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P N Fultz

Publications and source records attributed to P N Fultz.

At least 55 records · Page 3Linked to original sources
PubMed1994

An acutely lethal simian immunodeficiency virus stimulates expansion of V beta 7- and V beta 14-expressing T lymphocytes.

SIVsmmPBj14, a variant simian immunodeficiency virus isolated from a pig-tailed macaque, stimulates the proliferation of macaque T lymphocytes in vitro and induces an acutely lethal disease in macaques characterized, in part, by lymphadenopathy and splenomegaly. To determine whether SIVsmmPBj14 exhibits superantigen-like activity, in vitro and in vivo studies of T-cell receptor V beta repertoire were undertaken using PCR-based quantitative methods. Whereas in vitro phytohemagglutinin stimulation of macaque peripheral blood lymphocytes did not cause a perturbation of T-cell receptor V beta repertoire, SIVsmmPBj14 stimulated the expansion of both CD4+ and CD8+ T-lymphocyte subpopulations expressing the V beta 7 and V beta 14 gene families. Such V beta 7 and V beta 14 expansions could be confirmed by a multiple RNase protection assay. Furthermore, the expansion of the same lymphocyte subpopulations was also detected in peripheral blood lymphocytes and lymph node cells of virus-infected macaques. These observations suggest that SIVsmmPBj14-mediated V beta expansion may contribute to the induction of an acutely lethal disease in macaques.

Acute Disease↗
PubMed1994

SIVsmmPBj14: an atypical lentivirus.

SIV-PBj14 is atypical for a lentivirus in that infection of pig-tailed macaques usually does not result in long-term progressive disease; however, this model may potentially provide valuable information about the pathogenesis of HIV and the development of AIDS. By capitalizing on some of the unique properties of the virus and the model system discussed above, new insights may be gained in: (a) understanding pathogenic mechanisms of acute lentiviral infections, (b) dissecting lentivirus-host cell interactions, (c) evaluating the role(s) of cytokines in lentivirus-induced disease, (d) rapidly assessing therapeutic and prophylactic benefits of new drugs and vaccines, and (e) identifying regions of the viral genome that influence specific biological properties. While it is unlikely, but possible, that HIV-1 variants as virulent as SIV-PBj14 will become a threat to humans, SIV-PBj14 may possess properties important to the development of lentivirus-induced disease. An understanding of all possible virus-host interactions, from the most virulent to the most benign, may be required to make a significant, positive impact on the HIV-1 pandemic.

Animals↗
PubMed1994

Unique lentivirus--host interactions: SIVsmmPBj14 infection of macaques.

The most virulent primate lentivirus identified to date, the simian virus SIVsmmPBj14 (SIV-PBj14), is unique not only because it causes acute disease and death within days instead of months or years, but also because of its replicative and cellular activation properties. The acute disease syndrome has many features in common with primary HIV-1 disease, but differences in the respective outcomes of these two acute lentiviral infections appear to be linked to the rapidity with which SIV-PBj14 replicates and the high titers of virus that subsequently accumulate in lymphoid tissues. The most prominent pathologic feature of SIV-PBj14 is extensive lymphoid hyperplasia of T-cell zones, especially in the gut-associated lymphoid tissue. These expanded T-cell zones contain a high proportion of lymphoblasts, activated macrophages and syncytial cells, which are positively correlated with high numbers of SIV antigen-positive cells. Replication of the virus to high titers, accompanied by extensive cellular activation and proliferation, leading to high levels of cytokines, such as interleukin-6 and tumor necrosis factor-alpha, are consistent with acute inflammatory disease. The pathogenesis of SIV-PBj14 also appears to correlate most directly with some of its unique biologic properties, such as the ability to replicate in resting peripheral blood mononuclear cells, to activate lymphocytes, and to induce lymphocyte proliferation. Biologically and molecularly cloned viruses derived from SIV-PBj14 and isolates obtained from macaque PBj at earlier times, are being used to identify viral determinants that influence biologic and pathogenic properties of SIV-PBj14. Further characterization of this virus should provide new insights into lentivirus-cell interactions and their contributions to disease.

