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Haun A, Fain B, Dobrovolny HM. Effect of cellular regeneration and viral transmission mode on viral spread. J Theor Biol 2023; 558:111370. [PMID: 36460057 DOI: 10.1016/j.jtbi.2022.111370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Revised: 11/03/2022] [Accepted: 11/18/2022] [Indexed: 12/03/2022]
Abstract
Illness negatively affects all aspects of life and one major cause of illness is viral infections. Some viral infections can last for weeks; others, like influenza (the flu), can resolve quickly. During infections, uninfected cells can replicate in order to replenish the cells that have died due to the virus. Many viral models, especially those for short-lived infections like influenza, tend to ignore cellular regeneration since many think that uncomplicated influenza resolves much faster than cells regenerate. This research accounts for cellular regeneration, using an agent-based framework, and varies the regeneration rate in order to understand how cell regeneration affects viral infection dynamics under assumptions of different modes of transmission. We find that although the general trends in peak viral load, time of viral peak, and chronic viral load as regeneration rate changes are the same for cell-free or cell-to-cell transmission, the changes are more extreme for cell-to-cell transmission due to limited access of infected cells to newly generated cells.
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Affiliation(s)
- Asher Haun
- Department of Physics & Astronomy, Texas Christian University, Fort Worth, TX, United States of America
| | - Baylor Fain
- Department of Physics & Astronomy, Texas Christian University, Fort Worth, TX, United States of America
| | - Hana M Dobrovolny
- Department of Physics & Astronomy, Texas Christian University, Fort Worth, TX, United States of America.
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Fain B, Dobrovolny HM. Initial Inoculum and the Severity of COVID-19: A Mathematical Modeling Study of the Dose-Response of SARS-CoV-2 Infections. EPIDEMIOLGIA (BASEL, SWITZERLAND) 2020; 1:5-15. [PMID: 36417207 PMCID: PMC9620883 DOI: 10.3390/epidemiologia1010003] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Revised: 09/30/2020] [Accepted: 10/14/2020] [Indexed: 12/14/2022]
Abstract
SARS-CoV-2 (Severe acute respiratory syndrome coronavirus 2) causes a variety of responses in those who contract the virus, ranging from asymptomatic infections to acute respiratory failure and death. While there are likely multiple mechanisms triggering severe disease, one potential cause of severe disease is the size of the initial inoculum. For other respiratory diseases, larger initial doses lead to more severe outcomes. We investigate whether there is a similar link for SARS-CoV-2 infections using the combination of an agent-based model (ABM) and a partial differential equation model (PDM). We use the model to examine the viral time course for different sizes of initial inocula, generating dose-response curves for peak viral load, time of viral peak, viral growth rate, infection duration, and area under the viral titer curve. We find that large initial inocula lead to short infections, but with higher viral titer peaks; and that smaller initial inocula lower the viral titer peak, but make the infection last longer.
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Andraud M, Rose N. Modelling infectious viral diseases in swine populations: a state of the art. Porcine Health Manag 2020; 6:22. [PMID: 32843990 PMCID: PMC7439688 DOI: 10.1186/s40813-020-00160-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Accepted: 06/25/2020] [Indexed: 02/06/2023] Open
Abstract
Mathematical modelling is nowadays a pivotal tool for infectious diseases studies, completing regular biological investigations. The rapid growth of computer technology allowed for development of computational tools to address biological issues that could not be unravelled in the past. The global understanding of viral disease dynamics requires to account for all interactions at all levels, from within-host to between-herd, to have all the keys for development of control measures. A literature review was performed to disentangle modelling frameworks according to their major objectives and methodologies. One hundred and seventeen articles published between 1994 and 2020 were found to meet our inclusion criteria, which were defined to target papers representative of studies dealing with models of viral infection dynamics in pigs. A first descriptive analysis, using bibliometric indexes, permitted to identify keywords strongly related to the study scopes. Modelling studies were focused on particular infectious agents, with a shared objective: to better understand the viral dynamics for appropriate control measure adaptation. In a second step, selected papers were analysed to disentangle the modelling structures according to the objectives of the studies. The system representation was highly dependent on the nature of the pathogens. Enzootic viruses, such as swine influenza or porcine reproductive and respiratory syndrome, were generally investigated at the herd scale to analyse the impact of husbandry practices and prophylactic measures on infection dynamics. Epizootic agents (classical swine fever, foot-and-mouth disease or African swine fever viruses) were mostly studied using spatio-temporal simulation tools, to investigate the efficiency of surveillance and control protocols, which are predetermined for regulated diseases. A huge effort was made on model parameterization through the development of specific studies and methodologies insuring the robustness of parameter values to feed simulation tools. Integrative modelling frameworks, from within-host to spatio-temporal models, is clearly on the way. This would allow to capture the complexity of individual biological variabilities and to assess their consequences on the whole system at the population level. This would offer the opportunity to test and evaluate in silico the efficiency of possible control measures targeting specific epidemiological units, from hosts to herds, either individually or through their contact networks. Such decision support tools represent a strength for stakeholders to help mitigating infectious diseases dynamics and limiting economic consequences.
