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Biomedical subjects

T F Schulz

Publications and source records attributed to T F Schulz.

At least 73 records · Page 4Linked to original sources
PubMed1996

Prevalence of Kaposi's sarcoma associated herpesvirus infection measured by antibodies to recombinant capsid protein and latent immunofluorescence antigen.

BACKGROUND: Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8, may be the infectious cause of KS. Its prevalence in the general population, on the basis of detection of the virus genome, is controversial. To investigate the seroprevalence, we measured antibodies to a recombinant capsid-related (lytic cycle) KSHV antigen and a latent antigen complex. METHODS: We selected potentially immunoreactive capsid-related proteins of KSHV by expressing them as recombinant proteins and testing them in western blot assays. We used a truncated recombinant protein encoded by KSHV open reading frame 65 (orf 65) to develop a diagnostic enzyme-linked immunosorbent assay (ELISA) and tested sera from HIV-infected individuals with KS, HIV-uninfected patients with "classic" KS, other HIV risk groups, and blood donors. We also compared the antibody response to this capsid-related protein to the response to latent antigen(s) in an immunofluorescence assay. FINDINGS: 77/92 (84%) sera from KS patients reacted with the KSHV orf 65 protein and 84/103 (81.5%) reacted with KSHV latent antigen(s). The dominant immunogenic region of orf 65 is within the carboxyterminal 80 aminoacids, a region with little sequence similarity to the related Epstein-Barr virus, suggesting that orf 65 is a KSHV specific antigen. Only three sera from patients with haemophilia (1/84) or from intravenous drug users (2/63) had KSHV specific antibodies in the orf 65 assay whereas none of these sera reacted with latent antigen. Antibodies to KSHV were also infrequently found in UK and US blood donors by either assay (UK, 3/174 with orf 65 and 4/150 with latent antigen; US, 6/117 with orf 65 and 0/117 with latent antigen). They were more common among HIV-infected gay men without KS (5/16 by orf 65 ELISA, 10/33 by IFA), HIV-uninfected STD clinic attenders (14/166 by IFA), and Ugandan HIV-uninfected controls (6/17 by orf 65 ELISA, 9/17 by IFA). Antibody reactivity to the orf 65 protein (ELISA) and to latent antigen(s) (IFA) was concordant in 89% of 462 sera tested but reactive blood donor sera were discordant in both assays. Four AIDS-KS sera were unreactive in both assays. INTERPRETATION: The distribution of antibodies to both a capsid-related recombinant protein and latent antigen(s) of KSHV strongly supports the view that infection with this virus is largely confined to individuals with, or at increased risk for, KS. However, infection with KSHV does occur, rarely, in the general UK and US population and is more common in Uganda. Antibodies to latent antigen(s) or to orf 65 encoded capsid protein will not detect all cases of KSHV infection, and a combination of several antigens will probably be required for accurate screening and confirmatory assays.

Adult↗
PubMed1996

HIV infection and neoplasia.

HIV infection predisposes to several neoplastic conditions, especially non-Hodgkin lymphoma (NHL) and Kaposi's sarcoma (KS), and also intraepithelial cervical neoplasia (CIN) and anal neoplasia (AIN) (but not cervical or anal invasive cancer) and possibly seminoma. For neoplasias associated with oncogenic human viruses (ie, some NHL, CIN, AIN, and probably KS) the role of HIV is most probably linked to its immunosuppressive effect and interference with immune-mediated tumour surveillance. HIV-1, through its regulatory protein tat, might also have a direct promoting effect on KS lesions but it is not essential for their development. The increased frequency of Burkitt's lymphoma and Epstein-Barr-virus-negative large-cell lymphoma in AIDS patients, but not in immunosuppressed transplant patients, and the increased rate of testicular tumours in HIV-infected individuals remain unexplained and may indicate either a direct role for HIV or other cofactors.

Acquired Immunodeficiency Syndrome↗
PubMed1996

Probing the conformation of the human T-lymphotropic virus I envelope protein complex with monoclonal antibodies.

We are investigating the binding of a series of monoclonal antibodies to native and detergent-treated human T-lymphotropic virus I (HTLV-I) envelope proteins to explore their conformation. A comparison of our data with previously published findings suggests that a central neutralization domain (aa 175-200) is folded such that only short stretches are exposed at the surface of the native envelope protein complex. However, the complete domain becomes accessible after treatment with mild non-ionic detergents, suggesting that envelope subunit interaction may partially obscure this domain. We further provide immunochemical evidence that a region containing a heptad repeat in the extracellular part of the transmembrane protein is folded towards the interior of the HTLV-I envelope complex.

