Search PubMed⌕ Search

Biomedical subjects

P N Fultz

Publications and source records attributed to P N Fultz.

At least 73 records · Page 4Linked to original sources
PubMed1991

Are we detouring from a direct route to development of HIV vaccines?

Experiments in animal model systems have demonstrated that it is possible for vaccination to elicit immune responses that can prevent or significantly delay lentiviral infection and perhaps disease. To facilitate the development of effective HIV vaccines, current research and development efforts must utilize the appropriate HIV strains. International scientific communities and vaccine manufacturers, with the support of governments, should now unite to ensure that the most direct route possible will be taken.

Animals↗
PubMed1991

Prolonged CD4+ lymphocytopenia and thrombocytopenia in a chimpanzee persistently infected with human immunodeficiency virus type 1.

The immunologic and virologic status of a chimpanzee inoculated with multiple isolates of the human immunodeficiency virus type 1 (HIV-1) were assessed over 57 months to determine whether prolonged thrombocytopenia and CD4+ lymphocytopenia observed in the animal might be associated with long-term HIV infection. Although the chimpanzee showed no signs of disease, it lost both CD4+ (as low as 134 cells/microliter) and CD8+ lymphocytes approximately 30 months after initial infection, followed by thrombocytopenia that has persisted for greater than 2 years. Lymphopenia and thrombocytopenia were preceded by or coincided with the appearance of antibodies cross-reactive with histone H2B and decreased levels of complement component C4; an eightfold decrease in HIV-specific antibody titers; the inability of CD8+ lymphocytes to suppress virus replication; impaired proliferative responses to T cell mitogens; and the isolation of cell-free HIV from plasma. These data suggest that, given sufficient time, HIV-infected chimpanzees may develop disease.

Animals↗
PubMed1991

Isolation from African Sykes' monkeys (Cercopithecus mitis) of a lentivirus related to human and simian immunodeficiency viruses.

Analysis of serum samples from 100 wild-caught or colony-born Sykes' monkeys (Cercopithecus mitis) in Kenya revealed that 59 animals had antibodies cross-reactive to human immunodeficiency virus type 2 (HIV-2) and to simian immunodeficiency viruses (SIVs). A lentivirus, designated SIVsyk, was isolated from five of six seropositive asymptomatic Sykes' monkeys, but in four cases isolation was possible only after depletion of CD8+ lymphocytes and cocultivation of the CD4(+)-enriched cell population with peripheral blood mononuclear cells from seronegative Sykes' monkeys. SIVsyk resembled other SIVs and HIVs morphologically, had an Mg2(+)-dependent reverse transcriptase enzyme, and replicated in and was cytopathic for CEMx174 and Sup-T1 cells. SIVsyk differred substantially from other SIVs, however, in that it failed to replicate in normal human, mangabey, and macaque peripheral blood mononuclear cells and serum from seropositive Sykes' monkeys immunoprecipitated env antigens from HIV-1 as well as from HIV-2, SIVsmm, and SIVagm. These data demonstrate a high prevalence of natural infection in Sykes' monkeys in Kenya with a lentivirus that appears to be unique with respect to its host range and antigenic cross-reactivity.

Animals↗
PubMed1991

A chimpanzee-passaged human immunodeficiency virus isolate is cytopathic for chimpanzee cells but does not induce disease.

The human immunodeficiency virus type 1 (HIV-1) readily infects both humans and chimpanzees, but the pathologic outcomes of infection in these two species differ greatly. In attempts to identify virus-cell interactions that might account for this differential pathogenicity, chimpanzee peripheral blood lymphocytes and bone marrow macrophages were assessed in vitro for their ability to support the replication of several HIV-1 isolates. Although the IIIb, RF, and MN isolates did not readily infect chimpanzee peripheral blood lymphocytes, an isolate of HIV-1 passaged in vivo in chimpanzees not only replicated well in both chimpanzee peripheral blood lymphocytes and bone marrow macrophages but also was cytopathic for chimpanzee CD4+ lymphocytes. Because no evidence of HIV-induced disease has been observed in chimpanzees infected with this isolate, in vitro replication to high titers with concomitant loss of CD4+ cells is not, in this instance, a correlate of pathogenicity. These observations, therefore, indicate that caution must be used when making extrapolations from in vitro data to in vivo pathogenesis.

