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P C Guenthner

Publications and source records attributed to P C Guenthner.

10 recordsLinked to original sources
PubMed2005

Mycobacterium xenopi multiplies within human macrophages and enhances HIV replication in vitro.

Mycobacterium xenopi can cause opportunistic infections, particularly in persons infected with human immunodeficiency virus type 1 (HIV-1). The primary focus of this effort was to determine if M. xenopi isolates could survive and grow in human peripheral blood macrophage (MPhi), and if these isolates could promote the replication of HIV-1 in vitro. M. xenopi bacilli survived and replicated 10-fold within 48 h in human MPhi while avirulent Mycobacterium smegmatis, did not grow within the MPhi. M. xenopi bacilli when cultured with peripheral blood mononuclear cells enhanced HIV-1 replication 30- and 50-fold with the macrophage-tropic HIV-1(Ba-L) and 50- and 75-fold with T-cell-tropic strain HIV-1(LAI) by 6 days post-infection when compared to M. smegmatis. The enhanced HIV replication was associated with increased production of TNF-alpha. Partial inhibition of HIV-1 induction was observed using a neutralizing anti-TNF-alpha monoclonal antibody, pentoxifylline, and matrix metalloproteinase (MMP) inhibitor I. Similar mechanisms of pathogenesis among mycobacterial species may help elucidate better treatment approaches in HIV co-infected persons.

AIDS-Related Opportunistic Infections↗
PubMed2001

Cervical and prostate primary epithelial cells are not productively infected but sequester human immunodeficiency virus type 1.

Primary prostate and cervical epithelial cells and epithelial cell lines were examined for human immunodeficiency virus type 1 (HIV-1) infection or transmission to peripheral blood mononuclear cells (PBMC). Neither cell-free nor cell-associated HIV-1 infected primary epithelial cells or cell lines. Pretreatment of HIV-1 to enhance CD4-independent entry did not augment infection. Cell surface expression was detected for galactosyl ceramide but not for CC-chemokine receptor 5, CXC-chemokine receptor 4, or CD4. The ability to transfer HIV-1 to resting or activated PBMC was tested by culturing with rinsed or trypsinized and replated HIV-1-exposed epithelial cells. Virus was not recovered from the rinsed or replated cocultures with resting PBMC; however, activated PBMC recovered HIV-1 from rinsed epithelial cells and rarely from replated epithelial cells. Although urogenital epithelial cells are not infected, these data suggest that they can transfer virus to activated immune cells and have implications for sexual transmission of HIV-1.

CD4 Antigens↗
PubMed2001

Effects of human T-lymphotropic virus type II on human immunodeficiency virus type 1 phenotypic evolution.

Phenotypic change and broader coreceptor usage by HIV-1 have been associated with disease progression. HIV-1 coreceptor usage by primary isolates obtained from HIV-1-infected and HIV-1/HTLV-II-coinfected individuals was determined. HIV-1 was isolated from 15 of 20 HIV-1-infected and 17 of 24 HIV-1/HTLV-II-coinfected individuals. None of the isolates from either the HIV-1-infected or the coinfected group infected CCR5delta32 PBMCs, suggesting that they all were R5-tropic. Further, both spontaneous and PHA-stimulated production of MIP-1beta and RANTES were similar in HIV-1-infected and coinfected individuals. These data indicate that coinfection with HTLV-II has no effect on HIV-1 coreceptor usage or ex vivo beta-chemokine production.

CD4-Positive T-Lymphocytes↗
PubMed1999

Involvement of matrix metalloproteinases in human immunodeficiency virus type 1-induced replication by clinical Mycobacterium avium isolates.

The role of Mycobacterium avium isolates in modulating human immunodeficiency virus type 1 (HIV-1) replication was examined by use of an in vitro, resting T cell system. Two human clinical isolates (serotypes 1 and 4) but not an environmental M. avium isolate (serotype 2) enhanced HIV-1 replication. The M. avium-induced HIV-1 replication was not associated with cell activation or differential cytokine production or utilization. Addition of matrix metalloproteinase (MMP) inhibitors and their in vivo regulators, tissue inhibitors of metalloproteinases-1 and -2, abrogated M. avium-induced HIV-1 replication 80%-95%. The MMP inhibitors did not have any effect on the HIV-1 protease activity, suggesting that they may affect cellular processes. Furthermore, MMP-9 protein was differentially expressed after infection with clinical M. avium isolates and paralleled HIV-1 p24 production. Collectively, these data suggest that M. avium-induced HIV-1 replication is mediated, in part, through the induction of MMP-9.

Animals↗
PubMed1998

Quantitative, competitive PCR assay for HIV-1 using a microplate-based detection system.

We have developed a quantitative competitive PCR (QC-PCR) assay in a microplate format for quantifying human immunodeficiency virus Type 1 (HIV-1) DNA or RNA in a broad range of source materials. Our QC-PCR assay is a modification of technique originally described by Piatak et al. (1993), which is based on the presence of a competitive internal standard containing an internal 80-bp deletion of HIV-1 gag target sequence. For improved detection and quantification of the wild-type and internal-standard PCR products in a microplate format, we introduced a non-HIV, 31-bp insert into the internal standard as a probe hybridization site that does not cross-hybridize with wild-type HIV-1 products. By using a primer pair in which one primer is biotinylated, QC-PCRs can be bound to a streptavidin-coated microplate, denatured and probed with a digoxigenin (Dig)-labeled, wild-type or internal-standard probe. The hybridized Dig-labeled probes are detected with an anti-Dig antibody conjugated to detector molecules for luminometry (aequorin) or optical densitometry (peroxidase), yielding results that are quantifiable over the range of 100-10,000 copies of HIV gag. Tested source materials for HIV-1 DNA or RNA quantification include plasma, vaginal lavage and cultured cells. The application of the QC-PCR assay using the microplate format affords a convenient and cost-effective method for quantifying HIV-1 proviral and viral loads from a variety of body fluids, cells and tissues.

