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

Cardiorespiratory arrest and autonomic neuropathy in AIDS

Four of five patients with AIDS and pulmonary infection had syncopal reactions as a result of fine-needle aspiration of the lung; in one patient the reaction was fatal. Subsequently, in one of these patients and four further patients with AIDS or human immunodeficiency virus (HIV) infection, the autonomic nervous system proved to be abnormal. This preliminary evidence suggests HIV infection may be associated with an autonomic neuropathy, which may expose these patients to particular risk after invasive procedures.

Comparative studies on use of fresh and frozen peripheral blood lymphocyte specimens for isolation of human immunodeficiency virus and effects of cell lysis on isolation efficiency

Heparinized blood specimens (n = 44) and frozen peripheral blood lymphocyte (PBL) specimens (n = 42) were used to evaluate the effects of lysis on human immunodeficiency virus (HIV) isolation. In the two respective groups, 17 and 27 specimens were HIV antibody positive. In the first group there were 8 and in the second group there were 25 that were symptomatic and were classified as indicating an acquired immunodeficiency syndrome-related condition or a pre-acquired immunodeficiency syndrome-related condition by the Centers for Disease Control definition. One-half of the cells from each specimen were frozen and thawed three times before cocultivation with uninfected lymphocytes, and the isolation rates from whole and lysed cells were compared. HIV was isolated from 15 (88%) of 17 fresh specimens and from 24 (89%) of 27 frozen PBLs from HIV antibody-positive patients, and lysis had no overall effect on the isolation rate, which suggested that frozen PBLs were as suitable as fresh blood for HIV isolation attempts and that it was not necessary to maintain cell integrity when submitting PBL samples. Of 21 asymptomatic patients, 20 were culture positive, and of 23 symptomatic patients, 19 were culture positive. Specimens from the 42 antibody-negative individuals were culture negative.

The role of HIV infectivity and composition of factor VIII concentrates on the immunity of haemophiliacs positive for HIV antibodies

Forty-six subjects (44 HIV antibody-positive) with some degree of immune deficiency (at least TH/TS ratio below 1) were randomly distributed into 4 treatment groups. Each group was assigned to 1 of 4 products to be used exclusively for a 1-year period: 1 concentrate was of intermediate purity and not heat-treated, and 3 were heat-treated in order to inactivate HIV, 2 of them being of higher purity. At 4-6-month intervals, check-ups, including as markers clinical examination, platelet, lymphocyte and T cell subset counts, IgG levels and delayed hypersensitivity test, were carried out. At entry as well as at the end of the study, groups were not statistically distinguishable. No intra- nor inter-group differences were demonstrable for any of the markers. In contrast, using a scoring system for each marker and the results of check-up at entry as reference, significant differences between groups appeared on subsequent check-ups. Patients receiving intermediate-purity factor VIII, whether heat-treated or not, were mostly steady, while groups receiving heat-treated concentrates of a higher purity significantly worsened. This surprising outcome was no related to differences in anti-HIV titers or specificities. From this study, the potential long-term predictive value of this scoring system could not be established.

Myositis and acquired immunodeficiency syndrome

Clinical and pathologic observations made in a patient with inflammatory myopathy associated with the acquired immunodeficiency syndrome (AIDS) are presented. Multinucleated giant cells were a prominent histopathologic feature in the muscle biopsy samples. The findings indicate that in some patients with AIDS myositis, inflammatory myopathy may be the direct result of infection with the human immunodeficiency virus.

