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Biomedical subjects

M Robert-Guroff

Publications and source records attributed to M Robert-Guroff.

At least 55 records · Page 3Linked to original sources
PubMed1990

Persistent infection of rhesus macaques with a molecular clone of human immunodeficiency virus type 2: evidence of minimal genetic drift and low pathogenetic effects.

In an attempt to generate a suitable animal model to study the infectivity and possible pathogenicity of human immunodeficiency viruses, we intravenously inoculated juvenile rhesus macaques and African green monkeys with a molecularly cloned virus, human immunodeficiency virus type 2 HIV-2sbl/isy, as well as with the uncloned HIV-2nih-z virus. Infection was monitored by virus recovery from the peripheral blood cells and by seroconversion against HIV-2 antigens measured by Western immunoblot, radioimmunoprecipitation, and enzyme-linked immunosorbent assay. We successfully infected two out of two macaques with the molecularly cloned virus and one macaque out of two with the HIV-2nih-z. No evidence of infection was seen in the African green monkeys with either virus. We followed the infected animals for 2 years. The animals remained healthy, although we observed intermittent lymphadenopathy and a transient decrease in the absolute number of circulating CD4+ T lymphocytes in both animals infected with the molecularly cloned virus. Virus isolation from the peripheral blood cells of the infected animals was successful only within the first few months after inoculation. Evidence of persistent infection was provided by the detection of proviral DNA by polymerase chain reaction analysis of the blood cells of the inoculated animals and by the stability of antiviral antibody titers. To evaluate the genetic drift of the proviral DNA, we molecularly cloned viruses which were reisolated 1 and 5 months postinoculation from one of these animals. Comparison of the DNA sequences of the envelope genes of both these isolates indicated that a low degree of variation (0.2%) in the envelope protein had occurred in vivo during the 5-month period. These data suggest that the use of HIV-2sbl/isy in rhesus macaques may represent a good animal model system to study prevention of viral infection. In particular, molecularly cloned virus can be manipulated for functional studies of viral genes in the pathogenesis of acquired immune deficiency syndrome and provides a reproducible source of virus for vaccine studies.

Animals↗
PubMed1989

Mother-to-infant transmission of human immunodeficiency virus type 1: association with prematurity or low anti-gp120.

In a prospective study of pregnant women infected with human immunodeficiency virus type 1 (HIV-1) in Brooklyn, New York, USA, 16 (29%) of 55 evaluable infants were infected with HIV-1. 9 infants had paediatric acquired immunodeficiency syndrome, 6 had less severe clinical manifestations of HIV-1 infection, and 1 was symptom-free but was seropositive for HIV-1 beyond 15 months of age. The 10 infants born at 37 weeks of gestation or earlier were at higher risk of HIV-1 infection than infants born at 38 weeks of gestation or later (60% vs 22%) but the median age at appearance of disease was approximately 5 months in both groups. The HIV-1 transmission rate was not associated with predelivery levels of maternal T cells, anti-p24, or neutralising antibodies but it was higher, among full-term infants, for those with mothers in the lowest third of the distribution of anti-gp120 levels (53%). On immunoblot, transmitting mothers lacked a gp120 band but not other bands. Protection was not associated with antibody to recombinant peptides from the hypervariable region of the major neutralising gp120 epitope, and the anti-gp120 endpoint dilution titre was similar in transmitting and non-transmitting mothers. Mothers of uninfected full-term infants appear to confer immunological protection against HIV-1 infection of their offspring by way of a high-affinity antibody to a gp120 epitope, whose specificity has importance for vaccine development and possibly perinatal immunotherapy.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Seroprevalence of HTLV-I in Portugal and evidence of double retrovirus infection of a healthy donor.

