Intra-blood-brain-barrier synthesis of HTLV-III-specific IgG in patients with neurologic symptoms associated with AIDS or AIDS-related complex

Soluble class 1 antigens (sHLA) in CSF and serum of patients with HIV infection

sHLA are secreted by B and T lymphocytes upon activation. These antigens are present in serum and cerebrospinal fluid (CSF). The establishment of a sHLA index, IH = (CSF sHLA/serum sHLA)/(CSF albumin/serum albumin) helped us to define that values above 9.7 reflect an intrathecal synthesis of these proteins. IH was significantly increased in a group of patients with intrathecal production of IgG against HIV-1 (HIV) and directly correlated with the synthesis of such antibodies. Therefore, IH seems to be an index of lymphocyte activation in CNS.

Electroencephalogram and HIV infection: a prospective study in 100 patients

In order to study the correlation between central nervous system (CNS) involvement and EEG abnormalities in HIV infection we studied 100 consecutive HIV patients. Patients were divided into 4 groups; Group I: 42 neurologically asymptomatic subjects; Group II: 6 patients with peripheral neuropathies; Group III: 28 patients with AIDS Dementia Complex; Group IV: 24 patients with secondary CNS involvement. The results of this study emphasize that abnormal EEGs are correlated with CNS involvement. Neurologically asymptomatic patients showed no abnormal tracings, but the presence of borderline EEGs (33%) in asymptomatic patients should be evaluated prospectively.

Evaluation of a human immunodeficiency virus test algorithm utilizing a recombinant protein enzyme immunoassay

Many truly human immunodeficiency virus (HIV) antibody-negative serum samples may be unnecessarily subjected to costly and time-consuming Western blots (immunoblots). An investigation was undertaken to evaluate the efficiency of using a recombinant protein-based enzyme immunosorbent assay (EIA; Cambridge BioScience [CBC] Recombigen HIV EIA) as an adjunct to whole viral lysate EIA. A total of 2,212 serum samples which had been screened by viral lysate EIA were tested by CBC EIA in parallel with the Western blot. The sensitivity and specificity of the CBC kit were 99.9 and 99.7%, respectively. Positive and negative predictive values were 99.7 and 99.9%, respectively. The high sensitivity of this kit and its high negative predictive value make it an attractive addition to an HIV testing algorithm by reducing the number of Western blot tests on truly antibody negative serum samples.

Biopsychosocial approach to the human immunodeficiency virus epidemic. A clinician's primer

The human immunodeficiency virus (HIV) epidemic has created a multidimensional crisis that is challenging the health care system. Individuals with or without risk behaviors have anxieties about acquired immunodeficiency syndrome (AIDS) and need support and counseling. Once symptoms of HIV infection develop, crisis intervention and support need to be integrated into ongoing medical care. A biopsychosocial approach enables persons with AIDS to develop strategies for coping, to improve adherence, and to prevent transmission and suicide. Persons with AIDS are confronted with severe illnesses, neuropsychiatric disorders, discrimination, and death. Each person deserves the best medical and psychologic care available and the services of other disciplines where indicated. Caregivers, anxious about contagion, are devastated by the complexity, severity, and multiplicity of the illnesses that comprise AIDS and the lack of adequate resources to combat the epidemic. AIDS is a paradigm of a medical illness that requires a biopsychosocial approach. Psychiatric sequelae complicate the HIV epidemic, affecting both the uninfected and infected. The psychiatric manifestations of the uninfected include anxiety, phobia, factitious disorder, delusions, and Munchausen's AIDS. Psychiatric disorders associated with HIV infection include organic mental disorders, substance abuse disorder, affective disorders, adjustment disorders, anxiety disorders, and personality disorders. The consultation-liaison (C-L) psychiatrist is in a unique position to clarify and treat the psychiatric complications and to provide leadership for multidisciplinary programs. The biopsychosocial approach enables persons with HIV infection, their loved ones, and caregivers to meet the challenges of the HIV epidemic with compassion, optimism, and dignity.

Mechanisms of infectivity and replication of HIV-1 and implications for therapy

Human immunodeficiency virus type 1 (HIV-1), a retrovirus, is the etiologic agent of AIDS. Like all retroviruses, the viral genes are carried in the viral particle in the form of single-stranded RNA. Once inside a susceptible host cell, this RNA template is reverse-transcribed by virally supplied enzyme functions into a DNA copy, which becomes integrated permanently into the host's own genetic material. The genome of HIV-1, comprising approximately 10,000 bases, is much more complex than those of classic retroviruses, encoding a minimum of six gene products in addition to the gag, pol, and env genes characteristic of all retroviruses. These genes encode regulatory functions that act at diverse points in the virus life cycle. Together, they provide HIV-1 with an exceptional ability to modulate its replication depending on its host environment. This characteristic is reflected in the different stages presented by the disease and the diverse behaviors of the virus in different types of host cells. A greater understanding of the mechanics of this regulation and the factors that influence it may someday permit therapeutic intervention in the disease process that will halt virus replication and the progression of pathology in infected individuals.