Nucleotide sequence analysis of equine infectious anemia virus proviral DNA

The nucleotide sequence of the integrated form of the genome of the equine infectious anemia virus was determined. By comparison with LTR sequences of other retroviruses, signals for the control of viral gene transcription and translation could be identified in the EIAV LTR. Open reading frames for gag and pol genes were identified and their sequences matched very closely to those determined previously by others. However, in the present study, the pol gene reading frame was open throughout its entire length. The open reading frame for the env gene product was constructed from the sequences of two independent EIAV clones. Thus, a noninfectious genomic-length clone was shown to contain a frameshift mutation approximately in the middle of the presumed env gene coding sequence, whereas the sequence of another clone was open in this region. The deduced amino acid sequences of the EIAV gag and pol products showed closer evolutionary relationships to those of known lentiviruses than to other retroviruses. There was also partial sequence homology between predicted env gene products of EIAV, visna virus, and HTLV-III/LAV. Sequences analogous to the sor region of other lentiviruses could not be identified in our EIAV clone. A short open reading frame at the 3' end of the genome that overlapped env but not the 3' LTR was present but lacked significant sequence similarity to the 3' open reading frames of other lentiviruses. Thus, the sequence and general structure of EIAV most closely resemble those of known lentiviruses.

Human immunodeficiency virus neutralizing antibodies recognize several conserved domains on the envelope glycoproteins

Serum neutralizing antibodies against the human immunodeficiency virus were frequently detected in infected individuals, and low or absent serum neutralizing titers correlated with poor prognosis. Multiple diverse human immunodeficiency virus isolates were found to exhibit similar susceptibility to neutralization by a panel of human seropositive sera, suggesting that neutralizing antibodies are largely directed against conserved viral domains. Furthermore, utilizing antisera raised against a library of synthetic env peptides, four regions which are important in the neutralization process have been identified within both human immunodeficiency virus envelope glycoproteins (gp41 and gp120). Three of these are in conserved domains and should be considered for inclusion in a candidate vaccine.

Histopathology of the central nervous system in the acquired immunodeficiency syndrome

Histopathologic findings in the central nervous system in 100 autopsy cases of the acquired immunodeficiency syndrome (AIDS) gave evidence of a variety of opportunistic infections and probably of infection by human immunodeficiency virus (HIV). Gliomesenchymal cell nodules (47 per cent of cases) and spongiform alterations with demyelination were common. Vasculitides (8 per cent) and lesions such as acute hemorrhagic leukoencephalitis may be attributable partly to hypersensitivity reactions. Multinucleated cells, including giant cells that could be a hallmark of HIV encephalitis, were common in normal neuropil, in gliomesenchymal cell nodules, near blood vessels, and in cavitating lesions. Degeneration in long tracts (13 per cent) included posterior column demyelination and spongiform change with or without corticospinal tract degeneration. Some long tract degeneration appeared to originate from bilateral degeneration of the internal capsule, and this may be part of the origin of subacute combined degeneration-like changes in AIDS vacuolar myelopathy. Prominent brainstem inflammatory infiltration suggests that the brainstem is a relatively prominent site of infection or immunopathologic activity. Early ependymal lesions in infants and frequent healed ependymal lesions in adults (16 per cent) could be related to the origin and pathogenesis of HIV lesions in the brain. Some characteristic lesions in AIDS encephalitis may result from immune-mediated responses to HIV antigens on neural cell receptors or from cross-reactivity occurring against epitopes common to neural constituents and to hematopoietic cells, with the latter being under direct antiviral attack.

Neurological complications in AIDS

Neurological complications in the acquired immunodeficiency syndrome (AIDS) are an important aspect of this new infectious disease and occur frequently. The existence of neurotropic variants of the human immunodeficiency virus (HIV), the causative agent of AIDS, is probable. Direct infection of the nervous system with HIV leads to a variety of HIV-induced neurological syndromes, the AIDS dementia complex being its most important representative. In addition, a large number of opportunistic infections and malignancies of the nervous system may complicate the disease. Major aspects of the clinical pictures, rational diagnostic approaches and treatment options of the most important sequels of HIV infection of the nervous system are discussed.