Aequorin↗
PubMed1997

Development of AIDS in a chimpanzee infected with human immunodeficiency virus type 1.

The condition of a chimpanzee (C499) infected with three different isolates of human immunodeficiency virus type 1 (HIV-1) for over 10 years progressed to AIDS. Disease development in this animal was characterized by (i) a decline in CD4+ cells over the last 3 years; (ii) an increase in viral loads in plasma; (iii) the presence of a virus, termed HIV-1JC, which is cytopathic for chimpanzee peripheral blood mononuclear cells; and (iv) the presence of an opportunistic infection and blood dyscrasias. Genetic analysis of the V1-V2 region of the envelope gene of HIV-1JC showed that the virus present in C499 was significantly divergent from all inoculating viruses (> or = 16% divergent at the amino acid level) and was suggestive of a large quasispecies. Blood from C499 transfused into an uninfected chimpanzee (C455) induced a rapid and sustained CD4+-cell decline in the latter animal, concomitant with high plasma viral loads. These results show that HIV-1 can induce AIDS in chimpanzees and suggest that long-term passage of HIV-1 in chimpanzees can result in the development of a more pathogenic virus.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Characterization of a HTLV-I-infected cell line derived from a patient with adult T-cell leukemia with stable co-expression of CD4 and CD8.

A long-term T-cell line, termed SP+, was developed from a human T-cell leukemia virus type I (HTLV-I)-infected patient with adult T-cell leukemia that is dependent on exogenous IL-2 for growth. The SP+ expresses a full complimentation of HTLV-I-specific viral proteins, and contains replication competent viral particles. Restriction enzyme digestion followed by Southern blot analysis demonstrated the presence of a single integrated proviral copy and limiting dilution analysis confirmed the clonality of the cell line. Interestingly, phenotypically, the SP+ cell line is CD2+, CD3+ and coexpresses CD4 and CD8, yet lacks TCR alpha beta and TCR tau delta expression. Further ontogenetic characterization of the SP+ cell line demonstrated the lack of thymic T-cell precursor markers, including absence of cell surface expression of CD1, intracellular thymic terminal deoxynucleotidyl transferase (TdT) enzyme, as well as message expression for V(D)J recombinase activating gene-1 (RAG-1). Furthermore, the SP+ cell did express the message for the CD3 delta chain. Taken together, these data suggest that the SP+ cell line resulted from HTLV-I infection of a mature CD4+/CDB+ lymphocyte. This cell line can be potentially useful as a model, both for regulation of cellular functions by HTLV-I and for immunologic functions of mature dual CD4/CD8 positive T-cells.

Antigens, Viral↗
PubMed1991

DNA CpG methylation inhibits binding of NF-kappa B proteins to the HIV-1 long terminal repeat cognate DNA motifs.

The regulation of cellular or viral gene expression is directly influenced by the pattern of methylated cytosine residues localized in the DNA of enhancer/promoter sequences. The mechanism of transcriptional silencing has been explained on the basis of either an indirect model, in which densely methylated DNA is recognized by proteins that may displace crucial transcription factors, or a direct model, in which binding of a single transcription protein is prevented by the presence of a methylated CpG dinucleotide localized in a sensitive region of a DNA motif. In this study, we have determined that methylation of the core CpG dinucleotide located within the NF-kappa B repeated motifs of the human immunodeficiency virus type 1 (HIV-1) long terminal repeat can inhibit the binding of the NF-kappa B protein complex from crude nuclear extracts or from purified bovine spleen and specifically inhibit the binding of recombinant p50 protein. We have used the electrophoretic mobility shift assay (EMSA) and DNaseI footprinting analysis to demonstrate that binding of the NF-kappa B proteins to their cognate motifs can be inhibited via the direct model proposed for methylation-mediated inhibition of DNA-protein interaction.

5-Methylcytosine↗
PubMed1986

Conversion of an M- group A streptococcus to M+ by transfer of a plasmid containing an M6 gene.

An M28-derived group A streptococcal strain deleted for the gene encoding M protein was converted to M+ by introduction of a plasmid carrying emm6, the structural gene for type 6 M protein from strain D471. The reconstituted M+ strain, JRS2, resists phagocytosis in human blood and is opsonized by anti-M6 hyperimmune serum, but not by anti-M28 serum. Immunofluorescent microscopy and ELISA demonstrate the presence of M protein on its surface. In addition, JRS2 removes opsonic antibodies from hyperimmune rabbit sera generated by immunization with purified ColiM6 protein and with a synthetic amino-terminal peptide derived from M6. Immunization of rabbits with JRS2 generates opsonic anti-M6 antibodies. These results indicate that the cloned emm6 gene contains the information necessary to convert a phagocytosis-sensitive streptococcus to phagocytosis resistance. Furthermore, it also contains the determinants for M type specificity and those required to elicit opsonic antibodies. It thus appears to determine all the traits associated with M protein.

Antibodies, Bacterial↗