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F J Novembre

Publications and source records attributed to F J Novembre.

At least 19 recordsLinked to original sources
PubMed2001

Resistance to neutralizing antibody and expanded coreceptor usage are associated with human immunodeficiency virus type 1 isolates derived from chimpanzees with pathogenic infections.

Immunologic and biologic factors associated with the progression to AIDS in HIV-1-infected chimpanzees were investigated. Chimpanzee C499 was euthanized in 1996 as a result of the development of AIDS approximately 11 years after infection with HIV-1. At the time of initial disease development (September 1995), blood from this animal was transfused to an uninfected chimpanzee, C455, resulting in a rapid loss of CD4(+) T cells. Virus isolates were derived from both animals and termed HIV-1(JC) (derived from C499 at the time of disease development; JC isolate) and HIV-1(NC) (derived from C455 1 month posttransfusion; NC isolate). In vitro studies demonstrate that the parental viruses used to inoculate C499 were susceptible to neutralization by serum from that animal. In contrast, serum from C499 at any time was unable to neutralize the JC or NC isolates. Similarly, the JC and NC isolates were highly resistant to neutralization by serum from C455. However, serum from C455 was also unable to neutralize either of the parental viruses or any of the normally neutralization sensitive isolates tested. Serum samples from the two additional chimpanzees that were inoculated with the NC isolate were also unable to neutralize these isolates. Coreceptor usage of the uncloned JC and NC isolates was somewhat expanded when compared with that of LAV1b and SF2. However, molecular clones derived from the JC and NC isolates (JC16 and NC7) displayed only a limited coreceptor repertoire despite having unique V3 loop sequences. The results suggest that the JC and NC isolates are neutralization escape mutants and display a different phenotype than the parental strains LAV1b and SF2.

Animals↗
PubMed2001

Rapid CD4(+) T-cell loss induced by human immunodeficiency virus type 1(NC) in uninfected and previously infected chimpanzees.

To investigate the pathogenicity of a virus originating in a chimpanzee with AIDS (C499), two chimpanzees were inoculated with a plasma-derived isolate termed human immunodeficiency virus type 1(NC) (HIV-1(NC)). A previously uninfected chimpanzee, C534, experienced rapid peripheral CD4(+) T-cell loss to fewer than 26 cells/microl by 14 weeks after infection. CD4(+) T-cell depletion was associated with high plasma HIV-1 loads but a low virus burden in the peripheral lymph node. The second chimpanzee, C459, infected 13 years previously with HIV-1(LAV), experienced a more protracted course of peripheral CD4(+) T-cell loss after HIV-1(NC) inoculation, resulting in fewer than 200 cells/microl by 96 weeks postinoculation. The quantities of viral RNA in the plasma and peripheral lymph node from C459 were below the lower limits of detection prior to inoculation with HIV-1(NC) but were significantly and persistently increased after superinfection, with HIV-1(NC) representing the predominant viral genotype. These results show that viruses derived from C499 are more pathogenic for chimpanzees than any other HIV-1 isolates described to date.

Acquired Immunodeficiency Syndrome↗
PubMed2000

Progressive infection in a subset of HIV-1-positive chimpanzees.

Chimpanzees are susceptible to infection with human immunodeficiency virus (HIV)-1; however, infected animals usually maintain normal numbers of CD4(+) T lymphocytes and do not develop immunodeficiency. We have examined 10 chronically infected HIV-1-positive chimpanzees for evidence of progressive infection. In addition to 1 animal that developed AIDS, 3 chimpanzees exhibit evidence of progressive HIV infection. All progressors have low CD4(+) T cell counts (<200 cells/microL), severe CD4:CD8 inversion, and marked reduction in interleukin-2 receptor expression by CD4(+) T cells. In comparison with HIV-positive nonprogressor chimpanzees, progressors have higher plasma and lymphoid virus loads, greater CD38 expression in CD8(+)/HLA-DR(+) T cells, and greater serum concentrations of soluble tumor necrosis factor type II receptors and beta2-microglobulin, all markers of HIV progression in humans. These observations show that progressive HIV-1 infection can occur in chimpanzees and suggest that the pathogenesis of progressive infection in this species resembles that in humans.

ADP-ribosyl Cyclase↗
PubMed2000

In vitro and in vivo responses to interleukin 12 are maintained until the late SIV infection stage but lost during AIDS.

