based primarily on the autopsy, have provided valuable insights into the spectrum and pathogenesis of acquired immunodeficiency syndrome-associated neurologic disorders, including primary human immunodeficiency virus encephalopathy and as the spectrum of infectious, neoplastic, and cerebrovascular diseases that may complicate the course of acquired immunodeficiency syndrome. Progressive encephalopathy represents the single most common neurologic disorder in pediatric acquired immunodeficiency syndrome and appears to be caused in most cases by direct infection in brain parenchyma by human immunodeficiency virus. Central nervous system lymphoma and cerebrovascular disease continue to account for most focal central nervous system lesions in the pediatric population. In contrast to adults with acquired immunodeficiency syndrome, opportunistic central nervous system infections remain relatively uncommon in the pediatric population. Our understanding of acquired immunodeficiency syndrome-associated neurologic disease remains far from complete. A plea is made for regular postmortem examination of the central nervous system in all patients dying with human immunodeficiency virus infection.

Neuropathology of the spinal cord in the acquired immunodeficiency syndrome

The neuropathologic findings in the spinal cord were reviewed in 138 consecutive autopsies of patients with the acquired immunodeficiency syndrome. In all cases both the brain and spinal cord were examined by conventional histologic techniques, and in 63 cases immunohistochemistry was used to detect human immunodeficiency virus (HIV), Toxoplasma gondii, cytomegalovirus, and JC papovavirus antigens. The most common observation was a normal spinal cord (60%). Vacuolar myelopathy (VM) was observed in 23 (17%) cases. Human immunodeficiency virus myelitis was evident in 8% of cases. Human immunodeficiency virus myelitis was associated with HIV encephalitis in 65% of the cases. Opportunistic infections of the spinal cord were uncommon, consisting of cryptococcosis (five cases), cytomegalovirus (four cases), toxoplasmosis (one case), and progressive multifocal leukoencephalopathy (one case), and almost always were seen with cerebral and/or systemic infection by these agents. Malignant lymphoma rarely involved the spinal cord (four cases); all were B-cell lymphomas and were associated with cerebral and/or systemic lymphoma. Other abnormalities rarely observed were Wallerian degeneration of the corticospinal tracts or posterior columns (6%) and focal microinfarcts. Most cases of VM (78%) were not associated with HIV myelitis, and in the five patients with both VM and HIV myelitis, HIV-infected cells were not found in the regions affected by VM. In contrast, 65% of cases with VM were associated with HIV encephalitis. The pathogenesis of VM remains unknown; it is probably not due to direct infection by HIV.

Spectrum of human immunodeficiency virus-associated neocortical damage

A spectrum of neurocognitive defects, termed human immunodeficiency virus type 1 (HIV-1)-associated cognitive/motor complex, has been described in patients with acquired immunodeficiency syndrome (AIDS). AIDS dementia complex (ADC) is a severe form of this disease seen in 20 to 30% of terminally ill patients. The etiology of this complex is distinct from commonly observed opportunistic infections seen in brains of patients with AIDS and has been attributed to HIV infection within the brain. At autopsy, the brains of patients with ADC contain numerous HIV-infected macrophages/microglia with prominent subcortical damage, together termed HIV encephalitis. We retrospectively analyzed all 107 brains from a three-year period (1988-1990) of AIDS autopsies using immunocytochemistry to detect HIV. Rather than breaking into distinct groups of HIV encephalitis versus non-HIV encephalitis, the specimens revealed a spectrum of severity of HIV infection. Although only 16% of the brains showed the histological hallmarks of HIV encephalitis, more than 50% of the autopsies showed moderate to severe HIV infection. In a subset of 23 AIDS autopsies during which short postmortem times and absence of significant opportunistic infection permitted quantitative analysis of dendritic and synaptic complexities, we identified a strong correlation between neocortical dendritic and presynaptic damage and abundance of HIV envelope protein in the neocortical gray and deep white matter. This correlation suggests that the presence of HIV-1 in the neocortex may be responsible by direct or indirect mechanisms for dendritic and synaptic damage.

