Biomedical subjects
Publications and source records attributed to D D Ho.
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Human immunodeficiency virus (HIV) elicits the production of virus-specific antibodies in infected individuals. We investigated the ability of serum from HIV-infected individuals to mediate antibody-dependent cellular cytotoxicity in an in vitro 51Cr release assay system. Fresh peripheral blood mononuclear cells from healthy donors seronegative for HIV were used as cellular effectors against HIV-infected and uninfected H9 target cells in the presence of serum from HIV-infected or uninfected donors. Serum from HIV-infected, but not uninfected, donors significantly augmented cytolysis of virus-infected targets (P less than .005). There was no augmented killing of uninfected H9 cells with sera from either group. Studies using serum from mice that had been immunized with synthetic peptides from the HIV envelope region suggested that this response is directed, at least in part, at several determinants of the transmembrane portion of the HIV envelope glycoprotein.
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.
Subacute encephalitis, characterized by demyelination, gliosis of the gray and white matter, focal necrosis, microglial nodules, atypical oligodendrocyte nuclei, and multinucleation of cells, was present in 27 of 30 (90%) autopsied patients with acquired immune deficiency syndrome (AIDS) or AIDS-related complex. Subacute encephalitis was mainly distributed in the frontal (58%) and temporal (69%) lobes, basal ganglia (77%), amygdala (80%), and hippocampus (64%). Ten (37%) with moderate or severe subacute encephalitis were demented; 82% with mild subacute encephalitis had no recognized neurologic disorder. Human T-lymphotropic virus type III (HTLV-III) was isolated from neural tissue or CSF in 11 of 13 patients, 10 with subacute encephalitis, and 1 without CNS lesions. We conclude that subacute encephalitis is common in AIDS patients and is most likely caused by CNS infection with HTLV-III.
Randomly sheared DNA fragments from HTLV-III proviral DNA were cloned into an E. coli open reading frame (ORF) expression vector. The inserted ORF DNA was expressed in E. coli transformants as a polypeptide fused to the lambda CI protein at the amino terminus and to beta-galactosidase at the carboxyl terminus. The reactivity of the recombinant peptides with antibodies from sera of AIDS patients was determined by the Western blot technique. The coordinates of the DNA inserts of the immunoreactive clones were then determined by DNA sequencing. A clone, ORF 628, was found to contain a short DNA segment located between the sor and env genes (nucleotide positions 5367 to 5597), a region previously thought to be noncoding. Inspection of the DNA sequences of this clone and of other HTLV-III isolates revealed the presence of a small ORF located between nucleotide position 5411 and 5625, capable of encoding a polypeptide of 72 amino acids. The biosynthesis of the polypeptide of ORF 628 initiates from an ATG codon within the HTLV-III insert. The fusion protein of ORF 628 was partially purified by affinity chromatography on CH Sepharose 4B coupled to a beta-galactosidase ligand, and tested against a panel of sera from AIDS patients by Western blot analysis. Approximately 35% of the sera from patients with AIDS or ARC contained antibodies reactive with the peptide. The DNA region spanned by ORF 628 is now thought to be the major functional element of the trans-activator gene, tat.
Human T-cell lymphotropic virus type III (HTLV-III) has been isolated from neural tissues and cerebrospinal fluid (CSF) of patients with neurological syndromes associated with the acquired immune deficiency syndrome (AIDS) and the virus may be directly involved in the pathogenesis of the syndromes. To detect HTLV-III antigen in neural tissues from patients with AIDS, immunoperoxidase studies using a goat anti-HTLV-III serum were performed on frozen tissue sections of brain, spinal cord, and nerve from 13 patients with AIDS or HTLV-III-related neurological syndromes. HTLV-III was cultured from neural tissues or CSF in 11 of 13 of these patients. HTLV-III antigen was detected in the brains of 5 patients with AIDS and in none of the 13 non-AIDS control subjects. Rare positively stained cells were seen, frequently associated with capillaries and often located near microglial nodules. Morphologically, the cells resembled monocyte/macrophages and were found most frequently in the cortex of the frontal, temporal, and parietal lobes. These results provide further evidence that the subacute encephalitis of AIDS is associated with central nervous system infection by HTLV-III and that monocyte/macrophages are among the infected cell populations.