The in vitro proliferative responses of macaque peripheral blood mononuclear cells (PBMCs) to IL-12 appeared similar before and early after SIV infection, whereas macaque PBMCs sampled during symptomatic stages of SIV infection showed markedly decreased responses. IL-12 was administered to SIVmac239-infected rhesus macaques either during the asymptomatic or the AIDS stage of infection in efforts to evaluate the effect of this cytokine on immune responses, viral loads, and hematopoietic functions in vivo. IFN-gamma secretion levels induced during the asymptomatic or early symptomatic phase were similar to preinfection induced levels, whereas in later AIDS stages this response was lost. The constitutive levels of other measured cytokines were not affected by IL-12 administration in vivo. The frequency and activity of circulating NK cells were markedly enhanced at early stages but not at symptomatic stages of SIV infection. pCTL frequencies were enhanced at early symptomatic stages but not at late AIDS stages. Despite its immunomodulatory effect, IL-12 did not seem to exacerbate or inhibit the replication of SIV in vivo, or the frequency of circulating infected lymphocytes. IL-12 administration was associated with a significant yet subclinical and transient decrease in hematocrit and hemoglobin levels without evidence of hemolysis, hemodilution, or reduction in the frequency of colony-forming unit potential of bone marrow CD34+ cells. This phenomenon may be explained by a functional inhibition of differentiation rather than an altered generation of bone marrow precursors. Thus, these results suggest that IL-12 may benefit HIV-1-infected patients only as long as their immune system retains its capability to respond to cytokine stimulation.

Animals↗
PubMed1999

Postinoculation PMPA treatment, but not preinoculation immunomodulatory therapy, protects against development of acute disease induced by the unique simian immunodeficiency virus SIVsmmPBj.

The fatal disease induced by SIVsmmPBj4 clinically resembles endotoxic shock, with the development of severe gastrointestinal disease. While the exact mechanism of disease induction has not been fully elucidated, aspects of virus biology suggest that immune activation contributes to pathogenesis. These biological characteristics include induction of peripheral blood mononuclear cell (PBMC) proliferation, upregulation of activation markers and Fas ligand expression, and increased levels of apoptosis. To investigate the role of immune activation and viral replication on disease induction, animals infected with SIVsmmPBj14 were treated with one of two drugs: FK-506, a potent immunosuppressive agent, or PMPA, a potent antiretroviral agent. While PBMC proliferation was blocked in vitro with FK-506, pig-tailed macaques treated preinoculation with FK-506 were not protected from acutely lethal disease. However, these animals did show some evidence of modulation of immune activation, including reduced levels of CD25 antigen and FasL expression, as well as lower tissue viral loads. In contrast, macaques treated postinoculation with PMPA were completely protected from the development of acutely lethal disease. Treatment with PMPA beginning as late as 5 days postinfection was able to prevent the PBj syndrome. Plasma and cellular viral loads in PMPA-treated animals were significantly lower than those in untreated controls. Although PMPA-treated animals showed acute lymphopenia due to SIVsmmPBj14 infection, cell subset levels subsequently recovered and returned to normal. Based upon subsequent CD4(+) cell counts, the results suggest that very early treatment following retroviral infection can have a significant effect on modifying the subsequent course of disease. These results also suggest that viral replication is an important factor involved in PBJ-induced disease. These studies reinforce the idea that the SIVsmmPBj model system is useful for therapy and vaccine testing.

Animals↗
PubMed1998

Induction of fas ligand expression by an acutely lethal simian immunodeficiency virus, SIVsmmPBj14.

Simian immunodeficiency virus strain PBj14, SIVsmmPBj14, is unique among primate lentiviruses in its ability to trigger the proliferation of resting simian lymphocytes and to cause the rapid death of experimentally inoculated pigtailed macaques. Severe enteropathy, immune activation, and extensive apoptosis, particularly within gut-associated lymphoid tissue, characterize the acute disease syndrome associated with SIVsmmPBj14 infection. In the present study, we examined whether the ability of this virus to cause widespread apoptosis might be linked to the up-regulation of Fas ligand (CD95L) expression in virally infected cells. In vitro studies revealed that expression of the viral Nef protein, in the absence of any other viral gene product, was sufficient to up-regulate the transcriptional activity of the CD95L promoter and to cause cell surface expression of Fas ligand. This up-regulation was NFAT dependent (inhibited by cyclosporin A) and did not occur in cells that expressed a mutated derivative of the viral Nef protein, lacking a previously defined immunoreceptor tyrosine-based activation motif. These findings were corroborated by analysis of tissue sections from virally infected macaques. Immunohistochemical staining revealed that Fas ligand expression was efficiently up-regulated in the GALT of animals that had been experimentally infected with wild-type SIVsmmPBj14 but not in animals that were infected with a nonacutely pathogenic viral mutant lacking the Nef ITAM. Taken together, these results suggest that the ability of SIVsmmPBj14 to cause acutely lethal disease and to up-regulate FasL expression may be linked. Additional studies will be required to determine whether the induction of FasL expression is in itself important for acute disease pathogenesis.

