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R C Gallo

Publications and source records attributed to R C Gallo.

At least 19 recordsLinked to original sources
PubMed1992

Effects of cytokines from activated immune cells on vascular cell growth and HIV-1 gene expression. Implications for AIDS-Kaposi's sarcoma pathogenesis.

Kaposi's sarcoma (KS) arises more frequently in homosexual and bisexual men than in other groups of HIV-1 infected individuals. Clinico-epidemiologic data indicate that homosexuals often are infected with multiple microbial agents and/or subjected to other antigenic stimuli, preceding or accompanying HIV-1 infection. Signs of immune activation, in fact, frequently have been detected in these individuals, and the onset of KS can precede any sign of immunodeficiency. These data have suggested that products from activated immune cells may affect the development of AIDS-KS. Here we report that conditioned media from activated or dysregulated T cells contain a variety of cytokines that promote the growth of spindle cells derived from KS lesions of AIDS patients (AIDS-KS cells) and induce normal vascular cells, potential cell progenitors of the AIDS-KS cells, to acquire features of the KS cell phenotype ("spindle" cell morphology and growth responsiveness to the mitogenic effect of extracellular HIV-1 Tat protein). The same conditioned media or cytokines promote HIV-1 gene expression and rescue defective HIV-1 proviruses, interrupting HIV-1 latency and increasing Tat production. The cellular and viral effects of cytokines are increased in an additive or synergistic manner by picomolar concentrations of extracellular Tat. These data suggest that cytokines produced by activated immune cells cooperate with HIV-1 infection in AIDS-KS pathogenesis.

Cell Division↗
PubMed1992

Human herpesvirus 7 is a T-lymphotropic virus and is related to, but significantly different from, human herpesvirus 6 and human cytomegalovirus.

An independent strain (JI) of human herpesvirus 7 (HHV-7) was isolated from a patient with chronic fatigue syndrome (CFS). No significant association could be established by seroepidemiology between HHV-7 and CFS. HHV-7 is a T-lymphotropic virus, infecting CD4+ and CD8+ primary lymphocytes. HHV-7 can also infect SUP-T1, an immature T-cell line, with variable success. Southern blot analysis with DNA probes scanning 58.8% of the human herpesvirus 6 (HHV-6) genome and hybridizing to all HHV-6 strains tested so far revealed homology to HHV-7 with only 37.4% of the total probe length. HHV-7 contains the GGGTTA repetitive sequence, as do HHV-6 and Marek's disease chicken herpesvirus. DNA sequencing of a 186-base-pair fragment of HHV-7(JI) revealed an identity with HHV-6 and human cytomegalovirus of 57.5% and 36%, respectively. Oligonucleotide primers derived from this sequence (HV7/HV8, HV10/HV11) amplified HHV-7 DNA only and did not amplify DNA from other human herpesviruses, including 12 different HHV-6 strains. Southern blot analysis with the p43L3 probe containing the 186-base-pair HHV-7 DNA fragment hybridized to HHV-7 DNA only. The molecular divergence between human cytomegalovirus, on the one hand, and HHV-6 and HHV-7, on the other, is greater than between HHV-6 and HHV-7, which, in turn, is greater than the difference between HHV-6 strains. This study supports the classification of HHV-7 as an additional member of the human beta-herpesviruses.

Amino Acid Sequence↗
PubMed1992

Modulatory effects of Epstein-Barr, herpes simplex, and human herpes-6 viral infections and coinfections on cytokine synthesis. A comparative study.

Herpesviruses such as EBV, HSV, and human herpes virus-6 (HHV-6) have a marked tropism for cells of the immune system and therefore infection by these viruses may result in alterations of immune functions, leading at times to a state of immunosuppression. We report the results of a comparative study in which we found that EBV, HSV-1, and HHV-6 act differentially on the immune system with regard to their effect on the synthesis of IL-1 beta, IL-6, and TNF-alpha, i.e., three immunoregulatory cytokines mainly secreted by activated monocytes/macrophages. Using the polymerase chain reaction technique, analyses of the mRNA levels for each of the three monokines after viral infection indicated that the effect exerted by each of these herpesviruses on cytokine synthesis by human PBMC was detectable at the transcriptional level. Different amounts of IL-1 beta protein were detected in infected PBMC cultures, HHV-6 being the strongest IL-1 beta up-regulatory among these three herpesviruses. Spontaneous releases of IL-6 and TNF-alpha were found reduced after infection by HHV-6 and EBV, respectively. In comparison to EBV and HHV-6, HSV-1 proved to be a weak monokine enhancer. Results of coinfection studies indicated that virus-induced suppressive effects on cytokine synthesis are dominant. In fact, EBV inhibited TNF-alpha synthesis even in the presence of HHV-6, a strong up-regulator of TNF-alpha synthesis. Similarly, EBV was unable to stimulate IL-6 production in the presence of HHV-6. Viral structural component(s) appeared to be responsible for the up-regulation of IL-6 by both EBV and HSV-1, and of TNF-alpha by HSV-1. Taken together, our observations illustrate that herpesviruses can selectively regulate cytokine synthesis thereby disturbing immune homeostasis; this effect may favor pathogenic events, including the reactivation and/or spread of other infectious agents within the host.

