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  1. Article ; Online: How robust are estimates of key parameters in standard viral dynamic models?

    Zitzmann, Carolin / Ke, Ruian / Ribeiro, Ruy M / Perelson, Alan S

    PLoS computational biology

    2024  Volume 20, Issue 4, Page(s) e1011437

    Abstract: Mathematical models of viral infection have been developed, fitted to data, and provide insight into disease pathogenesis for multiple agents that cause chronic infection, including HIV, hepatitis C, and B virus. However, for agents that cause acute ... ...

    Abstract Mathematical models of viral infection have been developed, fitted to data, and provide insight into disease pathogenesis for multiple agents that cause chronic infection, including HIV, hepatitis C, and B virus. However, for agents that cause acute infections or during the acute stage of agents that cause chronic infections, viral load data are often collected after symptoms develop, usually around or after the peak viral load. Consequently, we frequently lack data in the initial phase of viral growth, i.e., when pre-symptomatic transmission events occur. Missing data may make estimating the time of infection, the infectious period, and parameters in viral dynamic models, such as the cell infection rate, difficult. However, having extra information, such as the average time to peak viral load, may improve the robustness of the estimation. Here, we evaluated the robustness of estimates of key model parameters when viral load data prior to the viral load peak is missing, when we know the values of some parameters and/or the time from infection to peak viral load. Although estimates of the time of infection are sensitive to the quality and amount of available data, particularly pre-peak, other parameters important in understanding disease pathogenesis, such as the loss rate of infected cells, are less sensitive. Viral infectivity and the viral production rate are key parameters affecting the robustness of data fits. Fixing their values to literature values can help estimate the remaining model parameters when pre-peak data is missing or limited. We find a lack of data in the pre-peak growth phase underestimates the time to peak viral load by several days, leading to a shorter predicted growth phase. On the other hand, knowing the time of infection (e.g., from epidemiological data) and fixing it results in good estimates of dynamical parameters even in the absence of early data. While we provide ways to approximate model parameters in the absence of early viral load data, our results also suggest that these data, when available, are needed to estimate model parameters more precisely.
    MeSH term(s) Viral Load ; Humans ; Models, Biological ; Virus Diseases/virology ; Computational Biology/methods ; Computer Simulation
    Language English
    Publishing date 2024-04-16
    Publishing country United States
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, N.I.H., Extramural
    ZDB-ID 2193340-6
    ISSN 1553-7358 ; 1553-734X
    ISSN (online) 1553-7358
    ISSN 1553-734X
    DOI 10.1371/journal.pcbi.1011437
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: How reliable are estimates of key parameters in viral dynamic models?

    Zitzmann, Carolin / Ke, Ruian / Ribeiro, Ruy M. / Perelson, Alan S.

    bioRxiv

    Abstract: Mathematical models of viral infection have been developed and fit to data to gain insight into disease pathogenesis for a number of agents including HIV, hepatitis C and B virus. However, for acute infections such as influenza and SARS-CoV-2, as well as ...

    Abstract Mathematical models of viral infection have been developed and fit to data to gain insight into disease pathogenesis for a number of agents including HIV, hepatitis C and B virus. However, for acute infections such as influenza and SARS-CoV-2, as well as for infections such as hepatitis C and B that can be acute or progress to being chronic, viral load data are often collected after symptoms develop, usually around or after the peak viral load. Consequently, we frequently lack data in the exponential phase of viral growth, i.e., when most transmission events occur. Missing data may make estimation of the time of infection, the infectious period, and parameters in viral dynamic models, such as the cell infection rate, difficult. Here, we evaluated the reliability of estimates of key model parameters when viral load data prior to the viral load peak is missing. We estimated the time from infection to peak viral load by fitting non-linear mixed models to a dataset with frequent viral RNA measurements, including pre-peak. We quantified the reliability of estimated infection times, key model parameters, and the time to peak viral load. Although estimates of the time of infection are sensitive to the quality and amount of available data, other parameters important in understanding disease pathogenesis, such as the loss rate of infected cells, are less sensitive. We find a lack of data in the exponential growth phase underestimates the time to peak viral load by several days leading to a shorter predicted exponential growth phase. On the other hand, having an idea of the time of infection and fixing it, results in relatively good estimates of dynamical parameters even in the absence of early data.
    Keywords covid19
    Language English
    Publishing date 2023-08-18
    Publisher Cold Spring Harbor Laboratory
    Document type Article ; Online
    DOI 10.1101/2023.08.17.553792
    Database COVID19

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  3. Article: Mathematical Analysis of Viral Replication Dynamics and Antiviral Treatment Strategies: From Basic Models to Age-Based Multi-Scale Modeling.

