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  • Kirchhoff, Frank  (9)
  • Englisch  (9)
  • 1
    Online-Ressource
    Online-Ressource
    Sequences Just Upstream of the Simian Immunodeficiency Virus Core Enhancer Allow Efficient Replication in the Absence of NF-κB and Sp1 Binding Elements
    American Society for Microbiology ; 1998
    In:  Journal of Virology Vol. 72, No. 7 ( 1998-07), p. 5589-5598
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 72, No. 7 ( 1998-07), p. 5589-5598
    Kurzfassung: Large deletions of the upstream U3 sequences in the long terminal repeats (LTRs) of human immunodeficiency virus and simian immunodeficiency virus (SIV) accumulate in vivo in the absence of an intact nef gene. In the SIV U3 region, about 65 bp just upstream of the single NF-κB binding site always remained intact, and some evidence for a novel enhancer element in this region exists. We analyzed the transcriptional and replicative capacities of SIVmac239 mutants containing deletions or mutations in these upstream U3 sequences and/or the NF-κB and Sp1 binding sites. Even in the absence of 400 bp of upstream U3 sequences, the NF-κB site and all four Sp1 binding sites, the SIV promoter maintained about 15% of the wild-type LTR activity and was fully responsive to Tat activation in transient reporter assays. The effects of these deletions on virus production after transfection of COS-1 cells with full-length proviral constructs were much greater. Deletion of the upstream U3 sequences had no significant influence on viral replication when either the single NF-κB site or the Sp1 binding sites were intact. In contrast, the 26 bp of sequence located immediately upstream of the NF-κB site was essential for efficient replication when all core enhancer elements were deleted. A purine-rich site in this region binds specifically to the transcription factor Elf-1, a member of the ets proto-oncogene-encoded family. Our results indicate a high degree of functional redundancy in the SIVmac U3 region. Furthermore, we defined a novel regulatory element located immediately upstream of the NF-κB binding site that allows efficient viral replication in the absence of the entire core enhancer region.
    Materialart: Online-Ressource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.72.7.5589-5598.1998
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 1998
    ZDB Id: 1495529-5
    Standort Signatur Einschränkungen Verfügbarkeit
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    Online-Ressource
  • 2
    Online-Ressource
    Online-Ressource
    Simian Immunodeficiency Virus Utilizes Human and Sooty Mangabey but Not Rhesus Macaque STRL33 for Efficient Entry
    American Society for Microbiology ; 2000
    In:  Journal of Virology Vol. 74, No. 11 ( 2000), p. 5075-5082
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 74, No. 11 ( 2000), p. 5075-5082
    Materialart: Online-Ressource
    ISSN: 1098-5514 , 0022-538X
    URL: Article
    DOI: 10.1128/.74.11.5075-5082.2000
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2000
    ZDB Id: 1495529-5
    Standort Signatur Einschränkungen Verfügbarkeit
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    Online-Ressource
  • 3
    Online-Ressource
    Online-Ressource
    DC-SIGN Interactions with Human Immunodeficiency Virus Type 1 and 2 and Simian Immunodeficiency Virus
    American Society for Microbiology ; 2001
    In:  Journal of Virology Vol. 75, No. 10 ( 2001-05-15), p. 4664-4672
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 75, No. 10 ( 2001-05-15), p. 4664-4672
    Kurzfassung: Dendritic cells (DCs) efficiently bind and transmit human immunodeficiency virus (HIV) to cocultured T cells and so may play an important role in HIV transmission. DC-SIGN, a novel C-type lectin that is expressed in DCs, has recently been shown to bind R5 HIV type 1 (HIV-1) strains and a laboratory-adapted X4 strain. To characterize the interaction of DC-SIGN with primate lentiviruses, we investigated the structural determinants of DC-SIGN required for virus binding and transmission to permissive cells. We constructed a panel of DC-SIGN mutants and established conditions which allowed comparable cell surface expression of all mutants. We found that R5, X4, and R5X4 HIV-1 isolates as well as simian immunodeficiency and HIV-2 strains bound to DC-SIGN and could be transmitted to CD4/coreceptor-positive cell types. DC-SIGN contains a single N-linked carbohydrate chain that is important for efficient cell surface expression but is not required for DC-SIGN-mediated virus binding and transmission. In contrast, C-terminal deletions removing either the lectin binding domain or the repeat region abrogated DC-SIGN function. Trypsin-EDTA treatment inhibited DC-SIGN mediated infection, indicating that virus was maintained at the surface of the DC-SIGN-expressing cells used in this study. Finally, quantitative fluorescence-activated cell sorting analysis of AU1-tagged DC-SIGN revealed that the efficiency of virus transmission was strongly affected by variations in DC-SIGN expression levels. Thus, variations in DC-SIGN expression levels on DCs could greatly affect the susceptibility of human individuals to HIV infection.
