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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: Predicting Impacts of Contact Tracing on Epidemiological Inference from Phylogenetic Data.

    Kupperman, Michael D / Ke, Ruian / Leitner, Thomas

    bioRxiv : the preprint server for biology

    2023  

    Abstract: Robust sampling methods are foundational to many inference problems in the phylodynamic field, yet the impact of using contact tracing, a type of non-uniform sampling used in public health applications, is not well understood. To investigate and quantify ...

    Abstract Robust sampling methods are foundational to many inference problems in the phylodynamic field, yet the impact of using contact tracing, a type of non-uniform sampling used in public health applications, is not well understood. To investigate and quantify how this non-uniform sampling method influences recovered phylogenetic tree structure, we developed a new simulation tool called SEEPS (Sequence Evolution and Epidemiological Process Simulator) that allows for the simulation of contact tracing and the resulting transmission tree, pathogen phylogeny, and corresponding virus genetic sequences. Importantly, SEEPS takes within-host evolution into account when generating pathogen phylogenies and sequences from transmission histories. Using SEEPS, we demonstrate that contact tracing can significantly impact the structure of the resulting tree as described by popular tree statistics. Contact tracing generates phylogenies that are less balanced than the underlying transmission process, less representative of the larger epidemiological process, and affects the internal/external branch length ratios that characterize specific epidemiological scenarios. We also examine a 2007-2008 Swedish HIV-1 outbreak and the broader 1998-2010 European HIV-1 epidemic to highlight the differences in contact tracing and expected phylogenies. Aided by SEEPS, we show that the Swedish outbreak was strongly influenced by contact tracing even after downsampling, while the broader European Union epidemic showed little evidence of universal contact tracing, agreeing with the known epidemiological information about sampling and spread. SEEPS is available at github.com/MolEvolEpid/SEEPS.
    Language English
    Publishing date 2023-12-04
    Publishing country United States
    Document type Preprint
    DOI 10.1101/2023.11.30.567148
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Swift and extensive Omicron outbreak in China after sudden exit from 'zero-COVID' policy.

    Goldberg, Emma E / Lin, Qianying / Romero-Severson, Ethan O / Ke, Ruian

    Nature communications

    2023  Volume 14, Issue 1, Page(s) 3888

    Abstract: In late 2022, China transitioned from a strict 'zero-COVID' policy to rapidly abandoning nearly all interventions and data reporting. This raised great concern about the presumably-rapid but unreported spread of the SARS-CoV-2 Omicron variant in a very ... ...

    Abstract In late 2022, China transitioned from a strict 'zero-COVID' policy to rapidly abandoning nearly all interventions and data reporting. This raised great concern about the presumably-rapid but unreported spread of the SARS-CoV-2 Omicron variant in a very large population of very low pre-existing immunity. By modeling a combination of case count and survey data, we show that Omicron spread extremely rapidly, at a rate of 0.42/day (95% credibility interval: [0.35, 0.51]/day), translating to an epidemic doubling time of 1.6 days ([1.6, 2.0] days) after the full exit from zero-COVID on Dec. 7, 2022. Consequently, we estimate that the vast majority of the population (97% [95%, 99%], sensitivity analysis lower limit of 90%) was infected during December, with the nation-wide epidemic peaking on Dec. 23. Overall, our results highlight the extremely high transmissibility of the variant and the importance of proper design of intervention exit strategies to avoid large infection waves.
    MeSH term(s) Animals ; COVID-19/epidemiology ; SARS-CoV-2 ; Disease Outbreaks ; Birds ; China/epidemiology ; Policy
    Language English
    Publishing date 2023-07-01
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't
    ZDB-ID 2553671-0
    ISSN 2041-1723 ; 2041-1723
    ISSN (online) 2041-1723
    ISSN 2041-1723
    DOI 10.1038/s41467-023-39638-4
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Mechanistic Modeling of SARS-CoV-2 and Other Infectious Diseases and the Effects of Therapeutics.

    Perelson, Alan S / Ke, Ruian

    Clinical pharmacology and therapeutics

    2021  Volume 109, Issue 4, Page(s) 829–840

    Abstract: Modern viral kinetic modeling and its application to therapeutics is a field that attracted the attention of the medical, pharmaceutical, and modeling communities during the early days of the AIDS epidemic. Its successes led to applications of modeling ... ...