Infrequent detection of HIV-1 components in tears compared to blood of HIV-1-infected persons

Beside the risk of infection via HIV-1-contaminated blood, ophthalmologists are especially interested in the possibility of HIV-1 infection via tears. Therefore we tried to isolate HIV-1 from tears of 50 HIV-1-infected persons in different stages of disease by reverse transcriptase (RT) and by p24-antigen (p24-AG) in the cultures. Simultaneously we tried to isolate HIV-1 in the supernatant from peripheral blood lymphocytes (PBL), which was successful in 32 of the 50 examined specimens. HIV-1 could not be isolated from the tears of these persons. In addition, polymerasechain-reaction (PCR) was performed to detect proviral sequences (gag, pol, env) of HIV-1 in tears and blood of ten HIV-1-infected patients. While in all the examined patients gag, pol and env could be detected in the blood samples, only one tear sample was found positive for gag and pol DNA fragments. These results indicate that tears of HIV-1-positive contain extremely low quantities of tissue culture infectious doses (TCID) of HIV-1 in contrast to PBL. HIV-1 infection via tears therefore appears to be unlikely.

Acquired immunodeficiency syndrome and the child's central nervous system

Human immunodeficiency virus-1 (HIV-1) associated central nervous system disease may complicate the course of HIV-1 infection in infants and children. Neurologic dysfunction in these young patients adds significantly to the morbidity of the disease and is often a devastating complication. It is apparent that HIV-1 infection in infants and young children is complicated by numerous developmental parameters. The developmental stage of the nervous and immune systems when exposed to the virus is likely to interact in complex ways with HIV-1 variables. In order to care for these children and to design rational approaches for treatment and prevention, it is now critical to develop a better understanding of how HIV-1 affects the developing nervous system.

Human immunodeficiency virus type 1 is present in the cerebrospinal fluid of a majority of infected individuals

Cerebrospinal fluid (CSF) specimens from 63 patients with different severities of human immunodeficiency virus (HIV-1) infection, including asymptomatic virus carriers, were examined for the presence of HIV-1 by using polymerase chain reaction (PCR) and virus isolation. Polyadenylated RNA, presumably associated with virus particles, was extracted and reverse transcribed, and the pol region was amplified in a nested PCR. Virus could be detected in 90% of the CSF specimens examined by PCR, and data on isolation of virus from CSF were in agreement with these figures. In fact, when several CSF specimens from the same individual were studied, HIV-1 could be isolated from 80% of the patients. The presence of the viral RNA in CSF was independent of the clinical stage of infection and of neurological symptoms. These results show that the spread of HIV-1 to the brain represents an early event during infection and occurs in the majority of asymptomatic individuals.

The pathology of the posterior root ganglia in AIDS and its relationship to the pallor of the gracile tract

The spinal cord and the thoracic and lumbar posterior root ganglia (PRGs) of 14 HIV-positive men and 7 age- and sex-matched controls were studied by routine histology, morphometric analysis of the number of nodules of Nageotte (nN) and the diameters of sensory ganglion cells, immunohistochemistry and in situ hybridization. In 7 patients (2 of whom had evidence of cytomegalovirus ganglionitis) there were increased numbers of nN and diffuse, mild infiltration with CD45R+ T lymphocytes; no B lymphocytes were observed. Macrophages were increased in number in all cases. Whenever more than one ganglion was examined from the same patient, the appearances were similar in all. There was no alteration in the distribution of ganglion cell diameters. Changes in the spinal cord included vacuolar myelopathy (5 cases), HIV myelitis (1 case), microglial nodules (3 cases) and pallor of the gracile tracts (GTP) in 7 cases, in 6 of whom it co-existed with increased numbers of nN. Seven cases had no abnormalities, except the increase in number of macrophages in PRGs. In spite of a correlation between sensory nerve cell loss and GTP our findings suggest that other mechanisms, such as 'dying back' may contribute to the pathogenesis of GTP. Moreover, sensory disturbances were found most commonly in association with nerve cell loss; however, loss of sensory ganglion cells was not necessarily associated with evidence of sensory impairment.

