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M Tersmette

Publications and source records attributed to M Tersmette.

65 records · Page 4Linked to original sources
PubMed1989

Detection and subtyping of HIV-1 isolates with a panel of characterized monoclonal antibodies to HIV p24gag.

A panel of monoclonal antibodies (Mabs) was used to analyze the number and localization of B-cell epitopes on human immunodeficiency virus (HIV) p24gag and the variability of these epitopes in sequential HIV isolates and in isolates from different geographical origin. The specificity of these Mabs was demonstrated by immunoblotting and radioimmunoprecipitation assays. Cross-inhibition experiments indicated the presence of at least five different epitopes on p24. Analysis with p24 recombinant products revealed that three of the Mabs to p24 were directed to epitopes localized on the C-terminal part. Four other Mabs were directed to epitopes localized on the N-terminal half of the protein. Anti-p24 Mabs were used to develop HIV p24 antigen-capture assays. Application of these assays in HIV isolation resulted in more efficient recovery of HIV. Serotyping of HIV-1 isolates with five anti-p24 Mabs demonstrated that 55/65 isolates recovered from Dutch and Belgian individuals, but only 4/9 HIV-1 African isolates, were recognized by all five Mabs. Five of nine Central African HIV-1 isolates were not reactive with at least one of these Mabs. The variability of p24 appeared to be predominantly localized on the N-terminal part of the protein. Lack of expression of antigenic determinants on p24 was shown to be independent of culture conditions. Moreover, an infectious molecular clone was shown to have the same serotype as the corresponding HIV isolate. The serotype of sequential isolates obtained from 17 individuals over a 1 1/2- to 2 1/2-year period did not change, suggesting a limited in vivo p24 variation over time.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Blood donors with indeterminate anti-p24gag reactivity in HIV-1 western blot: absence of infectivity to transfused patients and in virus culture.

During a follow-up period of 23-40 months, 7 regular blood donors had persistently, and 4 had intermittently indeterminate anti-p24gag reactivity in human immunodeficiency virus (HIV)-1 Western Blot. Serological testing and viral cultures revealed that these donors had no signs of infection for HIV-1, HIV-2, human T-cell lymphotropic virus (HTLV)-4, and HTLV-1. Extensive interviewing and physical examination of these donors revealed neither risk factors, nor signs of HIV infection in the tested donors. Ten recipients, who were transfused with blood products from 6 of these 11 anti-p24gag-positive donors, were traced back. Six months after transfusion, no serological or clinical signs of HIV-1, HIV-2, or HTLV-1 infection were observed in these patients. It is concluded that blood donors with persistent or intermittent anti-p24gag reactivity in HIV-1 Western Blot, without development of antibodies to other HIV-encoded proteins in later blood samples, do not transmit the described retroviruses to transfused patients.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Evidence for a role of virulent human immunodeficiency virus (HIV) variants in the pathogenesis of acquired immunodeficiency syndrome: studies on sequential HIV isolates.

Sequential human immunodeficiency virus (HIV) isolates, recovered from a panel of longitudinally collected peripheral blood mononuclear cells obtained from 20 initially asymptomatic HIV-seropositive homosexual men, were studied for differences in replication rate, syncytium-inducing capacity, and host range. Eleven individuals remained asymptomatic; nine progressed to acquired immunodeficiency syndrome (AIDS) or AIDS-related complex (ARC) at the time point at which the last HIV isolate was obtained. In 16 individuals, only non-syncytium-inducing (NSI) isolates, with a host range restricted to mononuclear cells, were observed. From four individuals, high-replicating, syncytium-inducing (SI) isolates that could be transmitted to the H9, RC2A, and U937 cell lines were recovered. From two of these four individuals, SI isolates were obtained throughout the observation period. In the two others, a transition from NSI to SI HIV isolates was observed during the period of study. Three of these four individuals developed ARC or AIDS 9 to 15 months after the first isolation of an SI isolate. With the exception of the two individuals in whom a transition from NSI to SI isolates was observed, within a given individual the replication rate of sequential HIV isolates was constant. A significant correlation was found between the mean replication rate of isolates obtained from an individual and the rate of CD4+ cell decrease observed in this individual. In individuals with low-replicating HIV isolates, no significant CD4+ cell loss was observed. In contrast, recovery of high-replicating isolates, in particular when these were SI isolates, was associated with rapid decline of CD4+ cell numbers and development of ARC or AIDS. These findings indicate that variability in the biological properties of HIV isolates is one of the factors influencing the course of HIV infection.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Decreased accessory cell function by human monocytic cells after infection with HIV.

