Stanca M Ciupe

University of Louisiana at Lafayette, Lafayette, Louisiana, United States

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Publications (14)38.57 Total impact

  • Ryan Nikin-Beers, Stanca M. Ciupe
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    ABSTRACT: Dengue virus has four distinct serotypes whose cross-reactive immune responses contribute to increased disease severity following heterologous infections. It was proposed that non-protective cross-reactive antibodies may play a role in disease enhancement. In this study we develop a mathematical model of host-virus interaction and predict the mechanisms responsible for virus expansion and loss during primary and secondary dengue infections. We use the model to determine the role of cross-reactive antibodies during dengue fever and dengue hemorrhagic fever-inducing secondary infections, and then compare the model to published patient data. We predict that the cross-reactive antibodies interfere with the non-neutralizing antibody effects by reducing the phagocyte-mediated removal of antibody-virus immune complexes. Copyright © 2015 Elsevier Inc. All rights reserved.
    Mathematical Biosciences 02/2015; 263. DOI:10.1016/j.mbs.2015.02.004 · 1.49 Impact Factor
  • Stanca M Ciupe
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    ABSTRACT: Antibodies that bind viral surface proteins can limit the spread of the infection through neutralizing and non-neutralizing functions. During both acute and chronic Human Immunodeficiency Virus infection, antibody-virion immune complexes are formed, but fail to ensure protection. In this study, we develop a mathematical model of multivalent antibody binding and use it to determine the dynamical interactions that lead to immune complexes formation and the role of complexes with increased numbers of bound antibodies in the pathogenesis of the disease. We compare our predictions with published temporal virus and immune complex data from acute infected patients. Finally, we derive quantitative and qualitative conditions needed for antibody-induced protection.
    Journal of Mathematical Biology 09/2014; DOI:10.1007/s00285-014-0826-3 · 2.39 Impact Factor
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    Stanca M Ciupe, Ruy M Ribeiro, Alan S Perelson
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    ABSTRACT: Hepatitis B is a DNA virus that infects liver cells and can cause both acute and chronic disease. It is believed that both viral and host factors are responsible for determining whether the infection is cleared or becomes chronic. Here we investigate the mechanism of protection by developing a mathematical model of the antibody response following hepatitis B virus (HBV) infection. We fitted the model to data from seven infected adults identified during acute infection and determined the ability of the virus to escape neutralization through overproduction of non-infectious subviral particles, which have HBs proteins on their surface, but do not contain nucleocapsid protein and viral nucleic acids. We showed that viral clearance can be achieved for high anti-HBV antibody levels, as in vaccinated individuals, when: (1) the rate of synthesis of hepatitis B subviral particles is slow; (2) the rate of synthesis of hepatitis B subviral particles is high but either anti-HBV antibody production is fast, the antibody affinity is high, or the levels of pre-existent HBV-specific antibody at the time of infection are high, as could be attained by vaccination. We further showed that viral clearance can be achieved for low equilibrium anti-HBV antibody levels, as in unvaccinated individuals, when a strong cellular immune response controls early infection.
    PLoS Computational Biology 07/2014; 10(7):e1003730. DOI:10.1371/journal.pcbi.1003730 · 4.83 Impact Factor
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    Stanca M Ciupe, Elissa J Schwartz
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    ABSTRACT: We develop a mathematical model for the interaction between two competing equine infectious anemia virus strains and neutralizing antibodies. We predict that elimination of one or both virus strains depends on the initial antibody levels, the strength of antibody mediated neutralization, and the persistence of antibody over time. We further show that the ability of a subdominant, neutralization resistant virus to dominate the infection transiently or permanently is dependent on the antibody-mediated neutralization effect. Finally, we determine conditions for persistence of both virus strains. We fit our models to virus titers from horses (foals) with severe combined immunodeficiency to estimate virus-host parameters and to validate analytical results.
    Journal of Theoretical Biology 11/2013; 343. DOI:10.1016/j.jtbi.2013.11.003 · 2.30 Impact Factor
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    ABSTRACT: T-cell receptor diversity correlates with immune competency and is of particular interest in patients undergoing immune reconstitution. Spectratyping generates data about T-cell receptor CDR3 length distribution for each BV gene but is technically complex. Flow cytometry can also be used to generate data about T-cell receptor BV gene usage, but its utility has not been compared to or tested in combination with spectratyping. Using flow cytometry and spectratype data, we have defined a divergence metric that quantifies the deviation from normal of T-cell receptor repertoire. We have shown that the sample size is a sensitive parameter in the predicted flow divergence values, but not in the spectratype divergence values. We have derived two ways to correct for the measurement bias using mathematical and statistical approaches and have predicted a lower bound in the number of lymphocytes needed when using the divergence as a substitute for diversity. Using both flow cytometry and spectratyping of T-cells, we have defined the divergence measure as an indirect measure of T-cell receptor diversity. We have shown the dependence of the divergence measure on the sample size before it can be used to make predictions regarding the diversity of the T-cell receptor repertoire.