CD4-independent, productive infection of a neuronal cell line by human immunodeficiency virus type 1

One neuronal cell line (SK-N-MC) was found to be susceptible to productive infection by multiple isolates of the human immunodeficiency virus type 1 (HIV-1). Characterization of SK-N-MC cells showed that these cells are neuroectodermal in origin in that they express dopamine hydroxylase, catecholamines, neuron-specific enolase, and neurofilaments. Despite their susceptibility to HIV-1 infection, SK-N-MC cells had no detectable CD4 and this infection was not blocked by anti-CD4 monoclonal antibodies (OKT4A, Leu3A) or recombinant soluble CD4. These experiments demonstrated that certain cells of neuroectodermal origin are susceptible to infection in vitro by HIV-1 via a CD4-independent mechanism.

Older adults as an HIV-positive risk group

When older adults are admitted to the hospital, they are usually admitted with multiple diagnoses and are not usually considered to be at risk for HIV infection. The review of hospital records discussed in this article documents that people over 60 years of age are indeed infected with HIV and that 42% of the population studied were in the age range of 70 to 100 years. The review of hospital records documented that people over 60 years of age and older fell into the same high risk populations as did people from any other age group. Gerontological nurses must be informed about the methods of prevention, expected course of infection, response to treatment, and effective ways to implement nursing care for older adults who are HIV positive.

Multimodal evoked potentials in HIV infected patients

We studied 126 HIV seropositive patients (106 men, 20 women; mean age: 32 years): 45 had neurological signs, 81 had none. Multimodal evoked potential (MEP) assessment included: visual EPs by flash and reversal checkerboard; brain-stem auditory EPs; somatosensory EPs by stimulation of the median nerve. Evaluation also included: electroencephalography, electromyography with measurement of conduction velocities, neuroimaging (CT scan and MRI). We found abnormal MEPs for all modalities. The prevalence of abnormal results was high in neurologically symptomatic patients; in non-neurological subjects, the changes were more dramatic as HIV infection progressed. Whatever the stage of the disease, the modalities were equally affected. MEPs were abnormal in 54.7% of patients: in 41.8% of those without neurological signs vs. 85.7% of those with these signs. Comparison of MEPs and other electrophysiological procedures and neuroimaging techniques showed the high sensitivity of MEPs at all stages of the disease. EMG was sensitive and complementary to MEPs. EEG and neuroimaging showed abnormalities principally at the neurological symptomatic stage. Our results agree with those found in the literature. Abnormal MEPs may: (1) indicate latent neurological involvement of the visual, auditory and somatosensory pathways, (2) help diagnose an encephalitis suspected on neuropsychological, non-quantifiable testing.

Human immunodeficiency virus: infection of the nervous system

Cynics would say it has taken the scientific community a long time to achieve very little progress in our understanding of HIV-mediated CNS damage. We cannot yet say with surity how neuronal function is affected. However, when viewed through the perspective that retroviral diseases of the human nervous system are newly recognized diseases, significant progress has been made in the 3 years since HIV infection was noted within the CNS. We have a lot to learn about how retroviruses damage the CNS, but at least the questions are better defined.

Antibody specificity for human immunodeficiency virus type 1 in serum and cerebrospinal fluid from patients with AIDS and AIDS-related complex

Since little information has been reported about the specificity of antibodies to human immunodeficiency virus type 1 (HIV-1) found in the cerebrospinal fluid (CSF), 21 CSF and serum specimens were examined from 19 patients with clinical AIDS, AIDS-related complex, or asymptomatic HIV-1 infection. The predominant specificity of antibodies using Western blot analysis in both serum (100%) and CSF (100%) was directed toward env gene products. The next most common antibody specificities were to the pol gene products (serum 95%; CSF 62%). Less commonly found was antibody to the gag-encoded proteins (serum 71%; CSF 38%). The level of antibody to HIV-1 in CSF could not be predicted from the level found in serum. Also, the spectrum of antibodies seen did not correlate with disease stage or with the quantity of antibody present. The serum/CSF pairs were also examined for the presence of HIV-1 antigen by commercial enzyme immunoassay. HIV-1 antigen was present in eight of 19 (43%) of the serum samples and five of 20 (25%) of the CSF samples tested.