Animals↗
PubMed1998

The tyrosine-17 residue of Nef in SIVsmmPBj14 is required for acute pathogenesis and contributes to replication in macrophages.

The variant simian immunodeficiency virus termed SIVsmmPBj14 induces a rapidly fatal disease in pig-tailed macaques. The acute pathogenic effects of this virus appear to be associated with at least two in vitro characteristics: the ability to induce lymphocyte proliferation; and the ability to replicate in unstimulated PBMC. Two of the amino acids in Nef of PBj14 (the No. 17 residue, tyrosine, and the No. 18 residue, glutamic acid) appear to be linked to the virus' ability to induce lymphocyte activation. To further study the effects of these amino acids on PBj14-induced pathogenesis, we generated two mutant viruses from our molecular clone, PBj6.6, containing either changes in both the No. 17 and No. 18 residues (termed PBj6.6YE-RQ), or a single change in the No. 17 residue (termed PBj6.6Y-R). In vitro analyses of these viruses showed that while their replicative abilities in stimulated peripheral blood mononuclear cells (PBMC) were altered, they still maintained the ability to replicate in unstimulated PBMC. Replication of these viruses in macrophage populations was impaired relative to the wild-type virus. Both mutant viruses were unable to induce proliferation of macaque PBMC in vitro. Virus derived from PBj6.6Y-R was unable to induce acute disease in macaques, but did maintain the ability to induce lymphopenia and intestinal lymphoid hyperplasia. These results show that the tyrosine-17 residue of Nef is linked to lymphocyte proliferation and disease development, but also suggest that the pathogenic characteristics of SIVsmmPBj14 are dependent upon multiple genetic determinants.

Alleles↗
PubMed1998

Endogenous tumor necrosis factor-alpha contributes to lymphoproliferation induced by simian immunodeficiency virus variant, SIVsmmPBj14.

The simian immunodeficiency virus (SIV) isolate, SIVsmmPBj14, contains an immunoreceptor tyrosine-based activation motif (ITAM) within its nef gene product and triggers efficient lymphoproliferation in vitro. In experimentally inoculated macaque monkeys, this virus causes acutely lethal enteropathy, which is accompanied by high levels of pro-inflammatory cytokines, including tumor necrosis factor (TNF)-alpha. Since TNF-alpha has been shown to possess weak comitogenic activity for antigen- or mitogen-induced human T-cell proliferation, experiments were conducted to examine whether TNF-alpha might also contribute to SIVsmmPBj14-induced lymphoproliferation. Addition of a dimeric soluble human TNF receptor (sTNFR):Fc fusion protein to SIVsmmPBj14-infected simian peripheral blood mononuclear cells (PBMC) resulted in a partial (> 50%) inhibition of virally-induced lymphoproliferation, but had no effect on the strong T-cell activation signal provided by phytohemagglutinin and interleukin-2. Finally, the addition of exogenous human TNF-alpha to simian PBMC infected with a non-mitogenic variant of SIVsmmPBj14 failed to result in detectable lymphoproliferation, suggesting that TNF-alpha alone is not sufficient to cause the proliferation of SIV infected T-cells. Taken together, the data suggest that endogenous TNF-alpha enhances SIVsmmPBj14-induced lymphoproliferation in simian PBMC cultures.

Animals↗
PubMed1998

Isolation and characterization of a neuropathogenic simian immunodeficiency virus derived from a sooty mangabey.

Transfusion of blood from a simian immunodeficiency virus (SIV)- and simian T-cell lymphotropic virus-infected sooty mangabey (designated FGb) to rhesus and pig-tailed macaques resulted in the development of neurologic disease in addition to AIDS. To investigate the role of SIV in neurologic disease, virus was isolated from a lymph node of a pig-tailed macaque (designated PGm) and the cerebrospinal fluid of a rhesus macaque (designated ROn2) and passaged to additional macaques. SIV-related neuropathogenic effects were observed in 100% of the pig-tailed macaques inoculated with either virus. Lesions in these animals included extensive formation of SIV RNA-positive giant cells in the brain parenchyma and meninges. Based upon morphology, the majority of infected cells in both lymphoid and brain tissue appeared to be of macrophage lineage. The virus isolates replicated very well in pig-tailed and rhesus macaque peripheral blood mononuclear cells (PBMC) with rapid kinetics. Differential replicative abilities were observed in both PBMC and macrophage populations, with viruses growing to higher titers in pig-tailed macaque cells than in rhesus macaque cells. An infectious molecular clone of virus derived from the isolate from macaque PGm (PGm5.3) was generated and was shown to have in vitro replication characteristics similar to those of the uncloned virus stock. While molecular analyses of this virus revealed its similarity to SIV isolates from sooty mangabeys, significant amino acid differences in Env and Nef were observed. This virus should provide an excellent system for investigating the mechanism of lentivirus-induced neurologic disease.