Animals↗
PubMed1994

Enhanced responsiveness to nuclear factor kappa B contributes to the unique phenotype of simian immunodeficiency virus variant SIVsmmPBj14.

Infection with a variant of simian immunodeficiency virus, SIVsmmPBj14, leads to severe acute disease in macaques. This study was designed to investigate the functional significance of previously described mutations in the viral long terminal repeat (LTR) and to elucidate their contribution to the unique phenotype of SIVsmmPBj14. LTR-directed transcription was measured by using luciferase reporter constructs that were transiently transfected into cultured cells. In a wide range of cell types, the basal transcriptional activity of the LTR from SIVsmmPBj14 was found to be 2- to 4.5-fold higher than that of an LTR from a non-acutely pathogenic strain. These LTRs differ by five point mutations and a 22-bp duplication in SIVsmmPBj14, which includes a nuclear factor kappa B (NF kappa B) site. Transcriptional differences between these LTRs were further enhanced by two- to threefold upon treatment of cells with phorbol ester or tumor necrosis factor alpha or by cotransfection with plasmids expressing NF kappa B subunits. Mutagenesis studies, and the use of a reporter construct containing an enhancerless promoter, indicate that these transcriptional effects are due principally to the 22-bp sequence duplication and the NF kappa B site contained within it. Finally, infectious virus stocks that were isogenic except for the LTR were generated. The LTR from SIVsmmPBj14 was found to confer an increase in the kinetics of virus replication in cultured cells. Inclusion of this LTR in recombinant SIVs also resulted in a two- to threefold rise in the extent of cellular proliferation that was induced in quiescent simian peripheral blood mononuclear cells. These studies are consistent with the hypothesis that LTR mutations assist SIVsmmPBj14 in responding efficiently to cellular stimulation and allow it to replicate to high titers during the acute phase of viral infection.

Animals↗
PubMed1994

Immune activation and viral burden in acute disease induced by simian immunodeficiency virus SIVsmmPBj14: correlation between in vitro and in vivo events.

The simian immunodeficiency virus SIVsmmPBj14 (SIV-PBj14) is an atypical lentivirus that causes acute disease and death in pig-tailed macaques and in vitro replicates efficiently in resting macaque lymphocytes and activates and induces proliferation of lymphocytes. The present study was conducted to test the hypothesis that production of large quantities of SIV-PBj14 induces widespread immune activation and elaboration of cytokines which lead directly to the death of infected pig-tailed macaques. Following intravenous inoculation of pig-tailed macaques with SIV-PBj14, acute disease developed and was characterized by high levels of plasma viremia, p27gag antigenemia, tumor necrosis factor alpha, and interleukin-6 (IL-6). All animals died within 10 days of infection, at which time some animals had as many as 100% CD4+ cells in the periphery and lymphoid tissues infected. During the last few days before death, titers of infectious virus in blood increased as much as 10(5)-fold. By using dual-label immunofluorescence assays for detection of cell surface activation markers, both CD4+ and CD8+ lymphocytes were shown to express the IL-2 and transferrin receptors following either in vivo or in vitro infection with SIV-PBj14. Furthermore, in vitro infection of quiescent macaque lymphocytes by SIV-PBj14 was accompanied by proliferation of both CD4+ and CD8+ lymphocyte subsets, as measured by incorporation of [3H]thymidine. Increases in numbers of activated lymphocytes and levels of proinflammatory cytokines in plasma coincided with increased amounts of detectable virus in vivo. Clinical signs of disease and pathologic findings were most consistent with death from a shock-like syndrome, in which acute-phase inflammatory cytokines are known to play a major role. Tumor necrosis factor alpha, IL-2, and IL-6 were detected in some cultures infected with SIV-PBj14, but this finding was not consistent. When cytokines were detected, their concentrations were essentially no different from those found in control cultures infected with SIVsmm9, a prototypic strain from which SIV-PBj14 was derived. The in vivo results suggest a synergistic cycle of activation of lymphocytes and monocytes, elaboration of cytokines, and virus production that accelerates uncontrolled and culminates in death. The observed correlations between in vivo and in vitro activation events following SIV-PBj14 infection validate the use of in vitro studies to clarify lentivirus-lymphocyte interactions that may contribute to the virulence of SIV-PBj14.

