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Biomedical subjects

R C Gallo

Publications and source records attributed to R C Gallo.

At least 289 records · Page 16Linked to original sources
PubMed1987

Restricted neutralization of divergent HTLV-III/LAV isolates by antibodies to the major envelope glycoprotein.

By analogy to other retroviruses, the major envelope glycoprotein - gp120 - of HTLV-III/LAV is a probable target for neutralizing antibody. This antigen has been purified from H9 cells chronically infected with the HTLV-IIIB prototype strain. Several goats immunized with the gp120 produced antibodies that neutralized infection of H9 by the homologous virus isolate. These same sera failed to neutralize the divergent HTLV-IIIRF isolate. Individuals infected with HTLV-III/LAV commonly develop antibodies to gp120 which could be isolated using the gp120 antigen coupled to an immunoadsorbent resin. The antibody fraction that bound tightly to such a resin was found to neutralize the IIIB but not the RF isolate in a fashion similar to that of the goat anti-gp120 sera. However, the nonbinding fraction (effluent) from the resin also contained neutralizing activity which was able to block infection by both virus isolates with similar efficacy. Human antibodies to the other virus envelope gene product, the transmembrane gp41, were also affinity-purified utilizing the recombinant peptide 121, but they failed to influence infection by either virus isolate.

Antibodies, Viral↗
PubMed1987

Interaction of viral and cellular factors with the HTLV-III LTR target sequences in vitro.

The location of cis-acting regulatory sequences within the long terminal repeat (LTR) of the human T-cell lymphotropic virus type III was determined by eukaryotic cell transfection and chloramphenicol acetyltransferase (CAT) assay or in vitro cell-free transcription. A 160 base pair (bp) region of the LTR at position - 104 to 56 is required for trans-activation (cap site 1). A 24 bp enhancer element (EHE) capable of increasing the rate of transcription, irrespective of orientation, is located between nucleotides -105 to -80. It contains two 10 bp repeats. Three Sp1 binding sites (Sp1 III-I) are located between -78 and -45. A deletion of Sp1 III allowed for limited TATIII response while the presence of a functional enhancer restored the activity in HTLV-III infected cells. Complete loss of transcriptional activity and CAT gene expression could be attributed to the absence of EHE and Sp1 III-I at position -48. However, reinsertion of the enhancer restored accurate initiation but at a decreased level suggesting that the presence of a Sp1 binding site is not a prerequisite for the accurate initiation of transcription but is required for transcriptional activation independent of a promoter. The presence of a negative regulatory element (NRE) has been demonstrated by removal of the 5' part of U3 to position -117. Nucleotide sequences around the cap site and poly (A) site contain a trans-activator response element (TRE) and could be arranged into a unique secondary structure. A deletion of four nucleotides TCTGAGCCTGGGAGCTC causes a loss of three dimer linkage sequence binding. The CAT gene enzyme expression is completely abolished but transcriptional activity remains at reduced level.

Acetyltransferases↗
PubMed1987

Sequential changes in antibody levels to the env and gag antigens in human immunodeficiency virus infected subjects.

Sera from 51 HTLV-III (human immunodeficiency virus, HIV)-antibody positive subjects consisting of 21 asymptomatic individuals and 15 ARC and 15 AIDS patients were analyzed for their serological profiles toward the viral antigens. One of the asymptomatic subjects only showed a p24 reactivity in the immunoblot, but antibodies to the env antigens were clearly identified by immunoprecipitation of viral antigens (RIP) followed by SDS-polyacrylamide gel electrophoresis. RIP patterns of different subjects and even different bleeds from the same subjects showed a varying reactivity to the gag antigens whereas the reactivity towards the env antigens appeared to be generally stable. RIP analysis of sequential sera of virus-infected individuals indicated a pattern consistent with an initial steady rise of antibody reactivities to the gag antigens relative to the reactivities to the envelope antigens. These reactivities reached a plateau and then slowly declined. While all sera tested had antibodies to the envelope antigens gp160, gp120 and gp41, 86% of the asymptomatic subjects, 67% of the ARC patients and only 33% of the AIDS patients had antibodies to the gag proteins p24 and pr53gag.