Neuropsychopathology of HIV/AIDS

Most, if not all, patients with HIV/AIDS experience significant problems in adjusting to a probably fatal illness and require psychological or psychiatric assistance. This places an enormous neuropsychiatric burden on the psychiatric services.

Diagnostic accuracy of AIDS-related CNS lesions

Because of the high incidence of neurological complications seen in patients with acquired immunodeficiency syndrome (AIDS), an increasing number of these cases are being referred to neurosurgeons for consideration of intracranial biopsy. To better determine the need for biopsy in these patients we evaluated the accuracy of non-tissue-based neurological diagnoses in AIDS patients who subsequently had a final diagnosis on the basis of biopsy or postmortem brain examinations. The records of 56 AIDS patients who had undergone either autopsy or brain biopsy were retrospectively reviewed. Of the ten patients who underwent biopsy, three were found to have a lesion that was different from the suspected diagnosis and that resulted in a change in treatment. Thirty patients with neurological symptoms had postmortem brain examinations. In the case of the 12 patients who had carried specific diagnoses and received treatments based on those diagnoses, only six diagnoses (50%) were proven correct at autopsy. Of the 18 cases that did not record a specific antemortem diagnosis, in only 5 were normal brains reported, while the others reported a variety of nonspecific or infectious findings. Twelve patients without neurological symptoms had postmortem brain examinations and only six of these (50%) had normal or slightly atrophic brains. Case reports of the others noted nonspecific findings most of which were suggestive of subacute HIV encephalitis. The poor rate of diagnostic accuracy in this series suggests that biopsy should be considered for atypical lesions or those that do not respond to empiric therapy. The use and relative sensitivities of various diagnostic studies are also discussed.

Detection of human immunodeficiency virus type 1 (HIV-1) in urine cell pellets from HIV-1-seropositive individuals

Fresh urine pellets from human immunodeficiency virus type 1 (HIV-1)-seropositive individuals were examined for the presence of the HIV-1 genomic sequence and gene products. By using the polymerase chain reaction technique, HIV-1 DNA proviral sequences were detected in 53 of 80 (66.25%) fresh urine pellets from HIV-1-seropositive individuals, while urine pellets from all 24 healthy heterosexual controls were negative. HIV-1 RNA in urine pellets was detected by reverse transcriptase polymerase chain reaction in 2 of 43 (4.7%) HIV-1-seropositive individuals. In addition, HIV-1 p24 core antigen was demonstrated in 3 of 80 urine pellets from HIV-1-seropositive individuals by enzyme-linked immunosorbent assay. Moreover, HIV-1 p24 core antigen and HIV-1 RNA were shown in the cellular component of urine pellets from HIV-1-seropositive individuals by immunohistochemical staining and in situ hybridization. These results indicate that HIV-1 can be present in urine pellets from HIV-1-infected individuals.