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Affiliation(s)
- M. Andraud
- Anses, French Agency for Food, Environmental and Occupational Health & Safety, Ploufragan-Plouzané-Niort Laboratory, Epidemiology, Health and Welfare research unit, F22440 Ploufragan, France
| | - N. Rose
- Anses, French Agency for Food, Environmental and Occupational Health & Safety, Ploufragan-Plouzané-Niort Laboratory, Epidemiology, Health and Welfare research unit, F22440 Ploufragan, France
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Coinfections and their molecular consequences in the porcine respiratory tract. Vet Res 2020; 51:80. [PMID: 32546263 PMCID: PMC7296899 DOI: 10.1186/s13567-020-00807-8] [Citation(s) in RCA: 114] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 06/02/2020] [Indexed: 01/15/2023] Open
Abstract
Understudied, coinfections are more frequent in pig farms than single infections. In pigs, the term “Porcine Respiratory Disease Complex” (PRDC) is often used to describe coinfections involving viruses such as swine Influenza A Virus (swIAV), Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), and Porcine CircoVirus type 2 (PCV2) as well as bacteria like Actinobacillus pleuropneumoniae, Mycoplasma hyopneumoniae and Bordetella bronchiseptica. The clinical outcome of the various coinfection or superinfection situations is usually assessed in the studies while in most of cases there is no clear elucidation of the fine mechanisms shaping the complex interactions occurring between microorganisms. In this comprehensive review, we aimed at identifying the studies dealing with coinfections or superinfections in the pig respiratory tract and at presenting the interactions between pathogens and, when possible, the mechanisms controlling them. Coinfections and superinfections involving viruses and bacteria were considered while research articles including protozoan and fungi were excluded. We discuss the main limitations complicating the interpretation of coinfection/superinfection studies, and the high potential perspectives in this fascinating research field, which is expecting to gain more and more interest in the next years for the obvious benefit of animal health.
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Go N, Touzeau S, Islam Z, Belloc C, Doeschl-Wilson A. How to prevent viremia rebound? Evidence from a PRRSv data-supported model of immune response. BMC SYSTEMS BIOLOGY 2019; 13:15. [PMID: 30696429 PMCID: PMC6352383 DOI: 10.1186/s12918-018-0666-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 11/21/2018] [Indexed: 01/24/2023]
Abstract
Background Understanding what determines the between-host variability in infection dynamics is a key issue to better control the infection spread. In particular, pathogen clearance is desirable over rebounds for the health of the infected individual and its contact group. In this context, the Porcine Respiratory and Reproductive Syndrome virus (PRRSv) is of particular interest. Numerous studies have shown that pigs similarly infected with this highly ubiquitous virus elicit diverse response profiles. Whilst some manage to clear the virus within a few weeks, others experience prolonged infection with a rebound. Despite much speculation, the underlying mechanisms responsible for this undesirable rebound phenomenon remain unclear. Results We aimed at identifying immune mechanisms that can reproduce and explain the rebound patterns observed in PRRSv infection using a mathematical modelling approach of the within-host dynamics. As diverse mechanisms were found to influence PRRSv infection, we established a model that details the major mechanisms and their regulations at the between-cell scale. We developed an ABC-like optimisation method to fit our model to an extensive set of experimental data, consisting of non-rebounder and rebounder viremia profiles. We compared, between both profiles, the estimated parameter values, the resulting immune dynamics and the efficacies of the underlying immune mechanisms. Exploring the influence of these mechanisms, we showed that rebound was promoted by high apoptosis, high cell infection and low cytolysis by Cytotoxic T Lymphocytes, while increasing neutralisation was very efficient to prevent rebounds. Conclusions Our paper provides an original model of the immune response and an appropriate systematic fitting method, whose interest extends beyond PRRS infection. It gives the first mechanistic explanation for emergence of rebounds during PRRSv infection. Moreover, results suggest that vaccines or genetic selection promoting strong neutralising and cytolytic responses, ideally associated with low apoptotic activity and cell permissiveness, would prevent rebound. Electronic supplementary material The online version of this article (10.1186/s12918-018-0666-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Natacha Go
- BIOEPAR, INRA, Oniris, Route de Gachet, CS 40706, Nantes, France. .,BIOCORE, Inria, INRA, CNRS, UPMC Univ Paris 06, Université Côte d'Azur, 2004 route des Lucioles, BP 93, Sophia Antipolis, France. .,Division of Genetics and Genomics, The Roslin Institute, Easter Bush, Midlothian, UK.
| | - Suzanne Touzeau
- BIOCORE, Inria, INRA, CNRS, UPMC Univ Paris 06, Université Côte d'Azur, 2004 route des Lucioles, BP 93, Sophia Antipolis, France.,ISA, INRA, CNRS, Université Côte d'Azur, 400 route des Chappes, BP 167, Sophia Antipolis, France
| | - Zeenath Islam
- Division of Genetics and Genomics, The Roslin Institute, Easter Bush, Midlothian, UK
| | - Catherine Belloc
- BIOEPAR, INRA, Oniris, Route de Gachet, CS 40706, Nantes, France
| | - Andrea Doeschl-Wilson
- Division of Genetics and Genomics, The Roslin Institute, Easter Bush, Midlothian, UK
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