AIDS-Related Complex↗
PubMed1987

Neoplastic complications of HTLV-III infection. Lymphomas and solid tumors.

Neoplastic disease arose in 29 of 200 patients infected with human T lymphotropic virus type III (HTLV-III) seen at a suburban hospital. Seventeen patients had Kaposi's sarcoma, one of whom also had colon carcinoma. Nine patients had lymphoproliferative disorders (seven lymphomas, one T suppressor cell chronic lymphocytic leukemia, and one multiple myeloma), including three with concomitant Kaposi's sarcoma and one with colon cancer. One other patient had colon cancer, one had a seminoma, and one had pancreatic cancer. Kaposi's sarcoma as a complication of AIDS occurred mainly in homosexuals (17 of 42 homosexuals, one of 17 drug abusers, one of five heterosexually promiscuous patients, and one of six patients who had previously received transfusions). The high-grade lymphomas did not show a predilection for any particular AIDS risk group. Three of four solid tumors arose in elderly AIDS patients. Twenty-five of 75 patients with CDC-defined AIDS had a neoplastic disorder (26 are still alive and may yet demonstrate malignancy). Few other diseases of man have been associated with as high an incidence of neoplastic transformation as occurs with HTLV-III infection.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Helper T-cell antigenic site identification in the acquired immunodeficiency syndrome virus gp120 envelope protein and induction of immunity in mice to the native protein using a 16-residue synthetic peptide.

Much effort has been devoted to the analysis of antibodies to acquired immunodeficiency syndrome virus antigens, but no studies, to our knowledge, have defined antigenic sites of this virus that elicit T-cell immunity, even though such immunity is important in protection against many other viruses. T cells tend to recognize only a limited number of discrete sites on a protein antigen. Analysis of immunodominant helper T-cell sites has suggested that such sites tend to form amphipathic helices. An algorithm based on this model was used to identify two candidate T-cell sites, env T1 and env T2, in the envelope protein of human T-lymphotropic virus type IIIB that were conserved in other human immunodeficiency virus isolates. Corresponding peptides were synthesized and studied in genetically defined inbred and F1 mice for induction of lymph node proliferation. After immunization with a 426-residue recombinant envelope protein fragment, significant responses to native gp 120, as well as to each peptide, were observed in both F1 combinations studied. Conversely, immunization with env T1 peptide induced T-cell immunity to the native gp 120 envelope protein. The genetics of the response to env T1 peptide were further examined and revealed a significant response in three of four independent major histocompatibility haplotypes tested, an indication of high frequency responsiveness in the population. Identification of helper T-cell sites should facilitate development of a highly immunogenic, carrier-free vaccine that induces T-cell and B-cell immunity. The ability to elicit T-cell immunity to the native viral protein by immunization with a 16-residue peptide suggests that such sites represent potentially important components of an effective vaccine for acquired immunodeficiency syndrome.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Specific cellular immune response and neutralizing antibodies in goats immunized with native or recombinant envelope proteins derived from human T-lymphotropic virus type IIIB and in human immunodeficiency virus-infected men.

Animals immunized with native or recombinant envelope proteins from the human immunodeficiency virus (HIV, formerly referred to as human T-lymphotropic virus type III) human T-lymphotropic virus type IIIB and naturally HIV-infected men were assessed for neutralizing antibodies and cell-mediated immunity toward the virus. Immunization of rabbits or goats with the native external envelope glycoprotein gp120 or with corresponding recombinant proteins elicited strictly type-specific neutralizing antibodies. A broad, group-specific cellular immune response to gp120 and to three different HIV isolates was seen in goats immunized with the native gp120 but not in animals immunized with the nonglycosylated recombinant envelope proteins. In HIV-infected people, no T-cell response was seen, even though their T-cell response toward other foreign antigens was intact. The results show type- and group-specific epitopes on gp120, some of which may be of importance for the development of a vaccine against HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Humoral immune response to the entire human immunodeficiency virus envelope glycoprotein made in insect cells.