    Abstract Modern viral kinetic modeling and its application to therapeutics is a field that attracted the attention of the medical, pharmaceutical, and modeling communities during the early days of the AIDS epidemic. Its successes led to applications of modeling methods not only to HIV but a plethora of other viruses, such as hepatitis C virus (HCV), hepatitis B virus and cytomegalovirus, which along with HIV cause chronic diseases, and viruses such as influenza, respiratory syncytial virus, West Nile virus, Zika virus, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which generally cause acute infections. Here we first review the historical development of mathematical models to understand HIV and HCV infections and the effects of treatment by fitting the models to clinical data. We then focus on recent efforts and contributions of applying these models towards understanding SARS-CoV-2 infection and highlight outstanding questions where modeling can provide crucial insights and help to optimize nonpharmaceutical and pharmaceutical interventions of the coronavirus disease 2019 (COVID-19) pandemic. The review is written from our personal perspective emphasizing the power of simple target cell limited models that provided important insights and then their evolution into more complex models that captured more of the virology and immunology. To quote Albert Einstein, "Everything should be made as simple as possible, but not simpler," and this idea underlies the modeling we describe below.
    MeSH term(s) Anti-Retroviral Agents/therapeutic use ; COVID-19/epidemiology ; COVID-19/immunology ; COVID-19/prevention & control ; COVID-19/therapy ; Communicable Diseases/epidemiology ; HIV Infections/drug therapy ; HIV Infections/epidemiology ; HIV Infections/immunology ; Hepatitis C/epidemiology ; Hepatitis C/immunology ; Humans ; Models, Theoretical ; Pandemics ; SARS-CoV-2 ; Viral Load
    Chemical Substances Anti-Retroviral Agents
    Language English
    Publishing date 2021-03-08
    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. ; Review
    ZDB-ID 123793-7
    ISSN 1532-6535 ; 0009-9236
    ISSN (online) 1532-6535
    ISSN 0009-9236
    DOI 10.1002/cpt.2160
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: A deep learning approach to real-time HIV outbreak detection using genetic data.

    Michael D Kupperman / Thomas Leitner / Ruian Ke

    PLoS Computational Biology, Vol 18, Iss 10, p e

    2022  Volume 1010598

    Abstract: Pathogen genomic sequence data are increasingly made available for epidemiological monitoring. A main interest is to identify and assess the potential of infectious disease outbreaks. While popular methods to analyze sequence data often involve ... ...

    Abstract Pathogen genomic sequence data are increasingly made available for epidemiological monitoring. A main interest is to identify and assess the potential of infectious disease outbreaks. While popular methods to analyze sequence data often involve phylogenetic tree inference, they are vulnerable to errors from recombination and impose a high computational cost, making it difficult to obtain real-time results when the number of sequences is in or above the thousands. Here, we propose an alternative strategy to outbreak detection using genomic data based on deep learning methods developed for image classification. The key idea is to use a pairwise genetic distance matrix calculated from viral sequences as an image, and develop convolutional neutral network (CNN) models to classify areas of the images that show signatures of active outbreak, leading to identification of subsets of sequences taken from an active outbreak. We showed that our method is efficient in finding HIV-1 outbreaks with R0 ≥ 2.5, and overall a specificity exceeding 98% and sensitivity better than 92%. We validated our approach using data from HIV-1 CRF01 in Europe, containing both endemic sequences and a well-known dual outbreak in intravenous drug users. Our model accurately identified known outbreak sequences in the background of slower spreading HIV. Importantly, we detected both outbreaks early on, before they were over, implying that had this method been applied in real-time as data became available, one would have been able to intervene and possibly prevent the extent of these outbreaks. This approach is scalable to processing hundreds of thousands of sequences, making it useful for current and future real-time epidemiological investigations, including public health monitoring using large databases and especially for rapid outbreak identification.
    Keywords Biology (General) ; QH301-705.5
    Subject code 006
    Language English
    Publishing date 2022-10-01T00:00:00Z
    Publisher Public Library of Science (PLoS)
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  6. Article ; Online: A deep learning approach to real-time HIV outbreak detection using genetic data.