The prevalence of antibodies to HTLV-I in 5,475 Portuguese from 6 regions spanning the country was studied. Overall seroprevalence was 0.55%, indicating that Portugal is not an endemic area for this virus. Seropositives were distributed throughout the country, and no geographic clustering was observed. The seroprevalence of individuals who had lived in former Portuguese colonies in Africa (0.7%) was significantly higher than that of individuals who had not been in Africa (0.36%). An increase in seroprevalence with age was noted, and more females than males were antibody-positive, though not significantly so. Serum from one donor (1711), originating from Guinea-Bissau, was shown by Western blot and radioimmune precipitation to react with various proteins of HTLV-I, HIV-1 and -2, and SIV. Based on the serologic profiles and isolation of bona fide HTLV-I from her lymphocytes (confirmed by immunologic analysis, molecular cloning of the provirus and restriction enzyme analysis and sequencing of the DNA), together with the reactivity of her sera with an HIV-2 isolate obtained from her husband, we conclude that this donor was doubly infected with HTLV-I and HIV-2, rather than being the host to an as yet unidentified retrovirus.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Regulation of viral expression of human immunodeficiency virus in vitro by an antisense phosphorothioate oligodeoxynucleotide against rev (art/trs) in chronically infected cells.

In this report, we demonstrate the sequence-specific suppression of viral expression in T cells chronically infected with human immunodeficiency virus 1 (HIV-1), using antisense phosphorothioate oligodeoxynucleotides. As a target for antisense intervention, we used the HIV-1 gene rev, which is essential for viral replication and regulates the expression of virion proteins, in part, by affecting the splicing of the viral mRNA. A phosphorothioate oligomer complementary to the initiation sequence of HIV-1 rev had a significant and selective inhibitory effect on the production of several viral proteins in chronically HIV-1-infected T cells and drastically reduced the unspliced (genomic) viral mRNA transcripts, with relative sparing of smaller (spliced) transcripts. By contrast, the antisense sequence with unmodified normal phosphodiester linkages as well as phosphorothioate oligomers containing sense, random, homopolymeric sequences, or antisense sequence with N3-methylthymidine residues did not have an inhibitory effect on viral expression. Thus, sequence specificity and nuclease resistance were critical for the anti-viral-gene regulatory effect of the antisense molecules. The altered HIV-1 mRNA profile induced by the antisense phosphorothioate oligomer suggests that the mechanism for the inhibition of viral expression is due to an interference with the regulatory gene, rev, by translation arrest.

Base Sequence↗
PubMed1989

Isolate- and group-specific immune responses to the envelope protein of human immunodeficiency virus induced by a live recombinant vaccinia virus in macaques.

The immune responses produced by four macaques inoculated intradermally with a recombinant vaccinia virus that expresses the envelope gene of human immunodeficiency virus (HIV) were analyzed. Antibody capable of immunoprecipitating the glycosylated envelope protein precursor gp160 was detected in all animals within 3 weeks after the primary intradermal vaccination. The level of antibody was increased following a booster inoculation, and the sera from three of the four animals were then capable of immunoprecipitating gp120. Sera from two of the macaques with anti-gp120 antibody were able to prevent syncytium formation mediated by the parent HIV but not that induced by an unrelated HIV isolate. The fusion-inhibiting antibody was directed toward the highly variable central portion of the gp120 molecule since the effect was abrogated by incubation with PB1. The latter is a recombinant protein produced in Escherichia coli containing amino acids 295-474, a major neutralizing epitope. Sera from the three macaques with anti-gp120 neutralized HIV infectivity in an isolate-specific manner. The serum with highest neutralizing activity was also best at inhibiting syncytium formation. In contrast to the isolate-specific nature of the neutralizing antibody, T lymphocytes from immunized animals proliferated in response to divergent HIV isolates as well as to purified gp120. These studies provide baseline immunologic information for further development of recombinant vaccinia virus vectors.

Animals↗
PubMed1989

Human T-lymphotropic virus I-infected T cells constitutively express lymphotoxin in vitro.