    Materialart: Online-Ressource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.75.10.4664-4672.2001
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2001
    ZDB Id: 1495529-5
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 4
    Online-Ressource
    Online-Ressource
    DC-SIGN Interactions with Human Immunodeficiency Virus: Virus Binding and Transfer Are Dissociable Functions
    American Society for Microbiology ; 2001
    In:  Journal of Virology Vol. 75, No. 21 ( 2001-11), p. 10523-10526
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 75, No. 21 ( 2001-11), p. 10523-10526
    Kurzfassung: The C-type lectins DC-SIGN and DC-SIGNR capture and transfer human immunodeficiency virus (HIV) to susceptible cells, although the underlying mechanism is unclear. Here we show that DC-SIGN/DC-SIGNR-mediated HIV transmission involves dissociable binding and transfer steps, indicating that efficient virus transmission is not simply due to tethering of virus to the cell surface.
    Materialart: Online-Ressource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.75.21.10523-10526.2001
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2001
    ZDB Id: 1495529-5
    Standort Signatur Einschränkungen Verfügbarkeit
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    Online-Ressource
  • 5
    Online-Ressource
    Online-Ressource
    Hemofiltrate CC Chemokine 1[9-74] Causes Effective Internalization of CCR5 and Is a Potent Inhibitor of R5-Tropic Human Immunodeficiency Virus Type 1 Strains in Primary T Cells and Macrophages
    American Society for Microbiology ; 2002
    In:  Antimicrobial Agents and Chemotherapy Vol. 46, No. 4 ( 2002-04), p. 982-990
    Details
    In: Antimicrobial Agents and Chemotherapy, American Society for Microbiology, Vol. 46, No. 4 ( 2002-04), p. 982-990
    Kurzfassung: Proteolytic processing of the abundant plasmatic human CC chemokine 1 (HCC-1) generates a truncated form, HCC-1[9-74], which is a potent agonist of CCR1, CCR3, and CCR5; promotes calcium influx and chemotaxis of T lymphoblasts, monocytes, and eosinophils; and inhibits infection by CCR5-tropic human immunodeficiency virus type 1 (HIV-1) isolates. In the present study we demonstrate that HCC-1[9-74] interacts with the second external loop of CCR5 and inhibits replication of CCR5-tropic HIV-1 strains in both primary T cells and monocyte-derived macrophages. Low concentrations of the chemokine, however, frequently enhanced the replication of CCR5-tropic HIV-1 isolates but not the replication of X4-tropic HIV-1 isolates. Only HCC-1[9-74] and HCC-1[10-74] , but not other HCC-1 length variants, displayed potent anti-HIV-1 activities. Fluorescence-activated cell sorter analysis revealed that HCC-1[9-74] caused up to 75% down-regulation of CCR5 cell surfa ce expression, whereas RANTES (regulated on activation, normal T-cell expressed and secreted) achieved a reduction of only about 40%. Studies performed with green fluorescent protein-tagged CCR5 confirmed that both HCC-1[9-74] and RANTES, but not full-length HCC-1, mediated specific internalization of the CCR5 HIV-1 entry cofactor. Our results demonstrate that the interaction with HCC-1[9-74] causes effective intracellular sequestration of CCR5, but they also indicate that the effect of HCC-1[9-74] on viral replication is subject to marked cell donor- and HIV-1 isolate-dependent variations.
    Materialart: Online-Ressource
    ISSN: 0066-4804 , 1098-6596
    URL: Article
    DOI: 10.1128/AAC.46.4.982-990.2002
    RVK:
    XA 24552
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2002
    ZDB Id: 1496156-8
    SSG: 12
    SSG: 15,3
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 6
    Online-Ressource
    Online-Ressource
    Amino Acid 324 in the Simian Immunodeficiency Virus SIVmac V3 Loop Can Confer CD4 Independence and Modulate the Interaction with CCR5 and Alternative Coreceptors
    American Society for Microbiology ; 2004
    In:  Journal of Virology Vol. 78, No. 7 ( 2004-04), p. 3223-3232
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 78, No. 7 ( 2004-04), p. 3223-3232
    Kurzfassung: The V3 loop of the simian immunodeficiency virus (SIV) envelope protein (Env) largely determines interactions with viral coreceptors. To define amino acids in V3 that are critical for coreceptor engagement, we functionally characterized Env variants with amino acid substitutions at position 324 in V3, which has previously been shown to impact SIV cell tropism. These changes modulated CCR5 engagement and, in some cases, allowed the efficient usage of CCR5 in the absence of CD4. The tested amino acid substitutions had highly differential effects on viral infectivity. Eleven of sixteen substitutions disrupted entry via CCR5 or the alternative coreceptor GPR15. Nevertheless, most of these variants replicated in the macaque T-cell line 221-89 and some also replicated in rhesus macaque peripheral blood monocytes, suggesting that efficient usage of CCR5 and GPR15 on cell lines is not a prerequisite for SIV replication in primary cells. Four variants showed enhanced entry into the macaque sMagi reporter cell line. However, sMagi cells did not express appreciable amounts of CCR5 and GPR15 mRNA, and entry into these cells was not efficiently blocked by a small-molecule CCR5 antagonist, suggesting that sMagi cells express as-yet-unidentified entry cofactors. In summary, we found that a single amino acid at position 324 in the SIV Env V3 loop can modulate both the efficiency and the types of coreceptors engaged by Env and allow for CD4-independent fusion in some cases.