    Zitzmann, Carolin / Kaderali, Lars

    Frontiers in microbiology

    2018  Volume 9, Page(s) 1546

    Abstract: Viral infectious diseases are a global health concern, as is evident by recent outbreaks of the middle east respiratory syndrome, Ebola virus disease, and re-emerging zika, dengue, and chikungunya fevers. Viral epidemics are a socio-economic burden that ... ...

    Abstract Viral infectious diseases are a global health concern, as is evident by recent outbreaks of the middle east respiratory syndrome, Ebola virus disease, and re-emerging zika, dengue, and chikungunya fevers. Viral epidemics are a socio-economic burden that causes short- and long-term costs for disease diagnosis and treatment as well as a loss in productivity by absenteeism. These outbreaks and their socio-economic costs underline the necessity for a precise analysis of virus-host interactions, which would help to understand disease mechanisms and to develop therapeutic interventions. The combination of quantitative measurements and dynamic mathematical modeling has increased our understanding of the within-host infection dynamics and has led to important insights into viral pathogenesis, transmission, and disease progression. Furthermore, virus-host models helped to identify drug targets, to predict the treatment duration to achieve cure, and to reduce treatment costs. In this article, we review important achievements made by mathematical modeling of viral kinetics on the extracellular, intracellular, and multi-scale level for Human Immunodeficiency Virus, Hepatitis C Virus, Influenza A Virus, Ebola Virus, Dengue Virus, and Zika Virus. Herein, we focus on basic mathematical models on the population scale (so-called target cell-limited models), detailed models regarding the most important steps in the viral life cycle, and the combination of both. For this purpose, we review how mathematical modeling of viral dynamics helped to understand the virus-host interactions and disease progression or clearance. Additionally, we review different types and effects of therapeutic strategies and how mathematical modeling has been used to predict new treatment regimens.
    Keywords covid19
    Language English
    Publishing date 2018-07-11
    Publishing country Switzerland
    Document type Journal Article ; Review
    ZDB-ID 2587354-4
    ISSN 1664-302X
    ISSN 1664-302X
    DOI 10.3389/fmicb.2018.01546
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Mathematical modeling of hepatitis C RNA replication, exosome secretion and virus release.

    Zitzmann, Carolin / Kaderali, Lars / Perelson, Alan S

    PLoS computational biology

    2020  Volume 16, Issue 11, Page(s) e1008421

    Abstract: Hepatitis C virus (HCV) causes acute hepatitis C and can lead to life-threatening complications if it becomes chronic. The HCV genome is a single plus strand of RNA. Its intracellular replication is a spatiotemporally coordinated process of RNA ... ...

    Abstract Hepatitis C virus (HCV) causes acute hepatitis C and can lead to life-threatening complications if it becomes chronic. The HCV genome is a single plus strand of RNA. Its intracellular replication is a spatiotemporally coordinated process of RNA translation upon cell infection, RNA synthesis within a replication compartment, and virus particle production. While HCV is mainly transmitted via mature infectious virus particles, it has also been suggested that HCV-infected cells can secrete HCV RNA carrying exosomes that can infect cells in a receptor independent manner. In order to gain insight into these two routes of transmission, we developed a series of intracellular HCV replication models that include HCV RNA secretion and/or virus assembly and release. Fitting our models to in vitro data, in which cells were infected with HCV, suggests that initially most secreted HCV RNA derives from intracellular cytosolic plus-strand RNA, but subsequently secreted HCV RNA derives equally from the cytoplasm and the replication compartments. Furthermore, our model fits to the data suggest that the rate of virus assembly and release is limited by host cell resources. Including the effects of direct acting antivirals in our models, we found that in spite of decreasing intracellular HCV RNA and extracellular virus concentration, low level HCV RNA secretion may continue as long as intracellular RNA is available. This may possibly explain the presence of detectable levels of plasma HCV RNA at the end of treatment even in patients that ultimately attain a sustained virologic response.
    MeSH term(s) Antiviral Agents/pharmacology ; Computational Biology ; Computer Simulation ; Exosomes/virology ; Hepacivirus/genetics ; Hepacivirus/pathogenicity ; Hepacivirus/physiology ; Hepatitis C, Chronic/drug therapy ; Hepatitis C, Chronic/virology ; Host Microbial Interactions/genetics ; Host Microbial Interactions/physiology ; Humans ; Mathematical Concepts ; Models, Biological ; RNA, Viral/biosynthesis ; RNA, Viral/genetics ; Viral Replication Compartments/physiology ; Virion/genetics ; Virion/physiology ; Virus Assembly/drug effects ; Virus Assembly/genetics ; Virus Assembly/physiology ; Virus Release/genetics ; Virus Release/physiology ; Virus Replication/drug effects ; Virus Replication/genetics ; Virus Replication/physiology
    Chemical Substances Antiviral Agents ; RNA, Viral
    Language English
    Publishing date 2020-11-05
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 2193340-6
    ISSN 1553-7358 ; 1553-734X
    ISSN (online) 1553-7358
    ISSN 1553-734X
    DOI 10.1371/journal.pcbi.1008421
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Book ; Online ; Thesis: Mathematical Modeling of Plus‐Strand RNA Virus Replication

