Search PubMed⌕ Search

Biomedical subjects

R C Gallo

Publications and source records attributed to R C Gallo.

At least 325 records · Page 18Linked to original sources
PubMed1986

Evidence for HTLV-III/LAV expression by primary cultures of T8 cells.

The selective targets for HTLV-III/LAV, the causal infectious agent of AIDS and AIDS-related complex (ARC), are T4 cells, apparently because the virus receptor is associated with T4 antigen determinants. This accounts for T4 cell depletion in AIDS and for a decrease of IL-2 production by AIDS peripheral blood lymphocytes (PBL) after in vitro PHA activation. By contrast, T8 cells are not targets for HTLV-III/LAV, since T8 cells from PBL and from long-term cultured T cells (CTC) could not be infected by the virus. We describe 2 samples of PBL from Zairian patients with HTLV-III infection in which HTLV-III was expressed by T8 cells. Evidence that T8 cells were expressing virus was obtained by complement cytotoxicity experiments performed in the presence of OKT8 monoclonal antibody (MAb), which removed HTLV-III-positive cells from cultured T cells producing the virus, and by double labelling experiments, in which some cells exhibit both T8 antigens detected either by IFA (rhodamine) or by rosetting in presence of OKT8 MAbs and HTLV-III antigens detected by IFA (fluorescein) with of anti-HTLV-III p24 and p15 MAbs. Since normal T cells have previously been shown to undergo antigenic diversity, we think these results can be explained by HTLV-III infection of T4 cells which later lost T4 antigens and acquired the T8 phenotype.

Acquired Immunodeficiency Syndrome↗
PubMed1986

In vitro generation of an HTLV-III variant by neutralizing antibody.

Transmission and culture of "parental" virus (HTLV-III) from H9 cells transfected with the cloned isolate (lambda HXB-2D) in human serum possessing HTLV-III neutralizing antibody selected for a "variant" that was not neutralized by the selecting serum but was neutralized by another antibody-positive serum "Control" virus, selected in serum lacking neutralizing antibody, and the variant showed highly similar tryptic peptide maps of the major envelope glycoprotein, and no changes in restriction enzyme patterns of viral DNA. These findings show that HTLV-III type-specific neutralizing antibodies occur, can influence the propagation of variant viruses that may arise, and presumably result from minor changes in the eliciting antigen. The extent to which such type-specific neutralizing antibodies influence immune surveillance against HTLV-III infection in vivo, a question with relevance to future vaccination attempts, remains to be determined. Nucleotide sequencing of the control and variant envelope genes may elucidate a region important for virus neutralization and vaccine development.

Antibodies, Viral↗
PubMed1986

Detection of HTLV-III RNA in lungs of patients with AIDS and pulmonary involvement.

A majority of pediatric patients and rare adult patients with the acquired immunodeficiency syndrome (AIDS) develop a chronic respiratory disorder referred to as "lymphocytic interstitial pneumonitis" (LIP). Efforts to identify an infectious agent responsible for this process so far have failed. In this study, frozen sections of lungs from patients with AIDS and pulmonary disease were tested by in situ molecular hybridization for the presence of cells infected with human T-cell lymphotropic virus type III (HTLV-III) and expressing viral RNA. In the case of an infant with LIP, a relatively high frequency (0.1%) of cells in the lung were found to be positive for HTLV-III RNA. This number is the lower limit of total cells infected since the in situ hybridization technique as applied in this study depends on expression of HTLV-III genes, and previous evidence indicates that a proportion of cells infected with HTLV-III may not express viral RNA. Moreover, this degree of infection of the lung is likely limited to LIP, since in ten patients with AIDS and pulmonary diseases other than LIP, only 0% to 0.002% of cells in lung were positive for viral RNA expression. Thus, HTLV-III may play a direct causal role in the development of LIP in infected patients, implicating its involvement in yet another of the diverse clinical diseases associated with this virus.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Genomic analysis of the human B-lymphotropic virus (HBLV).

The human B-lymphotropic virus (HBLV) has a double-stranded DNA genome of greater than 110 kilobase pairs, which is consistent with its morphological classification as a herpesvirus. A 9000-base pair cloned probe of HBLV detected specific sequences in DNA and RNA of infected cells but did not hybridize to the genomic DNA of other human herpesviruses including the Epstein-Barr virus, human cytomegalovirus, herpes simplex type I, and varicella-zoster virus. Conversely, while probes obtained from each of the known human herpesvirus readily detected the homologous viral DNA, they did not hybridize to genomic HBLV DNA. This evidence, in addition to serological and morphological distinctions and the biological effects of this virus demonstrate that HBLV is a novel human herpesvirus.

