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Biomedical subjects

Reinhard Kurth

Publications and source records attributed to Reinhard Kurth.

At least 19 recordsLinked to original sources
PubMed2006

Failure to detect Borna disease virus antigen and RNA in human blood.

BACKGROUND: Borna disease virus (BDV) is the etiological agent of a rare progressive meningoencephalitis that affects mostly horses and sheep. There is an unresolved debate whether also humans are susceptible to infection with BDV and if so, whether this might be associated with neuropsychiatric diseases. One recent key publication employing an ELISA-based sandwich assay reported prevalences of BDV-specific circulating immune complexes in human blood as high as 30% in the normal population and up to 100% in psychiatric patients [Bode L, Reckwald P, Severus WE, Stoyloff R, Ferszt R, Dietrich DE, et al. Borna disease virus-specific circulating immune complexes, antigenemia, and free antibodies--the key marker triplet determining infection and prevailing in severe mood disorders. Mol Psychiatry 2001;6(4):481-91]. However, this report did not examine for the physical presence of BDV antigens in human blood, and therefore, these seemingly high prevalences may not reflect Borna virus-specific signals. OBJECTIVES: We attempted to correlate string plasma signals in the particular sandwich ELISA system with the presence of BDV antigens. STUDY DESIGN: Four preselected plasma samples with high reactivity in the described assay were analysed by immunoaffinity purification and highly sensitive real-time RT-PCR. RESULTS: Neither method did provide any evidence for the presence of viral proteins or nucleic acids. CONCLUSIONS: Our findings argue against the concept that the described sandwich ELISA reliably detects BDV-specific antigens in human blood, therefore do not support the hypothesis that BDV is a pathogen of humans.

Antigens, Viral↗
PubMed2006

Expression of the human endogenous retrovirus-K transmembrane envelope, Rec and Np9 proteins in melanomas and melanoma cell lines.

The human endogenous retrovirus-K encodes two potential tumor proteins, Rec and Np9. Rec is related to the Rev protein of HIV-1 and has been shown to be associated with tumor development in nude mice. Having shown the expression of human endogenous retrovirus-K in human melanomas and melanoma cell lines, tools were developed to allow the expression of the transmembrane envelope, Rec and Np9 mRNA and proteins to be studied in more detail. The expression of spliced env, rec and np9 was investigated by reverse transcriptase-polymerase chain reaction using a set of primers developed to discriminate between full-length and spliced mRNA. Env-specific, Rec-specific and Np9-specific antisera were produced, characterized and used to study protein expression in melanomas and melanoma cell lines by immunohistochemistry, immunofluorescence and Western blot analyses. Existence of human endogenous retrovirus-K Rec and Np9-specific antibodies in the sera of melanoma patients were analyzed by Western blot of immunofluorescence studies. The expression of both spliced env and rec mRNA was detected in 39% of the melanomas and in 40% of the melanoma cell lines and np9 mRNA was detected in 29 and 21%, respectively. In normal neonatal melanocytes, spliced rec mRNA was detected in the absence of spliced env mRNA. Using antisera specific for Rec and Np9, Rec protein was found in 14% of the melanomas but Np9 in none. In addition, cell surface expression of the putatively immunosuppressive transmembrane envelope protein and release of virus particles were shown. Antibodies specific for neither Rec nor Np9 were detected. The transmembrane envelope protein, Rec and Np9 proteins are expressed in melanoma cells with a pattern similar to that seen in teratocarcinoma cell lines. Additional experiments are needed to determine their involvement, if any, in cell proliferation and tumor progression.

Amino Acid Sequence↗
PubMed2006

Antibodies neutralizing feline leukaemia virus (FeLV) in cats immunized with the transmembrane envelope protein p15E.

The feline leukaemia virus (FeLV) vaccines that are currently in wide use are generally poor inducers of virus-neutralizing antibodies, although such antibodies appear after recovering from challenge. However, the presence of neutralizing antibodies in cats recovering from natural FeLV infection clearly correlates with resistance to subsequent infection and passive transfer of antibodies can protect other animals. After demonstrating the induction of neutralizing antibodies in rats and goats immunized with the transmembrane envelope protein p15E of FeLV, cats were immunized with the same antigen. High titres of neutralizing antibodies specific for FeLV were induced and epitope mapping revealed a pattern of recognition similar to that seen following immunization of rats and goats. These epitopes are highly related to epitopes recognized after immunization with porcine endogenous retrovirus (PERV) p15E and to epitopes recognized by neutralizing antibodies in patients infected with human immunodeficiency virus type 1. The ability of p15E to induce neutralizing antibodies in cats suggests that it should be included in the next generation of vaccines. In contrast, sera from FeLV-infected animals usually fail to recognize the neutralization-relevant epitopes in p15E. Since homologous epitope sequences are present in feline endogenous retroviruses, it appears that tolerance against these sequences is not induced.

Amino Acid Sequence↗
PubMed2006

Transspecies transmission of the endogenous koala retrovirus.

