The guinea pig as a transmission model for human influenza. It comprises key steps of their replication, from virus entry to budding. Mitigating the impact of pandemic influenza through vaccine. Birds, pigs, horses, ferrets, dogs, and cats can all be infected with various strains of the influenza virus. Influenza negatively affects swine health and production, and represents a significant threat to public health due to the risk of zoonotic infections. Research open access the tree shrew provides a useful. Validation of the wildtype influenza a human challenge. Mathematical analysis of influenza a dynamics in the. Predicting hotspots for influenza virus reassortment. Pr8 h1n1 influenza virus injected into the ovarian bursa of balbc mice grew well, with peak titers between days 3 and 5. Influenza virus capsule model 3d molecular designs. Ferrets as models for influenza virus transmission studies.
Influenza b virus is a main causative pathogen of annual influenza epidemics, however, research on influenza b virus in general lags behind that on influenza a viruses, one of the important reasons is studies. Although the exact biological mechanisms involved remain unelucidated, secondary bacterial infections are known to account for a large part of the influenzaassociated burden, during seasonal and pandemic outbreaks. Jun 08, 2017 efficacy of fluv in an h1n1 influenza human challenge model the safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Interaction among influenza viruses ah1n1, ah3n2, and b. The render settings and materials are included in the max 9. An agentbased model simulation of influenza interactions at. These pandemics are associated with major shifts in the ha and na proteins that define viral strains. The outside of the virus capsule is covered with three specific proteins. Statistical errors of predicted and posterior wrightian fitness. The united states is not currently experiencing an influenza pandemic. Hostlevel influenza virusrespiratory pathogen interactions are often reported.
Influenza, commonly known as the flu, is an infectious disease caused by an influenza virus. The outside of the virus capsule is covered with 3 specific proteins. Aug 27, 2014 influenza a virus infections are widespread in swine herds across the world. Influenza a virus causes influenza in birds and some mammals, and is the only species of the genus alphainfluenzavirus of the virus family orthomyxoviridae. Full text modeling human influenza infection in the laboratory idr. In this paper, a mathematical model is formulated and used to analyze the transmission dynamics of influenza a virus having incorporated the aspect of drug resistance. To identify geographic areas where agricultural production systems are conducive to reassortment, we fitted multivariate regression models to surveillance data on influenza a virus subtype h5n1 among poultry in china and egypt and subtype h3n2 among humans. Since that time, our nation has experienced, and learned from, the 2009 influenza ah1n1 pandemic and the emergence of other influenza viruses of concern, such as h7n9 that emerged in 20 in china and continues to cause periodic outbreaks. More routinely, influenza virus also generates epidemics or large outbreaks. Influenza, influenzaassociated mortality, and novel. Pdf mathematical models of influenza a virus infection.
The severity of epidemic and pandemic influenza outbreaks is dictated in part by the efficiency with which the causative strain transmits between human hosts. In the united states alone, its estimated that in the 20172018 season there were 959,000 hospitalizations related to influenza illness, and 79,400 deaths cdc, 2018. The first part of this work covers a model for the intracellular life cycle of influenza a viruses. Swine herds can act as reservoirs for potentially pandemic influenza strains. Currently there is no licensed treatment or vaccine for the ebola virus. Once a novel virus has been identified by cdc, confirmation may be made by public health laboratories following cdcapproved protocols for that specific virus, or by laboratories using an fdaauthorized test specific for detection of that novel influenza virus. Pdf influenza is a human pathogen that continues to pose a public health threat. Pigs should be considered a suitable and valuable model for influenza a virus infection, in regards to pathogenesis, transmission, and immune response to infection or vaccines. Listing a study does not mean it has been evaluated by the u. Characteristics of the emergent influenza a h1n1 viruses. Most are roughly spherical, but influenza virions can sometimes be filamentous. Antibodydependent enhancement of influenza disease. Although influenza virus was recognized as an important pathogen over a century ago, influenza continues to cause a significant burden of disease.
The spatialtemporal model for the nationwide influenza epidemic is also presented in this section. Mathematical modeling of influenza a virus dynamics within. Because of its clinical importance, many investigators use animal models to understand the biologic mechanisms of influenza a virus. The emergence of drug resistance has been a major challenge in curbing the spread of influenza. Influenza in humans is often referred to as the seasonal flu. Those interactions probably impact the microorganisms transmission dynamics and the influenza. Oct 12, 2015 influenza a virus iav infection represents a global threat causing seasonal outbreaks and pandemics. Indeed, despite extremely efficient transmission among humans and virulence. Here we investigated the tree shrew as a potential model for influenza b virus studies.