Animals↗
PubMed1994

New approaches for mucosal vaccines for AIDS: encapsidation and serial passages of poliovirus replicons that express HIV-1 proteins on infection.

It is apparent that a safe and effective HIV vaccine is an important component in the development of rational approaches for the control and prevention of HIV transmission. Given the fact that the virus most often encounters a mucosal surface during sexual transmission, a vaccine designed to stimulate both the systemic and mucosal immune systems is essential. Poliovirus is attractive as a delivery system because of several biological features inherent to the virus. First, the pathogenesis of the virus has been well studied, and important features have been identified. The virus is naturally transmitted by a fecal-oral route and is stable in the harsh conditions of the gastrointestinal tract. Second, previous studies using attenuated vaccine strains of poliovirus showed that a long-lasting systemic and mucosal immunity is generated after administration of the vaccines. Studies have demonstrated the presence of circulating T cells that proliferate to whole inactive poliovirus or peptides corresponding to amino acids of the VP1 proteins in previously immunized individuals. These results established that immunization with poliovirus stimulates both the humoral and cell-mediated components of the immune system. Third, the attenuated strains of poliovirus are safe for humans and are given to infants as early as 6 months of age. The incorporation of foreign genes into the attenuated strains would be an attractive feature that should pose no more of a health risk than that associated with administration of the attenuated vaccines. Finally, studies from this laboratory, as well as others, have established the feasibility of incorporating foreign genes into the poliovirus cDNA.(ABSTRACT TRUNCATED AT 250 WORDS)

AIDS Vaccines↗
PubMed1993

A molecular clone of HIV-1 tropic and cytopathic for human and chimpanzee lymphocytes.

Previous studies of HIV-1 replication in chimpanzee lymphocytes have been limited to a small number of virus isolates which generally replicated poorly and without cytopathic effect. Here, we describe an HIV-1 provirus (SG3), cloned as a single proviral unit, which replicates more efficiently in chimpanzee than in human lymphocytes, resulting in syncytium formation and cell death. This provirus also replicates efficiently and with extraordinary cytopathic effect in immortalized human T-cell lines. The SG3 genome was completely sequenced and found to contain all genes typical of HIV-1 with the exception of vpu. Phylogenetically, SG3 is representative of North American/European strains of HIV-1 and shows no greater similarity to SIVCPZ in its envelope sequence than do other HIV-1 strains. Pilot studies indicate that SG3 can infect and replicate in chimpanzees and SCID-hu mice in vivo following intravenous or intrathymic inoculation. The SG3 proviral clone, because of its replication efficiency in human and chimpanzee cells and its complete molecular description, represents a new virologic reagent for the coordinated molecular analysis of HIV-1 replication and pathogenesis in relevant animal model systems.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Immune response of chimpanzees after immunization with the inactivated whole immunodeficiency virus (HIV-1), three different adjuvants and challenge.

