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P Lusso

Publications and source records attributed to P Lusso.

At least 37 records · Page 2Linked to original sources
PubMed1998

Human herpesvirus type 7 in Hodgkin's disease.

Several lines of evidence have pointed to the involvement of a viral agent in the pathogenesis of Hodgkin's disease (HD). Therefore we investigated the presence of human herpesvirus type 7 (HHV-7) in 53 cases of HD by polymerase chain reaction (PCR), DNA in situ hybridization (ISH) and immunohistochemistry. HHV-7 DNA was frequently detected (68% of the cases) in HD biopsies by PCR independently of the histological type, whereas only 32% (P<0.05) of positive cases were found in 19 reactive lymph nodes. However, by applying the quantitative PCR technique, the majority of the samples showed a low level of viral load. Moreover, ISH for HHV-7 DNA was positive in a low number of small T lymphocytes and consistently negative in Hodgkin and Reed-Sternberg (HRS) cells, which appeared negative for HHV-7 also at immunohistochemistry. These results indicate that the high frequency of HHV-7 infection in HD: (i) is probably non-productive, (ii) mainly involves small lymphocytes belonging to the T-lineage, and (iii) is probably due to the recruitment of non-malignant reactive cells in HD tissue.

DNA, Viral↗
PubMed1997

C-C chemokine RANTES and HIV long terminal repeat-driven gene expression.

The C-C chemokines RANTES, MIP-1alpha, and MIP-1beta have been characterized as constituents of an HIV- and SIV-suppressive factor released by CD8+ cells. Furthermore, it has been demonstrated that chemokine receptors cooperate in HIV entry. However, these proteins are also known to have an effect on multiple intracellular signaling cascades that may affect the process of transcription. In the present study we demonstrate that treatment of CD4+ T cells with these chemokines or with cell supernatants from HTLV-I-immortalized CD8+ T cells results in significant reduction in the abundance of HIV-1-specific RNA as analyzed by Northern blot hybridization. To examine the possibility that such suppressive factors may inhibit HIV RNA transcription, we studied the effect of RANTES, the most effective HIV-suppressive chemokine, on basal and Tat-induced HIV-directed LTR expression of a reporter gene. Neither recombinant RANTES nor conditioned medium from CD8+ cells significantly altered HIV-1 LTR-directed chloramphenicol acetyltransferase expression in either transiently or stably transfected CD4+ T cell lines, either in the presence or in the absence of Tat. These results suggest that C-C chemokines do not inhibit viral RNA transcription.

CD4-Positive T-Lymphocytes↗
PubMed1997

Antigen-driven C-C chemokine-mediated HIV-1 suppression by CD4(+) T cells from exposed uninfected individuals expressing the wild-type CCR-5 allele.

Despite repeated exposure to HIV-1, certain individuals remain persistently uninfected. Such exposed uninfected (EU) people show evidence of HIV-1-specific T cell immunity and, in rare cases, selective resistance to infection by macrophage-tropic strains of HIV-1. The latter has been associated with a 32-base pair deletion in the C-C chemokine receptor gene CCR-5, the major coreceptor of macrophage-tropic strains of HIV-1. We have undertaken an analysis of the HIV-specific T cell responses in 12 EU individuals who were either homozygous for the wild-type CCR-5 allele or heterozygous for the deletion allele (CCR-5Delta32). We have found evidence of an oligoclonal T cell response mediated by helper T cells specific for a conserved region of the HIV-1 envelope. These cells produce very high levels of C-C chemokines when stimulated by the specific antigen and suppress selectively the replication of macrophage-tropic, but not T cell-tropic, strains of HIV-1. These chemokine-producing helper cells may be part of a protective immune response that could be potentially exploited for vaccine development.

Alleles↗
PubMed1997

C-C chemokines released by lipopolysaccharide (LPS)-stimulated human macrophages suppress HIV-1 infection in both macrophages and T cells.

Human immunodeficiency virus-1 (HIV-1) expression in monocyte-derived macrophages (MDM) infected in vitro is known to be inhibited by lipopolysaccharide (LPS). However, the mechanisms are incompletely understood. We show here that HIV-1 suppression is mediated by soluble factors released by MDM stimulated with physiologically significant concentrations of LPS. LPS-conditioned supernatants from MDM inhibited HIV-1 replication in both MDM and T cells. Depletion of C-C chemokines (RANTES, MIP-1 alpha, and MIP-1 beta) neutralized the ability of LPS-conditioned supernatants to inhibit HIV-1 replication in MDM. A combination of recombinant C-C chemokines blocked HIV-1 infection as effectively as LPS. Here, we report an inhibitory effect of C-C chemokines on HIV replication in primary macrophages. Our results raise the possibility that monocytes may play a dual role in HIV infection: while representing a reservoir for the virus, they may contribute to the containment of the infection by releasing factors that suppress HIV replication not only in monocytes but also in T lymphocytes.