Cytokine expression in the brain during the acquired immunodeficiency syndrome

The pathogenesis of central nervous system (CNS) disease in acquired immunodeficiency syndrome (AIDS) is poorly understood but may be related to specific effects of the immune system. Cytokines such as tumor necrosis factor and interleukin-1 may have toxic effects on CNS cells and have been postulated to contribute to the pathogenesis of the neurological complications of human immunodeficiency virus (HIV) infection. To characterize viral and immunological activity in the CNS, frozen specimens taken at autopsy from the cerebral cortex and white matter of HIV-seropositive and -seronegative individuals were stained immunocytochemically for mononuclear cells, major histocompatibility complex (MHC) antigens, HIV, astrocytes, and the cytokines interleukin-1 and -6, tumor necrosis factor-alpha and -beta, and interferon gamma. Levels of soluble CD4, CD8, and interleukin-2 receptor, as well as interferon gamma, tumor necrosis factor-alpha, beta 2-microglobulin, neopterin, and interleukin-6 and -1 beta were assayed in the cerebrospinal fluid and plasma of many of these individuals during life. The HIV-seropositive group included individuals without neurological disease, those with CNS opportunistic infections, and those with HIV encephalopathy. Perivascular cells, consisting primarily of macrophages with some CD4+ and CD8+ T cells and rare B cells, were consistently MHC class II positive. MHC class II antigen was also present on microglial cells, which were frequently positive for tumor necrosis factor-alpha. HIV p24 antigen, when present, was found on macrophages and microglia. Endothelial cells were frequently positive for interleukin-1 and interferon gamma and less frequently for tumor necrosis factor and interleukin-6. There were gliosis and significant increases in MHC class II antigen, interleukin-1, and tumor necrosis factor-alpha in HIV-positive patients compared to HIV-negative brains. Cerebrospinal fluid from most of the patients tested had increased levels of tumor necrosis factor, beta 2-microglobulin, and neopterin. There was no correlation in HIV-positive individuals between levels of cytokines and the presence or absence of CNS disease. These data indicate that there is a relative state of "immune activation" in the brains of HIV-positive compared to HIV-negative individuals, and suggest a potential role for the immune system in the pathogenesis of HIV encephalopathy.

Auditory function in patients infected with the human immunodeficiency virus

A prospective study of auditory function in 18 HIV positive male patients at different CDC (Centres for Disease Control) stages was undertaken. One-third had abnormalities on either auditory evoked response testing or pure tone audiometry. No correlation was found between interwave latencies I-V, I-III, III-V and stage of disease determined either clinically or by T-cell subset. There was a weak correlation between pure tone averages at 1,2,4 kHz and 2,4,8 kHz and T-cell subset ratio in CDC Group IV disease (Rs = 0.56 and 0.57 respectively; P less than 0.05). Abnormalities of BSER were similar to those previously reported in HIV infection, and suggest isolated changes within the brain-stem.

Early signs of cognitive deficits among human immunodeficiency virus-positive hemophiliacs

A total of 181 human immunodeficiency virus (HIV)-seropositive hemophiliacs and 28 hemophilic controls were evaluated by psychometric tests and by electroencephalogram (EEG). Patients were classified from stages 1-6 according to the immunological criteria of the Walter Reed staging system. Statistical analysis of psychometric data showed an effect of the stage of the disease on test performances, indicating a decline in attention, accumulation of perceptual interferences, decline in visuoperceptual speed and visuomotor response speed and reduced verbal memory performance, especially in stage 6 patients. Comparison of performance levels with normative test data already revealed cognitive deficits in about 20-30% of the patients in stages 2-5. As regards verbal memory, especially learning and recognition of new verbal information were impaired. In contrast, there was no significant deficit for nonverbal memory processing. Compared with the controls, patients exhibited an increasing number of abnormal EEG findings in stages 2-6. As a conclusion, in the stages before acquired immunodeficiency syndrome (AIDS) develops, EEG findings as well as psychometric findings indicate central nervous system involvement of AIDS in about 20-30% of cases, whereas in full-blown AIDS there is a marked increase to 80%. Besides a more general deficit of attention and psychomotor speed as is seen in subcortical dementia, there is evidence for a particular verbal learning disorder, suggesting additional selective impairment of the brain.

[Electromyographic, histoenzymologic and immunocytochemical aspects of affected muscles in HIV infection. Observations of five cases]

In 5 acquired-immunodeficiency syndrome (AIDS) cases without peripheral neuropathy, we observed myogen clinical signs (diffuse amyotrophy of lower limbs or cramps) or an isolated increase in seric enzyme (LDH, CK). EMG abnormalities were observed in all cases: spontaneous activities (fibrillations and positive sharp waves) in 5 cases, myogenic signs in 2 case. Muscular biopsies were normal in 3 cases and showed myopathic changes in 1 case and polymyositis in another case. Antidystrophin and antilaminin antibodies reactions were altered in 1 case. The spontaneous activities together with these modifications could be in favour of a lesion at the membrane level.