Base Sequence↗
PubMed1992

Expression of alternatively spliced human T-lymphotropic virus type I pX mRNA in infected cell lines and in primary uncultured cells from patients with adult T-cell leukemia/lymphoma and healthy carriers.

Although human T-cell lymphotropic virus type I (HTLV-I) is the etiologic agent of adult T-cell leukemia/lymphoma (ATL), the role of viral gene expression in the progression to and maintenance of the leukemic state in vivo is unclear because of the inability of most previous studies to readily detect HTLV-I RNA in infected individuals. By using the reverse transcriptase-polymerase chain reaction, we detected spliced messages for the HTLV-I pX regulatory genes in primary uncultured cells from ATL patients and healthy asymptomatic carriers. In addition to the expected doubly spliced pX message, three alternatively spliced mRNAs were demonstrated (pX delta 17, pX-p21rex, and pX-orfII mRNAs, where orf = open reading frame). The same splice sites were shown in the messages from uncultured ATL cells and from the HTLV-I-producing C10/MJ cell line. Alternatively spliced pX mRNAs have the potential to code for known and putative pX gene products. Among the transcripts is a monocistronic mRNA likely to code for p21rex (pX-p21rex mRNA). Since alternative splicing of HTLV-I pX mRNA can be found in primary uncultured cells, it is likely to have a functional significance in vivo. This suggests possible roles for HTLV-I gene expression in the progression to and maintenance of ATL, as well as in the phase preceding it.

Base Sequence↗
PubMed1992

Inhibition of development of Kaposi's sarcoma-related lesions by a bacterial cell wall complex.

In vitro and in vivo model systems for the study of human immunodeficiency virus (HIV)-associated Kaposi's sarcoma (KS) were used to evaluate compounds for their potential as therapeutic agents. A sulfated polysaccharide-peptidoglycan compound (SP-PG) produced by bacteria controlled the in vitro growth of acquired immunodeficiency syndrome (AIDS)-associated, KS-derived spindle-shaped cells (AIDS-KS cells) at noncytotoxic concentrations. Angiogenesis induced by AIDS-KS cells in the chicken chorioallantoic membrane assay was blocked by SP-PG, which also inhibited the vascular hyperpermeability response and the angiogenesis associated with the induction of KS-like lesions that develop after subcutaneous inoculation of AIDS-KS cells into nude mice. Suramin, pentosan polysulfate, and interferon alpha, which are currently in use for therapy of KS, were either less effective than SP-PG or much more cytotoxic, or both.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Identification of a major growth factor for AIDS-Kaposi's sarcoma cells as oncostatin M.

Conditioned medium from human T cell leukemia virus type 2 (HTLV-II)-infected T cells supports the growth and long-term culture of cells derived from acquired immunodeficiency syndrome (AIDS)-associated Kaposi's sarcoma lesions (AIDS-KS cells). A protein of 30 kilodaltons was purified from conditioned medium that supports the growth of AIDS-KS cells. The amino-terminal sequence of this protein was identical to the amino-terminal sequence of Oncostatin M, a glycoprotein that inhibits the growth of a variety of cancer cells. Oncostatin M from conditioned medium stimulated a twofold increase in the growth of AIDS-KS cells at a concentration of less than 1 nanogram of the protein per milliliter of medium.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Biological characterization of noninfectious HIV-1 particles lacking the envelope protein.

To understand the role of the HIV-1 envelope protein in the assembly of virus, we constructed a proviral clone of HIV-1 where the methionine initiator codon of the env gene was substituted with a translational stop codon. Upon DNA transfection into permissive cells in culture, this clone produces virus-like particles similar in size to parental virus but are noninfectious in human T-cells, promonocytic cells, and primary macrophages. This mutant readily recombines with a deletion mutant provirus lacking the entire gag-pol region producing a recombinant virus that is infectious. Substitution of the same initiator methionine codon with valine results in a leaky missense mutant provirus capable of a low level of Env protein synthesis that leads to a productive infection. Thus, the prototype initiation codon AUG is dispensable for virus infectivity. Further, the expression of the envelope protein is not a prerequisite for the assembly of the virus particles in the HIV-1 system. These noninfectious envelope-less particles revert readily to wild-type phenotype upon cotransfection with Env-producing plasmid DNAs.