We studied the effect of HIV infection on the human monocytic cell line U937. The cell line was infected with cellfree HIV, strain HTLV-IIIB. After 3 wk, a high reverse transcriptase activity was continuously detected in the supernatant of the cell line. Neither cytopathic effects nor changes in cell growth were observed. After infection, accessory cell function on T cell proliferation induced by anti-CD3 mAb of both IgG1 and IgG2a subclasses and Con A was tested. Accessory cell function provided by U937 cells started to decline 3 wk after inoculation with HIV. This correlated with detectable reverse transcriptase activity. The remaining accessory cell capacity varied between 10 and 60% of accessory cell function mediated by noninfected U937 cells. It was excluded that decreased FcR expression on U937/HIV cells contributed to the accessory cell defect in the anti-CD3-driven system. IL-2R expression on T cells, cocultivated with U937/HIV and anti-CD3, was minimal. The accessory cell defect could only be partly overcome by addition of rIL-2 or IL-1. Addition of high titer (10(4) TCID50) HIV or U937/HIV cells did not affect T cell proliferation, which rules out that the observed inhibition is caused by HIV infection of T cells or suppressive effects of U937/HIV cells. These results suggest that infection of APC may contribute to the induction of immunologic abnormalities in early HIV infection. Thus, monocytes/macrophages may not only serve as a reservoir for the dissemination of HIV, but may be an important target cell through which the immune system is affected.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Confirmation of HIV seropositivity: comparison of a novel radioimmunoprecipitation assay to immunoblotting and virus culture.

A recently developed radioimmunoprecipitation assay, using 125I-labeled human immunodeficiency virus (HIV) viral proteins enriched for glycoproteins gp120env, gp41env (GRIPA), was compared to the immunoblot assay with respect to sensitivity and specificity for the detection of antibodies to HIV. Longitudinal sets of serum samples of seroconverting homosexual men were studied, as were sera of six blood-bank donors likely to be false-positive in immunoblot. In addition, HIV isolation was attempted from white blood cells of these blood-bank donors and of seropositive and seronegative individuals. In sets of seroconversion samples, the GRIPA appeared at least as sensitive as the immunoblot. Some sera already were clearly positive in the GRIPA at a time when there was only weak reactivity in immunoblot. In contrast, sera from blood-bank donors that were regarded as false-positive in immunoblot were negative in GRIPA. Virus culture from these donors was also negative. It is concluded that reactivity in immunoblot to core proteins only may well be false-positive, whereas antibody reactivity in the radioimmunoprecipitation assay to p24gag solely suggests ongoing seroconversion. This feature, in addition to a sensitivity for anti-gp120env comparable to immunoblotting, makes the GRIPA a useful confirmatory assay in sera that yield conflicting results in other HIV-antibody assays.

Antibodies, Viral↗
PubMed1988

Differential syncytium-inducing capacity of human immunodeficiency virus isolates: frequent detection of syncytium-inducing isolates in patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex.

Human immunodeficiency virus isolates were studied with respect to syncytium-inducing capacity, replicative properties, and host range. Five of 10 isolates from patients with acquired immunodeficiency syndrome (AIDS) and AIDS-related complex were able to induce syncytia in cultures of peripheral blood mononuclear cells (MNC). In contrast, only 2 of 12 isolates from asymptomatic individuals had syncytium-inducing capacity. Syncytium-inducing isolates were reproducibly obtained from the same MNC sample in over 90% of the cases, independent of the donor MNC used for propagation. Syncytium-inducing capacity was shown to be a stable property of an isolate, independent of viral replication rates. Evidence was obtained that the high replication rate of syncytium-inducing isolates observed during primary isolation may be due to higher infectivity of these isolates. The finding that only syncytium-inducing isolates could be transmitted to the H9 cell line is compatible with this higher infectivity. The frequent isolation of syncytium-inducing isolates from individuals with AIDS-related complex or AIDS and the apparent higher in vitro infectivity of these isolates suggest that syncytium-inducing isolates may unfavorably influence the course of human immunodeficiency virus infection.

AIDS-Related Complex↗
PubMed1987

Detection of early anti-p24 HIV responses in EIA- and immunoblot-negative individuals. Implications for confirmatory testing.