We have studied the pattern of expression of the lymphokines tumor necrosis factor (TNF alpha) and lymphotoxin (TNF beta) in T-cell lines established by transformation with human T-lymphotropic virus, type I (HTLV-I), the etiologic agent of adult T-cell leukemia (ATL). We report here that nine of nine HTLV-I-infected T-cell lines, established by in vitro infection with HTLV-I, including those with CD4+ or CD8+ as well as CD4-/CD8- phenotypes, constitutively produce high levels of TNF alpha and -beta mRNA and secrete biologically active TNF beta into the culture medium. Similar patterns of expression are seen in six of six HTLV-I-infected T-cell lines directly established from ATL patients. In contrast, several T-cell lines, either uninfected or infected with human immunodeficiency virus I, did not produce comparable levels of the TNF beta. Comparisons of a normal functional T-cell clone before and after infection with HTLV-I show that expression of TNF beta mRNA is induced in the infected cells. The high level expression in HTLV-I-infected cell lines dose not seem to involve perturbation of the TNF alpha/beta genetic loci by proviral integration. A cell line (81-66/45) nonproductively transformed with HTLV-I that produces tat-1 in the absence of viral structural proteins, produces both TNF alpha and -beta mRNA. This suggests that expression of these cytokines could be mediated in trans by the tat-1 gene product.

Blotting, Southern↗
PubMed1988

Geographic distribution of HTLV-I and identification of a new high-risk population.

Epidemiologic studies indicate that human T-cell lymphotropic virus type I (HTLV-I), the causative agent of most cases of adult T-cell leukemia/lymphoma (ATLL) in Southeast Japan and the Caribbean islands and the probable cause of a progressive neurological disorder often referred to as tropical spastic paraparesis, occurs with unusual geographic clustering. The current large-scale serosurvey was undertaken to improve our understanding of HTLV-I prevalence in different parts of the world. We analyzed 43,445 serum samples collected from various geographic locales worldwide; 76% of these sera came from clinically healthy donors. Samples were initially screened by an enzyme-linked immunosorbent assay (ELISA) and 4,353 were further evaluated by means of competition assays. In this study, which did not include sera from endemic areas of Japan, a high prevalence of infection was observed in several countries in the Caribbean basin. A significant age-sex difference was observed between populations in the Caribbean and non-endemic regions of Japan. The reason for the male excess in non-endemic areas of Japan will require further study, while the female excess in the Caribbean basin is compatible with the previously described pattern for other HTLV-I-endemic areas. A newly recognized area of possible endemicity was southern Florida, where evidence of infection with HTLV-I or a related virus was found in a group of native Americans whose sera were collected in 1968. In certain parts of the world, particularly sub-Saharan Africa, important problems in determining specificity of reactivity occurred, probably because of cross-reacting antibodies. No pattern was detected that could explain the cross-reactivity solely on the basis of geographic areas, specific patterns of non-viral parasitic infection, or methods of handling the specimens. It is possible that these cross-reactivities are antibodies to proteins from HTLV-I-related retroviruses yet to be discovered.

Adult↗
PubMed1988

Generation of a neutralization-resistant variant of HIV-1 is due to selection for a point mutation in the envelope gene.

Transmission and growth of HIV-1 produced from the biologically active clone HTLV-III/HXB2D in the constant presence of a neutralizing antiserum yielded a viral population specifically resistant to neutralization by the same antiserum. Molecular clones MX-1 and -2, containing the entire envelope gene, were obtained from cultures of the resistant variant. The coding regions for the large envelope protein and most of the transmembrane envelope protein of two such clones were substituted for the homologous segment of HXB2D. Infectious viruses from these constructs were also specifically resistant to neutralization by the selecting antiserum. The exchanged fragment contained only one base change, resulting in an Ala----Thr replacement at position 582. When this substitution was introduced into HXB2D it conferred the resistant phenotype. Thus, small differences may be selected for in vivo by the host immune response and result in relatively large differences in susceptibility of the virus to such a response.

Antibodies, Viral↗
PubMed1988

Human T-cell lymphotropic virus I and adult T-cell leukemia: report of a cluster in North Carolina.