    BMC Immunology 08/2013; 14(1):35. DOI:10.1186/1471-2172-14-35 · 2.25 Impact Factor
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    Stanca M Ciupe, Sarah Hews
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    ABSTRACT: We develop mathematical models for the role of hepatitis B e-antigen in creating immunological tolerance during hepatitis B virus infection and propose mechanisms for hepatitis B e-antigen clearance, subsequent emergence of a potent cellular immune response, and the effect of these on liver damage. We investigate the dynamics of virus-immune cells interactions, and derive parameter regimes that allow for viral persistence. We modify the model to account for mechanisms responsible for hepatitis B e-antigen loss, such as seroconversion and virus mutations that lead to emergence of cellular immune response to the mutant virus. Our models demonstrate that either seroconversion or mutations can induce immune activation and that instantaneous loss of e-antigen by either mechanism is associated with least liver damage and is therefore more beneficial for disease outcomes.
    PLoS ONE 07/2012; 7(7):e39591. DOI:10.1371/journal.pone.0039591 · 3.53 Impact Factor
  • Jonathan Forde, Joseph M Volpe, Stanca M Ciupe
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    ABSTRACT: While antiretroviral drugs can drive HIV to undetectably low levels in the blood, eradication is hindered by the persistence of long-lived, latently infected memory CD4 T cells. Immune activation therapy aims to eliminate this latent reservoir by reactivating these memory cells, exposing them to removal by the immune system and the cytotoxic effects of active infection. In this paper, we develop a mathematical model that investigates the use of immune activation strategies while limiting virus and latent class rebound. Our model considers infection of two memory classes, central and transitional CD4 T cells and the role that general immune activation therapy has on their elimination. Further, we incorporate ways to control viral rebound by blocking activated cell proliferation through anti proliferation therapy. Using the model, we provide insight into the control of latent infection and subsequently into the long term control of HIV infection.
    Bulletin of Mathematical Biology 05/2012; 74(7):1651-72. DOI:10.1007/s11538-012-9729-x · 1.29 Impact Factor
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    ABSTRACT: The virus Hepatitis B infects liver cells, leading to either acute or chronic liver disease. Immune responses involve both curing and killing of cells. Stability analyses show that viral clearance depends only on the strength of the combined killing and curing, independent of the characteristics of the cured cells.
    Mathematical Population Studies 04/2011; 18(2):87-105. DOI:10.1080/08898480.2011.564563 · 0.38 Impact Factor
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    ABSTRACT: One of the first immunologic responses against HIV infection is the presence of neutralizing antibodies that seem able to inactivate several HIV strains. Moreover, in vitro studies have shown the existence of monoclonal antibodies that exhibit broad crossclade neutralizing potential. Yet their number is low and slow to develop in vivo. In this paper, we investigate the potential benefits of inducing poly-specific neutralizing antibodies in vivo throughout immunization. We develop a mathematical model that considers the activation of families of B lymphocytes producing poly-specific and strain-specific antibodies and use it to demonstrate that, even if such families are successful in producing neutralizing antibodies, the competition between them may limit the poly-specific response allowing the virus to escape. We modify this model to account for viral evolution under the pressure of antibody responses in natural HIV infection. The model can reproduce viral escape under certain conditions of B lymphocyte competition. Using these models we provide explanations for the observed antibody failure in controlling natural infection and predict quantitative measures that need to be satisfied for long-term control of HIV infection.
    Journal of Theoretical Biology 02/2011; 277(1):55-66. DOI:10.1016/j.jtbi.2011.01.050 · 2.30 Impact Factor
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    ABSTRACT: Type 1 diabetes (T1DM) is a chronic autoimmune disease with a long prodrome, which is characterized by dysfunction and ultimately destruction of pancreatic beta-cells. Because of the limited access to pancreatic tissue and pancreatic lymph nodes during the normoglycemic phase of the disease, little is known about the dynamics involved in the chain of events leading to the clinical onset of the disease in humans. In particular, during T1DM progression there is limited information about temporal fluctuations of immunologic abnormalities and their effect on pancreatic beta-cell function and mass. Therefore, our understanding of the pathoetiology of T1DM relies almost entirely on studies in animal models of this disease. In an effort to elucidate important mechanisms that may play a critical role in the progression to overt disease, we propose a mathematical model that takes into account the dynamics of functional and dysfunctional beta-cells, regulatory T cells, and pathogenic T cells. The model assumes that all individuals carrying susceptible HLA haplotypes will develop variable degrees of T1DM-related immunologic abnormalities. The results provide information about the concentrations and ratios of pathogenic T cells and regulatory T cells, the timing in which beta-cells become dysfunctional, and how certain kinetic parameters affect the progression to T1DM. Our model is able to describe changes in the ratio of pathogenic T cells and regulatory T cells after the appearance of islet antibodies in the pancreas. Finally, we discuss the robustness of the model and its ability to assist experimentalists in designing studies to test complicated theories about the disease.