Development and characterization of a whole-cell radioligand binding assay for [125I]gp120 of HIV-1

The binding of HIV-1 envelope glycoprotein, gp120, to the CD4 receptor is an important step in productive infection. The development of agents which interrupt this binding phenomenon should be of therapeutic interest. The present study characterizes a whole cell gp120/CD4 radioligand binding assay (radioligand binding assay) modified for use in a high volume screening format. Modifications include the use of human CD4 receptor stably expressed in a Chinese hamster ovary cell line and the gentle fixation (paraformaldehyde) of the CD4 receptor just prior to assay. Binding of [125I]gp120 to fixed CD4 was of high affinity (KD = 6 nM), saturable, reversible, and specific. The kinetics of binding were identical to those of viable (non-fixed) CD4 receptor. [125I]gp120 binding was inhibited by unlabeled recombinant gp120, soluble CD4, and the anti-CD4 monoclonals OKT4A and LEU3A. A number of compounds reported to inhibit gp120 binding and/or gp120 induced syncytium formation were also active in this assay. This modified radioligand binding assay was developed to initiate a rational and extensive screening program to assist in the identification of potential chemotherapeutic agents based on their ability to inhibit gp120 binding to host cells.

Neurological and neuropsychological performance in HIV seropositive men without symptoms

Ninety five HIV seropositive and 32 seronegative homosexual men were recruited to a prospective study of the early features and natural history of the neurological manifestations of HIV infection. There was no evidence from the initial neurological examination, a neuropsychological test battery, nerve conduction studies, somatosensory evoked potentials from the legs, P300 event related auditory evoked potentials, magnetic stimulation of the motor cortex, or MRI scans that HIV infected men without symptoms in CDC groups II/III differed significantly from a well matched seronegative comparison group. Only the subgroup in CDC IV showed evidence of impairment, and this was restricted to their performance on some of the cognitive tests. The results imply that, despite early invasion of the CNS by HIV, major disturbances of function manifest themselves only when the patient becomes immunosuppressed. The importance of an appropriate comparison group and awareness of the potentially confounding influences such as age, education, exposure to alcohol and drugs, and mood and anxiety in such studies is stressed. The essentially negative findings are important in the understanding of the pathogenesis of neurological effect in HIV infection and in the design and interpretation of therapeutic trials.

Sensitive microculture method for isolation of human immunodeficiency virus type 1 from blood leukocytes

A study was conducted to compare our standard culture with a new microculture procedure for isolation of human immunodeficiency virus type 1 (HIV-1) from blood leukocytes. A total of 137 blood specimens from 102 HIV-1 antibody-positive individuals (52 were asymptomatic, 31 were symptomatic, and 19 had AIDS) were cultured in a microculture system in which 10(6) of the patients' peripheral blood mononuclear cells (PBMC) were cocultured with 10(6) phytohemagglutinin (PHA)-stimulated PBMC from an HIV-1 antibody-negative blood donor in 1.2 ml of culture medium. Results were compared with those of a historical control group of 139 standard HIV-1 cultures from 108 HIV-1 antibody-positive subjects (58 were asymptomatic, 36 were symptomatic, and 14 had AIDS). For standard cultures, 10 x 10(6) of the patients' PBMC were cocultured with 5 x 10(6) PHA-stimulated PBMC from an HIV-1 antibody-negative blood donor in 15 ml of culture medium. HIV-1 was isolated in 128 (93%) microcultures and 133 (96%) standard cultures. Both methods identified more than 75% of the positive cultures within 7 days and 100% of the positive cultures within 14 days. The isolation rates for HIV-1 in microcultures compared with standard cultures were 91 versus 93% (specimens from asymptomatic individuals), 93 versus 96% (specimens from symptomatic individuals), and 97 versus 100% (specimens from patients with AIDS). The median time to positivity for both culture methods was 7 days, and this correlated significantly with symptoms and CD4+ cell counts. The microculture method is a sensitive and less expensive system for isolation of HIV-1 from PBMC of HIV-1 antibody-positive individuals, and we recommend it as the culture method of choice, especially for children and patients with AIDS and severe anemia or leukopenia whose blood volume is an important consideration.