Purified whole virus preparations of HIV-1 were produced from supernatants of infected cells and concentrated 5000-fold. After inactivation with formaldehyde, the concentrates were combined with one of three different adjuvants, and used to immunize three groups of three chimpanzees each. The chimpanzees were monitored for HIV-specific humoral and cellular immune responses by ELISA, immunoblot, virus neutralization, delayed-type hypersensitivity, lymphocyte proliferation and antibody-dependent cell-mediated cytotoxicity. Weak and inconsistent responses were observed in animals that received HIV-1 formulated with alum as adjuvant, whereas HIV-1 formulated with incomplete Freund's adjuvant or an experimental adjuvant (BWZL) induced good humoral and cellular immune responses to the virus. The three animals that received HIV-1 with the BWZL adjuvant generated overall the best immune responses; therefore, 2 weeks after the sixth immunization these animals were challenged with infectious HIV-1. Despite the presence of good humoral and cell-mediated immunity, all three immunized animals and a control animal became infected within 4 weeks, as evidenced by repeated isolation of HIV-1 from peripheral blood mononuclear cells and anamnestic antibody responses. The new experimental adjuvant has to be further investigated in other vaccine trials and different animal models.

AIDS Vaccines↗
PubMed1993

Early pathogenesis of disease caused by SIVsmmPBj14 molecular clone 1.9 in macaques.

We have studied the early pathogenesis of infection by molecular clone 1.9 of SIVsmmPBj14 in pig-tailed and cynomolgus macaques. Like the uncloned PBj14 parent, SIVsmmPBj14-1.9 consistently induced an acute clinical syndrome characterized by behavioral depression, fever, profuse diarrhea, dehydration, lymphadenopathy, splenomegaly, and mucocutaneous exanthema that began at 7 days postinfection (DPI). The acute clinical disease coincided with a marked cell-associated and cell-free viremia, during which SIV p27 was demonstrated in 4 to 68% of circulating mononuclear leukocytes between 4 and 17 DPI. Also characteristic were monocytosis and reductions in CD4+ and CD8+ T lymphocytes, as well as CD20+ B lymphocytes. The most profound depletion occurred in the CD44hi subset of CD4+ T cells. Unlike animals infected previously with uncloned or biologically cloned PBj14, however, all SIVsmmPBj14-1.9-infected macaques survived the acute-phase disease to progress to a chronic, largely asymptomatic phase of infection. Recovery from the acute-phase disease correlated with down modulation of virus replication and the appearance of antibodies to SIV Env and Gag proteins. Similar to the PBj14 parent, PBj14-1.9 targeted to intestine, spleen, bone marrow, lymph node, and cerebellum. Saliva contained substantial quantities of infectious virus and no viral antibodies during the early phase of infection. By contrast, saliva from chronically infected animals usually contained antibodies but no virus. This study extends previous work demonstrating that the acute clinical syndrome produced by SIVsmmPBj14 in pig-tailed macaques represents a unique model of lentiviral pathogenesis.

Animals↗
PubMed1993

Nonhuman primate models for AIDS.

Historically, animal model systems have been important components of biomedical research, and the same is proving true for research directed at the human immunodeficiency virus (HIV) pandemic. The most relevant and valuable models for studying infection by HIV-1 and HIV-2 and progression to AIDS involve infection of nonhuman primates with HIV-1, HIV-2, or some of the closely related simian immunodeficiency viruses (SIVs). The SIV macaque model has proven valuable in all aspects of AIDS-related research, with primary emphasis on defining pathogenic properties of lentiretroviruses and on testing novel approaches for prophylactic and therapeutic intervention. Because of certain limitations with the HIV-1 chimpanzee model, not the least of which is the expense involved, the use of HIV-naive chimpanzees should be limited to experiments related to vaccine development, an area for which their value has been demonstrated. Continued efforts to halt the spread of HIV infection and progression of HIV-related diseases will require further use of these animal models.

Acquired Immunodeficiency Syndrome↗
PubMed1993

A distinct African lentivirus from Sykes' monkeys.