    Materialart: Online-Ressource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.78.7.3223-3232.2004
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2004
    ZDB Id: 1495529-5
    Standort Signatur Einschränkungen Verfügbarkeit
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    Online-Ressource
  • 7
    Online-Ressource
    Online-Ressource
    Simian Immunodeficiency Virus Utilizes Human and Sooty Mangabey but Not Rhesus Macaque STRL33 for Efficient Entry
    American Society for Microbiology ; 2000
    In:  Journal of Virology Vol. 74, No. 11 ( 2000-06), p. 5075-5082
    Details
    In: Journal of Virology, American Society for Microbiology, Vol. 74, No. 11 ( 2000-06), p. 5075-5082
    Kurzfassung: It has been established that many simian immunodeficiency virus (SIV) isolates utilize the orphan receptors GPR15 and STRL33 about as efficiently as the chemokine receptor CCR5 for entry into target cells. Most studies were performed, however, with coreceptors of human origin. We found that SIV from captive rhesus macaques (SIVmac) can utilize both human and simian CCR5 and GPR15 with comparable efficiencies. Strikingly, however, only human STRL33 (huSTRL33), not rhesus macaque STRL33 (rhSTRL33), functioned efficiently as an entry cofactor for a variety of isolates of SIVmac and SIV from sooty mangabeys. A single amino acid substitution of S30R in huSTRL33 impaired coreceptor activity, and the reverse change in rhSTRL33 greatly increased coreceptor activity. In comparison, species-specific sequence variations in N-terminal tyrosines in STRL33 had only moderate effects on SIV entry. These results show that a serine residue located just outside of the cellular membrane in the N terminus of STRL33 is critical for SIV coreceptor function. Interestingly, STRL33 derived from sooty mangabeys, a natural host of SIV, also contained a serine at the corresponding position and was used efficiently as an entry cofactor. These results suggest that STRL33 is not a relevant coreceptor in the SIV/macaque model but may play a role in SIV replication and transmission in naturally infected sooty mangabeys.
    Materialart: Online-Ressource
    ISSN: 0022-538X , 1098-5514
    URL: Article
    DOI: 10.1128/JVI.74.11.5075-5082.2000
    Sprache: Englisch
    Verlag: American Society for Microbiology
    Publikationsdatum: 2000
    ZDB Id: 1495529-5
    Standort Signatur Einschränkungen Verfügbarkeit
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    Online-Ressource
  • 8
    Online-Ressource
    Online-Ressource
    Expression and coreceptor activity of STRL33/Bonzo on primary peripheral blood lymphocytes
    American Society of Hematology ; 2000
    In:  Blood Vol. 96, No. 1 ( 2000-07-01), p. 41-49
    Details
    In: Blood, American Society of Hematology, Vol. 96, No. 1 ( 2000-07-01), p. 41-49
    Kurzfassung: CCR5 and CXCR4 are the major coreceptors that mediate human immunodeficiency virus 1 (HIV-1) infection, while most simian immunodeficiency virus (SIV) isolates use CCR5. A number of alternative coreceptors can also mediate infection of some virus strains in vitro, although little is known about their in vivo relevance. Therefore, we characterized the expression pattern and coreceptor activity of one of these alternative coreceptors, STRL33/Bonzo, using a newly developed monoclonal antibody. In addition to being highly expressed (approximately 1000-7000 STRL33 ABS [antibody binding sites]) on specific subsets of natural killer cells (CD3−/CD16−/low/CD56+ and CD3−/CD16low/CD56−) and CD19+ B lymphocytes (approximately 300-5000 STRL33 ABS), STRL33 was expressed at levels sufficient to support virus infection on freshly isolated, truly naive CD4+/CD45RA+/CD62L+cells (6000-11 000 ABS). STRL33 expression on peripheral blood mononuclear cells (PBMCs) was increased by mitogenic stimulation (OKT3/IL-2 [interleukin-2] had a greater effect than phytohemaglutinin (PHA)/IL-2), but it was dramatically decreased upon Ficoll purification. Infection of CCR5− human peripheral blood lymphocytes (PBLs) showed that 2 different SIV envelope (Env) proteins mediated entry into STRL33+cells. More importantly, the preferential infection of STRL33+ cells in CCR5− PBLs by an R5/X4/STRL33 HIV-1 maternal isolate in the presence of a potent CXCR4 antagonist (AMD3100) suggests that STRL33 can be used as a coreceptor by HIV-1 on primary cells. Rhesus macaque (rh) STRL33 was used less efficiently than human STRL33 by the majority of SIV Env proteins tested despite similar levels of expression, thereby making it less likely that STRL33 is a relevant coreceptor in the rhesus macaque system. In summary, the expression pattern and coreceptor activity of STRL33 suggest its involvement in trafficking of tumor-infiltrating lymphocytes and indicate that STRL33 may be a relevant coreceptor in vivo.
