How the influenza virus adapts vaccine makers project. I found the following animation on youtube depicting replication of an h1n1 influenza virus. This results in a new strain that requires yearly reformulation of the seasonal influenza vaccine. Antigenic drift of the pandemic 2009 ah1n1 influenza.
Each strain is coloured to represent the antigenic cluster to which that strain belongs, while the antisera used in the hi assays are shown as uncoloured open shapes. Antigenic shift is a more major change in the influenza virus. Differences between antigenic shift and antigenic drift. Avian influenza a virus is playing a key role to the emergence of human influenza. Antigenic shift, genetic alteration occurring in an infectious agent that causes a dramatic change in a protein called an antigen, which stimulates the production of antibodies by the immune systems of humans and other animals. Antigenic shift requires an exchange of genomic segments between two different strains of influenza a and result in occasional flu pandemics. Antigenic distance upper right and number of amino acid changes in the ha1 lower left in 55 pairwise comparisons among 11 influenza h3n2 viruses tables performance of the five prediction models. The current flu in circulation is an entirely new, mutated pathogen formed from elements of human, pig, and avian virus strains. In making your selection, you should indicate your first and second choice of topic, since duplication will not be permitted. How the influenza virus adapts vaccine makers project on vimeo. It also occurs because the rna genome of influenza a viruses is in the form of eight segments, which during viral replication are susceptible to a type of genetic exchange known as genetic reassortment. These videos do not provide medical advice and are for informational purposes only.
Antigenic shift can be the result of a direct jump from an unknown animal strain to humans or a reassortment of two or more influenza viruses within the same. It results usually from the replacement of the hemagglutinin the viral attachment protein that also mediates the entry of the virus into the cell with a. Current inactivated influenza vaccines provide protection when vaccine antigens and circulating viruses share a high degree of similarity in hemagglutinin protein. Antigenic shift is seen only with influenza a viruses. Large topics can be subdivided to allow several nonoverlapping presentations.
The mechanism of antigenic shift and drift of human. Antigenic cartography is a computational and mathematical tool for the analysis of binding assay data, providing a quantification and visualisationcalled antigenic mapsof antigenic data. Antigenic shift article about antigenic shift by the. Although its utility was first established in both research and public health in the context of the influenza virus, the techniques of antigenic cartography have subsequently been applied to many other. Antigenic drift is the most common way that influenza viruses change. Influenza virus antigenic variation, host antibody. Antigenic shift is the molecular alteration of an antigen so that the human immune system can no longer recognize it, this increases its pathogenicity so that individuals who have previously been. Antigenic shift and the h1n1 influenza a virus youtube. The following is a list of suggested topics for your consideration.
Influenza vaccine outmaneuvering antigenic shift and. Antigenic cartography is the process of creating maps of antigenically variable pathogens. Understanding how flu viruses change nieman foundation for. Influenza vaccine outmaneuvering antigenic shift and drift. Antigenic shift from reassortment can produce major changes in the influenza virus and represents a significant way for viruses to evolve and create a new pandemic strain. It results usually from the replacement of the hemagglutinin the viral attachment protein that also mediates the entry of the virus into the cell with a novel subtype that has not been present in human. However, the accumulation of antigenic shift or drift within ha proteins. Immunodominance of antigenic site b over site a of.
Antigenic shift mechanism in influenza virus on vimeo. Ha acts to attach the virus into host cells and subsequently fuse it to cell membranes, which is essential for the virus life cycle. Influenza virus has a remarkable ability in escaping host defense mechanisms by. High antigen variability through antigenic drift and antigenic shift. Antigenic shifts can lead to serious diseases, and this quizworksheet combo will help you test your understanding of what an antigenic shift is and how an antigenic shift can lead to a dangerous.
Shift can result in a new influenza a subtype in humans. Antigenic shift is the process by which two or more different strains of a virus, or strain of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains. Nolting,c fred cunningham,d carol cardona,e jianqiang zhang,f kyoungjin yoon,f richard d. Made for the science ambassador scholarship category. The rabies virus glycoprotein is the virion component responsible for induction of virusneutralizing antibody and protection of animals against challenge. Two forms of vaccines against influenza viruses a and b.
