After the antigenic shift in the pig through genetic reassortment, the virus then jumped to infect humans. Background avian influenza a virus is playing a key role to the emergence of human influenza. Definitions antigenic drift is the mutation of a virus so that its new antigen form is sufficiently different from the old and thus it can evade immunity to the original strain of the virus. The videos are not intended to be a substitute for professional medical advice, diagnosis or treatment. Firstly, equine influenza, like other influenza viruses, undergoes continuous antigenic drift. Birds are the natural hosts for the flu, so they are infected first before infecting any other animals. Only the influenza typea virus is capable of what is known as antigenic shift. Each years flu vaccine contains three flu strains two a. The broad scope of the book appeals to all those working in the field of infectious disease, immunology of infection, pathogenesis, molecular biology and also to evolutionary biologists. Although influenza viruses are changing by antigenic drift all the time, antigenic shift happens only occasionally. As a result of antigenic shift or drift, influenza viruses with novel. 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. What you should know about this rare poliolike illness. Ha acts to attach the virus into host cells and subsequently fuse it to cell membranes, which is essential for the virus life cycle.
Antigenic drift occurs in ha and na, and is associated with seasonal epidemics. For antigenic drift, i imagine slowly drifting in the sea, looking out, and sipping a cool drink. Antigenic shift is a specific case of reassortment or viral shift that confers a phenotypic change. 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 has been studied most extensively in influenza type a. Shift can result in a new influenza a subtype in humans. Pdf simulating antigenic drift and shift in influenza a. Influenza antigenic properties are determined by both ha and na. Antigenic shift the spread of a new, mutated virus youtube.
One way shift can happen is when an influenza virus from an animal. Phylogenetic tree and antigenic shift analysis of hemagglutinin gene of influenza a virus in h5n1 strains found in 20052007. Shift results in a new influenza a subtype or a virus with a hemagglutinin or a hemagglutinin and neuraminidase combination. Antigenic shift is contrasted with antigenic drift, which is the natural mutation over time of known strains of influenza or other things, in a more general sense which may lead to a loss of immunity, or in vaccine mismatch. Examples of antigenic shift include the periodic outbreaks of asian flu and hong kong flu during the 20th century and, more recently, h1n1 flu and bird flu in humans. They had correctly inferred that antigenic drift was caused by point mutations in the. This file is licensed under the creative commons attributionshare alike 3. Difference between antigenic drift and antigenic shift.
To date, the 2009 pandemic virus ah1n1pdm09 has not undergone significant antigenic drift, with the result that the vaccine remains wellmatched and should provide good protection to ah1n1pdm09 circulating viruses. Here we take a look at the processes of antigenic drift and antigenic shift. Antigenic shift has been studied most extensively in influenza type a viruses. These are small changes or mutations in the genes of influenza viruses that can. Students read the fact sheet, fighting the flu, to provide background information for. You may do so in any reasonable manner, but not in. There are two main difficulties with this simple view. Antigenic shift is an abrupt, major change in the influenza a viruses, resulting in new hemagglutinin andor new hemagglutinin and neuraminidase proteins in influenza viruses that infect humans. It is commonly assumed that antibody responses against the influenza virus are polarized in the following manner. This image is in the public domain because it contains materials that originally came from the national institutes of health. 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. Antigenic drift vs antigenic shift technology networks.
This is a brand new influenza virus with new surface proteins that our immune system has never seen before. 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. The concepts of antigenic shift and drift are a classic example of influenzarelated content in the classroom. Antigenic shift and antigenic drift are two types of genetic variations that occur in influenza virus. This process leads to the appearance of new subtypes with dramatic changes in antigenicity 5,7. In the last 100 years, we have experienced three such. Influenza virus are remarkable because of the frequent antigenic change that. The process of antigenic shift should not be confused with another method viruses use to change antigens called antigenic drift. Influenza virus antigenic variation, host antibody. Influenza virus are remarkable because of the frequent antigenic change that occurs in ha hemagglutinin or na neuraminidase. The two surface antigens of influenza undergo antigenic variation independent of each other. Antigenic shift results when a new influenza a subtype to which most people have little. Periodically, the viruses undergo major evolutionary change by acquiring a new genome segment from another influenza virus antigenic shift, effectively becoming a new subtype. Key difference antigenic drift vs antigenic shift the antigenic structures of the influenza virus change its shape to a new shape which cannot be recognized by the antibodies.
This shift occurs typically when a human flu virus crosses with a flu virus that usually affects animals such as birds or pigs. Antigenic shift is a major antigenic change that occurs when an influenza a virus. When antigen shift occurs in a population, this is when we have huge pandemics. Please ensure that this image was actually created by the us federal government. When antigenic shift occurs, it is possible that an h1n1 virus and h3n2 virus may interact to produce an h1n2 virus and an h3. Antigenic shift occurs when a radical and abrupt change in influenza type a virus hemagglutinins occurs. Antigenic shift synonyms, antigenic shift antonyms. Antigenic variation is a major method by which microbes evade the immune response, and persist in the body.