A sensitive and specific radioimmunoprecipitation assay was developed for the detection and analysis of anti-HIV antibody response in human sera with the use of 125I-labelled purified HIV proteins with subsequent sodium-dodecylsulfate gel electrophoresis (125I-RIPA). The 125I-RIPA was shown to be as specific but at least 1 log more sensitive with respect to the detection of gp41env and p24gag than the immunoblot analysis as tested in serum samples from several risk groups. Sequential sera were obtained from 9 individuals who seroconverted for HIV antibodies. In 4 individuals, antibody to p24gag was detected in earlier serum samples by the 125I-RIPA than by EIA or immunoblot; in the other 5 individuals, the detection of p24gag concorded in enzyme-linked immunosorbent assay (EIA), immunoblot and 125I-RIPA. Moreover, in one of 78 randomly chosen EIA-negative sera from individuals at high risk, antibodies to p24gag could be detected by the 125I-RIPA. This early seroconversion was confirmed 3 months later by means of immunoblotting and EIA. The specificity of the 125I-RIPA was further demonstrated by analyzing sequential EIA-negative serum samples from 10 individuals at risk for AIDS, collected during 2 years at 3-monthly intervals. All 80 serum samples were found to be negative in the 125I-RIPA and the individuals revealed no signs of HIV infection. The 125I-RIPA technique may be a valuable confirmatory assay in the serology of HIV infections. The sensitivity of this test provides a reliable measure of effective sensitivity when new-generation screening tests are evaluated.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1986

Thermal inactivation of human immunodeficiency virus in lyophilised blood products evaluated by ID50 titrations.

Inactivation of human immunodeficiency virus (HIV) in lyophilised small pool cryoprecipitate, factor VIII concentrate, prothrombin complex and C1-esterase inhibitor concentrate by prolonged heat treatment (72 h, 60 degrees C) was studied. Plasma products, inoculated prior to lyophilisation, had infectious titres ranging from 10(7) to 10(10.5). Residual infectivity (TCID50) was assessed by multiple titrations on H9 cells in a macro system and subsequent detection of virus replication by determining reverse transcriptase activity. Kinetics of inactivation showed a biphasic pattern: during the first 8 h a variable TCID50 reduction up to 10(4.3) was observed, followed by an additional loss of 10(1)-10(2.7) during the next 64 h. Heat treatment for 72 h resulted in a mean TCID50 reduction of 10(5). It is concluded that prolonged heat treatment may lead to the adequate prevention of HIV transmission by lyophilised plasma products.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Interference with HIV-induced syncytium formation and viral infectivity by inhibitors of trimming glucosidase.

Human immunodeficiency virus (HIV), the causative agent of AIDS, infects human lymphocytes and monocytes. An interaction between the viral envelope gp 120 and CD4 protein is required to initiate an infectious cycle. HIV infection in vitro induces syncytium formation by cell-to-cell fusion; this aspect of viral cytopathogenicity is even more dependent on gp120-CD4 interactions. That gp120 is extremely heavily glycosylated (31-36 N-linked glycans per molecule), suggests involvement of N-linked glycans in the gp120-CD4 interaction. We therefore investigated the effects of castanospermine, 1-deoxynojirimycin (dNM) and 1-deoxymannojirimycin (dMM), three trimming glycosidase inhibitors which perturb N-linked glycan structure, on induction of the formation of syncytium between HIV-infected and CD4-expressing cells. The glucosidase inhibitors castanospermine and dNM, but not the mannosidase inhibitor dMM, inhibited syncytium formation and interfered with infectivity. The potential of glucosidase inhibitors as anti-HIV therapeutic agents deserves further investigation, especially because dNM and related compounds show little toxicity in vitro and in vivo.

1-Deoxynojirimycin↗
PubMedDate not supplied

Efficiency of white cell filtration and a freeze-thaw procedure for removal of HIV-infected cells from blood.

Strategies for diminishing the risk of blood transfusion-associated transmission of HIV-1 were evaluated. HIV-1-infected peripheral blood mononuclear cells were added to blood that was subsequently filtered by using different white cell (WBC) filters (cellulose acetate and polyester). The average log reduction of infected cells with polyester filters was at least 2.5 as measured by ID50 titration and polymerase chain reaction. In two WBC filtration experiments with blood from seropositive donors diluted 1:4 with seronegative blood, log reductions of 2.4 and greater than 2.5 were observed. No cell-free virus was retained by the filter used. A freeze-thaw procedure applied to HIV-1-contaminated blood resulted in a minimal log reduction. These results indicate that the reduction of HIV-1 infectivity as a result of filtration is mainly due to the removal of HIV-1-infected WBCs, and that complete removal of infected WBCs cannot be achieved by the current filtration or freeze-thaw procedures. However, the development of filters with enhanced ability to remove (possibly infected) WBCs may have the added benefit of improving the safety of donor blood, especially in multiply transfused patients.

Blood↗