Animals↗
PubMed1991

Replication of an acutely lethal simian immunodeficiency virus activates and induces proliferation of lymphocytes.

A variant of simian immunodeficiency virus from sooty mangabey monkeys (SIVsmm), termed SIVsmmPBj14, was previously identified and shown to induce acute disease and death within 1 to 2 weeks of inoculation of pig-tailed macaques and mangabey monkeys (P. N. Fultz, H. M. McClure, D. C. Anderson, and W. M. Switzer, AIDS Res. Hum. Retroviruses 5:397-409, 1989). SIVsmmPBj14 differed from its parent virus, SIVsmm9, not only in pathogenicity but also in multiple in vitro properties. As a first approach to understanding the biological and molecular mechanisms responsible for the acute disease and death induced by this variant, virus-host cell interactions of SIVsmmPBj14 and SIVsmm9 were studied. Initial rates of replication of the two viruses were identical in primary peripheral blood mononuclear cells (PBMC) from normal pig-tailed macaques and mangabey monkeys, but SIVsmmPBj14 infection always resulted in higher yields of virus than did SIVsmm9 infection, as assessed by levels of reverse transcriptase activity in culture supernatants. Surprisingly, despite its cytopathicity for macaque and mangabey CD4+ cells, replication of SIVsmmPBj14 was accompanied by up to 10-fold increases in number of viable cells compared with cell numbers in uninfected or SIVsmm9-infected cultures. Furthermore, SIVsmmPBj14 was shown to infect and replicate in resting PBMC just as efficiently as in mitogen-stimulated PBMC, irrespective of whether exogenous interleukin-2 (IL-2) or antibodies that neutralized IL-2 were added to culture media. Accumulation of virus in culture supernatants of resting PBMC preceded by several days the appearance of activated cells which expressed the IL-2 receptor alpha subunit (CD25), suggesting that activation of cells was not essential for replication. The ability to activate and to induce simian PBMC to proliferate appeared specific for the acutely lethal variant because incorporation of [3H]thymidine by PBMC from naive animals was observed only upon incubation with concentrated, heat-inactivated SIVsmmPBj14 and not with other viruses. Both CD4(+)- and CD8(+)-enriched cell populations proliferated in response to SIVsmmPBj14. These results are consistent with in vivo observations and suggest that the abilities both to replicate in resting cells and to induce lymphocytes to proliferate may contribute to the extreme virulence of SIVsmmPBj14.

Animals↗
PubMed1991

Maternal transmission of SIVsmm in rhesus macaques.

Fifteen SIV-infected rhesus monkeys delivered 13 livebirths and two stillbirths; one livebirth died at three days of age. While all infants were culture-negative for SIV at birth, nine had maternal antibodies that disappeared by six months of age. Three infants subsequently seroconverted and became virus positive at 9-15 months. Milk samples from all mothers were virus-negative at parturition but samples from four animals were virus-positive at nine and 12 months. This study documents maternal transmission of SIV and suggests transmission by breast-feeding.

Animals↗
PubMed1990

Sequence analysis and acute pathogenicity of molecularly cloned SIVSMM-PBj14.

The PBj14 isolate of simian immunodeficiency virus from sooty mangabey monkeys (SIVSMM-PBj14) is the most acutely pathogenic primate lentivirus so far described, always causing fatal disease in pig-tailed macaques (Macaca nemestrina) within 8 days of inoculation. As a first step in identifying viral genes and gene products that influence pathogenicity, the SIVSMM-PBj14 genome was amplified by the polymerase chain reaction as 5' and 3' genomic halves of 5.1 and 5.8 kilobases, respectively, and molecularly cloned. DNA sequence analysis revealed a high degree of conservation with other SIVs, except for a 22-base-pair duplication in the enhancer region of the viral long terminal repeat which included a second binding site for the transcription factor NF-kappa B. Of six genomic halves examined, four contributed to the formation of infectious virus that induced acute disease and death in pig-tailed macaques as early as 6 days post-inoculation, with pathology, disease syndromes and kinetics indistinguishable from those induced by the uncloned isolate. To our knowledge this is the first example of acute immunodeficiency disease induced by a molecularly defined lentivirus. Furthermore, the molecularly cloned SIVSMM-PBj14 viruses share with the uncloned virus cytopathicity for mangabey CD4+ cells, a property that may correlate with their observed pathogenicity in vivo.