    Kupperman, Michael D / Leitner, Thomas / Ke, Ruian

    PLoS computational biology

    2022  Volume 18, Issue 10, Page(s) e1010598

    Abstract: Pathogen genomic sequence data are increasingly made available for epidemiological monitoring. A main interest is to identify and assess the potential of infectious disease outbreaks. While popular methods to analyze sequence data often involve ... ...

    Abstract Pathogen genomic sequence data are increasingly made available for epidemiological monitoring. A main interest is to identify and assess the potential of infectious disease outbreaks. While popular methods to analyze sequence data often involve phylogenetic tree inference, they are vulnerable to errors from recombination and impose a high computational cost, making it difficult to obtain real-time results when the number of sequences is in or above the thousands. Here, we propose an alternative strategy to outbreak detection using genomic data based on deep learning methods developed for image classification. The key idea is to use a pairwise genetic distance matrix calculated from viral sequences as an image, and develop convolutional neutral network (CNN) models to classify areas of the images that show signatures of active outbreak, leading to identification of subsets of sequences taken from an active outbreak. We showed that our method is efficient in finding HIV-1 outbreaks with R0 ≥ 2.5, and overall a specificity exceeding 98% and sensitivity better than 92%. We validated our approach using data from HIV-1 CRF01 in Europe, containing both endemic sequences and a well-known dual outbreak in intravenous drug users. Our model accurately identified known outbreak sequences in the background of slower spreading HIV. Importantly, we detected both outbreaks early on, before they were over, implying that had this method been applied in real-time as data became available, one would have been able to intervene and possibly prevent the extent of these outbreaks. This approach is scalable to processing hundreds of thousands of sequences, making it useful for current and future real-time epidemiological investigations, including public health monitoring using large databases and especially for rapid outbreak identification.
    MeSH term(s) Humans ; Phylogeny ; Deep Learning ; Disease Outbreaks ; Europe ; HIV-1/genetics ; HIV Infections/epidemiology
    Language English
    Publishing date 2022-10-14
    Publishing country United States
    Document type Journal Article ; 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.1010598
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article ; Online: Swift and extensive Omicron outbreak in China after sudden exit from ‘zero-COVID’ policy

    Emma E. Goldberg / Qianying Lin / Ethan O. Romero-Severson / Ruian Ke

    Nature Communications, Vol 14, Iss 1, Pp 1-

    2023  Volume 10

    Abstract: Abstract In late 2022, China transitioned from a strict ‘zero-COVID’ policy to rapidly abandoning nearly all interventions and data reporting. This raised great concern about the presumably-rapid but unreported spread of the SARS-CoV-2 Omicron variant in ...

    Abstract Abstract In late 2022, China transitioned from a strict ‘zero-COVID’ policy to rapidly abandoning nearly all interventions and data reporting. This raised great concern about the presumably-rapid but unreported spread of the SARS-CoV-2 Omicron variant in a very large population of very low pre-existing immunity. By modeling a combination of case count and survey data, we show that Omicron spread extremely rapidly, at a rate of 0.42/day (95% credibility interval: [0.35, 0.51]/day), translating to an epidemic doubling time of 1.6 days ([1.6, 2.0] days) after the full exit from zero-COVID on Dec. 7, 2022. Consequently, we estimate that the vast majority of the population (97% [95%, 99%], sensitivity analysis lower limit of 90%) was infected during December, with the nation-wide epidemic peaking on Dec. 23. Overall, our results highlight the extremely high transmissibility of the variant and the importance of proper design of intervention exit strategies to avoid large infection waves.
    Keywords Science ; Q
    Language English
    Publishing date 2023-07-01T00:00:00Z
    Publisher Nature Portfolio
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  8. Article: Semi-infectious particles contribute substantially to influenza virus within-host dynamics when infection is dominated by spatial structure.

    Farrell, Alex / Phan, Tin / Brooke, Christopher B / Koelle, Katia / Ke, Ruian

    Virus evolution

    2023  Volume 9, Issue 1, Page(s) vead020

    Abstract: Influenza is an ribonucleic acid virus with a genome that comprises eight segments. Experiments show that the vast majority of virions fail to express one or more gene segments and thus cannot cause a productive infection on their own. These particles, ... ...