    Mathematical biosciences and engineering: MBE 10/2009; 6(4):753-78. DOI:10.3934/mbe.2009.6.753 · 0.87 Impact Factor
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    ABSTRACT: T cell populations are regulated both by signals specific to the T-cell receptor (TCR) and by signals and resources, such as cytokines and space, that act independently of TCR specificity. Although it has been demonstrated that disruption of either of these pathways has a profound effect on T-cell development, we do not yet have an understanding of the dynamical interactions of these pathways in their joint shaping of the T cell repertoire. Complete DiGeorge Anomaly is a developmental abnormality that results in the failure of the thymus to develop, absence of T cells, and profound immune deficiency. After receiving thymic tissue grafts, patients suffering from DiGeorge anomaly develop T cells derived from their own precursors but matured in the donor tissue. We followed three DiGeorge patients after thymus transplantation to utilize the remarkable opportunity these subjects provide to elucidate human T-cell developmental regulation. Our goal is the determination of the respective roles of TCR-specific vs. TCR-nonspecific regulatory signals in the growth of these emerging T-cell populations. During the course of the study, we measured peripheral blood T-cell concentrations, TCRbeta V gene-segment usage and CDR3-length spectratypes over two years or more for each of the subjects. We find, through statistical analysis based on a novel stochastic population-dynamic T-cell model, that the carrying capacity corresponding to TCR-specific resources is approximately 1000-fold larger than that of TCR-nonspecific resources, implying that the size of the peripheral T-cell pool at steady state is determined almost entirely by TCR-nonspecific mechanisms. Nevertheless, the diversity of the TCR repertoire depends crucially on TCR-specific regulation. The estimated strength of this TCR-specific regulation is sufficient to ensure rapid establishment of TCR repertoire diversity in the early phase of T cell population growth, and to maintain TCR repertoire diversity in the face of substantial clonal expansion-induced perturbation from the steady state.
    PLoS Computational Biology 07/2009; 5(6):e1000396. DOI:10.1371/journal.pcbi.1000396 · 4.83 Impact Factor
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    ABSTRACT: Mathematical models have been used to understand the factors that govern infectious disease progression in viral infections. Here we focus on hepatitis B virus (HBV) dynamics during the acute stages of the infection and analyze the immune mechanisms responsible for viral clearance. We start by presenting the basic model used to interpret HBV therapy studies conducted in chronically infected patients. We then introduce additional models to study acute infection where immune responses presumably play an important role in determining whether the infection will be cleared or become chronic. We add complexity incrementally and explain each step of the modeling process. Finally, we validate the model against experimental data to determine how well it represents the biological system and, consequently, how useful are its predictions. In particular, we find that a cell-mediated immune response plays an important role in controlling the virus after the peak in viral load.
    Journal of Theoretical Biology 08/2007; 247(1):23-35. DOI:10.1016/j.jtbi.2007.02.017 · 2.30 Impact Factor
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    ABSTRACT: During acute hepatitis B virus (HBV) infection viral loads reach high levels ( approximately 10(10) HBV DNA per ml), and nearly every hepatocyte becomes infected. Nonetheless, approximately 85-95% of infected adults clear the infection. Although the immune response has been implicated in mediating clearance, the precise mechanisms remain to be elucidated. As infection clears, infected cells are replaced by uninfected ones. During much of this process the virus remains plentiful but nonetheless does not rekindle infection. Here, we analyze data from a set of individuals identified during acute HBV infection and develop mathematical models to test the role of immune responses in various stages of early HBV infection. Fitting the models to data we are able to separate the kinetics of the noncytolytic and the cytolytic immune responses, thus explaining the relative contribution of these two processes. We further show that we need to hypothesize that newly generated uninfected cells are refractory to productive infection. Without this assumption, viral resurgence is observed as uninfected cells are regenerated. Such protection, possibly mediated by cytokines, may also be important in resolving other acute viral infections.
    Proceedings of the National Academy of Sciences 04/2007; 104(12):5050-5. DOI:10.1073/pnas.0603626104 · 9.81 Impact Factor
  • STANCA M. CIUPE, PATRICK W. NELSON
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    ABSTRACT: A nonlinear delay difierential equation of van der Pol type is con- sidered. Local stability conditions are derived together with the existence of a sequence of Hopf bifurcations. The direction and stability of the bifurcating periodic solutions is obtained using the center manifold theory. By perturba- tion analysis techniques we obtain periodic solutions for both a weak and a strong feedback equation. The efiect of a delay in the promotion or suppression of limit cycle oscillations is investigated.

Publication Stats

127 Citations
38.57 Total Impact Points

Institutions

  • 2011
    • University of Louisiana at Lafayette
      • Department of Mathematics
      Lafayette, Louisiana, United States
  • 2009
    • Duke University Medical Center
      Durham, North Carolina, United States
  • 2007
    • Santa Fe Institute
      Ann Arbor, Michigan, United States