Transient expression of human immunodeficiency virus type 1 genome results in a nonproductive infection in human fetal dorsal root ganglia glial cells

Human immunodeficiency virus type 1 (HIV-1), the etiologic agent of acquired immunodeficiency syndrome (AIDS), has been implicated in the generation of AIDS-associated neurologic dysfunction. We are currently examining the replicative processes involved in HIV-1 infection of selected human fetal neural cell populations in vitro. To determine whether infection of the human fetal dorsal root ganglia (DRG) glial cell population culminates in the production and release of infectious HIV-1, cocultivation and reverse transcriptase (RT) assays were performed. Direct assay of HIV-1 infected neural cell supernatants as well as exposure of permissive SupT1 cells to these HIV-1-infected neural cell supernatants detected no RT activity in either the HIV-1-infected DRG glial cell supernatants or the SupT1 cell supernatants. When SupT1 cells were cocultivated with the HIV-1-infected neural cells for 24-hr intervals, RT activity was detected in the SupT1 supernatants from cocultures initiated less than 2 days after infection (most likely resulting from infectious input virus) but not from cocultures initiated on 3, 5, 10, and 30 days after infection. Hybridization analysis demonstrated transient expression of HIV-1 cytoplasmic mRNA with accumulation reaching a maximum level by 2 to 3 days postinfection, declining thereafter with low, but detectable, levels at 16 days postinfection. In addition, polymerase chain reaction amplification in conjunction with DNA blot hybridization detected HIV-1-specific proviral DNA at 3 days postinfection. Cumulatively, these data suggest that HIV-1 infection of human fetal DRG glial cells culminates in a nonproductive infection with expression of at least a fraction of the virus genome but no detectable infectious virus production.

HIV-1-specific antibodies in cerebrospinal fluid mediate cellular cytotoxicity and neutralization

Antibodies mediating HIV-1-specific cellular cytotoxicity (ADCC) and virus neutralizing activity were detected in the cerebrospinal fluid (CSF) and, as previously reported, in sera of subjects with varying severity of HIV-1 infection, including patients with or without neurologic or psychiatric symptoms. ADCC-mediating antibodies against target cells infected with the HTLV-IIIB strain of HIV-1 were less frequently present in CSF than in sera, 32 and 60%, respectively. The frequency of ADCC-positive CSF was comparable for the different clinical stages of the disease and was apparently not influenced by the presence or absence of neurologic/psychiatric symptoms. Virus-neutralizing activity was tested against HTLV-IIIB and one CSF-derived viral isolate. Serum antibodies neutralized HTLV-IIIB more frequently than the CSF isolate, 53 and 35%, respectively. In contrast, only three (7%) of the CSF specimens contained neutralizing activity to the CSF-derived isolate and none to HTLV-IIIB. Despite an intact blood-brain barrier in many subjects, the serum/CSF ratios of ADCC or neutralizing antibodies were lower than normally expected. This indicates that both ADCC-mediating and virus neutralizing antibodies may be intrathecally synthesized. Whether these antibodies are protective against or contribute to the histopathologic changes in the brain is not known at present.

Infection of human fetal dorsal root ganglion glial cells with human immunodeficiency virus type 1 involves an entry mechanism independent of the CD4 T4A epitope

Human immunodeficiency virus type 1 (HIV-1) has been implicated in the generation of acquired immunodeficiency syndrome-associated neurological dysfunction, and it is believed that the presence of CD4 in the nervous system may be involved in the susceptibility of selected neural cell populations to HIV-1 infection. We previously demonstrated (B. Wigdahl, R. A. Guyton, and P. S. Sarin, Virology 159:440-445, 1987) that glial cells derived from human fetal dorsal root ganglion (DRG) are susceptible to HIV-1 infection and subsequently express at least a fraction of the virus genome. In contrast to HIV-1 infection of CD4+ lymphocytes, which can be blocked by treatment with monoclonal antibodies directed against the HIV-1-binding region of CD4 (T4A epitope), treatment of human fetal DRG glial cells with similar antibodies resulted in only a slight reduction in HIV-1-specific gag antigen expression. In addition, preincubation of the HIV-1 inoculum prior to infection with HIV-1-neutralizing antiserum did not reduce HIV-1 gag antigen expression in these cells. Furthermore, we were unable to detect the synthesis or accumulation of the CD4 molecule in neural cell populations derived from DRG. However, a protected CD4-specific RNA fragment was detected in RNA isolated from human fetal DRG and spinal cord tissue by an RNase protection assay with a CD4-specific antisense RNA probe. RNA blot hybridization analysis of total cellular RNA isolated from human fetal DRG and spinal cord demonstrated specific hybridization to an RNA species that comigrated with the mature 3.0-kilobase CD4 mRNA as well as two unique CD4 RNA species with relative molecular sizes of approximately 5.3 and 6.7 kilobases. Furthermore, all three CD4-related RNA species were polyadenylated when isolated from human fetal spinal cord tissue. These data suggest that HIV-1 infection of human fetal DRG glial cells may proceed via a mechanism of viral entry independent of the T4A epitope of CD4.