PURPOSE: Human adult T-cell leukemia-lymphoma is a malignant, proliferative disease of CD4+ lymphocytes associated with infection with human T-cell lymphotropic virus type I (HTLV-I). Following the presentation of a patient who was infected with the virus, we undertook a study of his family members and sexual contacts to see if a cluster of infected persons could be identified. CASE REPORT: A black heterosexual North Carolina native with a history of drug abuse presented with jaundice, and pancytopenia subsequently developed. He then became hypercalcemic and leukemic, with high numbers of circulating, morphologically abnormal CD4+ lymphocytes. RESULTS: As determined by radioimmunoassay and immunoblot analyses, the serum of the index case contained antibodies against core proteins (p19 and p24) of HTLV-I. When cultured in vitro with interleukin-2, the lymphocytes expressed HTLV-I specific core proteins. The virus recovered from these T cells was transmitted to cord blood T cells, which became immortalized for continuous growth in vitro, expressed HTLV-I p19 protein, and displayed characteristic C-type particles by electron microscopy. Studies of family members and sexual contacts, all of whom were black, heterosexual central North Carolina natives, revealed five of 28 whose serum had anti-HTLV-I antibodies as determined by radioimmunoassay and immunoblot. Neither the patient nor the seropositive family/contacts had antibodies against human immunodeficiency virus proteins. Four of the six people with HTLV-I infection had no history of intravenous drug abuse. Three of the five seropositive family/contacts had circulating, morphologically abnormal lymphocytes suggestive of "preleukemic" or "smoldering" human adult T-cell leukemia-lymphoma.

Adult↗
PubMed1988

Spectrum of HIV-1 neutralizing antibodies in a cohort of homosexual men: results of a 6 year prospective study.

Serum samples collected prospectively between 1982 and 1987 from a cohort of homosexual men were analyzed for HIV-1 neutralizing antibodies. Seven seroconverters who became infected between 1982 and 1984 and 12 seroprevalents who were already seropositive in 1982 remained free of AIDS. During the 6 year period, 1 seroconverter and 14 seroprevalents developed AIDS. Healthy seroconverters developed neutralizing antibodies slowly and reached moderate geometric mean titers (GMT) of 1:100 within 3 years of seroconversion. Healthy seroprevalents already had moderate titers in 1982, which increased markedly in 1985-1986 (GMT greater than 1:200) and subsequently returned to the previous level in 1987. Neutralizing antibody titers declined 3 years prior to diagnosis in men who developed AIDS and reached levels significantly lower than those of healthy counterparts 2 years before diagnosis. Analysis of neutralizing antibody activity to several HIV-1 isolates indicated that the lower titers of men who developed AIDS were not due to diminished group-specific reactivity. Thus, high neutralizing antibody titers correlated with better clinical outcome, and low or decreasing neutralizing antibody titer signaled poor prognosis. Although naturally developing neutralizing antibodies may ultimately be inadequate in controlling disease progression, measures able to boost the neutralizing antibody titer of individuals already infected with the virus or to elicit high-titer neutralizing antibodies in individuals at risk may yet prove beneficial in controlling viral spread in vivo or in preventing new infection, presumably in concert with cellular immunity.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Characterization of a human immunodeficiency virus neutralizing monoclonal antibody and mapping of the neutralizing epitope.

A monoclonal antibody was produced to the exterior envelope glycoprotein (gp120) of the human T-cell lymphotropic virus (HTLV)-IIIB isolate of the human immunodeficiency virus (HIV). This antibody binds to gp120 of HTLV-IIIB and lymphadenopathy-associated virus type 1 (LAV-1) and to the surface of HTLV-IIIB- and LAV-1-infected cells, neutralizes infection by cell-free virus, and prevents fusion of virus-infected cells. In contrast, it does not bind, or weakly binds, the envelope of four heterologous HIV isolates and does not neutralize heterologous isolates HTLV-IIIRF and HTLV-IIIMN. The antibody-binding site was mapped to a 24-amino-acid segment, using recombinant and synthetic segments of HTLV-IIIB gp120. This site is within a segment of amino acid variability known to contain the major neutralizing epitopes (S. D. Putney, T. J. Matthews, W. G. Robey, D. L. Lynn, M. Robert-Guroff, W. T. Mueller, A. J. Langlois, J. Ghrayeb, S. R. Petteway, K. J. Weinhold, P. J. Fischinger, F. Wong-Staal, R. C. Gallo, and D. P. Bolognesi, Science 234:1392-1395, 1986). These results localize an epitope of HIV type-specific neutralization and suggest that neutralizing antibodies may be effective in controlling cell-associated, as well as cell-free, virus infection.