Cytomegalovirus↗
PubMed1986

STLV-I antibodies in feral populations of East African vervet monkeys (Cercopithecus aethiops).

Serum samples from feral populations of African green monkeys (Cercopithecus aethiops) were screened for antibodies to the simian T-lymphotropic virus, type I (STLV-I). Blood samples had been collected from 336 monkeys in 4 regions of central and southern Kenya in 1978 and 1979, from 114 monkeys in central Ethiopia in 1973, and from 85 monkeys from the Kampala region of Uganda in 1966. A total of 178/535 monkeys (33%) were seropositive (STLV-I+). Only 4/114 monkeys (4%) from Ethiopia were seropositive compared to 25/85 Ugandan monkeys (29%) and 149/336 Kenyan monkeys (44%). Epidemiological analysis of the Kenyan monkeys showed that 37% of the males and 54% of the females were STLV-I+, and that there was a progressive increase in the proportion of STLV-I+ monkeys of both sexes with age, rising from an average of 16% in infants (less than 9 months) to an average of 69% in adults (greater than 42 months). The proportion of STLV-I+ monkeys was higher among females in each age category. Seropositivity for antibodies to STLV-I had no apparent effect on the health of monkeys, and no association with the occurrence of Hepatocystis parasitemia was seen in this species. The analysis of data from infants of STLV-I+ mothers showed that seroconversion had occurred in 1 of 3 cases, suggesting that vertical transmission of the STLV-I virus is not an inevitable consequence for infants of seropositive mothers.

Age Factors↗
PubMed1986

A model for the selective loss of major histocompatibility complex self-restricted T cell immune responses during the development of acquired immune deficiency syndrome (AIDS).

Functional analyses of peripheral blood leukocytes (PBL) from high risk HTLV-III antibody-negative and antibody-positive donors, as well as from patients with acquired immune deficiency syndrome (AIDS), lymphadenopathy syndrome (LAS), and AIDS-related complex (ARC) were performed by the in vitro generation of cytotoxic T lymphocyte (CTL) and proliferative responses to the HLA self-restricted antigens of influenza virus (S + X) and to nonself restricted HLA alloantigens (ALLO). All 40 antibody-negative donors tested responded to both S + X and ALLO in the CTL response, whereas six of 14 antibody-positive, two of three LAS, four of five ARC, and seven of 17 AIDS patients exhibited a selective absence of CTL to S + X, but generated normal or elevated CTL responses to ALLO. Of the remaining 10 AIDS patients, nine did not respond to either S + X or ALLO, and one responded to both S + X and ALLO. A similar selective loss of the proliferative response to S + X was found. We also observed antibody-positive donors who initially generated CTL responses to S + X and ALLO, but lost the S + X response as a function of time. We were able to restore the selective loss of S + X CTL activity in vitro by the addition of IL 2 and, to some extent, by co-stimulation with S + X plus ALLO. Depletion of CD4+ T helper cells and removal of autologous antigen-presenting cells from the PBL of healthy antibody-negative donors indicated that distinct T helper cell subsets exist in human PBL, and that S + X responses must use a CD4+ T helper population, whereas ALLO responses can utilize an alternate CD4- T helper pathway. A model is presented indicating the selective depletion of CD4+ T helper function in the developmental stages of AIDS. The functional test for T helper activity to self restricted antigens may be the earliest indicator of immune functional loss in the development of AIDS, and may precede a reduction in the absolute number of CD4+ cells.

AIDS-Related Complex↗
PubMed1986

HTLV-III expression and production involve complex regulation at the levels of splicing and translation of viral RNA.

The African green monkey nonlymphoid cell line cos-1 produces infectious HTLV-III virus following transfection with biologically active molecular clones of HTLV-III. Transfected cos-1 cells produce large amounts of viral RNA and protein. We have used this rapid transfection system to study the regulatory functions and synthetic capacity of the HTLV-III genome, as well as mutants derived from it. Analysis of transfected lymphoid and nonlymphoid cell lines suggests that tat-III-mediated trans-activation of viral gene expression is operative predominantly, if not exclusively, at a posttranscriptional level. We have also identified an additional HTLV-III-encoded gene that controls viral gene expression through regulation of the relative proportions of the various viral RNA transcripts and is required for viral replication.

Animals↗
PubMed1986

Functional modifications of alloreactive T cell clones infected with HTLV-I.