Sudden sensorineural hearing loss as a presentation of HIV infection

Two case reports of HIV positive patients presenting with sudden sensorineural hearing loss are described. The importance of CT scanning and cerebrospinal fluid examination are stressed. The possible aetiology and pathology of the condition are also discussed.

Low prevalence of neurological and neuropsychological abnormalities in otherwise healthy HIV-1-infected individuals: results from the multicenter AIDS Cohort Study

Accurate description of the prevalence of neurological impairment in healthy individuals who are infected with human immunodeficiency virus type 1 (HIV-1) has relevance for public health policy, for employment issues, and for planning future health needs. Within the Multicenter AIDS Cohort Study, we determined the cross-sectional prevalence of neurological abnormalities in 270 HIV-1 seropositive homosexual and bisexual men in Centers for Disease Control Groups II and III, using a control group of 193 HIV-1 seronegative homosexual men. Utilizing a neurological and neuropsychological screening battery, we found no differences in the prevalence of neuropsychiatric symptoms or in neuropsychological performance. One hundred nineteen subjects with abnormalities on screening tests completed additional neuropsychological testing and had neurological examinations. The majority had normal results and the frequency of neurological abnormalities and impaired neuropsychological performance was not significantly increased among HIV-1 seropositive subjects. Most of the abnormalities could be attributed to causes other than HIV-1. One subject had mild HIV-1-related dementia, yielding a prevalence of 3.7:1,000 (95% confidence interval: 0.19-23.7:1,000). Magnetic resonance imaging demonstrated sulcal prominence and focal areas of high signal intensity in white matter in 63% of HIV-1 seropositive subjects and 48% of uninfected control subjects. Abnormalities in cerebrospinal fluid were noted in 23 (85%) of 27 HIV-1-infected individuals. Our studies indicate that the prevalence of dementia and other HIV-1-related neurological disorders is very low among healthy HIV-1 seropositive homosexual men. The confounding effects of factors such as substance abuse or preexisting medical conditions must be considered in the neurological evaluation of such patients.

AIDS peripheral neuropathy

A young male IV drug abuser with multiple AIDS risk factors and positive HIV serology presented with acute onset of painful urinary retention as a result of a parasympathetic mononeuropathy. Because no other explanation could be found for his illness, despite a careful search for the most likely etiologic agents, the authors propose that his symptom complex may have resulted from infection with the AIDS virus. A review of the current literature relevant to the peripheral neuropathy associated with AIDS is presented.

Neuropsychological performance in HIV-1 immunocompromised patients: a preliminary report

This study examined the pattern of neuropsychologic abnormalities in three groups of subjects: 20 patients diagnosed with Acquired Immunodeficiency Syndrome (AIDS); 14 patients diagnosed with AIDS Related Complex (ARC); and 13 seronegative controls. Subjects with past history of chronic substance abuse, neurologic disease, or focal findings on MRI or CT were excluded. All subjects were administered a comprehensive neuropsychological battery. Results revealed a pattern of preserved attention and concentration, language skills, and most visuospatial construction abilities in the presence of more notable deficits in nonverbal memory and speeded psychomotor tasks. Practical implications for the early detection of HIV-1 related cognitive dysfunction are addressed.

Intrathecal synthesis of virus-specific oligoclonal antibodies in patients with enterovirus infection of the central nervous system

Cerebrospinal fluid (CSF) and serum samples from six patients with enterovirus infections were investigated by isoelectric focusing (IEF) and affinity-mediated immunoblot AMI) for the clonal distribution of entervirus-specific antibodies. In two patients with either acute meningitis or encephalitis and in one patient with a relapse of multiple sclerosis, oligoclonal IgG bands specific for enteroviruses were found predominantly in the CSF, revealing intrathecal synthesis of these antibodies. In three other patients with neurological symptoms probably unrelated to a current enterovirus infection, IEF and AMI disclosed nearly identical patterns of coxsackievirus-B-specific oligoclonal bands in the CSF and serum, indicating diffusion of these antibodies from the serum into the CSF. Although the number of patients in this study is small, the results suggest that intrathecally synthesized enterovirus-specific antibodies may be used as a means of identifying an enterovirus infection of the CNS.

Mutational analysis of the human immunodeficiency virus vpr open reading frame

Mutations were introduced by recombinant DNA techniques into the vpr open reading frame of an infectious molecular clone of human immunodeficiency virus type 1. The effect of these changes on the replicative and cytopathologic properties of the virus recovered from transfected cells was studied in several human CD4+ lymphocyte cell lines. In all cases, mutant viruses were infectious and cytopathic. However, when a low-input dose was used, mutants grew significantly more slowly than the wild-type virus. The growth kinetics of vpr mutants were distinct from those of vif and vpu mutants.