Intra-blood-brain barrier synthesis of human immunodeficiency virus antigen and antibody in humans and chimpanzees

The presence of human immunodeficiency virus (HIV) antigens in cerebrospinal fluid (CSF) was associated with progressive encephalopathy in adult and pediatric patients with acquired immunodeficiency syndrome (AIDS). HIV antigen was detected in CSF from 6 of 7 AIDS patients with progressive encephalopathy. By contrast, HIV antigen, whether free or complexed, was detected in CSF from only 1 of 18 HIV antibody seropositive patients without progressive encephalopathy and from 0 of 8 experimentally infected chimpanzees without clinical signs. Intra-blood-brain barrier synthesis of HIV-specific antibody was demonstrated in the majority of patients with AIDS (9/12) or at risk for AIDS (8/13) as well as in the experimentally infected chimpanzees, indicating HIV-specific B-cell reactivity in the brain without apparent neurological signs. In 6 of 11 patients with HIV infection, antibodies synthesized in the central nervous system were directed against HIV envelope proteins. Active viral expression appears to be necessary for both the immunodeficiency and progressive encephalopathy associated with HIV infection.

Dual infection of the central nervous system by AIDS viruses with distinct cellular tropisms

Human immunodeficiency virus (HIV) is the causative agent of the acquired immune deficiency syndrome (AIDS). A large number of AIDS patients show evidence of neurologic involvement, known as AIDS-related subacute encephalopathy, which has been correlated with the presence of HIV in the brain. In this study, two genetically distinct but related viruses were isolated from one patient from two different sources in the central nervous system: brain tissue and cerebrospinal fluid. Both viruses were found to replicate in peripheral blood lymphocytes, but only virus from brain tissue will efficiently infect macrophage/monocytes. The viruses also differ in their ability to infect a brain glioma explant culture. This infection of the brain-derived cells in vitro is generally nonproductive, and appears to be some form of persistent or latent infection. These results indicate that genetic variation of HIV in vivo may result in altered cell tropisms and possibly implicate strains of HIV with glial cell tropism in the pathogenesis of some neurologic disorders of AIDS.

AIDS and the geriatrician

Ten percent of acquired immune deficiency syndrome (AIDS) cases are in persons over 50 years of age with 25% of these cases in persons over 60, and 4% in persons over 70 years of age. If the present age distribution holds, there will be 27,000 AIDS cases in persons over 50, and 1100 cases in persons over 70 years of age, by 1991. Older persons are more likely to acquire AIDS through blood transfusions than to homosexual exposure or drug abuse. Changes in the management of blood products will benefit older persons. The nearly 1 million elderly homosexual men, who have been sheltered from the virus by their pattern of sexual activity, will face greater risks as the prevalence of the virus and the age of the carriers increases. The underappreciated neurological consequences of human T-cell lymphotrophic virus type III (HTLV-III) infection, subacute encephalitis, vacuolar myelopathy, and psychiatric disorders will be of particular interest to geriatricians who are often consulted to evaluate neurological dysfunction. Geriatricians will need to become familiar with the spectrum of HTLV-III infection and prepared to counsel patients and extended-care facilities.

CSF protein and cellular profiles in various stages of HIV infection related to neurological manifestations

CSF protein and cellular profiles were studied in 28 HIV-infected patients. Twenty of them had neurological complaints, but only 6 patients had objective neurological deficits such as dementia, ocular motility disorders or polyneuropathy. The serum/CSF HIV antibody ratio was on average lowest in acquired immunodeficiency syndrome (AIDS) (4 patients) and highest or almost normal in lymphadenopathy syndrome (LAS) (11) and asymptomatic seropositivity (ASX) (7), while it varied between these extremes in AIDS-related complex (ARC) (6). However, low values of the ratio were also found in the HIV-infected patients free of neurological symptoms and even in one ASX patient. The CSF IgG index was elevated in all these 4 general stages of HIV infection without any significant differences between them. The CSF/serum albumin ratio was slightly increased in patients with neurological deficits, but this ratio showed no association with any other clinical factor analysed. CSF leucocytes were increased in the early stages of the disease, but later the cellular reaction subsided. HIV was isolated from post mortem brain tissue of two AIDS patients and from the CSF of one of them. The results suggest increased intrathecal virus-specific IgG synthesis, not only in patients with neurological deficits and at advanced stages of infection, but also in neurologically symptom-free subjects and at early infection. The lack of correlation between the increased virus-specific IgG synthesis within the CNS and the presence of neurological symptoms suggests that neurologically "silent" areas of brain white matter are often affected in HIV infection.