Animals↗
PubMed1990

Requirements for simian immunodeficiency virus antigen-specific in vitro proliferation of T cells from infected rhesus macaques and sooty mangabeys.

The measurement of cell-mediated immunity against the etiologic agent of human AIDS (HIV) in the non-human primate model of AIDS (simian immunodeficiency virus, SIV) has been difficult. In general, culture of peripheral blood mononuclear cells from HIV-1- and SIV-infected humans and monkeys, respectively, with purified inactivated HIV and SIV virus preparations has given inconsistent or negative proliferative responses. However, we describe herein an assay which consists of coculturing monocytes that have been pulsed with inactivated SIVsmm with nylon-wool-purified autologous T cells, leading to antigen-specific T-cell proliferation. The proliferative response, which predominantly occurs in CD4+ T cells, is major histocompatibility complex (MHC) class II-restricted and requires antigen processing. This assay will greatly facilitate the identification of the immunodominant epitopes recognized by T cells in sooty mangabeys, which are naturally infected but remain clinically asymptomatic, and in rhesus macaques, in which experimental infection leads to clinical symptomatology similar to human AIDS, eventually resulting in death.

Animals↗
PubMed1990

Prevalence of natural infection with simian immunodeficiency virus and simian T-cell leukemia virus type I in a breeding colony of sooty mangabey monkeys.

The seroprevalence of antibodies to simian immunodeficiency virus (SIVsmm) and simian T-cell leukemia virus type I (STLV-I) in a captive breeding colony of sooty mangabey monkeys was determined, and infection by SIVsmm was confirmed in all cases by virus isolation. Among 138 animals tested, 57 and 33% were infected with SIVsmm and STLV-I, respectively. While the proportion of female mangabeys (66%) differed significantly (P less than 0.01) from the proportion of male mangabeys (42%) infected with SIVsmm, the proportions of males and females infected with STLV-I were similar, suggesting independent transmission of the two viruses. Among mangabeys less than 1 year old, none were infected with STLV-I and only five of 27 mangabeys, all of which were at least 6 months old when first tested, were infected with SIVsmm. The data document that natural infection of sooty mangabey monkeys with SIVsmm or in association with STLV-I infection does not result in increased disease or mortality, and that transmission of both SIVsmm and STLV-I appears to occur primarily through sexual activity.

Animals↗
PubMed1990

Nonhuman primate models for evaluation of AIDS therapy.

Infection of macaque monkeys with simian immunodeficiency virus (SIV) has been established as an excellent animal model system for studying the pathogenesis of an HIV-like virus and for evaluating newly developed antiretroviral drugs and vaccines. Based on their genetic, antigenic, and biologic properties, the simian immunodeficiency viruses are the closest known relatives of the human AIDS viruses, and experimental infection of macaque monkeys results in a disease that is remarkably similar to human AIDS. Infected macaques show diarrhea, weight loss, hematologic abnormalities including lymphopenia and thrombocytopenia, lymphadenopathy/lymphoid hyperplasia that progresses to lymphoid depletion, immunosuppression with marked reduction in CD4+ cells and in the CD4+/CD8+ cell ratio, and opportunistic infections. A majority of such macaques die from an AIDS-like disease within one to three years of infection. An acutely lethal variant of SIV has been identified that results in death in susceptible macaques within 7-12 days of infection. Preliminary prophylactic treatment trials with AZT in macaque monkeys exposed to the acutely lethal SIV variant indicate that some protection is provided when AZT treatment is initiated within 24 hours of virus exposure. Other studies with the more chronic SIV infection model, however, failed to show any prophylactic efficacy of CS-87, AZT, D4T, or FDT.

Animals↗
PubMed1990

Humoral response to SIV/SMM infection in macaque and mangabey monkeys.

