Understanding effector and memory immune responses against influenza A virus(IAV)and severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infections and reinfections is extremely important,given that they are no...Understanding effector and memory immune responses against influenza A virus(IAV)and severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infections and reinfections is extremely important,given that they are now endemic in the community.The goal of this study is to investigate the role of memory cells and antibodies in the immune responses against IAV and SARS-CoV-2 re-infections.To this end,we adapt a previously-published within-host mathematical model(Sadria&Layton,2021)for the primary immune response against SARS-CoV-2 infections,by including two types of memory immune cells,i.e.,memory CD8t T-cells and memory B-cells,and by parametrising the new model with values specific to the two viruses.We first investigate the long-term dynamics of the model by identifying the virus-free steady states and studying the conditions that ensure the stability of these states.Then,we investigate the transient dynamics of this in-host model by simulating different viral reinfection times:20 days,60 days and 400 days after the first encounter with the pathogen.This allows us to highlight which memory immune components have the greatest impact on the viral elimination depending on the time of reinfection.Our results suggest that memory immune responses have a greater impact in the case of IAV infections compared to SARS-CoV-2 infections.Moreover,we observe that the immune response after a secondary infection is more efficient when the reinfection occurs at a shorter time.展开更多
In this paper, we explain why the chaotic mutation （CM） model of J. M. Bahi and C. Michel （2008） simulates the genes mutations over time with good accuracy. It is firstly shown that the CM model is a truly chaotic...In this paper, we explain why the chaotic mutation （CM） model of J. M. Bahi and C. Michel （2008） simulates the genes mutations over time with good accuracy. It is firstly shown that the CM model is a truly chaotic one, as it is defined by Devaney. Then, it is established that mutations occurring in genes mutations have indeed a same chaotic dynamic, thus making relevant the use of chaotic models for genomes evolution. Transposition and inversion dynamics are finally investigated.展开更多
Climate change influences more and more of our activities. These changes led to envi- ronmental changes which has in turn affected the spatial and temporal distribution of the incidence of vector-borne diseases. To es...Climate change influences more and more of our activities. These changes led to envi- ronmental changes which has in turn affected the spatial and temporal distribution of the incidence of vector-borne diseases. To establish the impact of climate on contact rate of vector-borne diseases, we examine the variation of prevalence of diseases according to season. In this paper, the goal is to establish that the basic reproductive number R0 depends on the duration of transmission period and the date of the first conta- mination case that was declared （to） in the specific ease of malaria. We described the dynamics of transmission of malaria by using non-autonomous differential equations. We analyzed the stability of endemic equilibrium （EE） and disease-free equilibrium （DFE）. We prove that the persistence of disease depends on minimum and maximum values of contact rate of vector-borne diseases.展开更多
基金funded by MODCOV19 platform of“Centre National de la Recherche Scientifique(CNRS)”of France and Direction Europe&International of“Centre National de la Recherche Scientifique(CNRS)”of Francefunded by Direction Europe&International of“Centre National de la Recherche Scientifique(CNRS)”of France。
文摘Understanding effector and memory immune responses against influenza A virus(IAV)and severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infections and reinfections is extremely important,given that they are now endemic in the community.The goal of this study is to investigate the role of memory cells and antibodies in the immune responses against IAV and SARS-CoV-2 re-infections.To this end,we adapt a previously-published within-host mathematical model(Sadria&Layton,2021)for the primary immune response against SARS-CoV-2 infections,by including two types of memory immune cells,i.e.,memory CD8t T-cells and memory B-cells,and by parametrising the new model with values specific to the two viruses.We first investigate the long-term dynamics of the model by identifying the virus-free steady states and studying the conditions that ensure the stability of these states.Then,we investigate the transient dynamics of this in-host model by simulating different viral reinfection times:20 days,60 days and 400 days after the first encounter with the pathogen.This allows us to highlight which memory immune components have the greatest impact on the viral elimination depending on the time of reinfection.Our results suggest that memory immune responses have a greater impact in the case of IAV infections compared to SARS-CoV-2 infections.Moreover,we observe that the immune response after a secondary infection is more efficient when the reinfection occurs at a shorter time.
文摘In this paper, we explain why the chaotic mutation （CM） model of J. M. Bahi and C. Michel （2008） simulates the genes mutations over time with good accuracy. It is firstly shown that the CM model is a truly chaotic one, as it is defined by Devaney. Then, it is established that mutations occurring in genes mutations have indeed a same chaotic dynamic, thus making relevant the use of chaotic models for genomes evolution. Transposition and inversion dynamics are finally investigated.
文摘Climate change influences more and more of our activities. These changes led to envi- ronmental changes which has in turn affected the spatial and temporal distribution of the incidence of vector-borne diseases. To establish the impact of climate on contact rate of vector-borne diseases, we examine the variation of prevalence of diseases according to season. In this paper, the goal is to establish that the basic reproductive number R0 depends on the duration of transmission period and the date of the first conta- mination case that was declared （to） in the specific ease of malaria. We described the dynamics of transmission of malaria by using non-autonomous differential equations. We analyzed the stability of endemic equilibrium （EE） and disease-free equilibrium （DFE）. We prove that the persistence of disease depends on minimum and maximum values of contact rate of vector-borne diseases.