Human immunodeficiency virus can productively infect cultured human glial cells

Six isolates of the human immunodeficiency virus (HIV) showed differences in their ability to productively infect glioma-derived cell lines and early-passage human brain cell cultures. Susceptibility to HIV infection correlated well with the expression of the astrocyte marker glial fibrillary acidic protein. The CD4 molecule was expressed on some, but not all, of the brain-derived cells; however, no correlation was observed between CD4 protein expression and susceptibility to virus infection. The results show that HIV can productively infect human brain cells, particularly those of glial origin, and suggest that these cell types in the brain can harbor the virus.

Acquired immunodeficiency syndrome (AIDS)

The Acquired Immunodeficiency Syndrome (AIDS), caused by the human immunodeficiency virus (HIV), also called the human T-lymphotropic virus type III/lymphadenopathy-associated virus [HTLV-III/LAV], has affected over 23,000 people; more than half of those with the disease have died. The actual case fatality rate approaches 100%. AIDS affects all groups and classes of people, although some are at special risk. Distribution of the disease is worldwide. The illness' effects on the body are widespread; of special interest are the ophthalmologic manifestations. The eye may be infected by various viruses (cytomegalovirus, varicella-zoster virus, herpes simplex virus or HIV itself), toxoplasma gondii, candida sp, cryptococcus neoformans, M. tuberculosis, or M. avium-intracellulare. Kaposi's sarcoma may affect the eye as well. Retinal vascular abnormalities (e.g., cotton-wool spots, vasculitis) are not uncommon in AIDS. The syndrome may present with neuro-ophthalmologic manifestations. No effective treatment for the illness is currently available, although several hold promise and there is hope for an AIDS vaccine. Prevention of infection through reduction of risks appears to be the only defense against AIDS at this time.

HIV antigen in the brains of patients with the AIDS dementia complex

Human immunodeficiency virus infection was identified immunohistochemically in the brains of 8 patients with acquired immune deficiency syndrome dementia complex. Using a monoclonal antibody against a structural viral protein (p25), infection was detected in white matter and basal ganglia in a distribution paralleling that of the major neuropathological abnormalities. Viral antigen was identified principally in perivascular and parenchymal macrophages and in multinucleated cells of macrophage origin that were identified morphologically and by immunocytochemical staining for acid phosphatase isozyme. In 4 of the 8 patients, viral antigen was also detected in acid-phosphatase-negative, process-bearing neuroglial cells; in 2 patients, antigen was detected in basal ganglion cells that were morphologically consistent with neurons and in alkaline-phosphatase-positive cells with elongated nuclei that were most likely of endothelial origin.

Construction of a defective retrovirus containing the human hypoxanthine phosphoribosyltransferase cDNA and its expression in cultured cells and mouse bone marrow

