The relation of the concentration of unadapted and adapted influenza virus in the mouse lung to the death or survival of the infected host. The study found that all pigs in the infected groups developed typical signs of flulike symptoms on 14 days post infection dpi. Pathogenesis of influenza a h5n1 virus infection in a primate model. The story of the deadliest pandemic in history great writing 1 great sentences for great paragraphs pdf free download influenza in mauritius influenza virus california influenza and respiratory disease surveillance influenza the quest to cure the deadliest disease in history detecting influenza outbreaks by analyzing.
The origin of the 1918 pandemic influenza a virus iav and the reasons for its unusual severity are two of the foremost biomedical mysteries of the past century. The worst pandemic on record, in 1918, killed approximately 50 million people worldwide. Pathogenesis of influenzainduced acute respiratory distress. However, the mechanism of pathogenicity may differ in highly pathogenic strains of human influenza, such. Conducts immunologic and virologic pandemic risk assessment of novel influenza viruses. Impact of obesity on influenza a virus pathogenesis, immune. Influenza a virus falls under the family orthomyxoviridae. Thus, the pathogenesis of influenza virus infection in humans. Preexisting homosubtypic and heterosubtypic immunity to influenza viruses can have a major impact on the outcome of influenza virus infection. Determines virus and host factors that impact virulence and transmission of influenza viruses. Most of these viruses are not pathogenic to their natural hosts and do not change or evolve. Ards involves damage to the epithelialendothelial barrier, fluid leakage into the alveolar lumen, and respiratory insufficiency.
Influenza a virus, influenza b virus, and influenza c virus, respectively table 10. Mar 25, 2009 the objective of this study is to investigate the pathogenesis of swine influenza virus siv subtype h1n1 and h3n2 thai isolates in 22dayold spf pigs. This is a pdf file of an unedited manuscript that has. When influenza virus is introduced into the respiratory tract, by aerosol or by contact with saliva or other respiratory secretions from an infected. Structure of influenza viruses, connected with influenza life. There have been four influenza pandemics since the early 20 th century, and each has been caused by the emergence of a novel virus. The evolution and epidemiology of influenza a virus iav infections in swine have been integrally tied to the segmented nature of the genome of the virus, which facilitates gene reassortment, and to the adaptability of these genes through mutation, which sometimes facilitates replication in a new host. Influenza a viruses can be broken down into subtypes depending on the genes that make up the surface proteins. The swineorigin ah1n1 influenza virus that has emerged in humans in early 2009 has raised concerns about pandemic developments. The pathogenicity and virulence of the influenza virus is determined by several interacting factors. Pathogenesis and vaccination of influenza a virus in swine. This article has been cited by other articles in pmc. Influenza b generally causes milder disease than type a and primarily affects children.
Phylogenetic analyses of six full gene segments and two partial gene segments obtained from next. Influenza diagnosis clinical and epidemiological characteristics increase of febrile respiratory illness lab isolation of influenza virus from clinical specimen e. Since the reemergence of the h5n1 subtype in humans in 2003, there have been 600 documented cases of infection in humans worldwide, of. Viral disease is a sum of the effects on the host of virus replication and of the immune response. The h1n1infected pigs had greater lung lesion scores than those of the h3n2infected pigs. The objective of this study is to investigate the pathogenesis of swine influenza virus siv subtype h1n1 and h3n2 thai isolates in 22dayold spf pigs. The pathogenesis of avian influenza a h5n1 virus in humans has not been clearly elucidated. Weexpected that allopurinol, an inhibitor ofxo,wouldinhibit o2 generation by xoinduced in the virusinfected lung. The influenza viruses section of virology journal will publish articles on all aspects of influenza virus research, including molecular genetics, molecular biology, biochemistry, biophysics, structural biology, cell biology, immunology, morphology, and pathogenesis. The section will also welcome the case reports of influenza outbreaks in both. Pdf pathogenesis of the 1918 pandemic influenza virus. Influenza morbidity caused by 2009 pandemic h1n1 virus remained above seasonal baselines.