Animals↗
PubMed1992

Delineation of immunoreactive, conserved regions in the external glycoprotein of the human immunodeficiency virus type 1.

Immunization of mice and rats with purified external glycoprotein gp120 from two divergent human immunodeficiency virus type 1 (HIV-1) isolates resulted in the development of seven hybridomas secreting monoclonal antibodies able to recognize regions of gp120 which are common among divergent strains of HIV-1. These monoclonal antibodies cross-reacted with env glycoproteins from one African (Rutz), one Haitian (RF), and three North American viral isolates, namely IIIB, MN, and 451 by either immunoblot or radioimmunoprecipitation assays. All recognized denatured gp120 in immunoblots with the exception of one which required a conformationally intact glycoprotein for reactivity. The gp120 epitopes identified by these antibodies were mapped by screening of an env gene library in the lambda gt11 expression system. Three out of four epitopes were found to reside in the amino-terminal half of gp120 (Cys9 to Cys35, Thr44 to Glu72 and Val108 to Met130), the other was located in the middle region (Thr221 to Ser255). By virtue of their extent of cross-reactivity these reagents might provide a unique resource for the detection of new viral isolates related to HIV-1.

Amino Acid Sequence↗
PubMed1992

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

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

Base Sequence↗
PubMed1992

Cytokines and growth factors in the pathogenesis of AIDS-associated Kaposi's sarcoma.

In the past, the study of KS pathogenesis has been hampered by the lack of in vitro and in vivo experimental systems. Recently, the establishment of long-term cultures of KS spindle cells and the development of animal models have allowed a variety of studies on the pathobiology of the disease. The results from these studies, reviewed herein, indicate that KS is a cytokine-mediated disease and that inflammatory and angiogenic cytokines and the HIV-1 Tat protein cooperate in its induction and progression in HIV-1-infected individuals.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Effects of the human immunodeficiency virus type 1 Tat protein on the expression of inflammatory cytokines.

Increased levels of inflammatory cytokines, including tumor necrosis factor (TNF), interleukin-1 (IL-1), and IL-6, have been detected in specimens from human immunodeficiency virus type 1 (HIV-1)-infected individuals. Here we demonstrate that HIV-1 activates the expression of TNF but not of IL-1 and IL-6 in acutely and chronically infected T cells. The increase in TNF gene expression is due to activation of the TNF promoter by the viral gene product Tat. Transactivation of TNF gene expression requires the product of the first exon of the tat gene and is cell type independent. T cells chronically infected with pol-defective HIV-1 provirus constitutively express both Tat and TNF at levels significantly higher (fivefold) than those seen in control cells, and treatment with phorbol myristate acetate greatly enhances Tat expression and TNF production. As TNF can increase the production of IL-1 and IL-6 and these inflammatory cytokines all enhance HIV-1 gene expression and affect the immune, vascular, and central nervous systems, the activation of TNF by Tat may be part of a complex pathway in which HIV-1 uses viral products and host factors to increase its own expression and infectivity and to induce disease.

Animals↗
PubMed1992

Low degree of human T-cell leukemia/lymphoma virus type I genetic drift in vivo as a means of monitoring viral transmission and movement of ancient human populations.

We have studied the genetic variation of human T-cell leukemia/lymphoma virus type I (HTLV-I) isolates in the same individuals over time, as well as of HTLV-I isolates from various parts of the world. The viral DNA fragment studied encodes the carboxy terminus of gp46 and almost all of gp21, both of which are envelope glycoproteins. Samples were obtained from native inhabitants of five African countries, two South American countries, China, the French West Indies, and Haiti and included 14 patients with tropical spastic paraparesis/HTLV-I-associated myelopathy, 10 patients with adult T-cell leukemia, 1 patient with T-cell non-Hodgkin's lymphoma, and 3 healthy HTLV-I-seropositive individuals. DNA analyses of HTLV-I sequences demonstrated that (i) little or no genetic variation occurred in vivo in the same individual or in different hosts from the same region carrying the same virus, regardless of their clinical statuses; (ii) changes in nucleotide sequences in some regions of the HTLV-I genome were diagnostic of the geographical origin of the viruses; (iii) HTLV-I sequences from West African countries (Mauritania and Guinea Bissau) and some from the Ivory Coast and Central African Republic were virtually identical to those from the French West Indies, Haiti, French Guyana, and Peru, strongly suggesting that at least some HTLV-I strains were introduced into the New World through infected individuals during the slave trade events; and (iv) the Zairian HTLV-I isolates represent a separate HTLV-I cluster, in which intrastrain variability was also observed, and are more divergent from the other HTLV-I isolates. Because of the low genetic variability of HTLV-I in vivo, the study of the proviral DNA sequence in selected populations of infected individuals will increase our knowledge of the origin and evolution of HTLV-I and might be useful in anthropological studies.