Defective ecotropic and amphotropic retroviral vectors containing the cDNA for human hypoxanthine phosphoribosyltransferase (HPRT) were developed for efficient gene transfer and high-level cellular expression of HPRT. Helper cell clones which produced a high viral titer were generated by a simplified method which minimizes cell culture. We used the pZIP-NeoSV(X) vector containing a human hprt cDNA. Viral titers (1 X 10(3) to 5 X 10(4)/ml) of defective SVX HPRT B, a vector containing both the hprt and neo genes, were increased 3- to 10-fold by cocultivation of the ecotropic psi 2 and amphotropic PA-12 helper cells. Higher viral titers (8 X 10(5) to 7.5 X 10(6] were obtained when nonproducer NIH 3T3 cells or psi 2 cells carrying a single copy of SVX HPRT B were either transfected or infected by Moloney leukemia virus. The SVX HPRT B defective virus partially corrected the HPRT deficiency (4 to 56% of normal) of cultured rodent and human Lesch-Nyhan cells. However, instability of HPRT expression was detected in several infected clones. In these unstable variants, both retention and loss of the SVX HPRT B sequences were observed. In the former category, cells which became HPRT- (6-thioguanine resistant [6TGr]) also became G418s, indicative of a cis-acting down regulation of expression. Both hypoxanthine-aminopterin-thymidine resistance (HATr) and G418r could be regained by counterselection in hypoxanthine-aminopterin-thymidine. In vitro mouse bone marrow experiments indicated low-level expression of the neo gene in in vitro CFU assays. Individual CFU were isolated and pooled, and the human hprt gene was shown to be expressed. These studies demonstrated the applicability of vectors like SVX HPRT B for high-titer production of defective retroviruses required for hematopoietic gene transfer and expression.

Expression of human immunodeficiency virus in cerebrospinal fluid of children with progressive encephalopathy

The retrovirus that causes acquired immune deficiency syndrome (AIDS) is now designated the human immunodeficiency virus (HIV). The cerebrospinal fluid (CSF) of 27 children with HIV infection was assayed for intra-blood-brain barrier (IBBB) synthesis of HIV-specific antibodies and for the presence of HIV antigen. In this cohort, 11 children had a progressive encephalopathy (PE), 9 had a static encephalopathy (SE), and 7 had normal neurological findings (N). IBBB synthesis of HIV-specific antibodies was identified (using matched serum and CSF specimens) in 7 of 11 children with PE, 4 of 9 children with SE, and 2 of 7 children with N. HIV antigen was found (using a highly sensitive solid-phase enzyme immunoassay) in the CSF of 8 of 11 children with PE, none of the children with SE, and none of the 7 children with N. On the basis of these data, we conclude that: IBBB synthesis of HIV antibodies indicates invasion of the central nervous system but may reflect prior or current infection; and HIV antigen in CSF indicates viral expression and correlates with the occurrence of PE. These findings strongly implicate HIV as the causative agent of PE in these children. The assay for HIV antigen in the CSF may be of value in determining the prognosis of children with HIV infection and for evaluating the efficacy of therapeutic agents against this retrovirus.

The cellular receptor (CD4) of the human immunodeficiency virus is expressed on neurons and glial cells in human brain

The expression of the CD4 antigen in normal human brain was investigated in parallel by immunohistochemical and Northern blot analyses. With anti-CD4 antibodies detecting different epitopes of the molecule, CD4+ neurons were defined in the cerebellum, thalamus, and pons. CD4+ glial cells were identified in the thalamus and pons. CD4-specific mRNA was detected in all three subareas and in the hippocampus, while other subareas were negative. The CD4+ cells were negative with anti-T cell antibodies (anti-CD2 and anti-CD8), as well as with antimonocyte antibodies (M-M 522 and M-M 42).

Evidence for different immune responses to HIV in CSF and serum?

A case of acquired immune deficiency syndrome (AIDS) and a case of AIDS-related complex (ARC) are described. In both instances comparative Western blot analysis of cerebrospinal fluid (CSF) and serum samples show evidence of qualitative differences in antibody-binding patterns to viral polypeptides.

Ribavirin antagonizes the effect of azidothymidine on HIV replication

Azidothymidine and ribavirin both inhibit replication of human immunodeficiency virus in vitro and show promise of clinical utility in patients infected with this virus. In this study, the possible interactions of these drugs were examined in vitro, and a reproducible antagonism between azidothymidine and ribavirin was found to occur under a variety of experimental conditions. The mechanism responsible for this antagonism appeared to be inhibition of azidothymidine phosphorylation by ribavirin. Because similar effects may occur in vivo, clinical trials of these two drugs in combination must be performed only under carefully controlled conditions.