HIV and the older adult taking the necessary precautions

1. With the awareness that the population of older adults with whom nurses and other health-care workers come in contact may indeed be HIV infected, the need for universal precautions becomes imperative in all health-care settings. 2. The subpopulations of older adults in which HIV infection is most likely to be concentrated are the same as those for any other age group; ie, homosexual and bisexual men, IV drug users and their partners, people who have received blood products, and sexual partners of people who are HIV infected. 3. It is important for nurses to recognize that older adults may be manifesting the signs of symptoms of AIDS; for example, some people diagnosed with Alzheimer's disease may actually have AIDS-related dementia. 4. Gerontological nurses need to be the initiators of implementing universal precautions in their health-care settings.

New approaches to the delivery of drugs to the brain

The Human Immunodeficiency Virus (HIV) is the causative agent of AIDS and this has been found to be neurotropic. For this reason the development of an effective strategy for the delivery of antiviral drugs across the blood-brain barrier is of paramount importance in the treatment of HIV infection. There are insulin receptors on the capillary endothelial cells making up the blood-brain barrier (BBB) and it is proposed that these may play a role, along with exogenously administered insulin, in enhancing the transport of drug molecules across the BBB. Evidence is presented showing that insulin may be used as a pharmacologic adjunct in the therapy of HIV infection by allowing for higher concentrations of antiviral drugs to be obtained within the CNS using lower total doses of drug. This would enhance the drug's therapeutic effectiveness while simultaneously obviating potential dose-related side-effects.

Human immunodeficiency virus type 1 (HIV-1) infection of the central nervous system: an evaluation of cytokines in cerebrospinal fluid

Cytokines play an important role not only for initiation of immune reactivity but also for development of tissue injury. Of 38 patients infected with human immunodeficiency virus type 1 (HIV-1) interleukin-1 beta (IL-1 beta) and interleukin-6 (IL-6) were identified in cerebrospinal fluid (CSF) of 22 (58%) and 16 (42%) patients, respectively. Among the IL-1 beta- and IL-6-positive CSF were eight of 15 HIV-1 patients with no clinical signs of central nervous system involvement and four of five patients with acquired immunodeficiency syndrome (AIDS) dementia complex. The presence of IL-6 was often associated with IL-1 beta and soluble interleukin-2 receptor in CSF as well as with intrathecal IgG synthesis. In none of the CSF samples tumor necrosis factor-alpha or interleukin-2 was detected.

Pharmacokinetics and saturable renal tubular secretion of zidovudine in rats

The purpose of this study was to assess the effects of dose on the pharmacokinetics of zidovudine (3'-azido-3'-deoxythymidine; AZT) in rats. Zidovudine (AZT) was administered intravenously at doses of 10, 50, 100, and 250 mg/kg. Plasma and urine AZT concentrations were determined by HPLC. Plasma AZT concentrations declined rapidly with a terminal half-life ranging from 0.76 h at a dose of 10 mg/kg to 1.58 h at 250 mg/kg. Total clearance (CLT) was similar at the doses of 10 and 50 mg/kg, with values of 2.80 and 2.73 L/h/kg, respectively. However, there was a trend toward nonlinearity at the dose of 100 mg/kg (CLT = 2.13 L/h/kg) and a significant decrease in CLT (1.22 L/h/kg) at the dose of 250 mg/kg. Nonrenal clearance remained unaffected by dose with a mean value of 0.98 L/h/kg. Renal clearance (CLR) was similar at the doses of 10 and 50 mg/kg, with values of 1.89 and 1.37 L/h/kg, respectively. However, significant decreases in CLR were observed at the doses of 100 (CLR = 1.30 L/h/kg) and 250 mg/kg (CLR = 0.57 L/h/kg). The maximum transport capacity (Tmax) and the Michaelis-Menten constant (Km) for renal tubular secretion obtained after simultaneously fitting plasma concentration-time profiles at the four doses to a renal clearance model were 215.5 +/- 82.1 mg/h and 119.3 +/- 80.5 mg/L, respectively, thereby yielding an unbound secretory intrinsic clearance (CLus,int) of 1.81 L/h. The high Tmax and Km values account for the high CLR of AZT and explain the linearity of CLR over a wide range of AZT plasma concentrations.(ABSTRACT TRUNCATED AT 250 WORDS)

Human immunodeficiency virus infection: affinity-mediated immunoblot detects intrathecal synthesis of oligoclonal IgG specific for individual viral proteins

An affinity-mediated immunoblot (AMI) is introduced, able to identify virus-specific, oligoclonal IgG in unconcentrated cerebrospinal fluid (CSF) of patients infected by HIV. CSF specimens are isoelectrically focused in agarose gels and blotted to nitrocellulose (NC) strips coated with E. coli recombinant HIV-specific proteins. Virus-specific antibody clones transferred to the filter are detected by solid-phase enzyme immunoassay (EIA). Only 0.5 micrograms IgG is sufficient to demonstrate the clonal distribution of antibodies specific for an individual HIV protein. Intrathecal synthesis of oligoclonal antibodies is seen by AMI, comparing equal quantities of serum- and CSF-derived IgG. Because of its excellent sensitivity and specificity, AMI detects autochthonous HIV-specific IgG synthesis even when comparative EIA fails. Because multiple specimens can be processed within a few hours by AMI, this technique is recommendable for routine diagnosis.