    Abstract Influenza is an ribonucleic acid virus with a genome that comprises eight segments. Experiments show that the vast majority of virions fail to express one or more gene segments and thus cannot cause a productive infection on their own. These particles, called semi-infectious particles (SIPs), can induce virion production through complementation when multiple SIPs are present in an infected cell. Previous within-host influenza models did not explicitly consider SIPs and largely ignore the potential effects of coinfection during virus infection. Here, we constructed and analyzed two distinct models explicitly keeping track of SIPs and coinfection: one without spatial structure and the other implicitly considering spatial structure. While the model without spatial structure fails to reproduce key aspects of within-host influenza virus dynamics, we found that the model implicitly considering the spatial structure of the infection process makes predictions that are consistent with biological observations, highlighting the crucial role that spatial structure plays during an influenza infection. This model predicts two phases of viral growth prior to the viral peak: a first phase driven by fully infectious particles at the initiation of infection followed by a second phase largely driven by coinfections of fully infectious particles and SIPs. Fitting this model to two sets of data, we show that SIPs can contribute substantially to viral load during infection. Overall, the model provides a new interpretation of the
    Language English
    Publishing date 2023-03-21
    Publishing country England
    Document type Journal Article
    ZDB-ID 2818949-8
    ISSN 2057-1577
    ISSN 2057-1577
    DOI 10.1093/ve/vead020
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  9. Article ; Online: CovTransformer: A transformer model for SARS-CoV-2 lineage frequency forecasting

    Feng, Yinan / Goldberg, Emma E. / Kupperman, Michael / Zhang, Xitong / Lin, Youzuo / Ke, Ruian

    medRxiv

    Abstract: With hundreds of SARS-CoV-2 lineages circulating in the global population, there is an urgent need for forecasting lineage frequencies and thus identifying rapidly expanding lineages. To address this need, we constructed a framework for SARS-CoV-2 ... ...

    Abstract With hundreds of SARS-CoV-2 lineages circulating in the global population, there is an urgent need for forecasting lineage frequencies and thus identifying rapidly expanding lineages. To address this need, we constructed a framework for SARS-CoV-2 lineage frequency forecasting (CovTransformer), based on the transformer architecture. We designed our framework to navigate challenges such as a limited amount of data with high levels of noise and bias. We first trained and tested the model using data from the UK and the US, and then tested the generalization ability of the model on data collected across the globe. Remarkably, the model makes predictions two months into the future with high levels of accuracy in 31 countries. Finally, we show that our model performed substantially better than the current gold-standard, i.e. a regression-based model implemented in Nextstrain. Overall, our work demonstrates transformer models represent a promising approach for lineage forecasting and pandemic monitoring.
    Keywords covid19
    Language English
    Publishing date 2024-04-01
    Publisher Cold Spring Harbor Laboratory Press
    Document type Article ; Online
    DOI 10.1101/2024.04.01.24305089
    Database COVID19

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  10. Article ; Online: Estimating the reproductive number R

    Ke, Ruian / Romero-Severson, Ethan / Sanche, Steven / Hengartner, Nick

    Journal of theoretical biology

    2021  Volume 517, Page(s) 110621

    Abstract: SARS-CoV-2 rapidly spread from a regional outbreak to a global pandemic in just a few months. Global research efforts have focused on developing effective vaccines against COVID-19. However, some of the basic epidemiological parameters, such as the ... ...

    Abstract SARS-CoV-2 rapidly spread from a regional outbreak to a global pandemic in just a few months. Global research efforts have focused on developing effective vaccines against COVID-19. However, some of the basic epidemiological parameters, such as the exponential epidemic growth rate and the basic reproductive number, R
    MeSH term(s) COVID-19/epidemiology ; COVID-19/prevention & control ; COVID-19 Vaccines/therapeutic use ; Europe/epidemiology ; Female ; Humans ; Male ; Models, Biological ; SARS-CoV-2 ; United States/epidemiology ; Vaccination
    Chemical Substances COVID-19 Vaccines
    Language English
    Publishing date 2021-02-13
    Publishing country England
    Document type Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
    ZDB-ID 2972-5
    ISSN 1095-8541 ; 0022-5193
    ISSN (online) 1095-8541
    ISSN 0022-5193
    DOI 10.1016/j.jtbi.2021.110621
    Database MEDical Literature Analysis and Retrieval System OnLINE

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