    Zitzmann, Carolin [Verfasser] / Kaderali, Lars [Akademischer Betreuer] / Kaderali, Lars [Gutachter] / Figge, Mark Thilo [Gutachter]

    2023  

    Author's details Carolin Zitzmann ; Gutachter: Lars Kaderali, Mark Thilo Figge ; Betreuer: Lars Kaderali
    Keywords Medizin, Gesundheit ; Medicine, Health
    Subject code sg610
    Language English
    Publisher Universität Greifswald
    Publishing place Greifswald
    Document type Book ; Online ; Thesis
    Database Digital theses on the web

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  6. Article ; Online: In vivo kinetics of SARS-CoV-2 infection and its relationship with a person's infectiousness.

    Ke, Ruian / Zitzmann, Carolin / Ho, David D / Ribeiro, Ruy M / Perelson, Alan S

    Proceedings of the National Academy of Sciences of the United States of America

    2021  Volume 118, Issue 49

    Abstract: The within-host viral kinetics of SARS-CoV-2 infection and how they relate to a person's infectiousness are not well understood. This limits our ability to quantify the impact of interventions on viral transmission. Here, we develop viral dynamic models ... ...

    Abstract The within-host viral kinetics of SARS-CoV-2 infection and how they relate to a person's infectiousness are not well understood. This limits our ability to quantify the impact of interventions on viral transmission. Here, we develop viral dynamic models of SARS-CoV-2 infection and fit them to data to estimate key within-host parameters such as the infected cell half-life and the within-host reproductive number. We then develop a model linking viral load (VL) to infectiousness and show a person's infectiousness increases sublinearly with VL and that the logarithm of the VL in the upper respiratory tract is a better surrogate of infectiousness than the VL itself. Using data on VL and the predicted infectiousness, we further incorporated data on antigen and RT-PCR tests and compared their usefulness in detecting infection and preventing transmission. We found that RT-PCR tests perform better than antigen tests assuming equal testing frequency; however, more frequent antigen testing may perform equally well with RT-PCR tests at a lower cost but with many more false-negative tests. Overall, our models provide a quantitative framework for inferring the impact of therapeutics and vaccines that lower VL on the infectiousness of individuals and for evaluating rapid testing strategies.
    MeSH term(s) COVID-19/diagnosis ; COVID-19/virology ; COVID-19 Nucleic Acid Testing/methods ; False Positive Reactions ; Humans ; Kinetics ; SARS-CoV-2/genetics ; Serologic Tests/methods
    Language English
    Publishing date 2021-09-17
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 209104-5
    ISSN 1091-6490 ; 0027-8424
    ISSN (online) 1091-6490
    ISSN 0027-8424
    DOI 10.1073/pnas.2111477118
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: In vivo kinetics of SARS-CoV-2 infection and its relationship with a person's infectiousness.

    Ke, Ruian / Zitzmann, Carolin / Ho, David D / Ribeiro, Ruy M / Perelson, Alan S

    medRxiv : the preprint server for health sciences

    2021  

    Abstract: The within-host viral kinetics of SARS-CoV-2 infection and how they relate to a person's infectiousness are not well understood. This limits our ability to quantify the impact of interventions on viral transmission. Here, we develop data-driven viral ... ...