Amino Acid Sequence↗
PubMed1995

Kaposi's sarcoma-associated herpesvirus infects endothelial and spindle cells.

Kaposi's sarcoma (KS), a vascular tumour that contains characteristic spindle cells forming slit-like spaces, may have an infectious aetiology. Recently, sequences of a new human herpesvirus, KSHV/HHV-8, have been identified in both HIV-associated and classical KS. We sought to identify the target cell of this virus in KS tumour tissue. Using PCR in situ hybridization (PCR-ISH) we show that KSHV/HHV-8 is present in the flat endothelial cells lining vascular spaces of KS lesions as well as in typical KS spindle cells. These findings show that KSHV/HHV-8 is present in the cell types thought to represent neoplastic cells in these lesions.

AIDS-Related Opportunistic Infections↗
PubMed1995

Reduced glycosylation of human cell lines increases susceptibility to CD4-independent infection by human immunodeficiency virus type 2 (LAV-2/B).

The human immunodeficiency virus type 2 (HIV-2) strain LAV-2/B is able to infect a variety of human cell lines via a CD4-independent pathway. We have used the glycosylation inhibitors tunicamycin, swainsonine, and deoxymannojirimycin to further characterize this putative alternative receptor for HIV-2 (LAV-2/B). These antibiotics resulted in an increase (5- to 30-fold) in the susceptibility of a variety of CD4- human cell lines to infection by LAV-2/B (RD, HeLa, HT29, Rsb, Heb7a, Hos, and Daudi). Several nonprimate cell lines (mink Mv-1-lu, rabbit SIRC, hamster a23, mouse NIH 3T3, cat CCC, and rat HSN) remained resistant to infection by LAV-2/B after treatment with glycosylation inhibitors, suggesting that they do not express the HIV-2 CD4-independent receptor. Two of these nonprimate cell lines are readily infected by HIV-2 when they express CD4 (Mv-1-lu and CCC). Treatment of human cells with neuraminidase had no effect on subsequent infection by LAV-2/B, suggesting that the increase in susceptibility to infection of deglycosylated cells is not due to a change in the electrostatic charge of the cell surface. Treatment of RD CD4- cells and HeLa CD4+ cells with a variety of proteases resulted in a 75 to 90% decrease in infection by LAV-2/B when compared with untreated cells. Taken together, all these data suggest that HIV-2 can utilize a membrane glycoprotein other than CD4 to attach and fuse with a variety of human cells.

Animals↗
PubMed1994

A truncated HTLV-I envelope protein, lacking the hydrophobic membrane anchor domain, is associated with cellular membranes and virions.

The HTLV-I producer cell line C10/MJ2 does not induce syncytium formation with HTLV-I receptor expressing cells. Here we show that this cell line produces a truncated envelope protein, which, because of a premature stop codon, lacks the hydrophobic membrane anchor domain of the transmembrane protein (TM). Despite lacking a membrane anchor this envelope protein is expressed on the cell surface and associated with released virions. However, its incorporation into virions seems less efficient than that of a full-length envelope glycoprotein and some of its released into the cell culture supernatant as soluble surface glycoprotein (SU)-TM complexes. Small amounts of such a truncated envelope glycoprotein were also found in the fusion-competent HTLV-I producer cell line MT2. Premature truncation of HTLV-I envelope proteins in producer cell lines may result from in vitro selection for a less fusogenic phenotype. The association of truncated HTLV-I envelope proteins with virions and cell surfaces may reflect interactions between the SU domain and cellular membranes, possibly with the cellular receptor for HTLV-I.

Amino Acid Sequence↗
PubMed1994

Isolation of a new foamy retrovirus from orangutans.

We have isolated a new foamy virus from blood samples taken from two apparently healthy orangutans (Pongo pygmaeus). The older orangutan has since died with encephalopathy after a brief acute illness, while the younger one, his grandson, remains well. These animals and 12 other orangutans had specific antibodies to foamy virus as measured by immunofluorescence. The new foamy virus and the antisera showed strong and specific neutralization, with only weak cross-reaction with other simian foamy virus strains. Southern blotting with gag and env probes of human foamy virus and PCR amplification showed that the new foamy virus, designated SFV-11, is related to, yet distinct from, previously characterized strains from humans, chimpanzees, and monkeys.