Cells, Cultured↗
PubMed1997

In vivo evolution of HIV-1 co-receptor usage and sensitivity to chemokine-mediated suppression.

Following the identification of the C-C chemokines RANTES, MIP-1alpha and MIP-1beta as major human immunodeficiency virus (HIV)-suppressive factors produced by CD8+ T cells, several chemokine receptors were found to serve as membrane co-receptors for primate immunodeficiency lentiretroviruses. The two most widely used co-receptors thus far recognized, CCR5 and CXCR4, are expressed by both activated T lymphocytes and mononuclear phagocytes. CCR5, a specific RANTES, MIP-1alpha and MIP-1 receptor, is used preferentially by non-MT2-tropic HIV-1 and HIV-2 strains and by simian immunodeficiency virus (SIV), whereas CXCR4, a receptor for the C-X-C chemokine SDF-1, is used by MT2-tropic HIV-1 and HIV-2, but not by SIV. Other receptors with a more restricted cellular distribution, such as CCR2b, CCR3 and STRL33, can also function as co-receptors for selected viral isolates. The third variable region (V3) of the gp120 envelope glycoprotein of HIV-1 has been fingered as a critical determinant of the co-receptor choice. Here, we document a consistent pattern of evolution of viral co-receptor usage and sensitivity to chemokine-mediated suppression in a longitudinal follow-up of children with progressive HIV-1 infection. Viral isolates obtained during the asymptomatic stages generally used only CCR5 as a co-receptor and were inhibited by RANTES, MIP-1alpha and MIP-1beta, but not by SDF-1. By contrast, the majority of the isolates derived after the progression of the disease were resistant to C-C chemokines, having acquired the ability to use CXCR4 and, in some cases, CCR3, while gradually losing CCR5 usage. Surprisingly, most of these isolates were also insensitive to SDF-1, even when used in combination with RANTES. An early acquisition of CXCR4 usage predicted a poor prognosis. In children who progressed to AIDS without a shift to CXCR4 usage, all the sequential isolates were CCR5-dependent but showed a reduced sensitivity to C-C chemokines. Discrete changes in the V3 domain of gp120 were associated with the loss of sensitivity to C-C chemokines and the shift in co-receptor usage. These results suggest an adaptive evolution of HIV-1 in vivo, leading to escape from the control of the antiviral C-C chemokines.

Adolescent↗
PubMed1997

Role of the extracellular domain of human herpesvirus 7 glycoprotein B in virus binding to cell surface heparan sulfate proteoglycans.

In an attempt to identify the human herpesvirus 7 (HHV-7) envelope protein(s) involved in cell surface binding, the extracellular domain of the HHV-7 glycoprotein B (gB) homolog protein was cloned and expressed as a fusion product with the Fc domain of human immunoglobulin G heavy chain gamma1 (gB-Fc) in an eukaryotic cell system. Indirect immunofluorescence followed by flow cytometric analysis revealed specific binding of gB-Fc to the membrane of SupT1 cells but not to other CD4+ T-lymphoblastoid cell lines, such as Jurkat or PM1, clearly indicating that gB-Fc did not bind to the CD4 molecule. This was also suggested by the ability of gB-Fc to bind to CD4-negative fibroblastoid Chinese hamster ovary (CHO) cells. The binding was abrogated by enzymatic removal of cell surface heparan sulfate proteoglycans by heparinase and heparitinase but not by treatment with condroitinase ABC. In addition, binding of the gB-Fc fusion protein to CHO cells was severely impaired in the presence of soluble heparin, as well as when heparan sulfate-deficient mutant CHO cells were used. Consistent with these findings, soluble heparin was found to block HHV-7 infection and syncytium formation in the SupT1 cell line. Although the CD4 antigen is a critical component of the receptor for the T-lymphotropic HHV-7, these findings suggest that heparin-like molecules also play an important role in HHV-7-cell surface interactions required for infection and that gB represents one of the HHV-7 envelope proteins involved in the adsorption of virus-to-cell surface proteoglycans.

