In this paper we modify previous models to develop a new model of within-host dengue infection without the assumption that monocyte production is constant. We show that this new model exhibits behavior not seen in pre...In this paper we modify previous models to develop a new model of within-host dengue infection without the assumption that monocyte production is constant. We show that this new model exhibits behavior not seen in previous models. We then proceed by obtaining an expression for the net reproductive rate of the virus and thus establish a stability result. We also perform a sensitivity analysis to test various treatment strategies and find that two strategies might be fruitful. One is the reduction of the infection rate of monocytes by viruses and the other, more effective, theoretical approach is to reduce the number of new viruses per infected monocyte.展开更多
Based on a multi-scale view, in this paper, we study an age-structured within-host model with Crowley-Martin functional response for the control of viral infections. By means of semigroup and Lyapunov function, the gl...Based on a multi-scale view, in this paper, we study an age-structured within-host model with Crowley-Martin functional response for the control of viral infections. By means of semigroup and Lyapunov function, the global asymptotieal property of infected steady state of the model is obtained. The results show that when the basic reproductive number falls below unity, the infection dies out. However, when the basic reproductive number exceeds unity, there exists a unique positive equilibrium which is globally asymptotically stable. This model can be deduced to different viral models with or without time delay.展开更多
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
The breast milk of HIV infected women contains HIV virus particles,therefore children can become infected through breastfeeding.We develop a mathematical epidemiological model of HIV infection in infants,infected chil...The breast milk of HIV infected women contains HIV virus particles,therefore children can become infected through breastfeeding.We develop a mathematical epidemiological model of HIV infection in infants,infected children and infected women that represents infection of an infant/child as a series of exposures,by incorporating within-host virus dynamics in the individuals exposed to the virus through breastfeeding.We show that repeated exposures of the infant/child via breastfeeding can cause bi-stability dynamics and,subsequently,infection persistence even when the epidemiological basic reproduction number R0 is less than unity.This feature of the model,due to a backward bifurcation,gives new insight into the control mechanisms of HIV disease through breastfeeding.展开更多
We consider nested or multiscale models to study the effect of the temporal evolution of the disease within the host in the population dynamics of the disease,for one and two infectious agents.We assumed a coupling be...We consider nested or multiscale models to study the effect of the temporal evolution of the disease within the host in the population dynamics of the disease,for one and two infectious agents.We assumed a coupling between the within-host infection rate and the between-host transmission rate.The age of infection within each individual in a population affects the probability of transmission of the disease to a susceptible host and this will affect the temporal evolution of the disease in the host population.To analyze the infection within the host,we consider bacterial-like and viral-like infections.In the model for two infectious agents,we found that,when strain 2 has a basic reproduction number R02 greater than the basic reproduction number R01 of strain 1,strain 2 replaces strain 1 in the population.However,if R02>R01 but the values are closer,the replacement does not occur immediately and both strains can coexist for a long time.We applied the model to a scenario in which patients infected with the hepatitis C virus(HCV)are cleared of HCV when super-infected with the hepatitis A virus(HAV).We compared the time for the replacement of HCV by HAV in the population considering instantaneous and noninstantaneous replacement within the individuals.The model developed can be generalized for more than two infectious agents.展开更多
文摘In this paper we modify previous models to develop a new model of within-host dengue infection without the assumption that monocyte production is constant. We show that this new model exhibits behavior not seen in previous models. We then proceed by obtaining an expression for the net reproductive rate of the virus and thus establish a stability result. We also perform a sensitivity analysis to test various treatment strategies and find that two strategies might be fruitful. One is the reduction of the infection rate of monocytes by viruses and the other, more effective, theoretical approach is to reduce the number of new viruses per infected monocyte.
文摘Based on a multi-scale view, in this paper, we study an age-structured within-host model with Crowley-Martin functional response for the control of viral infections. By means of semigroup and Lyapunov function, the global asymptotieal property of infected steady state of the model is obtained. The results show that when the basic reproductive number falls below unity, the infection dies out. However, when the basic reproductive number exceeds unity, there exists a unique positive equilibrium which is globally asymptotically stable. This model can be deduced to different viral models with or without time delay.
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The breast milk of HIV infected women contains HIV virus particles,therefore children can become infected through breastfeeding.We develop a mathematical epidemiological model of HIV infection in infants,infected children and infected women that represents infection of an infant/child as a series of exposures,by incorporating within-host virus dynamics in the individuals exposed to the virus through breastfeeding.We show that repeated exposures of the infant/child via breastfeeding can cause bi-stability dynamics and,subsequently,infection persistence even when the epidemiological basic reproduction number R0 is less than unity.This feature of the model,due to a backward bifurcation,gives new insight into the control mechanisms of HIV disease through breastfeeding.
基金The authors thank CAPES,LIM-01 HCFMUSP and FAPESP for partial financial supportFA thanks CNPq for financial support through a post doctoral fellowship(grant number 501799/2013-3).
文摘We consider nested or multiscale models to study the effect of the temporal evolution of the disease within the host in the population dynamics of the disease,for one and two infectious agents.We assumed a coupling between the within-host infection rate and the between-host transmission rate.The age of infection within each individual in a population affects the probability of transmission of the disease to a susceptible host and this will affect the temporal evolution of the disease in the host population.To analyze the infection within the host,we consider bacterial-like and viral-like infections.In the model for two infectious agents,we found that,when strain 2 has a basic reproduction number R02 greater than the basic reproduction number R01 of strain 1,strain 2 replaces strain 1 in the population.However,if R02>R01 but the values are closer,the replacement does not occur immediately and both strains can coexist for a long time.We applied the model to a scenario in which patients infected with the hepatitis C virus(HCV)are cleared of HCV when super-infected with the hepatitis A virus(HAV).We compared the time for the replacement of HCV by HAV in the population considering instantaneous and noninstantaneous replacement within the individuals.The model developed can be generalized for more than two infectious agents.