Transmission dynamics of HIV infection

Simple mathematical models of the transmission dynamics of human immunodeficiency virus help to clarify some of the essential relations between epidemiological factors, such as distributed incubation periods and heterogeneity in sexual activity, and the overall pattern of the AIDS epidemic. They also help to identify what kinds of epidemiological data are needed to make predictions of future trends.

Dermatologic findings and manifestations of acquired immunodeficiency syndrome (AIDS)

We present a review of the spectrum of human T-lymphotropic virus type III (HTLV-III) infection with particular emphasis on cutaneous manifestations in 217 patients. Correlations are made with immunodeficiency as measured by absolute T-helper cell number. A classification is presented of these dermatologic findings.

Progressive multifocal leukoencephalopathy in a patient without other clinical manifestations of AIDS

The case is reported of a 46-year-old homosexual LAV/HTLV III seropositive man in whom progressive multifocal leukoencephalopathy was the first and only clinical manifestation of AIDS. The severity and extension of neurological disturbances in AIDS are discussed.

Cytomegalovirus encephalitis in patients with acquired immunodeficiency syndrome: an autopsy study of 30 cases and a review of the literature

The pathology of cytomegalovirus (CMV) encephalitis was studied at autopsy in thirty patients with acquired immunodeficiency syndrome. Lesions could be segregated into five major categories: microglial nodules, isolated inclusion-bearing cells, focal parenchymal necrosis, necrotizing ventriculo-encephalitis, and necrotizing radiculo-myelitis. Microglial nodules and CMV inclusions were present in all brains. Microglial nodules were found with variable frequency and had greatest density in subcortical grey matter. Only a small percentage (average, 6.5 per cent) contained CMV inclusion-bearing cells. Isolated inclusion-bearing cells unaccompanied by microglial nodules or inflammatory infiltrates were seen in half the patients. CMV inclusions were identified in capillary endothelia, astrocytes, and neurons. Focal CMV necrosis, ventriculo-encephalitis, and radiculo-myelitis were less frequent. The presence of CMV inclusions in capillary endothelia suggests a vascular portal of entry for the virus into the central nervous system. The diffuse ependymal and/or subpial distribution of CMV in several patients suggests additional dissemination via the cerebrospinal fluid. Isolated inclusion-bearing cells may reflect the relative nonpermissiveness of surrounding central nervous system parenchyma for CMV infection.

MRI appearance of AIDS subacute encephalopathy

A case of biopsy documented subacute encephalopathy of AIDS was evaluated by CT and MRI. CT scanning revealed ventriculomegaly and ill-defined nonspecific periventricular white matter hypodensities. MRI, however, demonstrated extensive unequivocal diffuse white matter disease as the cause of the ventriculomegaly. MRI findings in this patient support the preliminary suggestion that MRI is more useful than computed tomography (CT) in demonstrating AIDS subacute encephalopathy.

Development of antiretroviral therapy for the acquired immunodeficiency syndrome and related disorders. A progress report

We review the rationale for, and progress in, the development of antiviral therapy for the acquired immunodeficiency syndrome (AIDS). A consideration of the replicative cycle of the human immunodeficiency virus (HIV) can lead to the identification of several steps that represent potential targets for antiretroviral therapy, and several substances that can inhibit the replication of HIV in vitro have already been identified. The 2',3'-dideoxynucleosides are a class of nucleoside analogues in which the 3'-hydroxy group is modified so that it cannot form phosphodiester linkages for nucleic acid chains. Some are potent in vitro inhibitors of HIV replication, possibly acting as chain terminators of viral DNA during reverse transcription. One of these dideoxynucleoside analogues, 3'-azido-2',3'-dideoxythymidine (AZT), has now been administered for up to 18 months to patients with AIDS. The drug has been shown to improve immunologic function, to reverse, at least partially, HIV-induced neurologic dysfunction in some patients, and to improve certain other clinical abnormalities associated with AIDS. The principal toxic effect associated with AZT is dose-dependent suppression of bone marrow, resulting particularly in anemia and leukopenia; however, most patients in whom this toxic effect occurs can subsequently tolerate a lower dose of the drug. The demonstration that AZT can be beneficial in patients with AIDS has removed some of the uncertainty about the rationale for an antiretroviral intervention in HIV infection.