Animals↗
PubMed1996

Interference between human herpesvirus 7 and HIV-1 in mononuclear phagocytes.

Human herpesvirus 7 (HHV-7) uses CD4 as a cellular membrane receptor and thereby interferes with infection of CD4+ T cells by HIV-1. We studied the interactions between HHV-7 and a macrophage-tropic HIV-1 isolate (HIV-1BaL) in terminally differentiated human peripheral blood monocyte-derived macrophages, another critical target for infection by HIV-1 in vivo. Exposure of macrophages to HHV-7 alone yielded no signs of virus replication or cytopathic effects. Nevertheless, when macrophages were pre-exposed to either live or UV-inactivated HHV-7 and subsequently infected with HIV-1BaL, a significant dose-dependent inhibition of HIV-1 replication was documented. At day 7 postinfection, the average level of HIV-1 p24 Ag in cultures from five different donors was reduced by 91.7 +/- 8.3% by pretreatment with live HHV-7 and by 91.8 +/- 8.2% by pretreatment with UV-inactivated HHV-7. Moreover, the synthesis of HIV-1 proviral DNA in macrophages pretreated with HHV-7 was completely inhibited during the early stages after infection, suggesting that HHV-7 blocks HIV-1 at the level of interaction with the CD4 receptor. Consistent with this concept, both macrophage and CD4+ T cell cultures with pre-established HIV-1 infection were not susceptible to inhibitory effects of HHV-7. The proliferative response of PBMC to mitogens was only marginally inhibited by exposure to HHV-7 before mitogen stimulation, indicating that the inhibition of HIV-1 infection was not due to a negative effect on cell proliferation. These data demonstrate that HHV-7 is a powerful inhibitor of HIV-1 infection in cells of the mononuclear phagocytic lineage, despite its inability to replicate actively in such cells.

Adult↗
PubMed1996

Enhancement of TAT-induced transactivation of the HIV-1 LTR by two genomic fragments of HHV-6.

Clinical and experimental observations suggest that human herpesvirus-6 (HHV-6), a T-lymphotropic herpesvirus, may act as a cofactor in the acquired immunodeficiency syndrome (AIDS). Moreover, a possible role of HHV-6 in the increased incidence and severity of cervical carcinoma in human immunodeficiency virus (HIV)-infected women was suggested by the recent observation that HHV-6 can infect cervical carcinoma cells, accelerating their tumorigenicity in vivo. Therefore, the ability of four HHV-6 genomic clones derived from HHV-6 to transactivate the long terminal repeat (LTR) of HIV-1 in two cervical carcinoma cell lines and in a T-lymphoid cell line was tested. Two HHV-6 clones, pZVH-14 and pZVB-70, which were previously shown to increase the expression of human papillomavirus (HPV)-transforming genes, were, per se, weak transactivators of the HIV-1 LTR. However, an increased effect occurred when these clones were combined with the HIV-1 transactivator TAT-1. No such effect was seen with two other HHV-6 clones used as controls. Analysis with HIV-1 LTR deletion mutants indicated that this enhancing effect requires the presence of elements contained in both the enhancer region and the TAT activation region (TAR) of HIV-1. This data may have implications for the potential role of HHV-6 in AIDS and AIDS-related cervical carcinoma.

Genes, tat↗
PubMed1996

The V3 domain of the HIV-1 gp120 envelope glycoprotein is critical for chemokine-mediated blockade of infection.

The ability of CD8 T cells derived from human immunodeficiency virus (HIV)-infected patients to produce soluble HIV-suppressive factor(s) (HIV-SF) has been suggested as an important mechanism of control of HIV infection in vivo. The C-C chemokines RANTES, MIP-1 alpha and MIP-1 beta were recently identified as the major components of the HIV-SF produced by both immortalized and primary patient CD8 T cells. Whereas they potently inhibit infection by primary and macrophage-tropic HIV-1 isolates, T-cell line-adapted viral strains tend to be insensitive to their suppressive effects. Consistent with this discrepancy, two distinct chemokine receptors, namely, CXCR4 (ref. 7) and CCR5 (ref. 8), were recently identified as potential co-receptors for T-cell line-adapted and macrophage-tropic HIV-1 isolates, respectively. Here, we demonstrate that the third hypervariable domain of the gp 120 envelope glycoprotein is a critical determinant of the susceptibility of HIV-1 to chemokines. Moreover, we show that RANTES, MIP-1 alpha and MIP-1 beta block the entry of HIV-1 into cells and that their antiviral activity is independent of pertussis toxin-sensitive signal transduction pathways mediated by chemokine receptors. The ability of the chemokines to block the early steps of HIV infection could be exploited to develop novel therapeutic approaches for AIDS.