Two alloreactive T cell clones with anti-HLA-DR1 specificity showed significant alterations of cognitive and functional characteristics after infection with human T cell leukemia virus (HTLV-I). Similar to HTLV-I-infected lines derived from immunologically uncommitted lymphocytes, the transformed clones displayed blastogenic mixed lymphocyte culture (MLC) responses to cells carrying any of the allelic variants of human HLA-D/DR antigens, including self. Although these two clones were originally able to provide allospecific help only to B cells expressing the DR1 antigen, after infection with HTLV-I they stimulated B cells of any HLA-D/DR phenotype to produce immunoglobulin in cultures. The helper inducer activity of the transformed clones remained susceptible to the effect of monoclonal antibody anti-LDA1 that inhibits the helper function of normal human T cells. One of these clones (207TK), which before infection specifically killed DR1-positive target cells, lost its killing ability. The other clone (19TK) although originally noncytotoxic, acquired natural killer-like function after transformation. Study of the rearrangement of the genes coding for the beta-chain of the T cell antigen receptor revealed no differences between the wild (noninfected) and mutant (infected) clones. There was, however, an increased level of this message, as well as of the message encoded by the beta-chain gene of HLA-DR in the mutant clones. Such changes may be related to transacting transcriptional effects induced by the human T cell lymphotropic virus HTLV-I.

Antibodies, Monoclonal↗
PubMed1986

Infectious mutants of HTLV-III with changes in the 3' region and markedly reduced cytopathic effects.

A variant of human T-lymphotropic virus type III (HTLV-III) is described that replicates but does not kill normal human T cells in vitro. This variant, designated X10-1, was derived from the genome of a cytopathic HTLV-III clone (pHXB2D) by excision of a 200-base pair segment in the 3' region of the virus, spanning the env and 3'-orf genes. Comparable variants with 55 to 109 base pairs deleted exclusively in 3'-orf produced, in contrast, virus that was extremely cytopathic. On the basis of these findings it is concluded that the 3'-orf gene is not required for cytopathogenicity or replication of HTLV-III. In addition, the results suggest that virus replication and cytotoxicity are not intrinsically coupled. Furthermore, since clone X10-1 retains the ability to trans-activate genes linked to the viral long terminal repeats, trans-activation per se is not responsible for T-cell killing by HTLV-III. These results also raise the possibility that the carboxyl terminus of the envelope gene of HTLV-III has a direct role in T-cell killing by this virus.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Cytomegalovirus but not human T lymphotropic virus type III/lymphadenopathy associated virus detected by in situ hybridisation in retinal lesions in patients with the acquired immune deficiency syndrome.

Paraffin sections of retinal tissue from five patients who died from the acquired immune deficiency syndrome (AIDS) and retinopathy were examined by in situ hybridisation experiments with deoxyribonucleic acid (DNA) labelled with sulphur-35 of lentivirus, human T lymphotropic virus type III/lymphadenopathy associated virus (HTLV-III/LAV), and cytomegalovirus. HTLV-III/LAV ribonucleic acid (RNA) was not detected in any of the tissue sections. Cytomegalovirus RNA was identified, however, in three of the five patients. Retinopathy induced by cytomegalovirus may thus be one of the many syndromes potentiated by the immunosuppression caused by HTLV-III/LAV.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Reactivity of E. coli-derived trans-activating protein of human T lymphotropic virus type III with sera from patients with acquired immune deficiency syndrome.

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.

Acquired Immunodeficiency Syndrome↗
PubMed1986

The role of mononuclear phagocytes in HTLV-III/LAV infection.

Cells with properties characteristic of mononuclear phagocytes were evaluated for infectivity with five different isolates of the AIDS virus, HTLV-III/LAV. Mononuclear phagocytes cultured from brain and lung tissues of AIDS patients harbored the virus. In vitro-infected macrophages from the peripheral blood, bone marrow, or cord blood of healthy donors produced large quantities of virus. Virus production persisted for at least 40 days and was not dependent on host cell proliferation. Giant multinucleated cells were frequently observed in the macrophage cultures and numerous virus particles, often located within vacuole-like structures, were present in infected cells. The different virus isolates were compared for their ability to infect macrophages and T cells. Isolates from lung- and brain-derived macrophages had a significantly higher ability to infect macrophages than T cells. In contrast, the prototype HTLV-III beta showed a 10,000-fold lower ability to infect macrophages than T cells and virus production was one-tenth that in macrophage cultures infected with other isolates, indicating that a particular variant of HTLV-III/LAV may have a preferential tropism for macrophages or T cells. These results suggest that mononuclear phagocytes may serve as primary targets for infection and agents for virus dissemination and that these virus-infected cells may play a role in the pathogenesis of the disease.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Genetic variation in HTLV-III/LAV over time in patients with AIDS or at risk for AIDS.