Subclinical neurological and neuropsychological effect of infection with HIV

Thirty one homosexual men with antibody to human immunodeficiency virus (HIV) but without major neurological complaints were assessed in a cross sectional study of neurological and neuropsychological function. Eleven patients had AIDS, 10 had persistent generalised lymphadenopathy (PGL), and 10 had HIV infection without PGL (called "well"). Thirteen age matched homosexual men without antibody to HIV acted as controls. Significant abnormalities were found in six on clinical neurological examination, in eight on nerve conduction studies, in six on electroencephalography, in six on neuropsychological assessment, and in eight on computed tomography of the head. Eighteen patients (nine with AIDS, four with PGL, and five "well") performed abnormally in at least one section of the assessment. The study highlights the incidence of nervous system dysfunction in HIV infection even in people who do not have AIDS. Prospective evaluation using electrophysiological and imaging techniques is necessary to assess the natural history of such manifestations and the effect of antiviral treatment.

AIDS-dementia-complex: pathology, pathogenesis and future directions

Acquired immunodeficiency syndrome (AIDS), first described in 1981, is produced by infection with a retrovirus of the lentivirus family, now called human immunodeficiency virus (HIV). While, initially, the disease was almost exclusively seen in homosexual men, it has become apparent that numerous other categories of people are at risk, i.e., drug addicts who share dirty needles, hemophiliacs and haitians. In addition, epidemiological data from the industrialized nations clearly indicate that heterosexual contact is becoming an important source of viral transmission, as it has been known to occur in several african nations for many years. Initially, studies on patients with AIDS mainly focused on the immunosuppressive effects of the virus and on the various opportunistic infections and neoplastic complications that followed. Not much attention was given to a possible direct HIV infection of the nervous system. Consequently, patients who presented with neurological findings were simply considered to harbor in the CNS the same complications that occurred in other organs. While this was true in many cases, it has become also apparent that important changes in the central and peripheral nervous systems are due to direct viral involvement of these tissues. The first important step in the understanding of nervous system involvement in AIDS was the demonstration, in 1985, of HIV in the CSF and cerebral tissues of patients with neurological symptoms (47). Further studies have shown that, while opportunistic infections and neoplastic complications certainly contribute to the neurological morbidity of AIDS, the most important neuropathological changes, particularly in the brain, are due to direct HIV infection. The aim of this paper is to review the pathology of HIV-induced encephalitis and to discuss pathogenetic hypotheses regarding mechanisms of HIV-mediated tissue injury and the clinical manifestations that follow, particularly the syndrome now known as AIDS-Dementia-Complex (ADC). First, however, it may be appropriate to quickly review some basic notions on the biology of the virus.

A prospective study of immunoglobulin changes in relation to human immunodeficiency virus infection in a cohort of homosexual men

Changes in IgG levels and patterns in association with human immunodeficiency virus, (HIV) infection were characterized in a prospective investigation by studying serum electrophoresis and antibodies to HIV at least once a year in 144 homo/bisexual (HS) men during a 4-year period. Initially, 25 men (17.4%) were HIV-positive, and this increased to 44 at the end of the study period. HIV-negative men had IgG levels of 11.2 +/- 2.2 g/l. In the 19 HIV seroconverters the mean IgG level rose with time according to the equation IgG = 0.054x + 12.56 (x = months after the last HIV-negative test). Oligoclonal IgG bands were found in three of the 19 seroconverters (16%) prior to conversion and in 2/16 (13%), 5/13 (38%), 7/11 (64%), and 3/8 (38%) 1, 2, 3, and 4 years after conversion, respectively. Of the 25 initially HIV-positive men, five have developed acquired immunodeficiency syndrome (AIDS) during the 4.5 year follow-up. At the first investigation these five men had higher mean IgG levels (16.0 +/- 2.7 g/l) than the 20 men who have remained healthy (14.6 +/- 2.8 g/l), and all five had oligoclonal bands as compared to 9/20 of those who did not develop AIDS. Oligoclonal IgG bands reflect the IgG increase and seem to indicate long-standing HIV infection and a poor prognosis.

HIV-1 core proteins expressed from recombinant vaccinia viruses

The sequences encoding the core proteins p55, p25, and p18 of the human immunodeficiency virus (HIV-1) have been inserted into the vaccinia virus genome. Infection of cultured cells with the live recombinant viruses led to the expression of proteins that were recognized by sera from HIV-seropositive individuals. Immunization of mice with the recombinant virus expressing the HIV p25 protein and the p55 precursor yielded high levels of antibodies directed against the corresponding HIV antigens. The data obtained are discussed in terms of the possible use of these live recombinant viruses in the development of a strategy toward an AIDS vaccine.