Amino Acid Sequence↗
PubMed1996

Morphological and ultrastructural changes induced in corneal epithelial cells by HIV-1 and HHV-6 in vitro.

PURPOSE: The purpose of this study was to determine whether HIV-1 and HHV-6 are capable of infecting and inducing morphological and ultrastructural changes in corneal epithelial cells in vitro. METHODS: Primary and transformed corneal epithelial cell cultures were infected with HIV-1 or HHV-6 in vitro and analyzed for the presence or absence of viral antigens, DNA sequences, viral particles and inclusions. RESULTS: HIV-1 antigens were detected in 8% of the HIV-1 infected cells and early HHV-6 antigens were present in 12% of the HHV-6 infected cells. The presence of viral DNA sequences in the cultures confirmed these findings. Cells infected with HIV-1 morphologically were not different from uninfected cells, whereas the morphology of HHV-6 infected cells was very similar to cells infected with other human herpesviruses. Cytoplasmic tubuloreticular inclusions were detectable in corneal epithelia cells infected with HIV-1 and intact viral particles were visible only in PBMC used to recover HIV-1 from these cultures. Viral inclusions were also observed in corneal epithelial cells infected with HHV-6. CONCLUSION: These data indicate that HIV-1 and HHV-6 are capable of infecting corneal epithelial cells in vitro, but the viruses are not entering these cells via CD4 or galC receptors. This basic information is important in determining the pathogenic mechanism(s) involved in the development of AIDS-associated corneal disorders.

Antigens, Viral↗
PubMed1996

Human herpesvirus 6 and Epstein-Barr virus in Hodgkin's disease: a controlled study by polymerase chain reaction and in situ hybridization.

Human herpesvirus-6 (HHV-6), a T-lymphotropic double-stranded DNA virus highly endemic in human populations, has been suggested to play a possible role in the development of lymphoid neoplasms, especially Hodgkin's disease. To investigate this point, we evaluated the presence and distribution of HHV-6 DNA by Southern blot, nested polymerase chain reaction, and in situ hybridization in a series of lymphoproliferative disorders including 73 Hodgkin's disease cases, 15 non-Hodgkin lymphomas, and 19 reactive lymph nodes. A high prevalence of HHV-6 infection was observed within the Hodgkin's disease category by polymerase chain reaction (38 of 52, 73%) and in situ hybridization (47 of 57, 82.4%); however, a similar prevalence was found in non-Hodgkin's lymphomas (10 of 15, 66.6%) and reactive lymph nodes (13 of 19, 68.4%). In no case did Southern blot detect viral DNA, suggesting that the neoplastic tissue contained a low number of HHV-6 copies. In situ hybridization showed that the HHV-6 positivity was restricted to lymphocytes, whereas Hodgkin and Reed-Sternberg cells were consistently negative. Immunohistochemical staining with specific monoclonal antibodies against viral structural proteins was also negative, indicating the absence of a productive infection. No relationship was observed between HHV-6 positivity and histological type, clinical parameters, and outcome of the disease. In the same series, a high proportion of cases (39 of 52, 75%) showed the presence of the Epstein-Barr virus (EBV) genome by polymerase chain reaction; In situ hybridization for Epstein-Barr-virus-encoded small RNA and immunohistochemical detection of latent membrane protein-1 gave similar results (73.6% of positive cases with both methods). In 54.9% of the cases, both sequences of HHV-6 and Epstein-Barr virus DNA were found, suggesting that a synergism of the two viruses may occur. However, the lack of detectable HHV-6 DNA in Reed-Sternberg and Hodgkin's cells seems to argue against such an interpretation. Based on these results, HHV-6 does not appear to play a specific role in the pathogenesis of Hodgkin's disease.

Blotting, Southern↗
PubMed1995

Identification of RANTES, MIP-1 alpha, and MIP-1 beta as the major HIV-suppressive factors produced by CD8+ T cells.