The human immunodeficiency virus envelope gene was expressed in insect cells by using a Baculovirus expression vector. The protein has an apparent molecular mass of 160 kDa, appears on the surface of infected insect cells, and does not appear to be cleaved to glycoproteins gp120 and gp41. Goats immunized with the 160-kDa protein have high titers of antibody that neutralizes virus infection as measured by viral gene expression or cell cytolysis. In addition, immune sera can block fusion of human immunodeficiency virus-infected cells in culture. Both neutralization and fusion-blocking activities are bound to and eluted from immobilized gp120.

Animals↗
PubMed1987

Serological responses in chimpanzees inoculated with human immunodeficiency virus glycoprotein (gp120) subunit vaccine.

The major envelope glycoprotein of a human immunodeficiency virus (HIV) has been purified and was utilized as a prototype vaccine in chimpanzees. The 120,000-dalton glycoprotein (gp120) was purified from membranes of human T-lymphotropic virus (HTLV)-IIIB-infected cells and the final preparation contained low levels to no detectable HTLV-IIIB core antigen (p24) and low levels of endotoxin. Chimpanzees inoculated with gp120 responded by developing antibodies that precipitated radiolabeled gp120 and neutralized in vitro infection of HTLV-IIIB. Antibodies to HTLV-IIIB p24 were not detected in the gp120-immunized chimpanzees. Peripheral blood leukocytes from the vaccinated animals were examined for T4+ and T8+ cells, and no decrease in the T4/T8 ratio was found, indicating that immunization with a ligand (gp120) that binds to T4 has no detectable adverse effect on the population of T4+ cells. The only current animal model that can be reproducibly infected with HIV is the chimpanzee. Immunization of chimpanzees with HIV proteins will provide an experimental system for testing the effectiveness of prototype vaccines for preventing HIV infection in vivo.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Genetic analysis of a new subgroup of human and simian T-lymphotropic retroviruses: HTLV-IV, LAV-2, SBL-6669, and STLV-IIIAGM.

A new primate retrovirus, STLV-IIIAGM, has been recently isolated from healthy African green monkeys and is apparently nonpathogenic in its natural host. However, spontaneous infection as well as inoculation of STLV-IIIAGM into macaques induces a disease with clinical features that resemble human AIDS. Independent isolates of human retroviruses, serologically closely related to STLV-IIIAGM, have been obtained from healthy individuals (HTLV-IV) and patients with immunodeficiency (LAV-2FG and SBL 6669) from West Africa. The latter have also been referred to as HIV-2 because, like HTLV-III/HIV-1, they may be associated with immune deficiency, or as West African human retroviruses because of their prevalence and probable origin from that region. We have molecularly cloned the STLV-IIIAGM genome and have generated probes from the gag-pol and envelope genes to analyze the genetic relatedness of these simian and human retroviruses. Our results indicate that all these retroviruses are genetically closely related to each other, HTLV-IV and STLV-IIIAGM differing only by a few restriction enzyme sites while LAV-2FG and SBL 6669 exhibit greater polymorphism from HTLV-IV/STLV-IIIAGM. These data mirror the variable degree of relatedness among members of the first subgroup of human retroviruses, HTLV-III/HIV.

Animals↗
PubMed1987

Structure of the long terminal repeat of simian lymphotropic virus type III (African green monkey) and its relatedness to that of HIV.

The simian T-lymphotropic virus type III (STLV-III[AGM]) is a retrovirus in wild African green monkeys which is serologically related to the human T-lymphotropic virus type III (HTLV-III/LAV-1/HIV) and other related human retroviruses. The long terminal repeats (LTR) contained in clones of viral DNA of (STLV-III[AGM]) were subcloned in M13 and their DNA sequence was determined and compared with that of HIV (HTLV-III[BH10]). The STLV-III(AGM) LTR is considerably larger than that of HTLV-III(BH10) (800 bp vs 634 bp) and contains a 498 bp U3 region, a 176 bp R region, and a 126 bp U5 region. These two LTR sequences share regions of significant homology. Regions of greatest homology include the 5' portion of U3, a core enhancer sequence in U3, sequences including and surrounding the TATAA promoter box in U3 and the AATAAA polyadenylation/termination signal in R, and the 3'-most region of U5. The relatively larger size of the STLV-III LTR is due to the presence in all three parts of the LTR of sequences which have no apparent homolog in the HIV LTR. Overall, the two LTRs are 47% homologous. Even greater homology (75%) is evident with a 300 bp segment including R and some of U3 from the LTR of another human retrovirus, HIV-2/LAV-2. The STLV-III LTR contains an imperfect 28 bp direct repeat in the R region which is not present in HIV. There are no obvious direct repeats in U3 homologous to the 10 bp repeat in the U3 of HTLV-III.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Immunological and chemical analysis of P6, the carboxyl-terminal fragment of HIV P15.