AIDS Dementia Complex↗
PubMed1998

Molecular cloning and characterization of viruses isolated from chimpanzees with pathogenic human immunodeficiency virus type 1 infections.

We have previously described the development of AIDS in a chimpanzee (C499) infected with human immunodeficiency virus type 1 (HIV-1) and the subsequent pathogenic HIV-1 infection in another chimpanzee (C455) transfused with blood from C499 (F. J. Novembre et al., J. Virol. 71:4086-4091, 1997). In the present study, two virus isolates were derived from these animals: HIV-1JC from peripheral blood mononuclear cells (PBMC) of C499, and HIV-1NC from plasma of C455. These virus isolates were used to generate two infectious molecular clones, termed HIV-1JC16 and HIV-1NC7 (JC16 and NC7, respectively). Comparative analyses of the sequences of the two clones showed that they were highly interrelated but distinct. Based on heteroduplex mobility assays, JC16 and NC7 appear to represent dominant viruses in the uncloned stock population. Compared with amino acid sequences of the parental viruses HIV-1SF2, HIV-1LAV-1b, and HIV-1NDK, JC16 and NC7 showed a number of differences, including insertions, deletions, and point mutations spread throughout the genome. However, insertion/deletion footprints in several genes of both JC16 and NC7 suggested that recombination between SF2 and LAV-1b could have occurred, possibly contributing to the generation of a pathogenic virus. Comparative in vitro analyses of the molecular clones and the uncloned stocks of HIV-1JC and HIV-1NC revealed that these viruses had strikingly similar replicative abilities in mitogen-stimulated PBMC and in macrophages. Compared to the SF2 and LAV-1b isolates of HIV-1, HIV-1JC and HIV-1NC isolates were more similar to LAV-1b with respect to the ability to replicate in mitogen-stimulated PBMC and macrophages. These viruses should prove to be useful in mapping determinants of pathogenesis.

Amino Acid Sequence↗
PubMed1998

Costimulatory pathways in lymphocyte proliferation induced by the simian immunodeficiency virus SIVsmmPBj14.

The PBj14 isolate of the simian immunodeficiency virus SIVsmmPBj14 is unique among primate lentiviruses in its ability to induce lymphocyte proliferation and acutely lethal disease. The studies reported here show that viral induction of T-cell proliferation requires accessory cells, such as primary monocytes or Raji B-lymphoma cells, as well as the presence of a putative immunoreceptor tyrosine-based activation motif within the viral Nef protein. Addition of CTLA4-immunoglobulin fusion protein or anti-B7 antibodies to virally infected T cells led to substantial, but not complete, inhibition of monocyte-costimulated T-cell proliferation-suggesting that both CD28/B7-dependent and non-CD28-dependent pathways may contribute to the costimulation of virally induced lymphoproliferation. Finally, cyclosporin A, a specific inhibitor of the calcium-calmodulin-regulated phosphatase activity of calcineurin, which influences activation of the transcription factor nuclear factor of activated T cells, was shown to block virally mediated T-cell proliferation. Taken together, these findings suggest that the effect of SIVsmmPBj14 on T-cell activation may be functionally analogous, at least in part, to the effect of engagement of the T-cell receptor.

Abatacept↗
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↗
PubMed1996

Characterization of a novel baboon virus closely resembling human T-cell leukemia virus.

We report the isolation of a virus from a baboon imported from Kenya and the analysis of the nucleotide sequence of the env gene. Comparison of the complete nucleotide sequence of the env gene of different HTLV-1 strains and the baboon T-cell leukemia virus (designated BTLV) indicated similarities ranging from 92.5 to 97.4%. In contrast, only 89.1% similarity was observed between the BTLV env sequence and that of simian T-cell leukemia virus (PtM3). The sequences corresponding to the glycosylation sites, endoproteolytic processing site, and major immunological determinants were strictly conserved between BTLV and HTLV-1. To characterize the expressed protein we used a vaccinia expression system, which indicated that a protein of 62 kDa is encoded by the envelope gene. The protein acquired mostly high mannose modifications and was localized predominantly in the endoplasmic reticulum. A fraction of the protein was expressed at the cell surface, where it could induce membrane fusion of target cells. The existence of HTLV-1-like viruses in baboons indicates the potential risk of transmission of such virus from these nonhuman primates to humans, thus highlighting the need for specific screening for such viruses during xenotransplantation.