In a study of genetic variation in the AIDS virus, HTLV-III/LAV, sequential virus isolates from persistently infected individuals were examined by Southern blot genomic analysis, molecular cloning, and nucleotide sequencing. Four to six virus isolates were obtained from each of three individuals over a 1-year or 2-year period. Changes were detected throughout the viral genomes and consisted of isolated and clustered nucleotide point mutations as well as short deletions or insertions. Results from genomic restriction mapping and nucleotide sequence comparisons indicated that viruses isolated sequentially had evolved in parallel from a common progenitor virus. The rate of evolution of HTLV-III/LAV was estimated to be at least 10(-3) nucleotide substitutions per site per year for the env gene and 10(-4) for the gag gene, values a millionfold greater than for most DNA genomes. Despite this relatively rapid rate of sequence divergence, virus isolates from any one patient were all much more related to each other than to viruses from other individuals. In view of the substantial heterogeneity among most independent HTLV-III/LAV isolates, the repeated isolation from a given individual of only highly related viruses raises the possibility that some type of interference mechanism may prevent simultaneous infection by more than one major genotypic form of the virus.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Prevalence of antibodies to HTLV-I, -II, and -III in intravenous drug abusers from an AIDS endemic region.

Antibody prevalences for human T-cell lymphotropic virus (HTLV) types I, II, and III were determined for 56 intravenous drug abusers from Queens, NY. While control serum samples lacked antibodies to all HTLV subgroups, seropositivity among drug users was 41% for HTLV-III, 18% for HTLV-II, and 9% for HTLV-I. Infection by HTLV-I and -II occurred independently of HTLV-III infection. Blacks had greater HTLV-III antibody prevalence than whites (54% vs 16%) and were more likely than whites to be seropositive for HTLV-I or -II (46% vs 11%). They exhibited a greater incidence than whites of double infection with HTLV-I or -II and HTLV-III (27% vs 0%), and 73% were seropositive for at least one of the viruses, compared with only 26% of the whites. The increased HTLV-I and -II infection seen in intravenous drug users suggests that once introduced into a population, these viruses may be transmitted by the same routes as HTLV-III. Transmission may have been restricted mainly to blacks in this study because of local drug use practices.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Identification and characterization of conserved and variable regions in the envelope gene of HTLV-III/LAV, the retrovirus of AIDS.

To determine the extent and nature of genetic variation present in independent isolates of HTLV-III/LAV, the nucleotide sequences of the entire envelope gene and parts of gag and pol were determined for two AIDS viruses. The results indicated that variation throughout the viral genome is extensive and that the envelope gene in particular is most highly variable. Within the envelope, changes were most prevalent within the extracellular region where clustered nucleotide substitutions and deletions/insertions were evident. Based on predicted secondary protein structure and hydrophilicity, these hypervariable regions represent potential antigenic sites. In contrast to the hypervariable regions, other sequences in the extracellular envelope and the overall envelope structure (including 18 of 18 cysteine residues), as well as most of the transmembrane region, were highly conserved.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Spectrum of human T-cell lymphotropic virus type III infection in children. Recognition of symptomatic, asymptomatic, and seronegative patients.

This study was done to gain insight into the clinical spectrum and immunologic disturbances resulting from infection with the human T-cell lymphotropic virus type III/lymphadenopathy-associated virus (HTLV-III/LAV) in children. Serum antibody to p41 antigen of HTLV-III and/or direct evidence of HTLV-III in lymphocytes was considered indicative of HTLV-III/LAV infection. In 36 children with HTLV-III/LAV infection, a wide clinical spectrum was noted, ranging from asymptomatic (seven children) to symptomatic, the latter including 14 children with the acquired immunodeficiency syndrome. Microcephaly was noted in five symptomatic infants. Immunologic dysfunction was noted in all symptomatic and in two asymptomatic children. Panhypogammaglobulinemia was noted in one child. Two asymptomatic children who were HTLV-III antibody negative had virologic evidence of HTLV-III infection. All of 20 mothers who were studied were HTLV-III antibody positive and had immunologic abnormalities but only nine were symptomatic, indicating that apparently healthy women may transmit HTLV-III/LAV infection to their offspring.

Acquired Immunodeficiency Syndrome↗