Natural infection of sooty mangabey monkeys with simian immunodeficiency virus, designated SIV/SMM, results in long-term persistent infections with little or no disease. In contrast, experimental infection of macaques with isolates of SIV/SMM induces chronic and progressive disease that terminates in an AIDS-like illness and death in most animals. To determine whether antibodies might be important in preventing the development of disease in mangabeys or progression of disease in macaques, humoral immune responses to SIV/SMM were compared in 13 macaques infected for up to 43 months and in infected and uninfected mangabeys selected at random from among a breeding colony. Total SIV/SMM-specific antibody titers, profiles of antibodies to specific viral proteins, neutralizing antibodies that inhibited infectivity of cell-free virus or syncytia formation, antibodies that inhibited reverse transcriptase activity, and antibodies to lymphocyte cell-surface antigens were assessed. The results indicated that in macaques the magnitude of the SIV/SMM-specific antibody response and progression of disease were functions of virus load. Surprisingly, asymptomatic mangabeys also had high virus loads with, on average, lower antibody titers than macaques. In both species, the presence of neutralizing antibodies or antibodies that inhibited SIV/SMM reverse transcriptase activity did not correlate with protection from clinical disease. A correlation was observed, however, between the development of disease and the presence of antibodies to an 18-kDa protein that is found on the surface of activated lymphocytes and appears to be related to histone H2B. A similar correlation has been observed in association with HIV infection in humans, suggesting that some manifestations of both human and simian AIDS may result from autoimmune reactions.

Animals↗
PubMed1990

SIVsmm infection of macaque and mangabey monkeys: correlation between in vivo and in vitro properties of different isolates.

Simian immunodeficiency virus from sooty mangabey monkeys (SIVsmm), a lentivirus closely related to SIV from macaques and the human immunodeficiency virus type 2 (HIV-2), is pathogenic for various species of macaques but is nonpathogenic for mangabeys. Comparison of in vivo and in vitro responses of macaques and mangabeys or their lymphocytes, respectively, to SIVsmm infection indicated that lack of disease in mangabeys apparently was not due to effective control of virus expression by the immune system because SIVsmm-infected, asymptomatic mangabeys have high viral loads. Failure of mangabeys to develop disease may be related to the fact that the prototype SIVsmm (SMM-9) replicated in, but was not cytopathic for, mangabey CD4+ cells. In contrast, replication of SMM-9 in peripheral blood mononuclear cells from pigtailed macaques resulted in specific loss of CD4+ cells and induction of an AIDS-like disease. A variant of SMM-9, designated SMM-PBj14, was identified, however, that was extremely cytopathic for mangabey CD4+ cells and also induced acute lethal disease in both macaques and mangabeys. Acute disease was associated with extensive lymphoid hyperplasia, which was correlated in vitro with induction of proliferation of PBMC in SMM-PBj14-infected cultures. Infectious molecular clones of SMM-PBj14 exhibited the same in vitro and in vivo properties as SMM-PBj14. Future analysis of chimeric viruses may lead to the identification of specific regions of the viral genome that influence the various in vivo and in vitro properties of these SIVsmm isolates.

Animals↗
PubMed1989

Nonhuman primates and the acquired immunodeficiency syndrome: a union of necessity.

Because of the close phylogenetic relationship, nonhuman primates are highly susceptible to human pathogens, including infection of chimpanzees by the human immunodeficiency virus (HIV), the causative agent of AIDS. This, and the existence of a highly related simian virus, SIV, which causes an AIDS-like disease in macaques, emphasizes the continued importance of using nonhuman primates as model systems for identifying and developing prophylaxis and therapy for infectious agents and, in particular, for fighting the pandemic AIDS.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Phenotypic and functional differences in NK and LAK cells in the peripheral blood of sooty mangabeys and rhesus macaques.

Greater than 75% of the sooty mangabey monkeys at the Yerkes Regional Primate Research Center are naturally infected with SIV without any apparent clinical symptomology. On the other hand, experimental infection of rhesus macaques with SIV results in a clinical syndrome similar to human AIDS. These differences with regard to SIV infection prompted us to examine the natural immunosurveillance system of peripheral blood mononuclear cells (PBMC) from SIV-infected and uninfected monkeys of these two species. Phenotypic and functional studies of precursor and effector NK and LAK cells in the PBMC from these two species were carried out using monoclonal reagents, flow microfluorometry (FMF), and the standard in vitro 51Cr release assay against prototype K562 (NK sensitive) and RAJI (NK resistant, LAK susceptible) target cell lines. Data indicate that both NK and LAK cell activities in the PBMC of sooty mangabeys were significantly (P less than 0.01) greater than those in rhesus macaques. The predominant NK effector cells and LAK cell precursors were shown to be Leu 19-CD8+ in the PBMC of sooty mangabeys and Leu19+ CD8- in the PBMC of rhesus macaques as determined by panning depletion techniques and FMF analysis. On the other hand, the predominant LAK effector cells were found to be dual marked Leu 19+ CD8+ in rhesus macaques and Leu 19- CD8+ in sooty mangabeys. These qualitative and quantitative differences were not due to SIV infection of these two species since PBMC from both SIV-seropositive and virus-positive and SIV-sero-negative and virus-negative monkeys gave similar results. Moreover, of importance is the finding that the functional NK and LAK precursor cells are CD8+ and CD8- in sooty mangabeys and rhesus macaques, respectively. These data may have implications for the natural SIV/SMM virus-positive asymptomatic state of sooty mangabeys and may provide useful tools for tracing the ontogeny and lineage derivation of NK and LAK cells.