Animals↗
PubMed1993

Transcomplementation of VIF- HIV-1 mutants in CEM cells suggests that VIF affects late steps of the viral life cycle.

The vif gene of HIV-1 has previously been claimed to be essential for the ability of cell-free virus preparations to infect cells. Here we report that the CEM T-cell-line, stably transfected with and expressing vif, supports the replication of vif- HIV-1 viruses to the same extent as wild-type HIV1. Cell entry and early replication stages are the same for vif- and vif+ HIV-1 passaged in CEM, as measured both by a PCR-based cell entry assay and by fusogenic potential. These findings indicate that vif does not affect viral infectivity on CEM cells, but seems to act at a later stage of virus replication/maturation. We also show that the VIF proteins of two different HIV-1 strains can transcomplement different vif- HIV-1 mutants.

Cell Line↗
PubMed1993

Effect of mutations in the V3 loop of HIV-1 gp120 on infectivity and susceptibility to proteolytic cleavage.

It has been suggested that the V3 domain of human immunodeficiency virus type 1 (HIV-1) isolates has to interact with a cell-surface-associated or endosomal proteinase during virus entry into susceptible cells. To investigate this hypothesis, we examined the effect of several mutations in the V3 loop on its susceptibility to proteolytic cleavage by thrombin and cathepsin E and compared it with the effect of these mutations on viral infectivity. The data obtained indicate that, if an interaction between the V3 loop and a proteinase is indeed crucial for viral entry, the substrate requirements for such a proteinase(s) would have to be very complex. In particular, it seems unlikely that a single enzyme with a unique specificity would be able to interact with all of the different HIV-1 and HIV-2/SIV strains isolated so far. Therefore, one would have to postulate the involvement of several cellular proteinases, or proteases with multiple specificities, in V3-based viral tropism.

Amino Acid Sequence↗
PubMed1993

Expression of HIV-1 envelope glycoproteins by Semliki Forest virus vectors.

We have used Semliki Forest virus (SFV) vectors to express both the human immunodeficiency virus type 1 (HIV-1) envelope precursor gp160 and the cleaved external portion gp120. Expression of the foreign gene in this system is by transfection of recombinant SFV RNA, or by infection with a recombinant SFV virus that has a wide host range. pSFV1-gp120 or pSFV1-gp160 were expressed in baby hamster kidney (BHK) cells and two human cell lines: HeLa cervical carcinoma and MOLT-4 CD4+ T cells. After SFV1-gp120 infection of HeLa cells, 3.3 micrograms of gp120 was secreted into the media by 1 million cells in a 24-hr period. The secreted envelope glycoprotein was recognized by anti-gp120 monoclonal antibodies directed against both linear and conformation-dependent epitopes in different regions of the molecule. The recombinant gp120 also bound to a soluble form of the CD4 receptor. Syncytium formation was observed when MOLT-4 cells were infected with SFV1-gp160. The gp160 expressed by BHK cells induced syncytia during cocultivation with C8166 CD4+ T cells. These data indicate that SFV vectors can be used to produce the HIV-1 envelope glycoproteins to high levels, and that these proteins are correctly processed, folded, and transported to the cell surface. Furthermore, they exhibit functional activity as indicated by their ability to bind to soluble receptor and induce cell-to-cell fusion.

Animals↗
PubMed1993

Effects of D-penicillamine on human cell lines.

The effect of penicillamine on the proliferation and viability of human T, B and premacrophage/promyelocytic cell lines was evaluated. Whereas Raji cells and U937 cells were not negatively influenced by the addition of 0.03-0.97 mmol/l D-penicillamine (D-Pen, Trolovol, CAS 52-67-5), other cell lines such as H9, NC37 and HL60 were clearly impaired by concentrations between 0.12 and 0.49 mmol/l. Similar effects on the uptake of 3H-thymidine, 3H-uridine and 3H-leucine were observed with the addition of other stereoisomeric forms of penicillamine, D,L- and L-penicillamine to H9 cell cultures. The evaluation of cell number and viability by light microscopy revealed similar actions of penicillamine on cell cultures. By these means its repressing effect on Jurkat, NC37 and even on U937 became more transparent.

B-Lymphocytes↗
PubMed1992

Origin of AIDS.

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Acquired Immunodeficiency Syndrome↗