Amino Acid Sequence↗
PubMed1996

Apoptosis correlates with immune activation in intestinal lymphoid tissue from macaques acutely infected by a highly enteropathic simian immunodeficiency virus, SIVsmmPBj14.

The PBj14 isolate of simian immunodeficiency virus, SIVsmmPBj14, induces an acutely lethal disease in experimentally inoculated pigtailed macaques, that is characterized by severe enteropathy and extensive immune activation, particularly within gut-associated lymphoid tissue (GALT). Experiments were conducted to determine whether virally induced immune activation might promote the induction of apoptosis in GALT during acute SIVsmmPBj14 infection. In situ labeling studies revealed a significant increase in the number of apoptotic cells within GALT from macaques with acute SIVsmmPBj14 infection, compared to (i) other tissues from the same animals, (ii) GALT from virus-negative animals, or (iii) GALT from macaques that were sacrificed soon after infection with SIVmac239, which does not cause acutely lethal enteropathy. These findings were confirmed by biochemical assays of DNA fragmentation, using DNA laddering and ELISA techniques. Immunostaining experiments revealed a strong positive correlation between the extent of apoptosis and the degree of immune activation, as assessed either by the number of cells which contained nuclear (activated) RelA or by the number of cells immunoreactive for CD25, a T-cell activation marker. Additional analyses of SIV antigen expression revealed that the majority of the apoptotic cells were not productively infected by SIV (i.e., that they were bystander cells). Taken together, these findings support the hypothesis that SIVsmmPBj14 efficiently induces immune activation and that this results in extensive apoptosis within gut-associated lymphoid tissue during acute viral infection.

Animals↗
PubMed1996

Deletion of the nef gene abrogates the ability of SIV smmPBj to induce acutely lethal disease in pigtail macaques.

Simian immunodeficiency virus (SIV) infection in macaque species is typically associated with the development of a progressive immunodeficiency disease, similar to human AIDS, resulting in death of animals in months to years after infection. In contrast, a variant virus, termed SIVsmmPBj, induces an acute disease in macaques, resulting in death in 5 to 14 days after infection. Previously, we have shown that several viral determinants contribute to the pathogenesis of this disease. The present study was undertaken to evaluate the role of Nef in the pathogenesis of SIVsmmPBj-induced acute disease. A molecular clone of SIVsmmPBj was generated that contains a deletion in the nef coding region (PBj6.6 delta nef). Virus derived from this molecular clone was tested with the parental virus, PBj6.6, in replication studies in pigtail macaque and rhesus macaque peripheral blood mononuclear cells (PBMCs). In general, PBj6.6 delta nef displayed markedly reduced replication abilities when compared with PBj6.6; the only exception being in stimulated pigtail macaque PBMCs, where replication kinetics were nearly identical. In addition, PBj6.6 delta nef was unable to induce the proliferation of peripheral blood mononuclear cells (PBMCs) in vitro, a unique characteristic of acutely pathogenic SIVsmmPBj. Inoculation of this virus into pigtail macaques resulted in infection, but did not result in any detectable acute disease. These studies suggest that Nef is an important viral determinant in the pathogenesis of SIVsmmPBj-induced disease, and further suggest that Nef plays a significant role in viral replication in vivo.

Amino Acid Sequence↗
PubMed1996

SIVsmmPBj14 induces expression of a mucosal integrin on macaque lymphocytes.

The PBj14 isolate of simian immunodeficiency virus, SIVsmmPBj14, is an acutely pathogenic lentivirus that causes severe gastrointestinal disease in macaque monkeys. The studies reported here examine the basis for the enteropathic phenotype of SIVsmmPBj14, using flow cytometric analysis of cultured macaque lymphocytes and immunohistochemical staining of tissue specimens from virus-infected macaques. The data show that enteropathic molecular clones of SIVsmmPBj14 induce expression of the alpha E beta 7 integrin, which is believed to mediate mucosal retention of T-cells, whereas molecular clones from nonenteropathic derivatives of SIVsmmPBj14 do not do so. Thus, elevated expression of alpha E beta 7 may ber responsible, at least in part, for the accumulation of abnormally large numbers of T-cells within the intestinal mucosa during acute SIVsmmPBj14 infection.

Animals↗