A 42-year-old homosexual man without evidence of immune deficiency developed cerebral granulomatous angiitis in association with the isolation of human T-lymphotropic virus type III (HTLV-III) from brain tissue and cerebrospinal fluid. This syndrome may be an additional neurological sequela of HTLV-III infection.
Two synthetic peptides containing amino acid sequences analogous to the envelope glycoprotein of human T-lymphotropic virus (HTLV) type III (HTLV-III) and lymphadenopathy associated virus (LAV) were produced and used to immunize rabbits. The subsequent rabbit antisera neutralized HTLV-III infectivity in vitro. The two synthetic peptides corresponded to regions associated with the gp120 or gp41 subunits respectively, of human immunodeficiency virus (HIV). This data indicates that at least two neutralizing epitopes are present on the envelope glycoprotein of HIV and these epitopes are associated with two distinct virus envelope glycoproteins. Antisera generated against these peptides neutralized infectivity of two different isolates of HTLV-III. The data is discussed in terms of possible strategy for developing an effective vaccine against the etiologic agents of acquired immune deficiency syndrome (AIDS).
The human T-lymphotropic retrovirus type III (HTLV-III), the etiological agent of AIDS, has recently been detected in tears, cornea, and conjunctiva, raising the possibility of transmission of HTLV-III via contact lens trial sets used in routine fitting. We evaluated the ability of several contact lens cleaning solutions, with or without conditioning or disinfecting solutions, to disinfect contact lenses experimentally contaminated with HTLV-III. Following attempted disinfection, the lenses were cultured for residual HTLV-III on Hg cells for 28 days. Cultures without characteristic cytopathic effects, reverse transcriptase activity, and HTLV-III-specific antigen expression were considered negative. We found that all commercially available cleaning solutions tested were able to disinfect contact lenses exposed to HTLV-III.
Fragments of human T-cell lymphotropic virus type III (HTLV-III) proviral DNA carrying the gene for the core antigen (gag) was cloned in the plasmid REV. Several of the recombinants direct high levels of synthesis of the antigens. One clone, pG1, produced a hybrid protein containing 13 amino acid residues of the carboxyl terminus of the 17 kD virion protein, the entire p24, the major core protein of HTLV-III, and 74 amino acid residues of the amino terminal of the 15 kD core ribonucleoprotein. A second clone, pG2, was similar to pG1 except that it contained no p17 sequences and was missing the amino-terminal 77 amino acid residues of the p24. A third clone, pG3, was similar to pG2, except that all but 56 amino acids of the carboxyl terminus of p24 were removed. All three proteins were found to be strongly immunoreactive with anti-HTLV-III antibodies present in sera from patients with acquired immune deficiency syndrome (AIDS) or AIDS-related complex (ARC). In addition, pG1 and pG2, but not pG3, reacted with a monoclonal antibody (M26) specific for the p24 virion core protein. Whereas all three reacted with an anti-p15 monoclonal antibody, none of the clones reacted with an anti-p17 monoclonal antibody. These results provide direct evidence to support the predicted assignment of the coding region of the gag gene of HTLV-III. The product from pG2 was purified and was found to be potentially useful for the detection of anti-p24 antibodies in sera from patients with AIDS or ARC and from individuals at risk from AIDS.
The human T-cell lymphotropic virus type III (HTLV-III/LAV) is a retrovirus associated with acquired immune deficiency syndrome. The region on the viral genome that is necessary for trans-activation of the HTLV-III/LAV long terminal repeat called tatIII has previously been determined to lie between nucleotides 5365 and 5607. Here we report that a bacterial fusion protein containing amino acid sequences specified by the first coding exon of the tatIII gene is recognized by some patient antisera. We also demonstrate that lymphoid and epithelial cells that express the trans activator function express a 14-kilodalton (kDa) protein recognized by a patient antiserum that reacts with the bacterial tatIII fusion protein. Cells transiently transfected with a deletion mutant of the trans activator protein produce a 12-kDa protein rather than the 14-kDa protein. These observations indicate that the tatIII region contains a functional gene and is capable of expressing a protein that migrates with an apparent molecular size of 14 kDa in some lymphoid and epithelial cells transfected with plasmids containing the tatIII region. We propose that the product of the trans activator gene be designated p14tat-III.