The first open reading frame of the HIV genome has been identified as the gag gene. The proteins encoded by this gene are p17 as the amino-terminal protein, p24 as the middle peptide, and p15 as the carboxyl-terminal end. A monoclonal antibody recognizing an antigenic determinant on a fragment of p15 has been developed and designated M35/2F8. This monoclonal has been instrumental in radiosequencing the carboxyl-terminal product of p15, p6, and in determining the cleavage site between this protein and the amino-terminal product, p7. By immunoaffinity chromatography it was also possible to purify p6 from HIV lysates and all p6 containing polyproteins from HIV-infected cells. These results gave more insight into the composition and processing of the HIV gag gene.

Antibodies, Monoclonal↗
PubMed1987

Genomic diversity of Zairian HIV isolates: biological characteristics and clinical manifestation of HIV infection.

We describe here several African isolates of HIV, compare them to U.S.-European prototype isolates and to each other, correlate the number of isolates with serological results, and provide insights into the disease spectrum associated with HIV infection in Africa. Three of 25 healthy Zairian donors and 54 of 87 Zairian patients selected for specific pathology and hospitalized in the internal medicine department of the University Clinic of Kinshasa, Zaire, were HIV positive over a six month period in 1985 either by serum antibody (42 cases) or virus isolation (40 cases). The virus positive cases showed a decrease in number of T4 cells and interleukin-2 (IL2) production by mononuclear cells. Restriction endonuclease analysis of HIV sequences from these isolates showed that genomic diversity is also observed in the Zairian isolates but closely related viruses could also be found, similar to the spectrum of diversity among isolates obtained from the U.S. and Europe. A number of isolates (12 of 40) were obtained from serum antibody negative adults. These results are difficult to explain by viral antigenic diversity alone since hybridization with a HTLV-III-B (clone BH10) probe under stringent conditions indicated an overall high degree of relatedness. Rather, these results indicate that some African HIV infected patients fail to make detectable antibodies to HIV or the antibodies were bound in immune complexes not detectable by current techniques.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Stages in the progression of HIV infection in chimpanzees.

Circulating HIV antigens and HIV specific antibodies in sera of experimentally infected chimpanzees were monitored by ELISA immunoassay, Western blot, and radioimmunoprecipitation procedures. Three of three chimpanzees given plasma from patients with AIDS or ARC tested positive for HIV antigens beginning six to ten weeks after transfusion. Antigen production rose sharply but was of short duration. Despite their proven infectivity and the presence of anti-HIV antibody, all donors to these chimpanzees tested negative for the HIV antigen. Of the three animals that developed HIV antigen one animal did not produce any HIV antibodies or evidence of disease. A second produced antibodies to only the p24 and p18 antigens and remained clinically well. The third produced antibodies beginning with anti-p24, to all the major HIV proteins except gp120, and then developed marked lymphadenopathy which persisted for 32 weeks. Antibody persistence after the disappearance of clinical disease was variable and was greatest for gp41 and least for p24. These data may be of value in the interpretation of human serological testing for HIV and in further studies of the sequence of events leading to the pathological effects of HIV infection. A significant value of the chimpanzee model is the capacity of this animal to respond in a variety of ways to HIV infection, suggesting the existence of successive or alternate states of early HIV infection, and may have implications in the design of early interventions.

AIDS-Related Complex↗