Strategies for antiviral therapy in AIDS

The retrovirus that causes AIDS has revealed enough of its life history for a variety of therapeutic strategies to be apparent. Some of these are suitable for immediate application in clinical trials or have already yielded positive results in some patients.

Updating of methods for prevention of HIV transmission during ophthalmological procedures

The presence of HIV (human immunodeficiency virus) particles in the tear fluid, on the conjunctival surface or in the contact lenses of patients with chronic HIV infection has made it necessary to establish better for guide-lines for decontamination of instruments during ophthalmological procedures. The methods are now at the stage of evolution. The present paper describes the disinfection procedures used in the Helsinki University Eye Hospital and updates the present decontamination protocols.

Construction of a defective retrovirus containing the human hypoxanthine phosphoribosyltransferase cDNA and its expression in cultured cells and mouse bone marrow

Defective ecotropic and amphotropic retroviral vectors containing the cDNA for human hypoxanthine phosphoribosyltransferase (HPRT) were developed for efficient gene transfer and high-level cellular expression of HPRT. Helper cell clones which produced a high viral titer were generated by a simplified method which minimizes cell culture. We used the pZIP-NeoSV(X) vector containing a human hprt cDNA. Viral titers (1 X 10(3) to 5 X 10(4)/ml) of defective SVX HPRT B, a vector containing both the hprt and neo genes, were increased 3- to 10-fold by cocultivation of the ecotropic psi 2 and amphotropic PA-12 helper cells. Higher viral titers (8 X 10(5) to 7.5 X 10(6] were obtained when nonproducer NIH 3T3 cells or psi 2 cells carrying a single copy of SVX HPRT B were either transfected or infected by Moloney leukemia virus. The SVX HPRT B defective virus partially corrected the HPRT deficiency (4 to 56% of normal) of cultured rodent and human Lesch-Nyhan cells. However, instability of HPRT expression was detected in several infected clones. In these unstable variants, both retention and loss of the SVX HPRT B sequences were observed. In the former category, cells which became HPRT- (6-thioguanine resistant [6TGr]) also became G418s, indicative of a cis-acting down regulation of expression. Both hypoxanthine-aminopterin-thymidine resistance (HATr) and G418r could be regained by counterselection in hypoxanthine-aminopterin-thymidine. In vitro mouse bone marrow experiments indicated low-level expression of the neo gene in in vitro CFU assays. Individual CFU were isolated and pooled, and the human hprt gene was shown to be expressed. These studies demonstrated the applicability of vectors like SVX HPRT B for high-titer production of defective retroviruses required for hematopoietic gene transfer and expression.

Acquired immunodeficiency syndrome of childhood

AIDS of childhood is reviewed in this timely article, including care of the child with infectious complications, and other current and future management concerns.

Developmental abnormalities in children with acquired immunodeficiency syndrome (AIDS): a follow-up study

Developmental abnormalities in 16 pediatric patients with AIDS or AIDS-Related Complex (ARC) were previously described. Neurological deterioration was in evidence on follow-up in 9 of the children, 5 died since the original assessments were performed. Ten patients were reevaluated 14 months later by cognitive testing. Two showed greater progress than expected on the basis of earlier test results; 6 showed the expected level of developmental progress; and the remaining 2 showed regression in cognitive functioning. All patients who exhibited regression in their developmental course showed deterioration in their neurological examinations. Developmental progression was noted in some children who on follow-up serial examinations exhibited a clinically deteriorating neurological picture. Pediatric AIDS patients manifest variable neurodevelopmental courses. As a result, rehabilitative intervention services must be tailored to meet individual needs.