Base Sequence↗
PubMed1992

Multiple isolates and characteristics of human T-cell leukemia virus type II.

Human T-cell leukemia (or lymphotropic) virus type II (HTLV-II) was isolated from eight HTLV-seropositive patients, six of whom were also infected with human immunodeficiency virus, by cocultivation of peripheral blood mononuclear cells (PBMCs) with BJAB, a continuous B-cell line. Restriction endonuclease mapping of the proviruses demonstrated consistent differences among isolates, and two distinct physical map patterns were observed. The results suggest the existence of two closely related molecular subtypes of HTLV-II, which are tentatively designated HTLV-IIa and HTLV-IIb. This finding was supported by preliminary nucleotide sequence analysis of the env gene region encoding the transmembrane glycoprotein gp21, which showed consistent differences between the two proposed virus subtypes. Exploitation of differences in restriction endonuclease sites allowed polymerase chain reaction amplification to detect and differentiate the two subtypes in fresh PBMCs of HTLV-seropositive intravenous drug abusers (IVDAs). The results of these studies confirm that HTLV-II infection is the prominent HTLV infection in seropositive IVDAs and also show that infection with both subtypes occurs. The finding of genetic heterogeneity in the HTLV-II group of viruses may have important implications for studies on its role in human disease and will be useful in characterizing the viruses present in newly discovered endemic foci in New World indigenous populations.

Adult↗
PubMed1992

Cross-neutralization of human immunodeficiency virus type 1 and 2 and simian immunodeficiency virus isolates.

In contrast to infrequent and low-titer cross-neutralization of human immunodeficiency virus type 1 (HIV-1) isolates by HIV-2- and simian immunodeficiency virus (SIV)-positive sera, extensive cross-neutralization of HIV-2NIH-Z, SIVMAC251, and SIVAGM208K occurs with high titer, suggesting conservation of epitopes and mechanism(s) of neutralization. The V3 regions of HIV-2 and SIV isolates, minimally related to the HIV-1 homolog, share significant sequence homology and are immunogenic in monkeys as well as in humans. Whereas the crown of the V3 loop is cross-reactive among HIV-1 isolates and elicits neutralizing antibodies of broad specificity, the SIV and especially HIV-2 crown peptides were not well recognized by cross-neutralizing antisera. V3 loop peptides of HIV-2 isolates did not elicit neutralizing antibodies in mice, guinea pigs, or a goat and together with SIV V3 peptides did not inhibit serum neutralization of HIV-2 and SIV. Thus, the V3 loops of HIV-2 and SIV do not appear to constitute simple linear neutralizing epitopes. In view of the immunogenicity of V3 peptides, the failure of conserved crown peptides to react with natural sera implies a significant role of loop conformation in antibody recognition. Our studies suggest that in addition to their grouping by envelope genetic relatedness, HIV-2 and SIV are neutralized similarly to each other but differently from HIV-1. The use of linear peptides of HIV-2 and SIV as immunogens may require greater attention to microconformation, and alternate subunit approaches may be needed in exploiting these viruses as vaccine models. Such approaches may also be applicable to the HIV-1 system in which conformational epitopes, in addition to the V3 loop, participate in virus neutralization.

Acquired Immunodeficiency Syndrome↗
PubMed1992

Viral DNA carried by human immunodeficiency virus type 1 virions.

A fundamental step in the replication of retroviruses is the reverse transcription of the viral RNA genome into a double-stranded DNA provirus. Retroviruses are believed to carry genomic information only as RNA, and synthesis of DNA is thought to start only after virus entry into the infected cell. We report here that infectious mature human immunodeficiency virus type 1 virions contain viral DNA of heterogeneous size. This heterogeneity seems to result from random stops of reverse transcription during minus- and plus-strand synthesis. The DNA carried by human immunodeficiency virus type 1 virions presumably originates from reverse transcription which takes place prior to or during formation of the mature virus particle.

Blotting, Southern↗