May 09, 20 antigenic drift involves amino acid changes in antigenic regions of influenza proteins, facilitating escape from existing immunity. This animation provides an overview of the principles of antigenic shift and the h1n1 influenza a virus. Predicting antigenic variants of influenza ah3n2 viruses. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. The first antigenic map of the influenza ah3n2 virus from 1968 to 2003. In some cases, as in the image on the left, twodimensional maps can be produced which reveal interesting information about the. Watch and learn the story of antigenic drift and shift, and why they make preventing influenza a outbreaks so difficult. Much less frequent than antigenic drift occurring only in influenza a, it involves a profound change in the virus with. When explaining covid19, the antigenic shift of influenza that causes a pandemic offers a familiar example.
This project aims at providing a desktop application for working with antigenic maps. Antigenic shift definition of antigenic shift by the free. Antigenic shift occurs when two different strains of influenza virus simultaneously infect the same cell in your body and undergo a process called genetic reassortment. Surveillance of circulating ah1n1pdm09 viruses has revealed some genetic variation in the hemagglutinin ha and neuraminidase na, but no significant antigenic changes have occurred over. Seasonal and immediate mutations that enable influenza to escape immunity. Nelson,c jialiang yang,a brigitte martin,a kun jia,a jacqueline m. The term is often applied specifically to influenza, as that is the bestknown example, but the process is also known to occur with other viruses, such as visna. When the viruses mutate, they shift to create a new subtype that is different from any seen in humans before. Seminar topics for mic 491 michigan state university. Antigenic cartography therefore offers an improved understanding of genetic and antigenic evolution. Antigenic shift can be the result of a direct jump from an unknown animal strain to humans or a reassortment of two or more influenza viruses within the same cell.
Influenza virus has a remarkable ability in escaping host defense mechanisms by altering its the antigenic character. Learn how type b influenza virus has genetic drift, whereas type a influenza virus has genetic drift and shift. Within the hosts cells, antigenic shift mechanism in influenza virus on vimeo. Phylogenetic tree and antigenic shift analysis of hemagglutinin. Antigenic cartography is the process of creating maps of antigenically variable pathogens more details. Much less frequent than antigenic drift occurring only in influenza a, it involves a profound change in the virus with a new hemagglutinin or neuraminidase type produced, possibly from another species. See this vaccine makers project animation, antigenic drift. One way shift can happen is when an influenza virus from an animal. Antigenic shift 3 without undergoing genetic change, a bird strain of influenza a can jump directly from a duck or other aquatic bird to an intermediate animal host and then to humans. The term is often applied specifically to influenza, as that is the bestknown example, but the process is also. Antigenic shift is a sudden change in antigenicity caused by the recombination of the influenza genome, which can occur when a cell becomes simultaneously infected by two different strains of type a influenza. Antigenic shift is the process by which two or more different strains of a virus, or strains of two or more different viruses, combine to form a new subtype having a mixture of the surface antigens of the two or more original strains. Mapping the evolution of pathogens who collaborating centre. Feb 26, 2019 antigenic shift is the molecular alteration of an antigen so that the human immune system can no longer recognize it, this increases its pathogenicity so that individuals who have previously been.
Antigenic shift occurs when a radical and abrupt change in influenza type a virus hemagglutinins occurs. Antigenic drift of the pandemic 2009 ah1n1 influenza virus. Ha is synthesised as a single peptide but cleaved into ha1 and ha2 by specific host protease. Is an abrupt, major change in the influenza a viruses results in a new influenza a subtype or a virus with a hemagglutinin or a hemagglutinin and neuraminidase combination that has emerged from an animal population that is so different from the same subtype in humans that most people do not have immunity to the new e. Antigenic characterization of h3n2 influenza a viruses. The first influenza pandemic of the 21st century began in march 2009 with the emergence of a new swineorigin virus ah1n1pdm09 which replaced the previous seasonal ah1n1. Since new influenza virus antigenic variants emerge frequently from accumulation of point mutations in the ha protein i. Influenzas genome is made up of eight loosely linked segments, each of which harbors at least one important gene.