A manual for estimating disease burden associated with seasonal influenza. A mathematical model for the global spread of influenza leonid a. Pdf the ferret as a model organism to study influenza a virus. Influenza diagnosis clinical and epidemiological characteristics increase of febrile respiratory illness lab isolation of influenza virus from clinical specimen e. Antibodydependent enhancement of influenza disease promoted. Optimal control of influenza epidemic model with virus. How cdc estimates the burden of seasonal influenza in the. Additionally, secondary bacterial infections, caused mainly by streptococcus pneumoniae, are one of the main complications and responsible for the enhanced morbidity and mortality associated with iav infections. Pandemic influenza plan centers for disease control and.
May 19, 2015 more importantly, swine are genetically and physiologically closely related to humans, and show similar clinical signs and pathology upon iav infection. Pdf optimal control of influenza epidemic model with virus. Influenza research at the human and animal interface world health. Influenza is a respiratory virus that imposes a heavy burden on human populations by causing millions of severe illness cases and deaths worldwide every year, despite the development of public health policies to limit its propagation. The membrane contains two types of surface proteins and a number of protein channels. Research open access the tree shrew provides a useful alternative model for the study of influenza h1n1 virus zifeng yang1,2, jin zhao1, yutong zhu3, yutao wang1, rong liu1, suishan zhao1, runfeng li1, chunguang yang1, jiqiang li4 and nanshan zhong1 abstract. Autoplay when autoplay is enabled, a suggested video will automatically play next. The inability to provide lasting protection to humans against influenza b virus infection is due, in. The two temperaturesensltlve ts lesions present in influenza ahong kong68ts 1e h3n268 virus were transferred via genetic reassortment to influenza ageorgia74 h3n274 wildtype virus. Influenza a viruses iavs infect a variety of hosts, including humans, swine, and various avian species. Dec 20, 2006 novel influenza virus strains can be the source of infrequent but devastating pandemics, most famously the 1918 pandemic, which killed between 20 and 40 million people.
Mathematical models have been designed to enable public health officials, policymakers, and students of infectious disease to examine. Pandemic influenza continuity of operations annex template. Dynamics of virus spread at global and local levels 3. In section 3, the simulation results for transmission dynamics of the 2009 h1n1 influenza virus in the entire country are discussed. Influenza, known as the flu, is a highly contagious respiratory virus.
The last pandemic influenza plan for the department of health and human services update was issued in 2009. It is an orthomyxovirus that contains the glycoproteins haemagglutinin and neuraminidase. Determine which if any animal model provides the best information on cross. The susceptibility of ferrets to influenza virus infection has been known for nearly a century. An agentbased model simulation of influenza interactions. Pdf homology model of the structure of influenza b virus. Selection pressures and evolutionary constraints on influenza viruses. Modeling human influenza infection in the laboratory ncbi nih.
The virus infects the human respiratory tract where other species of bacteria or viruses cohabit. Metapopulation model using commuting flow for national. Murine model for the study of influenza d virus request pdf. Influenza in birds is often referred to as avian influenza, in pigs as swine influenza, in horses as equine influenza and so on. Among others, mice, ferrets, pigs, and nonhuman primates have been used to study influenza virus infection in vivo, as well as to do pre clinical. Strains of all subtypes of influenza a virus have been isolated from wild birds, although disease is uncommon. Influenza a virus infections are widespread in swine herds across the world. This model simulates the transmission and perpetuation of a virus in a human population. Although several avian influenza viruses were considered, emphasis was. Some isolates of influenza a virus cause severe disease both in domestic poultry and, rarely, in humans. Nonneutralizing antibodies have the potential to mediate enhancement of respiratory disease erd.
Every year, influenza causes high morbidity and mortality especially among the immunocompromised persons worldwide. Seasonality of influenza virus infection and implications for global virus spread 3. Optimal control of influenza epidemic model with virus mutations. A mathematical model for the global spread of influenza. Pandemic influenza continuity template guide instructions this template provides guidance to assist organizations in developing a pandemic influenza continuity of operations plan or, if the organization already has a continuity plan, a pandemic influenza annex. Viral recognition by pbmcs will be assessed by measuring secretion of inflammatory cytokines and other inflammatory mediators using techniques such as multiplex elisa.
Apr 26, 2006 a populationdynamic model for evaluating the potential spread of drugresistant influenza virus infections during communitybased use of antivirals. There are many different strains types of this virus. Influenza b virus is one of two types of influenza virus that cause substantial morbidity and mortality in humans, the other being influenza a virus. Influenza b virus is a main causative pathogen of annual influenza epidemics, however, research on influenza b virus in general lags behind that on influenza a viruses, one of the important reasons is studies on influenza b viruses in animal models are limited.
In virology, influenza a virus subtype h1n1 ah1n1 is the subtype of influenza a virus that was the most common cause of human influenza flu in 2009, and is associated with the 1918 spanish flu outbreak. A sectioned version and a closed version of the virus are included. Guidance has been developed to prepare, plan, and practice for the next influenza flu pandemic. Swine as a model for influenza a virus infection and immunity.