Animals↗
PubMed1989

Spectrum of disease in macaque monkeys chronically infected with SIV/SMM.

Twelve rhesus and one pig-tailed macaque have been monitored for 28-41 months following experimental infection with 10(4) TCID of SIV/SMM. Twelve of the 13 animals became virus positive and seroconverted within 3 to 6 weeks of exposure; the remaining animal seroconverted at 6 months, but has remained virus negative. Six of the 13 animals (46%) died between 14 and 28 months post-infection, following prolonged clinical disease characterized by chronic diarrhea and weight loss, peripheral lymphadenopathy and hemogram abnormalities. Histologic findings ranged from prominent follicular hyperplasia to severe lymphoid depletion, with lymphoid tissues often showing an infiltrate of syncytial giant cells. One animal had intestinal cryptosporidiosis and two had brain lesions comparable to those seen in AIDS encephalopathy in humans. Three of the remaining seven animals have an ARC-like disease and are showing gradual deterioration of their clinical condition. These animals, as well as animals that died, had progressive decreases in CD4+ cells and CD4+/CD8+ cell ratios. These observations further document the marked clinical, pathologic and immunologic similarities between human AIDS and the SIV-infected macaque model.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Identification and biologic characterization of an acutely lethal variant of simian immunodeficiency virus from sooty mangabeys (SIV/SMM).

A virus pool isolated from lymphoid tissue of a macaque (PBj) infected for 14 months with SIV/SMM was found to be associated with acute disease and death. Six of six pig-tailed macaques, one of three rhesus macaques, and three of four SIV/SMM-seronegative mangabeys developed acute disease within 5 days and died from 7 to 13 days postinoculation; however, neither of two SIV/SMM-infected mangabeys died or developed disease. The virus associated with acute disease and death was shown by electron microscopy to be a lentivirus and was serologically indistinguishable from SIV/SMM by immunofluorescence and radioimmunoprecipitation assays. A biologic clone generated from lymphoid tissue of an animal that died 7 days after inoculation of the lethal pool resulted in death within 8 days of three of three pig-tailed macaques. Comparison of the lethal virus, designated SIV/SMM(PBj14), with the parent virus, SIV/SMM-9 (the isolate with which macaque PBj was originally inoculated), showed that although the kinetics of replication in peripheral blood mononuclear cells (PBMC) from pig-tailed macaques and mangabey monkeys were similar, SIV/SMM(PBj14) replicated more efficiently than SIV/SMM-9 in human PBMC and also replicated in chimpanzee PBMC whereas SIV/SMM and other SIV isolates did not. In addition, the variant was shown to replicate efficiently in some established cell lines whereas replication of SIV/SMM-9 in cell lines could be demonstrated only occasionally. That parental SIV/SMM-9, but not SIV/SMM(PBj14), was neutralized by serum from macaque PBj suggests that the variant may have been generated by immune selection. Comparison of sequential virus isolates from macaque PBj for host range and the ability to be neutralized and of sequential serum samples for neutralization activity indicated that changes in biologic properties were detected in virus isolates and serum obtained at 6 months after infection and later. Normal macaque PBMC infected in vitro with SIV/SMM(PBj14), but not with SIV/SMM-9 or other virus pools from PBj, formed syncytia with Sup-T1 cells, whereas all isolates formed syncytia with MOLT-4 clone 8 cells. These data suggest that, relative to SIV/SMM-9, SIV/SMM(PBj14) acquired multiple mutations, at least one (or more) of which is in the gene coding for the envelope glycoprotein. Continued analysis of this series of SIV/SMM isolates with diverse properties may lead to the identification of specific regions of the viral genome that influence defined biologic properties. Furthermore, the availability of a strain of SIV that induces rapid onset of disease and death may facilitate screening of drugs for antiviral activity against lentiviruses.

Animals↗