Evidence suggests that CD8+ T lymphocytes are involved in the control of human immunodeficiency virus (HIV) infection in vivo, either by cytolytic mechanisms or by the release of HIV-suppressive factors (HIV-SF). The chemokines RANTES, MIP-1 alpha, and MIP-1 beta were identified as the major HIV-SF produced by CD8+ T cells. Two active proteins purified from the culture supernatant of an immortalized CD8+ T cell clone revealed sequence identity with human RANTES and MIP-1 alpha. RANTES, MIP-1 alpha, and MIP-1 beta were released by both immortalized and primary CD8+ T cells. HIV-SF activity produced by these cells was completely blocked by a combination of neutralizing antibodies against RANTES, MIP-1 alpha, and MIP-1 beta. Recombinant human RANTES, MIP-1 alpha, and MIP-1 beta induced a dose-dependent inhibition of different strains of HIV-1, HIV-2, and simian immunodeficiency virus (SIV). These data may have relevance for the prevention and therapy of AIDS.

Adult↗
PubMed1995

Monoclonal antibodies raised against covalently crosslinked complexes of human immunodeficiency virus type 1 gp120 and CD4 receptor identify a novel complex-dependent epitope on gp 120.

The binding of the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein, gp120, to its cell surface receptor, CD4, represents a molecular interaction involving distinct alterations in protein structure. Consequently, the pattern of epitopes presented on the gp120-CD4 complex should differ from those on free gp120. To investigate this concept, mice were immunized with covalently crosslinked complexes of viral HIV-1IIIBgp120 and soluble CD4. Two monoclonal antibodies (MoAbs) obtained from the immunized mice exhibited a novel epitope specificity. The MoAbs were marginally reactive with HIV-1IIIBgp120, highly reactive with gp120-CD4 complexes, and unreactive with soluble CD4. The same pattern of reactivity was seen in solid-phase assays using HIV-1(451)gp120. A similar specificity for complexes was evident in flow cytometry experiments, in which MoAb reactivity was dependent upon the attachment of gp120 to CD4-positive cells. In addition, MoAb reactivity was detected upon the interaction of CD4 receptors with purified HIV-1IIIB virions. Notably, seroantibodies from HIV-positive individuals competed for MoAb binding, indicating that the epitope is immunogenic in humans. The results demonstrated that crosslinked gp120-CD4 complexes elicit antibodies to cryptic gp120 epitopes that are exposed during infection in response to receptor binding. These findings may have important implications for the consideration of HIV envelope-receptor complexes as targets for virus neutralization.

Animals↗
PubMed1995

Infection of gamma/delta T lymphocytes by human herpesvirus 6: transcriptional induction of CD4 and susceptibility to HIV infection.

Human herpesvirus 6 (HHV-6), a T-lymphotropic human herpesvirus, is a potentially immunosuppressive agent that has been suggested to play a role as a cofactor in the natural history of human immunodeficiency virus (HIV) infection. We studied the interactions between HHV-6 and gamma/delta T lymphocytes, a subset of T cells involved in the protective immune response against specific microorganisms. Polyclonal gamma/delta T cell populations, purified from the peripheral blood of healthy adults and activated in vitro with phytohemagglutinin, were exposed to HHV-6, strain GS (subgroup A), at the approximate multiplicity of infection (MOI) of 1. Signs of virus replication were detected as early as 72 h after infection, as documented by immunofluorescence, electron microscopy, and transmission of extracellular virus. Progression of the infection was associated with the appearance of typical cytomorphological changes and, eventually, massive cell death. In contrast, no signs of infection or cytopathic effects were detected after exposure of gamma/delta T lymphocytes to HHV-7, a CD4+ T-lymphotropic virus closely related to HHV-6. Polyclonal gamma/delta T cells displayed cytolytic activity against both autologous and heterologous target cells infected with HHV-6 and maintained this activity for at least 72 h after infection with HHV-6, despite the high MOI used. As previously documented in mature CD8+ alpha/beta T cells and natural killer cells, HHV-6 infection induced gamma/delta T lymphocytes to express de novo CD4 messenger RNA and protein, as detected by reverse transcriptase-polymerase chain reaction and fluorocytometry, respectively. Whereas purified CD4- gamma/delta T cell populations were per se refractory to HIV infection, they became susceptible to productive infection by HIV-1, strain IIIB, after induction of CD4 expression by HHV-6. These results demonstrate that gamma/delta T cells can be directly targeted and killed by a herpesvirus and may have implications for the potential role of HHV-6 in AIDS.

Adult↗