Antigenic drift definition of antigenic drift by medical. Antigenic shift is an abrupt, major change in an influenza a virus, resulting in new ha andor new ha and na proteins in influenza viruses that infect humans. Animation of influenza virus replication virology blog. Rishi is a pediatric infectious disease physician and works at khan academy. It occurs in annual outbreaks, mainly during the winter season, in temperate climates.
A deep understanding of the antigenic patterns and evolution of human influenza. Five antigenic sites ae are mapped on the ha1 surface of h3n2 influenza viruses. One way influenza viruses change is called antigenic shift the other is antigenic. A second type of change is antigenic shift, where the virus acquires a completely new version of one of its surfaceprotein genes from a distantly related influenza virus. Mar 11, 2020 antigenic shift is a more major change in the influenza virus.
Antigenic map showing the evolution of the influenza a h3n2 virus evolution from 1968 to 2002. Antigenic site a red color and antigenic site b blue color are localized on the top of ha around the receptor binding pocket. Influenza antigenic properties are determined by both ha and na. Antigenic shift occurs because influenza a viruses have a large animal reservoir, consisting primarily of wild aquatic birds e. The two new mechanisms of change in influenza strains. Antigenic shift definition of antigenic shift by the. Understanding how flu viruses change nieman foundation.
The current flu in circulation is an entirely new, mutated pathogen formed from. The mechanism of antigenic shift and drift of human influenza virus. But, covid19 is not influenza, which means we do not have the history of experience that we have with the family of influenza viruses. Each pandemic of influenza acquired gene segments from the. Antigenic shift definition of antigenic shift by medical. The influenza a h1n1 virus causes seasonal epidemics that result in severe illnesses and deaths almost every year. The newly formed virions acquire ha and na from the other virus. The rate of antigenic drift is dependent on two characteristics. Influenza a also experiences another type of mutation called antigenic shift that results in a new subtype of the virus. H1n1 is the earliest emerging subtype of influenza a viruses with available genomic. Antigenic shift, which is seen only with influenza a viruses, results from the replacement of the hemagglutinin and sometimes the neuraminidase with novel subtypes that have not been present in. Oct 15, 2019 the other type of change is called antigenic shift. Drift mutations most commonly occur in the gene encoding the ha surface glycoprotein, which is the major target of neutralizing antibodies elicited as a result of vaccination andor natural infection.
In some cases, as in the image on the left, twodimensional maps can be produced which reveal interesting information about the antigenic evolution of a pathogen. Five antigenic sites in the hemagglutinin protein have been proposed, and 1 amino acid positions have been identified in the five antigenic sites. To determine its antigenic structure, a limited number of fragments were obtained by chemical cleavage and isolated by. Predicting antigenic variants of h1n1 influenza virus based on.
They constantly mutate, and those frequent changes make it hard for our bodies to recognize and fend off. Find out how the genetic material in the type a flu virus can get shuffled around to create brand new types of viruses. Antigenic shift and drift article pdf available in science teacher normal, ill. This shift typically occurs when a human flu virus crosses with a flu virus that usually affects animals such as birds or pigs. The other type of change is called antigenic shift. Influenza is an acute respiratory illness caused by influenza a or b viruses, and rarely influenza c viruses.
In addition, 20, 18, and 32 amino acid positions in the hemagglutinin protein have. A subtle change in the surface glycoprotein either hemagglutinin or neuraminidase caused by a point mutation or deletion in the viral gene. The antigenic structure of the rabies virus glycoprotein. Antigenic patterns and evolution of the human influenza a. In some cases twodimensional maps can be produced which reveal interesting information about the antigenic evolution of a pathogen. Within the hosts cells, new virus particles are assembled with new copies of each of 8 segments of the rna that represent the. Antigenic shift has been studied most extensively in influenza type a viruses, which experience this change about once every 10 years. In some cases, a 50% change occurs in the hemagglutinin structure. Only the influenza typea virus is capable of what is known as antigenic shift.
Sep 28, 2015 the influenza a h1n1 virus causes seasonal epidemics that result in severe illnesses and deaths almost every year. A sudden shift in the antigenicity of a virus resulting from the recombination of the genomes of two viral strains. Dec 11, 2017 watch and learn the story of antigenic drift and shift, and why they make preventing influenza a outbreaks so difficult. Antigenic shift article about antigenic shift by the free.