    Abstract The within-host viral kinetics of SARS-CoV-2 infection and how they relate to a person's infectiousness are not well understood. This limits our ability to quantify the impact of interventions on viral transmission. Here, we develop data-driven viral dynamic models of SARS-CoV-2 infection and estimate key within-host parameters such as the infected cell half-life and the within-host reproductive number. We then develop a model linking VL to infectiousness, showing that a person's infectiousness increases sub-linearly with VL. We show that the logarithm of the VL in the upper respiratory tract (URT) is a better surrogate of infectiousness than the VL itself. Using data on VL and the predicted infectiousness, we further incorporated data on antigen and reverse transcription polymerase chain reaction (RT-PCR) tests and compared their usefulness in detecting infection and preventing transmission. We found that RT-PCR tests perform better than antigen tests assuming equal testing frequency; however, more frequent antigen testing may perform equally well with RT-PCR tests at a lower cost, but with many more false-negative tests. Overall, our models provide a quantitative framework for inferring the impact of therapeutics and vaccines that lower VL on the infectiousness of individuals and for evaluating rapid testing strategies.
    Significance: Quantifying the kinetics of SARS-CoV-2 infection and individual infectiousness is key to quantitatively understanding SARS-CoV-2 transmission and evaluating intervention strategies. Here we developed data-driven within-host models of SARS-CoV-2 infection and by fitting them to clinical data we estimated key within-host viral dynamic parameters. We also developed a mechanistic model for viral transmission and show that the logarithm of the viral load in the upper respiratory tract serves an appropriate surrogate for a person's infectiousness. Using data on how viral load changes during infection, we further evaluated the effectiveness of PCR and antigen-based testing strategies for averting transmission and identifying infected individuals.
    Language English
    Publishing date 2021-06-30
    Publishing country United States
    Document type Preprint
    DOI 10.1101/2021.06.26.21259581
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  8. Article ; Online: Modeling the emergence of viral resistance for SARS-CoV-2 during treatment with an anti-spike monoclonal antibody.

    Phan, Tin / Zitzmann, Carolin / Chew, Kara W / Smith, Davey M / Daar, Eric S / Wohl, David A / Eron, Joseph J / Currier, Judith S / Hughes, Michael D / Choudhary, Manish C / Deo, Rinki / Li, Jonathan Z / Ribeiro, Ruy M / Ke, Ruian / Perelson, Alan S

    PLoS pathogens

    2024  Volume 20, Issue 4, Page(s) e1011680

    Abstract: To mitigate the loss of lives during the COVID-19 pandemic, emergency use authorization was given to several anti-SARS-CoV-2 monoclonal antibody (mAb) therapies for the treatment of mild-to-moderate COVID-19 in patients with a high risk of progressing to ...

    Abstract To mitigate the loss of lives during the COVID-19 pandemic, emergency use authorization was given to several anti-SARS-CoV-2 monoclonal antibody (mAb) therapies for the treatment of mild-to-moderate COVID-19 in patients with a high risk of progressing to severe disease. Monoclonal antibodies used to treat SARS-CoV-2 target the spike protein of the virus and block its ability to enter and infect target cells. Monoclonal antibody therapy can thus accelerate the decline in viral load and lower hospitalization rates among high-risk patients with variants susceptible to mAb therapy. However, viral resistance has been observed, in some cases leading to a transient viral rebound that can be as large as 3-4 orders of magnitude. As mAbs represent a proven treatment choice for SARS-CoV-2 and other viral infections, evaluation of treatment-emergent mAb resistance can help uncover underlying pathobiology of SARS-CoV-2 infection and may also help in the development of the next generation of mAb therapies. Although resistance can be expected, the large rebounds observed are much more difficult to explain. We hypothesize replenishment of target cells is necessary to generate the high transient viral rebound. Thus, we formulated two models with different mechanisms for target cell replenishment (homeostatic proliferation and return from an innate immune response antiviral state) and fit them to data from persons with SARS-CoV-2 treated with a mAb. We showed that both models can explain the emergence of resistant virus associated with high transient viral rebounds. We found that variations in the target cell supply rate and adaptive immunity parameters have a strong impact on the magnitude or observability of the viral rebound associated with the emergence of resistant virus. Both variations in target cell supply rate and adaptive immunity parameters may explain why only some individuals develop observable transient resistant viral rebound. Our study highlights the conditions that can lead to resistance and subsequent viral rebound in mAb treatments during acute infection.
    MeSH term(s) Humans ; SARS-CoV-2/immunology ; SARS-CoV-2/drug effects ; Antibodies, Monoclonal/therapeutic use ; Antibodies, Monoclonal/immunology ; Spike Glycoprotein, Coronavirus/immunology ; COVID-19/immunology ; COVID-19/virology ; COVID-19 Drug Treatment ; Antibodies, Viral/immunology ; Antibodies, Viral/therapeutic use ; Drug Resistance, Viral/immunology ; Viral Load/drug effects ; Antiviral Agents/therapeutic use ; Antiviral Agents/pharmacology ; Antibodies, Neutralizing/immunology ; Antibodies, Neutralizing/therapeutic use
    Chemical Substances Antibodies, Monoclonal ; Spike Glycoprotein, Coronavirus ; Antibodies, Viral ; spike protein, SARS-CoV-2 ; Antiviral Agents ; Antibodies, Neutralizing
    Language English
    Publishing date 2024-04-18
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2205412-1
    ISSN 1553-7374 ; 1553-7374
    ISSN (online) 1553-7374
    ISSN 1553-7374
    DOI 10.1371/journal.ppat.1011680
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article: Last in first out: SIV proviruses seeded later in infection are harbored in short-lived CD4