Asymptomatic infection with simian immunodeficiency virus (SIV) has been demonstrated in African Sykes' monkeys (Cercopithecus mitis albogularis), and virus isolation confirmed infection with a novel SIV from Sykes' monkeys (SIVsyk). Macaques inoculated with SIVsyk became persistently infected but remained clinically healthy. We utilized polymerase chain reaction amplification to generate a full-length, infectious molecular clone of SIVsyk. The genome organization of SIVsyk is similar to that of the other primate lentiviruses, consisting of gag, pol, vif, vpr, tat, rev, env, and nef. A unique feature is the absence of the highly conserved NF-kappa B binding site in the long terminal repeat. SIVsyk is genetically equidistant from other primate lentiviruses. Thus, SIVsyk represents a new group that is distinct from the four previously recognized primate lentivirus groups: human immunodeficiency virus type 1 (HIV-1), SIV from sooty mangabeys (SIVsmm) and HIV-2, SIV from African green monkeys (SIVagm), and SIV from mandrills (SIVmnd). The genetic differences between SIVsyk and SIVagm, isolates derived from monkeys of the same genus, underscore the potential for other distinct SIVs which have yet to be isolated and characterized.

Africa↗
PubMed1992

Vaccine protection of chimpanzees against challenge with HIV-1-infected peripheral blood mononuclear cells.

Because human immunodeficiency virus (HIV) can be transmitted as cell-free virus or as infected cells (cell-associated virus), vaccines must protect against infection by both viral forms. Vaccine-mediated protection of nonhuman primates against low doses of cell-free HIV-1, HIV-2, or simian immunodeficiency virus (SIV) has been demonstrated. It is now shown that multiple immunizations of chimpanzees with HIV-1 antigens protected against infection with cell-associated virus. Protection can persist for extended periods (one animal had not been exposed to viral antigens for 1 year before challenge). These results show that it is possible to elicit long-lasting protective immunity against cell-associated HIV-1.

AIDS Vaccines↗
PubMed1992

SIV from stump-tailed macaques: molecular characterization of a highly transmissible primate lentivirus.

Over the past 6 years, simian immunodeficiency viruses (SIVs) have been isolated from four distinct species of macaques (Macaca mulatta, M. fascicularis, M. nemestrina, and M. arctoides) in captivity in the United States. However, the epidemiologic and genetic relationships among SIVs from the four species are not well understood. SIV from stump-tailed macaques (M. arctoides) (SIVstm) is unusual in that it has been associated with outbreaks of infection characterized by aggressive spread within stump-tailed macaque colonies at two separate primate centers in the United States. To characterize SIVstm at the molecular level, we have derived six biologically active viral DNA clones by polymerase chain reaction amplification of genomic DNA from infected cells. Nucleotide sequence analyses of one clone (SIVstm/37.16) showed that SIVstm was indeed a member of the previously defined group of simian lentiviruses that are closely related to the human immunodeficiency virus type 2 (HIV-2). However, our data indicate that SIVstm is equidistantly related to the other SIVs from macaques (SIVmac 251/142 and SIVmne) and SIV from African sooty mangabeys (SIVsmm). These findings suggest that SIV from captive macaques may have originated from several cross-species transmissions from imported sooty mangabeys and that additional spread has been fostered by the exchange of macaques among primate centers.

Amino Acid Sequence↗
PubMed1992

Molecular clones from a non-acutely pathogenic derivative of SIVsmmPBj14: characterization and comparison to acutely pathogenic clones.

Molecularly cloned simian immunodeficiency viruses capable of inducing acute, fatal disease in pig-tailed macaques had been derived previously from a biological clone (bcl-3) of the PBj14 isolate of SIV from sooty mangabey monkeys (SIVsmmPBj14). The present study was undertaken in order to characterize virus from a second biological clone of SIVsmmPBj14, bcl-1, which fails to induce acute or fatal disease. Polymerase chain reaction was used to amplify 5' and 3' viral genome halves. The DNA sequence of two 3' halves was determined, and an infectious recombinant generated using a bcl-3-derived 5' half and a bcl-1-derived 3' half. Overall, bcl-1- and bcl-3-derived viruses displayed close homology, differing by a total of 2% at the DNA level and 1-6% at the amino acid level within the 8 open reading frames examined. In contrast to the bcl-3-derived viruses, the bcl-1-derived viruses encode a truncated transmembrane envelope glycoprotein. Another consistent difference was the presence of a 22 bp duplication in the U3 portion of the long terminal repeat (LTR) of bcl-3-derived viruses that includes the NF-kappa B transcriptional enhancer binding site. To assess the importance of this duplication, virus chimeras were generated which removed the duplication from the 3'-LTR or from both LTRs of a bcl-3 clone. The former virus was unstable, reacquiring the duplication through recombination with the 5' LTR. No consistent difference were observed, however, between viruses with or without the duplication in the in vitro studies conducted to date.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Transient increases in numbers of infectious cells in an HIV-infected chimpanzee following immune stimulation.