Pdf pathogenesis and vaccination of influenza a virus in. The pathogenesis of influenza in humans wiley online library. Jul 24, 2009 the swineorigin ah1n1 influenza virus that has emerged in humans in early 2009 has raised concerns about pandemic developments. Request pdf pathogenesis of influenza d virus in cattle impact. Influenza viruses are significant human respiratory pathogens that cause both seasonal, endemic infections and periodic, unpredictable pandemics. Viral pathogenesis this lecture will define and discuss the basic principles of viral pathogenesis, the entire process by which viruses cause disease. While some investigators have questioned the clinical benefit of oseltamivir for uncomplicated iav and influenza b virus infection 174, 175, most studies suggest improved clinical outcomes in severely ill patients, even when therapy is administered relatively late in the infection 59, 60, and higher dose parenteral therapy is recommended.
Genesis and pathogenesis of the 1918 pandemic h1n1 influenza. Symptoms monitored included nasal stuffiness, runny nose, sore throat, sneezing, hoarseness, ear pressure, earache, cough, breathing difficulty, chest discomfort, and fever. Introduction avian influenza ai viruses infect a wide variety of domestic poultry, captive birds, and freeranging wild bird species under natural and experimental conditions. Acute respiratory distress syndrome ards is a fatal complication of influenza infection. Virus transmission occurs through a susceptible individuals contact with aerosols or respiratory fomites from an.
Avian influenza, for most purposes, refers to the influenza a virus. Viral replication damages its infected cells to cause their apoptosis, which is the underlying mechanism of its pathogenesis. Endothelial activation and dysfunction in the pathogenesis of. The currently circulating strain of influenza is inoculated into embryonated eggs, harvested 23 days later and inactivated. Pb1f2 protein is involved in the induction of apoptosis of host cells, reacts with pb1, influences activity of the polymerase complex, and participates to the viral pathogenesis of some influenza virus strains 39. Since the reemergence of the h5n1 subtype in humans in 2003, there have been 600 documented cases of infection in humans worldwide, of which approximately 60% have been fatal. The genotype of the host is one of several factors involved in the pathogenesis of an infectious disease and may be a key parameter in the epidemiology of highly pathogenic h5n1 influenza virus infection in humans. Influenza virus affects the respiratory tract by direct viral infection or by damage from the immune system response. Though influenza a is adapted to birds, it can also stably adapt and sustain persontoperson transmission. Ciliated cells of respiratory tract are mainly susceptible, because its mucous membrane contains the specific mucoprotein receptors, for influenza virus. Trains and supports laboratories that perform immunologic testing. Three genera exist with this family that pertain to influenza viruses, influenzavirus a, influenzavirus b, and influenzavirus c, each of which contain a single species, or type. Pathogenesis of swine influenza virus thai isolates in.
Pathogenesis of influenza in humans 2 june 2009 when influenza virus is introduced into the respiratory tract, by aerosol or by contact with saliva or other respiratory secretions from an infected individual, it attaches to and replicates in epithelial cells. Virulence of influenza viruses is a polygenic viral trait. Role of receptor binding specificity in influenza a virus. Phylogenetic, seroarcheological, and epidemiological evidence indicates those born earlier or later than. Pandemic monovalent influenza vaccine produced and deployed in nationwide vaccination campaign. Pathogenesis and pathobiology of avian influenza virus. The clinical spectrum of disease caused by the swineorigin 2009 ah1n1 influenza virus and its transmissibility are not completely understood. July 20 this document is provided in order to clarify the differences among seasonal influenza, pandemic influenza, and zoonotic or variant influenza. Jul 10, 20 the new h7n9 influenza virus, recently emerged in china, can replicate in human airway cells and in the respiratory tract of ferrets to a higher level than can seasonal h3n2 virus and shows higher. Pinkbook influenza epidemiology of vaccine preventable. Pdf since their inception in march 1972, keystone symposia on molecular and cellular biology have brought together scientists from across the globe to. As a consequence of the 2009 h1n1 influenza a virus pandemic, obesity was identified for the first time as a risk factor for increased disease severity and mortality in.
By may 2009 the virus had spread to many areas of the world. The influenza a and b viruses that routinely spread in people human influenza viruses are responsible for seasonal flu epidemics each year. Avian diseases avian influenza virus highly pathogenic avian influenza low pathogenic avian influenza pathobiology pathogenesis pathotypes. In april 2009, a novel influenza a h1n1 virus appeared and quickly spread across north america.
Therefore, we decided to study the pathogenesis of influenza a h5n1 virus infection in primates. The influenza virus, as a pathogenic agent for humans, has been circulating in the human population since at least. Variable impact of the hemagglutinin polybasic cleavage site. Weexpected that allopurinol, an inhibitor ofxo,wouldinhibit o2 generation by xoinduced in the virus infected lung.