Human choroid plexus cells can be latently infected with human immunodeficiency virus

The human immunodeficiency virus (HIV) penetrates the central nervous system, particularly the cerebrospinal fluid, early in the course of HIV infection, and may cause a progressive encephalopathy in patients prior to the development of the acquired immunodeficiency syndrome. Neither the specific mechanism for penetration of the virus into the central nervous system nor the pathophysiological basis for these abnormalities is well understood. We cultured cells from the choroid plexus of 3 individuals who died of causes unrelated to the acquired immunodeficiency syndrome and demonstrated that these cells can be infected with type 1 HIV. Infection of cells of the choroid plexus may provide an initial route of entry of HIV into the cerebrospinal fluid and, together with the macrophage, a route of entry into the brain.

Analysis of oligoclonal antibody bands against individual HIV structural proteins in the CSF of patients infected with HIV

Intrathecal antibody responses to HIV were investigated by a highly sensitive immunoblot assay. Serum and CSF specimens were tested for reactivity with the recombinant HIV gag proteins p15, p17 and p24 and with the recombinant transmembrane protein p41. Autochthonous production of virus-specific IgG to one or more HIV structural proteins was seen in 8 of 10 asymptomatic seropositive subjects, in 3 of 4 men with AIDS-related complex, and in 9 of 13 patients with AIDS. These results were consonant with an elevated CSF/serum antibody ratio to total HIV antigen. The high frequency of local HIV-specific antibody synthesis in seropositive individuals without related clinical symptoms indicates an early involvement of the CNS in HIV infections.

CSF and serum beta-2-microglobulin in HIV infection related to neurological dysfunction

Elevated (greater than 2.2 mg/l) CSF beta-2-microglobulin (beta 2m) level was found in 9 of 16 neurologically symptomatic patients but in only 4 of 21 who were neurologically symptom-free (P less than 0.01). Serum beta 2m concentration was elevated (greater than 2.5 mg/l) in 12 of 16 neurologically symptomatic patients but in only 8 of 21 symptom-free patients (P less than 0.01). When the CSF and serum beta 2m levels were related to various stages of HIV infection, the highest mean values for both CSF and serum were found in patients with acquired immunodeficiency syndrome (AIDS), followed by lower values in AIDS-related complex (ARC), lymphadenopathy syndrome (LAS), and asymptomatic seropositive individuals (ASX), in decreasing order of preference. Our results suggest that elevated beta 2m in CSF and serum is related to the stage of general HIV infection and that elevated CSF beta 2m in the presence of intact BBB may be useful in evaluating CNS involvement in HIV-infected patients.

Immunoglobulins and complement components in 37 patients infected by HIV-1 virus: comparison of general (systemic) and intrathecal immunity

Intrathecal (IT) immunity was assessed by simultaneous analysis of paired cerebrospinal fluid (CSF) and sera of 37 patients infected by human immunodeficiency virus-1 (HIV-1). Only 8 of these 37 patients had no neurological or neuropsychiatric symptoms. There were 3 prominent abnormalities observed: (1) IT IgA production occurred in 15 patients, IT IgM production in 14 patients, and IT IgG production in 34 patients. (2) IT Anti-HIV-1 antibody specific activity (ASA) was higher than in serum in 33 of the 37 patients indicating that IT synthesis of antibody specific for HIV-1 occurs even in asymptomatic patients; IT anti-HIV-1 antibody synthesis was not correlated with clinical severity or neurological involvement. IT anti-herpes simplex ASA was also higher than serum ASA in 6 patients indicating a possible associated herpes simplex virus infection. (3) IT production of the complement component C4 was found frequently and was highly correlated with increased serum C4. IT C3 levels were decreased in 21 of 37 patients indicating that complement activation is a frequent accompaniment of the IT immune response in HIV-1-positive patients. These results indicate a unique and localized IT immune response which is different from the pattern observed in the systemic immune compartment in HIV-1-seropositive individuals and from the pattern common to the other CNS infectious diseases.

Central nervous system AIDS

The retrovirus that causes the acquired immunodeficiency syndrome (AIDS) has two targets: the immune system and the nervous system. Central nervous system (CNS) manifestations of AIDS are protean. This review describes the opportunistic infections and malignancies that affect the nervous system in AIDS, and discusses the syndromes resulting from primary infection of the CNS by the AIDS virus. Possible mechanisms of CNS injury are cited as well as potential predictors of neurologic expression of AIDS.