The koala retrovirus (KoRV) is a gammaretrovirus closely related to the gibbon ape leukemia virus and induces leukemias and immune deficiencies associated with opportunistic infections, such as chlamydiosis. Here we characterize a KoRV newly isolated from an animal in a German zoo and show infection of human and rat cell lines in vitro and of rats in vivo, using immunological and PCR methods for virus detection. The KoRV transmembrane envelope protein (p15E) was cloned and expressed, and p15E-specific neutralizing antibodies able to prevent virus infection in vitro were developed. Finally, evidence for immunosuppressive properties of the KoRV was obtained.

Animals↗
PubMed2006

The evolutionary dynamics of human endogenous retroviral families.

The capacity to integrate into the chromosomal DNA of germ-line cells has endowed retroviruses with the potential to be vertically transmitted from generation to generation and eventually become fixed in the genomes of the entire population. This has been independently accomplished by several ancient retroviruses that invaded the genomes of our early and more recent primate and hominoid ancestors. Some of the inherited elements then proliferated in the genome, resulting in a number of lineages with complex phylogenetic patterns. Although the vast majority of chromosomally integrated retroelements have suffered inactivating mutations and deletions, a significant impact on various aspects of human biology has been recently revealed and evidence for the present activity of at least one human endogenous retrovirus family continues to accumulate.

Biological Evolution↗
PubMed2005

Expression of human endogenous retrovirus K in melanomas and melanoma cell lines.

The human endogenous retrovirus K family (HERV-K) comprises 30 to 50 closely related proviruses, most of which are defective. In contrast to all other human endogenous retroviruses, some HERV-K proviruses have maintained open reading frames for all viral proteins. In addition to the structural proteins Gag and Env and the reverse transcriptase, two regulatory proteins (Rec and Np9) have been described. Malignant melanoma has the highest mortality among skin cancers and is particularly aggressive. To study the expression of HERV-K, a set of seven primers was developed that allows discrimination between full-length and spliced mRNA and mRNA from deleted and undeleted proviruses. Expression of full-length mRNA from deleted and undeleted proviruses was detected in all human cells investigated. Expression of spliced env and rec was detected in a teratocarcinoma cell line, in 45% of the metastatic melanoma biopsies, and in 44% of the melanoma cell lines. In normal neonatal melanocytes, spliced rec was detected but not spliced env. Viral proteins were shown to be expressed in primary melanomas, metastases, and melanoma cell lines by immunohistochemistry, immunofluorescence, and Western blot analyses using specific antisera. For the first time, antibodies against HERV-K were found in melanoma patients. Melanomas are, in addition to teratocarcinomas and human breast cancer, the third tumor type with enhanced expression of HERV-K.

Adult↗
PubMed2005

Porcine endogenous retroviruses PERV-A and PERV-B infect neither mouse cells in vitro nor SCID mice in vivo.

OBJECTIVE: Porcine endogenous retroviruses (PERVs) pose a risk for xenotransplantations using pig materials as they are present in the genome of all pigs and are able to infect human cells in vitro. Until recently, transmission of PERVs in vivo was only described in severe combined immunodeficient (SCID) and nude mice inoculated with PERV-producing cells. However, in this series of experiments microchimerism could not be excluded. To overcome this problem, the risk of PERV infection was addressed in a similar way but using cell-free inoculation of mouse cells in vitro and SCID mice in vivo. METHODS: Mouse cell lines and primary cells were incubated in vitro with PERV-A, with a recombinant PERV-A/C and with PERV-B. Provirus integration was assessed by PCR. Reverse transcriptase activity was measured in the cell supernatants. SCID mice were inoculated in vivo with cell-free virus at high titers. RESULTS: None of the mouse cell lines and primary cells could be infected by PERV and no provirus integration was observed in different organs of the inoculated SCID mice. CONCLUSION: The data indicate that PERV-A, PERV-A/C and PERV-B could not infect different mouse cells. These data correlate with the recent finding that mouse cells lack a functional receptor for PERV-A. Although the receptor for PERV-B is still unknown, these data suggest that previously reported PERV transmissions to SCID and nude mice in vivo might be due to microchimerism or pseudotyping with murine viruses and indicate that normal mice are an inappropriate model for the study of PERV infection and pathogenesis.

3T3 Cells↗
PubMed2004

Retroelements and the human genome: new perspectives on an old relation.

Retroelements constitute a large portion of our genomes. One class of these elements, the human endogenous retroviruses (HERVs), is comprised of remnants of ancient exogenous retroviruses that have gained access to the germ line. After integration, most proviruses have been the subject of numerous amplifications and have suffered extensive deletions and mutations. Nevertheless, HERV-derived transcripts and proteins have been detected in healthy and diseased human tissues, and HERV-K, the youngest, most conserved family, is able to form virus-like particles. Although it is generally accepted that the integration of retroelements can cause significant harm by disrupting or disregulating essential genes, the role of HERV expression in the etiology of malignancies and autoimmune and neurologic diseases remains controversial. In recent years, striking evidence has accumulated indicating that some proviral sequences and HERV proteins might even serve the needs of the host and are therefore under positive selection. The remarkable progress in the analysis of host genomes has brought to light the significant impact of HERVs and other retroelements on genetic variation, genome evolution, and gene regulation.