Host factors that modulate influenza virus pathogenesis. In humans, the respiratory epithelium is the only site where the hemagglutinin ha molecule is effectively cleaved, generating infectious virus particles. Influenza virus can infect various types of cells in human respiratory tract. Dependence generation by xanthine of pathogenesis of. Host factors can contribute to the pathogenesis of. In a ferret pathogenesis and transmission model, the 2009 ah1n1 influenza virus was found to be more pathogenic than a seasonal ah1n1 virus, with more extensive virus replication occurring in the respiratory tract. Jun 02, 2009 pathogenesis of influenza in humans 2 june 2009 when influenza virus is introduced into the respiratory tract, by aerosol or by contact with saliva or other respiratory secretions from an infected individual, it attaches to and replicates in epithelial cells. Influenza a virus particles are usually spherical and about 80 120 nm in diameter. Therefore, the pathogenesis of influenza virus depends on the function of the immune system. In humans, it is unclear which aspect dictates the severity of h5n1. A novel influenza virus, tentatively classified as influenza d virus idv, was identified in swine, cattle, sheep, and goats. When iav infect respiratory epithelial cells or alveolar macrophages, the singlestranded rna of the influenza virus is recognized by tolllike receptor tlr 7 and retinoic acidinducible genei rigi 30, 31. We infer that the virus arose via reassortment between a preexisting human h1 iav lineage and an avian virus.
Influenza a viruses are perpetuated in nature by wild birds, predominantly waterfowl. Inducible nitric oxide contributes to viral pathogenesis. Out of the three types of influenza viruses a, b, and c, influenza a virus is a zoonotic infection with a natural reservoir almost entirely in birds. Whole virus vaccines whole inactivated virus vaccines were the first influenza vaccines to be produced. Volunteers were infected with influenza virus by intranasal instillation, and virus titers were determined in daily nasal washes. Pathogenesis of influenza d virus in cattle request pdf. Elevated tnf levels have been shown to increase rho kinaseinduced stress fiber formation leading to induction of endothelial apoptosis. Genesis and pathogenesis of the 1918 pandemic h1n1 influenza a virus michael worobeya,1, guanzhu hana, and andrew rambautb,c,d adepartment of ecology and evolutionary biology, university of arizona, tucson, az 85721. We studied autopsy specimens from 2 patients who died of infection with this virus.
This infographic briefly summarises the natural history, replication cycle, and pathogenesis of influenza viruses, the cause of seasonal influenza and of influenza pandemics. Pdf the pathology of influenza virus infections researchgate. Apoptosis and pathogenesis of avian influenza a h5n1 virus. Recent work on virus attachment, replication, pathogenesis, and transmission and follow. Highlights tropism for upper or lower respiratory tract is a major determinant for the outcome of influenza virus infections and transmission. Apoptosis was observed in alveolar epithelial cells, which is the major target cell type for the viral replication. Pathogenesis and transmission of avian influenza a h7n9. The portal of entry of influenza virus is respiratory tract. Influenza viruses infect many vertebrates, with influenza a, b and c viruses iav, ibv, and icv infecting humans. During the spring of 2009, a novel influenza a h1n1 virus of swine origin caused human infection and acute respiratory illness in mexico. Seasonal influenza seasonal influenza viruses circulate and cause disease in humans every year. Influenza a virus virology online microbiology notes. The most important part of the epithelialendothelial barrier is the alveolar epithelium, strengthened. It is an enveloped virus and the envelope contains two glycoproteins, hemagglutinin ha and neuraminidase na, the membrane m2 protein and is internally lined by the matrix m1 protein.
Iav from different host species can reassort their. The new h7n9 influenza virus, recently emerged in china, can replicate in human airway cells and in the respiratory tract of ferrets to a higher level. Gene polymorphisms may affect the viral replication rate or alter the hosts immune response to the virus. In birds, the natural hosts of influenza, the virus causes gastrointestinal infection and is transmitted via the faecooral route.
In this article we will discuss about influenza viruses. H5n1 influenza virus pathogenesis in genetically diverse mice. Influenza, commonly known as the flu, is an infectious disease caused by an influenza virus. Influenza virus can infect various types of cells in human respiratory tract and replicate inside.
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