Estimation of the lipophilicity of anti-HIV nucleoside analogues by determination of the partition coefficient and retention time on a Lichrospher 60 RP-8 HPLC column

There is a close linear correlation between the log partition coefficient (Pa) of a series of 2'-deoxyriboside (dR), 2',3'-didehydro-3'-dideoxyriboside (ddeR), 2',3'-dideoxyriboside (ddR), 3'-fluoro-2',3'-dideoxyriboside (FddR) and 3'-azido-2',3'-dideoxyriboside (AzddR) derivatives of uracil, cytosine, thymine, guanine, adenine and 2,6-diaminopurine and their retention times (Rt) on a Lichrospher 60 RP-8 HPLC column (correlation coefficient r greater than 0.970). Within each class of compounds the following order of increasing lipophilicity was noted: dR less than ddeR less than ddR less than FddR less than AzddR. A straight-forward structure-lipophilicity relationship for both base and sugar modified purine and pyrimidine 2',3'-dideoxynucleosides could be delineated.

Neuropathology of the acquired immune deficiency syndrome (AIDS): a report of 135 consecutive autopsy cases from Switzerland

Neuropathological changes were studied in a consecutive autopsy series of 135 cases, comprising 73% of all patients who died of AIDS in Switzerland between April 1981 and December 1987. Central nervous system involvement was found in 119 patients (88%), 19 of which had multiple concomitant intracerebral lesions. Among the non-viral opportunistic infections, encephalitis due to Toxoplasma gondii was most frequent and occurred in 35 patients (26%), followed by central nervous system infection with Cryptococcus neoformans, which was found in five patients (4%). Cytomegalovirus (CMV) encephalitis was present in 14 patients (10%). Disseminated microglial nodules without morphological or immunocytochemical evidence of CMV was encountered in 18 patients (13%). However, in all but two of these patients there was evidence of extracerebral CMV infection, suggesting that CMV was responsible for these nodular encephalitides. Nine patients (7%) had progressive multifocal leukoencephalopathy (PML); in five of these, demyelination was associated with extensive tissue destruction and cyst formation. HIV-associated encephalopathy was observed in 21 patients (16%) and showed two characteristic morphological patterns: progressive diffuse leukoencephalopathy (PDL) and multifocal giant cell encephalitis (MGCE). PDL was observed in 13 cases and characterized by diffuse pallor and gliosis of the cerebral and cerebellar white matter with scattered multinucleated giant cells, but without significant inflammatory response. MGCE was found in eight patients and characterized by clusters of numerous multinucleated giant cells, rod cells, macrophages, lymphocytic infiltrates and occasional necroses. In our view, PDL and MGCE represent the two opposite variants of HIV-induced encephalopathies, with overlapping intermediate manifestations.

Human immunodeficiency virus (HIV)-induced disease of the central nervous system: pathology and implications for pathogenesis

Significant contributions from many different groups during the last 2 or 3 years have characterized relatively uniform neuropathological changes of the CNS in AIDS patients. They feature human immunodeficiency virus (HIV)-induced multinucleated giant cells as a histopathological hallmark and HIV demonstrable by electron microscopy, immunocytochemistry, and in situ hybridization. Unfortunately, a varying and confusing terminology is used to designate these changes which have been reported in surprisingly different incidences. Focal lesions have a microgranulomatous appearance and were designated as multifocal giant cell encephalitis or subacute encephalitis, which may be confused with the nodular encephalitis caused by cytomegalovirus. For some authors, the latter designation also covers characteristic diffuse white matter changes which have been termed progressive diffuse leukoencephalopathy by others, and which may overlap with focal lesions. Pathological features of these HIV-induced syndromes and other data do not support a major cytopathic effect of HIV on neural cells; rather, they suggest secondary pathogenetic events involving the predominant cell type in the lesion, the monocyte/macrophage/microglia. However, low-level, latent, and persisting HIV infections of neural cells cannot be excluded at present; the CNS may then serve as an early infected virus reservoir. A detailed correlation of clinical symptoms and stage of the infection to neuropathological changes is currently lacking but urgently needed. The presence of the HIV-receptor (CD4) molecule on brain cells is controversial; similarly, a putative cross-reaction of HIV proteins with trophic substances and transmitters needs to be substantiated.

Detection of antibodies against myelin basic protein and increased levels of HIV-IgG antibodies and HIV antigen after solubilization of immune complexes in sera and CSF of HIV infected patients

Fifteen HIV seropositive patients were studied. It was possible to enhance detection of HIV antigen and HIV and myelin basic protein (MBP) antibodies after dissociation of immune complexes by acid hydrolysis. HIV p24 antigen was then detected in four patients, three of whom were previously antigen negative. In 14 patients the treatment resulted in increased anti-HIV IgG subclass levels. Anti-MBP IgG was detected in 12 patients. Intrathecal synthesis of anti-MBP IgG subclasses was found in eight patients, five of whom had symptoms from the central nervous system.