    Sambaturu, Narmada / Fray, Emily J / Wu, Fengting / Zitzmann, Carolin / Simonetti, Francesco R / Barouch, Dan H / Siliciano, Janet D / Siliciano, Robert F / Ribeiro, Ruy M / Perelson, Alan S / Molina-París, Carmen / Leitner, Thomas

    bioRxiv : the preprint server for biology

    2023  

    Abstract: HIV can persist in a latent form as integrated DNA (provirus) in resting ... ...

    Abstract HIV can persist in a latent form as integrated DNA (provirus) in resting CD4
    Language English
    Publishing date 2023-11-03
    Publishing country United States
    Document type Preprint
    DOI 10.1101/2023.11.03.565539
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article ; Online: Mathematical modeling of plus-strand RNA virus replication to identify broad-spectrum antiviral treatment strategies.

    Zitzmann, Carolin / Dächert, Christopher / Schmid, Bianca / van der Schaar, Hilde / van Hemert, Martijn / Perelson, Alan S / van Kuppeveld, Frank J M / Bartenschlager, Ralf / Binder, Marco / Kaderali, Lars

    PLoS computational biology

    2023  Volume 19, Issue 4, Page(s) e1010423

    Abstract: Plus-strand RNA viruses are the largest group of viruses. Many are human pathogens that inflict a socio-economic burden. Interestingly, plus-strand RNA viruses share remarkable similarities in their replication. A hallmark of plus-strand RNA viruses is ... ...

    Abstract Plus-strand RNA viruses are the largest group of viruses. Many are human pathogens that inflict a socio-economic burden. Interestingly, plus-strand RNA viruses share remarkable similarities in their replication. A hallmark of plus-strand RNA viruses is the remodeling of intracellular membranes to establish replication organelles (so-called "replication factories"), which provide a protected environment for the replicase complex, consisting of the viral genome and proteins necessary for viral RNA synthesis. In the current study, we investigate pan-viral similarities and virus-specific differences in the life cycle of this highly relevant group of viruses. We first measured the kinetics of viral RNA, viral protein, and infectious virus particle production of hepatitis C virus (HCV), dengue virus (DENV), and coxsackievirus B3 (CVB3) in the immuno-compromised Huh7 cell line and thus without perturbations by an intrinsic immune response. Based on these measurements, we developed a detailed mathematical model of the replication of HCV, DENV, and CVB3 and showed that only small virus-specific changes in the model were necessary to describe the in vitro dynamics of the different viruses. Our model correctly predicted virus-specific mechanisms such as host cell translation shut off and different kinetics of replication organelles. Further, our model suggests that the ability to suppress or shut down host cell mRNA translation may be a key factor for in vitro replication efficiency, which may determine acute self-limited or chronic infection. We further analyzed potential broad-spectrum antiviral treatment options in silico and found that targeting viral RNA translation, such as polyprotein cleavage and viral RNA synthesis, may be the most promising drug targets for all plus-strand RNA viruses. Moreover, we found that targeting only the formation of replicase complexes did not stop the in vitro viral replication early in infection, while inhibiting intracellular trafficking processes may even lead to amplified viral growth.
    MeSH term(s) Humans ; Antiviral Agents/pharmacology ; RNA Viruses ; Virus Replication/physiology ; RNA, Viral/genetics ; Models, Theoretical ; Hepatitis C
    Chemical Substances Antiviral Agents ; RNA, Viral
    Language English
    Publishing date 2023-04-04
    Publishing country United States
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2193340-6
    ISSN 1553-7358 ; 1553-734X
    ISSN (online) 1553-7358
    ISSN 1553-734X
    DOI 10.1371/journal.pcbi.1010423
    Database MEDical Literature Analysis and Retrieval System OnLINE

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