Normal blood-derived monocyte/macrophages were found to be susceptible to infection in vitro by human T lymphotropic virus type III (HTLV-III), the etiologic agent of the acquired immunodeficiency syndrome. In addition, HTLV-III was recovered from monocyte/macrophages of patients infected with this virus. The above findings raise the possibility that HTLV-III-infected monocyte/macrophages may serve as a vehicle for the dissemination of virus to target organs and as a reservoir for viral persistence, as has been shown for other lentiviruses including visna virus and caprine arthritis encephalitis virus.
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We conducted virus-isolation studies on 56 specimens from the nervous system of 45 patients in order to determine whether human T-cell lymphotropic virus Type III (HTLV-III) is directly involved in the pathogenesis of the neurologic disorders frequently encountered in the acquired immunodeficiency syndrome (AIDS) and the AIDS-related complex. We recovered HTLV-III from at least one specimen from 24 of 33 patients with AIDS-related neurologic syndromes. In one patient, HTLV-III was isolated from the cerebrospinal fluid during acute aseptic meningitis associated with HTLV-III seroconversion. HTLV-III was also isolated from cerebrospinal fluid from six of seven patients with AIDS or its related complex and unexplained chronic meningitis. In addition, of 16 patients with AIDS-related dementia, 10 had positive cultures for HTLV-III in cerebrospinal fluid, brain tissue, or both. Furthermore, we cultured HTLV-III from the spinal cord of a patient with myelopathy and from the sural nerve of a patient with peripheral neuropathy. These findings suggest that HTLV-III is neurotropic, is capable of causing acute meningitis, is responsible for AIDS-related chronic meningitis and dementia, and may be the cause of the spinal-cord degeneration and peripheral neuropathy in AIDS and AIDS-related complex.
Intra-blood-brain-barrier production of virus-specific antibody is good evidence of infection within the blood-brain barrier. Patients with the acquired immuno-deficiency syndrome (AIDS) have an increased incidence of neurologic abnormalities--i.e., unexplained, diffuse encephalopathy manifested clinically as chronic progressive dementia. To define the role of human T-cell lymphotropic virus Type III (HTLV-III), the etiologic agent of AIDS, in the pathogenesis of neurologic dysfunction, we compared cerebrospinal fluid and serum from patients with neurologic symptoms associated with AIDS and the AIDS-related complex for the presence of antibodies directed against HTLV-III. Antibodies directed against HTLV-III antigens were detected by four immunologic tests: a fixed-cell immunofluorescence assay, an enzyme-linked immunosorbent assay, immunoblots of viral lysates, and immunoprecipitation of cellular lysates. All patients were seropositive, and 22 of 23 (96 per cent) had HTLV-III-specific antibodies in their cerebrospinal fluid. Unique oligoclonal IgG bands were detected in the cerebrospinal fluid, and the rate of IgG synthesis within the blood-brain barrier was elevated. In eight of nine patients tested, the enzyme-linked immunosorbent assay showed that the percentage of HTLV-III-specific IgG in cerebrospinal fluid was higher than in serum, suggesting that HTLV-III infection of neurologic tissue occurs in the majority of patients with neurologic disease associated with AIDS or its related complex.
Recombinant human interferon alfa-A (rIFN alpha A) had a dose-related suppressive effect on human T lymphotropic virus type III (HTLV-III) replication in vitro in normal peripheral-blood mononuclear cells (PBMC). Both single-dose and multiple-dose regimens were inhibitory. Such inhibitory concentrations (4-1024 units/ml) were not toxic to PBMC in culture, and were within the ranges achievable in blood after injection. These studies suggest that clinical trials of rIFN alpha A in early HTLV-III infection are warranted.
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Infection with human T-cell lymphotropic virus III (HTLV-III) is closely linked to the acquired immunodeficiency syndrome (AIDS). We evaluated the risk of nosocomial infection with HTLV-III by testing for antibodies to HTLV-III among hospital employees, including victims of needle-stick exposure, endoscopists, pathologists, and laboratory workers. Assays for antibody against the virus were performed by enzyme-linked immunosorbent assay and electrophoretic (Western blot) techniques. Although all 22 of our patients with AIDS and 6 of 7 with AIDS-related complex were found to have antibodies to HTLV-III when both assays were employed, none of the 85 employees with nosocomial exposure to specimens from patients with AIDS were positive for HTLV-III antibody. These studies must be regarded as preliminary, but they suggest that when current hospital isolation procedures are employed, the risk of nosocomial transmission of HTLV-III is low.