Efficient replication and production of human immunodeficiency virus (HIV) has been shown to be influenced greatly not only by the activation state of the infected cell but also by a variety of cytokines. Thus, it seems reasonable to assume, as has been hypothesized, that any stimulus to the immune system, whether by intercurrent infection, exposure to new or recall antigens, or injury with inflammation, could enhance HIV expression in infected individuals. To test this hypothesis, we subjected an HIV-1-infected chimpanzee to repeated specific and nonspecific immune stimulation by inoculation of various vaccine preparations, adjuvant alone, or HIV-specific immune globulin. Transient increases both in numbers of infectious peripheral blood cells and in some HIV-specific immune responses occurred within 1 to 2 weeks after most inoculations, including administration of the immune globulin. These results have important implications for the use of immunotherapy as a treatment for HIV-infected persons and for immunization of HIV-infected infants and children against other pathogens. They suggest that both immunotherapy and vaccination of HIV-infected individuals should be accompanied by administration of an antiviral drug(s).

Animals↗
PubMed1992

Genetic differences accounting for evolution and pathogenicity of simian immunodeficiency virus from a sooty mangabey monkey after cross-species transmission to a pig-tailed macaque.

We determined the nucleotide sequences of two related isolates of simian immunodeficiency virus from the sooty mangabey monkey (SIVsmm) that exhibit dramatic differences in virulence. These isolates are separated by one experimental cross-species transmission, from sooty mangabey to pig-tailed macaque. The parental virus (SIVsmm9), nonpathogenic in the original host (sooty mangabeys), causes a chronic AIDS-like disease in macaques. In contrast, the variant virus (SIVsmmPBj14) induces an acute lethal disease in various macaque species and is also pathogenic for sooty mangabeys. The combination of necessary and sufficient mutations that determined the acutely lethal phenotype on the SIVsmm9 genetic background is included within a maximal set of 57 point mutations, plus two insertions located in the long terminal repeat (22 bp spanning an NF-kappa B-like enhancer element) and in the surface envelope glycoprotein (5 amino acids). Comparisons of synonymous and nonsynonymous nucleotide substitutions in the genome of SIVsmm indicated that selective pressures, probably due to the host immune response, favored amino acid changes in the envelope. This immunoevolutionary mechanism could explain the increase in diversity and the apparition of new virulent phenotypes after cross-species transmission.

Animals↗
PubMed1992

Evidence for a lentiviral etiology in an epizootic of immune deficiency and lymphoma in stump-tailed macaques (Macaca arctoides).

A retrospective study determined that an epizootic of immune suppression and lymphoma in stump-tailed macaques (Macaca arctoides) that began in 1976 was associated with a horizontally spread lentivirus infection. This conclusion was based on serology, epidemiology, pathology, and virus isolation. The lesions found in the stump-tailed macaques were more compatible with lesions seen in SIV-infected rhesus than those seen in rhesus macaques infected with type D retroviruses. A lentivirus, isolated from a rhesus inoculated with lymph node homogenate from a stump-tailed macaque, was designed SIVstm and was pathogenic for rhesus macaques. The isolate was antigenically related to other SIVs as well as to HIV-1 and HIV-2. Two surviving stump-tailed macaques sent to another colony carried SIVstm latently for at least 7 years and disseminated it throughout that colony.

Animals↗