Research open access the tree shrew provides a useful alternative model for the study of influenza h1n1 virus zifeng yang1,2, jin zhao1, yutong zhu3, yutao wang1, rong liu1, suishan zhao1, runfeng li1. The viruss shape is determined by a layer of matrix protein underneath the influenza membrane. Influenza viruses are orthomyxoviruses that cause acute. Metapopulation model using commuting flow for national spread.
The tree shrew is a promising model for the study of influenza b virus infection. The mechanisms underlying influenza virus spread are poorly understood, in part because of the lack of a convenient animal model to study this phenomenon. Our study describes ade with two different functional mabs that destabilized ha stem domain, increased influenza virus fusion kinetics, and led to enhanced lung pathology and erd in a dosedependent manner in a mice model. Jul 23, 2019 nonneutralizing antibodies have the potential to mediate enhancement of respiratory disease erd. Efficacy of fluv in an h1n1 influenza human challenge model. The influenza a and b viruses that routinely spread in people human influenza viruses are responsible for seasonal flu epidemics each year. All strains are named starting with an a or b type such as influenza a h1n1 or influenza. The use of small mammalian models has become indispensable for. Additionally, secondary bacterial infections, caused mainly by streptococcus pneumoniae, are one of the main complications and responsible for the enhanced. Although the provisionally named influenza d virus was first isolated as an influenza c like virus from pigs with respiratory illness in oklahoma in 2011 1,2, epidemiologic. These symptoms typically begin two days after exposure to the virus and most last. The tree shrew is a promising model for the study of.
The effects of the nonpharmaceutical interventions based on the centrality analysis are discussed in this section. Rvachev gamaleya institute of epidemioloxy and microbiology, academy of medical sciences, moscow, u. Assessing spread of influenza under different epidemiological settings 3. Ferrets and humans share similarities in lung physiology, cellular receptor distribution, and clinical signs of infection, making the ferret an attractive small mammalian model for laboratory study of influenza viruses 1. Influenza virus in humans and domestic animals could reassort and cause another pandemic. Strategies for mitigating an influenza pandemic nature.
Influenza a virus iav infection represents a global threat causing seasonal outbreaks and pandemics. This study represents the first time a wildtype influenza virus challenge of healthy human volunteers has been performed using a reverse geneticsproduced virus under an ind, and serves as a standardized model for future healthy volunteer challenge studies with ah1n1pdm09 and other wildtype circulating influenza strains. Hemagglutinin purple, neuraminidase pink and the m2 channel blue. In this study, we develop mathematical models based on experimental data, representing. Request pdf murine model for the study of influenza d virus a novel genus within the orthomyxoviridae family was identified in the usa and named influenza d virus idv. These symptoms typically begin two days after exposure to the virus and most last less than a week. Influenza is an rna virus with a roughly spherical lipid envelope, which is colored yellow on our schematic model. The pandemic risk assessment model pram is a mathematical model developed to analyse two pandemic influenza control measures available to public health. Nevertheless, to capture the dynamic behaviour of an influenza pandemic we need an economic model that is also dynamic. Validation of the wildtype influenza a human challenge model. A computational approach for predicting the future evolution of the human influenza virus, based on populationgenetic data of previous strains, is presented. Influenza, influenzaassociated mortality, and novel influenza a. Further, the model must be able to capture the short, sharp duration of influenza pandemics.
Enhance your virus lesson with our influenza virus capsule. The influenza virion measures about 80120 nm in diameter. It typically spreads through respiratory droplets when a person. Activity of the novel influenza a h1n1, marchmay 2009 between march and 26 may 2009, novel influenza a h1n1 virus infections have been. In spite of the significant advances in our knowledge of iav infections, holistic. The geometry resolution of the model is suitable for close up and renderings in print resolution. Influenza a viruses can be broken down into subtypes depending on the genes that make up the surface proteins. Mitigating the impact of pandemic influenza through. The flu is a type of germ called a virus that you breathe in. Cea mitigating the impact of pandemic influenza through vaccine innovation. A populationdynamic model for evaluating the potential spread of drugresistant influenza virus infections during communitybased use of antivirals. This work is licensed under a creative commons attribution. Utility and timing of different response strategies during early spread of human cases of an animal or pandemic influenza virus.
Ecological biologists have suggested a number of factors which may influence the survival of a directly transmitted virus within a population. This will ensure that the risk assessment is informed by the latest and most comprehensive information available about the virus, the extent of its circulation in animals and the number and severity of human infections. The virus is transmitted to people from wild animals and spreads in the human population through humantohuman transmission. General guidance and sample information is provided for reference and. During the pandemic of 19181919, influenza a virus iav caused as many as 50100 million deaths. These three proteins are involved in virus docking, endocytosis and fusion. Novel influenza virus strains can be the source of infrequent but devastating pandemics, most famously the 1918 pandemic, which killed between 20 and 40 million people. Influenza virus, although not a normal pathogen of the reproductive tract, was used to develop a model for the investigation of mucosal immunity in the uterus.
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