    Materialart: Online-Ressource
    ISSN: 1528-0020 , 0006-4971
    URL: Article
    DOI: 10.1182/blood.V96.1.41.013k53_41_49
    RVK:
    XA 33000
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: American Society of Hematology
    Publikationsdatum: 2000
    ZDB Id: 1468538-3
    ZDB Id: 80069-7
    Standort Signatur Einschränkungen Verfügbarkeit
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  • 9
    Online-Ressource
    Online-Ressource
    Expression and coreceptor activity of STRL33/Bonzo on primary peripheral blood lymphocytes
    American Society of Hematology ; 2000
    In:  Blood Vol. 96, No. 1 ( 2000-07-01), p. 41-49
    Details
    In: Blood, American Society of Hematology, Vol. 96, No. 1 ( 2000-07-01), p. 41-49
    Kurzfassung: CCR5 and CXCR4 are the major coreceptors that mediate human immunodeficiency virus 1 (HIV-1) infection, while most simian immunodeficiency virus (SIV) isolates use CCR5. A number of alternative coreceptors can also mediate infection of some virus strains in vitro, although little is known about their in vivo relevance. Therefore, we characterized the expression pattern and coreceptor activity of one of these alternative coreceptors, STRL33/Bonzo, using a newly developed monoclonal antibody. In addition to being highly expressed (approximately 1000-7000 STRL33 ABS [antibody binding sites] ) on specific subsets of natural killer cells (CD3−/CD16−/low/CD56+ and CD3−/CD16low/CD56−) and CD19+ B lymphocytes (approximately 300-5000 STRL33 ABS), STRL33 was expressed at levels sufficient to support virus infection on freshly isolated, truly naive CD4+/CD45RA+/CD62L+cells (6000-11 000 ABS). STRL33 expression on peripheral blood mononuclear cells (PBMCs) was increased by mitogenic stimulation (OKT3/IL-2 [interleukin-2] had a greater effect than phytohemaglutinin (PHA)/IL-2), but it was dramatically decreased upon Ficoll purification. Infection of CCR5− human peripheral blood lymphocytes (PBLs) showed that 2 different SIV envelope (Env) proteins mediated entry into STRL33+cells. More importantly, the preferential infection of STRL33+ cells in CCR5− PBLs by an R5/X4/STRL33 HIV-1 maternal isolate in the presence of a potent CXCR4 antagonist (AMD3100) suggests that STRL33 can be used as a coreceptor by HIV-1 on primary cells. Rhesus macaque (rh) STRL33 was used less efficiently than human STRL33 by the majority of SIV Env proteins tested despite similar levels of expression, thereby making it less likely that STRL33 is a relevant coreceptor in the rhesus macaque system. In summary, the expression pattern and coreceptor activity of STRL33 suggest its involvement in trafficking of tumor-infiltrating lymphocytes and indicate that STRL33 may be a relevant coreceptor in vivo.
    Materialart: Online-Ressource
    ISSN: 1528-0020 , 0006-4971
    URL: Article
    DOI: 10.1182/blood.V96.1.41
    RVK:
    XA 33000
    RVK:
    XA 10000
    Sprache: Englisch
    Verlag: American Society of Hematology
    Publikationsdatum: 2000
    ZDB Id: 1468538-3
    ZDB Id: 80069-7
    Standort Signatur Einschränkungen Verfügbarkeit
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    Online-Ressource
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