Response of human-immunodeficiency-virus-associated neurological disease to 3'-azido-3'-deoxythymidine

Four patients with human-immuno-deficiency-virus-associated neurological disease were treated with 3'-azido-3'-deoxythymidine (AZT). Three (two with chronic dementia, and one with chronic dementia and peripheral neuropathy) improved as assessed by clinical examination, psychometric tests, nerve conduction studies, and/or positron emission tomography; there was no improvement in the fourth patient who presented with paraplegia. These results support the hypothesis that certain AIDS-virus-associated neurological abnormalities are reversible by antiretroviral chemotherapy.

Human immunodeficiency virus (HIV) infection in brains with AIDS-related leukoencephalopathy

In addition to central nervous system (CNS) opportunistic infections and neoplasms, patients with acquired immunodeficiency syndrome (AIDS) develop unexplained dementia and encephalopathy and degeneration of the white matter. We studied autopsied brains from 20 adult patients who expired from AIDS to determine the relationship of human immunodeficiency virus (HIV) infection to white matter lesions and to clinical findings. In four patients with dementia/encephalopathy and abnormalities of the white matter, there was evidence of HIV infection as shown by in situ hybridization. In contrast, the remaining 16 patients who had no evidence of white matter degeneration revealed no hybridization to the HIV probe. The cells infected with HIV included endothelial cells, perivascular macrophages/monocytes, and multinucleated giant cells and were found in or adjacent to white matter degeneration. These results demonstrate a correlation between HIV-infected cells and AIDS leukoencephalopathy and provide further evidence for HIV-related dementia/encephalopathy.

Brain pathology induced by infection with the human immunodeficiency virus (HIV). A histological, immunocytochemical, and electron microscopical study of 100 autopsy cases

Neuropathological examination of brain tissue of 100 patients with infection by the human immunodeficiency virus (HIV), including 98 with clinically manifest acquired immune deficiency syndrome (AIDS), revealed distinct multifocal-disseminated and diffuse brain tissue lesions, which can be regarded as HIV-induced brain lesions: multifocal giant cell encephalitis (MGCE; 4) and progressive diffuse leukoencephalopathy (PDL; 25). These lesions were found in 38 brains, and in 17 in absence of infectious, necrotizing or inflammatory changes of other types. In 13 brains, a combination of MGCE with PDL was seen, suggesting a spectrum of HIV-induced brain lesions. MGCE is characterized by perivascular accumulations predominantly of rod cells, monohistiocytes and macrophages, all of which are strongly labeled with a monoclonal antibody to macrophages. Most conspicuous are multinucleated giant cells which are also labeled by anti-macrophage antibody, and which can be regarded as evidence of the local presence of HIV, as confirmed by electron microscopical detection of HIV particles in four MGCE brains, and by immunocytochemical detection of HIV proteins in two MGCE brains. PDL is characterized by a triad: diffuse myelin loss, astroglial proliferation, and infiltration by mono- and multinucleated macrophages. HIV-induced lesions can be morphologically differentiated from histopathological brain lesions known in immunosuppression, including what is called here nodular encephalitis ["subacute encephalitis" of the literature, in most cases attributable to cytomegalovirus (CMV) or toxoplasmosis], by their characteristic histopathology including the hallmark presence of multinucleated giant cells, by direct immunocytochemical and electron microscopical demonstration of HIV in the lesions, and by the absence of opportunistic agents (bacteria, fungi, Toxoplasma, CMV, HSV or papovaviruses). Diffuse poliodystrophy (diffuse proliferation of astroglia with swollen nuclei, occasionally minor neuronal loss and rod cell proliferation) was found in the cerebral cortex and other gray matter in half of all brains, including cases with gyral atrophy, and may be another correlate of HIV damage to the brain. Morphological delineation of HIV-induced brain lesions is a necessary prerequisite for a meaningful clinical definition of HIV-induced cerebral disease.