Amino Acid Sequence↗
PubMed1987

HTLV-III neutralizing antibody development in transfusion-dependent seropositive patients with beta-thalassemia.

Sera collected in New York in 1984 from 77 patients with homozygous beta-thalassemia were assayed for antibodies to HTLV-III by ELISA and Western blot techniques. Eight (12%) of the 66 hypertransfused thalassemics were seropositive. Retrospective sera of these eight individuals were examined by radioimmune precipitation (RIP), and assays for neutralization of virus infectivity were performed. With seroconversion, antibodies to viral envelope proteins appeared first and were correlated with development of neutralizing antibody. Affinity purified gp120, the major envelope glycoprotein of HTLV-III, blocked viral infectivity and absorbed neutralizing antibody activity from a positive serum. Neutralizing antibody titers mirrored antibody titers to gp120 by RIP. Antibody to gp120 sometimes occurred in the absence of neutralizing antibody, although the reverse was not true. One thalassemia patient who exhibited antibody to gp120 for 3 yr post-seroconversion failed to develop neutralizing antibody, acquired the acquired immunodeficiency syndrome with central nervous system involvement and lymphoma, and subsequently died. In contrast, all other seropositive thalassemics possessed neutralizing antibodies, and were asymptomatic or exhibited only lymphadenopathy. These results indicate that gp120 elicits neutralizing antibodies in the course of natural infection with HTLV-III. The relationship seen here between neutralizing antibody and better clinical outcome needs to be verified by additional studies.

AIDS-Related Complex↗
PubMed1987

Expression of the HT462 antigen on fresh leukemic T cells and on cells of HTLV-I infected lines.

We have examined expression of antigens defined by HT462 monoclonal antibody (mAb), together with other HTLV-I related antigens using phorbol 12-myristate 13-acetate treated leukemic mature T cells. Thirteen patients with adult T-cell leukemia (ATL), 3 patients in remission states of ATL and 5 patients with non-ATL were examined. All ATL cells expressed the HT462 antigen, however cells from patients in remission did not express the HT462 antigen. A low percentage of cells from 2 out of 5 patients with non-ATL mature leukemic T cells expressed the HT462 antigen, although these cells did not express other HTLV-I related antigens. Cells of HTLV-I infected human cell lines expressed the HT462 antigen. Three HTLV-I infected rat cell lines (TARS-1, TART-1, TARL-2) did not express the HT462 antigen, although cells of these lines expressed other HTLV-I related antigens. Characterization of the HT462 antigen by strip radioimmunoassay based on western blotting technique using cell lysates of HUT102 cells revealed two additional bands (p68, p35) together with previously reported proteins (gp52, p42). Only p68 was seen in western blots using cell lysates of the rat cell lines. These findings further suggest that the HT462 antigen is a cellular component induced in virus transformed human cells and not a virus encoded protein.

Animals↗
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

Anti-HTLV-III and anti-HTLV-I antibodies and T cell subsets in hemophiliacs living in HTLV-I endemic and nonendemic areas of Japan.

Sera from 154 hemophiliacs, including 132 with hemophilia A and 22 with hemophilia B, were examined for antibodies against human T cell lymphotropic virus type III (HTLV-III) and type I by strip radioimmunoassay based on the Western blotting technique. Sixty-two patients lived in Kyushu, a known endemic area of HTLV-I and 92 patients lived in Tokyo, a nonendemic area of HTLV-I. Results showed a prevalence of HTLV-III antibodies of 64.5% in Kyushu and of 57.6% in Tokyo. There were no significant differences between these two groups. Helper/suppressor (T4/T8) ratios of seropositive patients were 0.69 +/- 0.41 and those of seronegative patients were 1.05 +/- 0.56. Ratios of both groups were lower than those of normal healthy people (1.35 +/- 0.45). Our findings confirmed that hemophiliacs living in an HTLV-I endemic area and those living in a nonendemic area in Japan equally possessed antibodies to HTLV-III. Low T4/T8 ratios and increases of serum IgG and IgM levels were found even in seronegative hemophiliacs.

Antibodies, Viral↗