Antibodies, Viral↗
PubMed2004

Inhibition of porcine endogenous retroviruses by RNA interference: increasing the safety of xenotransplantation.

Transplantation of porcine xenografts into human recipients is a realistic option to overcome the growing worldwide shortage of suitable allogeneic organs. However, there remains the risk of infection by porcine endogenous retroviruses (PERVs) that cannot be eliminated like that by other microorganisms by breeding pigs under specified pathogen-free conditions. To reduce the release of PERVs by porcine transplants, a new approach, RNA interference (RNAi), was applied. Here, we show significant reduction of PERV expression by synthetic short interfering RNAs (siRNAs) corresponding to different parts of the viral genes gag, pol, and env. The most inhibitory sequences were selected and expressed as short hairpin RNAs (shRNAs) by a polymerase III vector system leading to persistent suppression of PERV replication. Cells or organs from transgenic pigs producing such shRNAs should increase the safety of xenotransplantation.

Animals↗
PubMed2004

The role of the immune response during SIVagm infection of the African green monkey natural host.

The African green monkey (AGM) is one of many African species endemically infected with simian immunodeficiency virus (SIV). Like the other natural hosts, AGMs do not succumb to AIDS and understanding the basis for this resistance to disease progression would be of enormous theoretical and practical importance. Early efforts by our group that concentrated on identifying immune mechanisms presumed to keep the virus under control failed to find any obvious candidates. The presumption of virus control was invalidated by the finding that SIVagm replicates in AGMs with the same vigor as HIV-1 does in humans. Focus therefore shifted to identifying possible immunopathologic features present in disease susceptible hosts but absent in the AGM natural host. The apparent immunologic tolerance of AGMs to the SIVagm core protein led to the development of a hypothesis implicating anti-Gag antibodies in the formation of immune complexes, virus trapping in the lymph nodes and immune dysfunction. The idea proved difficult to test in vivo and present work focuses on the possibility that Gag tolerance at the T-cell level plays an important role in preventing the catastrophic demise of the immune system characteristic of immunodeficiency virus infection of the heterologous primate host.

Animals↗
PubMed2003

Genetic alterations of the long terminal repeat of an ecotropic porcine endogenous retrovirus during passage in human cells.

Human-tropic porcine endogenous retroviruses (PERV) such as PERV-A and PERV-B can infect human cells and are therefore a potential risk to recipients of xenotransplants. A similar risk is posed by recombinant viruses containing the receptor-binding site of PERV-A and large parts of the genome of the ecotropic PERV-C including its long terminal repeat (LTR). We describe here the unique organization of the PERV-C LTR and its changes during serial passage of recombinant virus in human cells. An increase in virus titer correlated with an increase in LTR length, caused by multiplication of 37-bp repeats containing nuclear factor Y binding sites. Luciferase dual reporter assays revealed a correlation between the number of repeats and the extent of expression. No alterations have been observed in the receptor-binding site, indicating that the increased titer is due to the changes in the LTR. These data indicate that recombinant PERVs generated during infection of human cells can adapt and subsequently replicate with greater efficiency.

Amino Acid Sequence↗
PubMed2003

PDZ Domain-mediated interaction of interleukin-16 precursor proteins with myosin phosphatase targeting subunits.

The cytokine interleukin-16 is generated by posttranscriptional cleavage by caspase-3 of two large precursor isoforms. The smaller protein of 67 kDa (pro-IL-16) is expressed in cells of the immune system and contains three PDZ (postsynaptic density/disc large/zona occludens-1) domains, whereas the larger 141-kDa neuronal variant (npro-IL-16) has two additional PDZ domains in its N-terminal extension that interact with neuronal ion channels. Using the yeast two-hybrid approach we have identified three closely related myosin phosphatase targeting subunits, MYPT1, MYPT2, and MBS85, as binding partners of the IL-16 precursor proteins. These interactions were verified using pull-down assays, coimmunoprecipitations, and plasmon resonance experiments. Binding requires the intact PDZ2 domain of pro-IL-16 and highly related C-terminal regions in the ligands consisting of a short leucine zipper and an indispensable serine at the -1 position, suggesting a novel unconventional PDZ binding mode. Pro-IL-16 and the myosin phosphatase targeting subunits colocalize along actomyosin filaments and stress fibers in transfected COS-7 cells. By modulating and targeting the catalytic phosphatase subunit to its substrates, MYPT1, MYPT2, and MBS85 regulate various contractile processes in muscle and non-muscle cells. Our findings indicate an involvement of the IL-16 precursor molecules in myosin-based contractile processes, most likely in cell motility, providing a functional link to the chemotactic activity of the mature cytokine. Alternatively, an intracellular complex of npro-IL-16, ion channels, and components of myosin motors in neurons suggests a role in protein targeting.

Actomyosin↗