Antigenic drift occurs in all types of influenza including influenzavirus a. Antigenic drift occurs in both influenza a and influenza b viruses. Antigenic shift is a variation that is brought about by intermixing reassortment of genomes from two or more strains of a virus. Antigenic shift occurs when a radical and abrupt change in influenza type a. Virus and disease, epidemics and pandemics steinhoff.
One way influenza viruses change is called antigenic drift. Antigenic shift article about antigenic shift by the. 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. Simulating antigenic drift and shift in influenza a core. These are small changes or mutations in the genes of influenza. It is a quick change of genes and is more complicated. Antigenic shift is the process by which two or more different strains of a virus, or strain of two or. These videos do not provide medical advice and are for informational purposes only. Understanding how flu viruses change flu viruses have the capacity to change both slowly, through small genetic changes that are passed down to daughter generations, and quickly, through a process called reassortment that mixes larger genetic segments from several viral strains to create a new virus. A sudden shift in the antigenicity of a virus resulting from the recombination of the genomes of two viral strains. This shift typically occurs when a human flu virus crosses with a flu virus that usually affects animals such as birds or pigs. Ha is synthesised as a single peptide but cleaved into ha1 and ha2 by specific host protease. Antigenic shift is the molecular alteration of an antigen so that the human immune system can no longer recognize it.
Find, read and cite all the research you need on researchgate. 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. Dissecting human antibody responses against influenza a viruses. To model antigenic shift, each pair of students is given a box with two viral. Antigenic drift and implications for vaccines elton. An example of a shift occurred in the spring of 2009, when a new h1n1 virus with a new combination of genes from american pigs, eurasian pigs, birds and humans emerged in people and quickly spread, causing a pandemic. Understanding how flu viruses change harvard university.
This is a featured picture, which means that members of the community have identified it as one of the finest images on the english wikipedia, adding significantly to its accompanying article. Antigenic shift is a more major change in the influenza virus. Antigenic shift is seen only with influenza a viruses. In this study, we induced antigenic drift in an ah1n1pdm09 virus in the ferret model. Antigenic shift is the process by which two different strains of influenza combine to form a new subtype having a mixture of the surface antigens of the two original strains. Molecular and antigenic characterization of reassortant. Learn how type b influenza virus has genetic drift, whereas type a influenza virus has genetic drift and shift.
Antigenic drift occurs in all types of influenza including influenza a. The term antigenic shift is specific to the influenza literature. A major change in the antigenicity of influenza a virus in 1946 presented a problem to the. The current flu in circulation is an entirely new, mutated pathogen formed from elements of human, pig, and avian. Antigenic cartography is a useful technique to visualize and minimize errors in immunological data by projecting antigens to 2d or 3d cartography. The human population isnt able to defend appropriately against this new virus.
Antigenic drift is variation in the viral genome that is brought about by accumulation of mutations in the genes of the virus. Antigenic drift and antigenic shift of influenza virus strains. 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. Viral reassortment is a more complex form of antigenic shift. Antigenic shift definition of antigenic shift by medical. Some of the differences between antigenic shift and antigenic drift are as. Antigenic drift in the neuraminidase and hemagglutinin proteins correctly identify antigenic drift versus antigenic shift, as well as the factors or events that contribute to antigenic shift. In some cases, a 50% change occurs in the hemagglutinin structure. This means that individuals who have previously been infected can become reinfected and develop symptoms once more. Rishi is a pediatric infectious disease physician and works at khan academy. Email the source site if it is not clearly stated that this specific work is in the public domain. The way by which i remember which one, antigenic drift or shift, causes which changes, is as follows.
Antigenic drift of the pandemic 2009 ah1n1 influenza. Antigenic drift definition of antigenic drift by medical. Antigenmap 3d presents an online, interactive, and robust 3d antigenic cartography construction and. A mechanism for variation by viruses that involves the accumulation of mutations within the antibodybinding sites so that the resulting viruses cannot be inhibited well by antibodies against previous strains making it easier for them to spread throughout a partially immune population. Confusion can arise with two very similar terms, antigenic shift and genetic drift.
In section 2 the influenza virus is pre sented from human and physiopathological points of view. Antigenic drift is the gradual mutation of flu genes that slightly alter the product of the genes. However, a 2d cartography may not be sufficient to capture the antigenic relationship from highdimensional immunological data. If you have a different image of similar quality, be sure to upload it using the proper free license tag, add it to a relevant article, and nominate it. This is antigenic shift the spread of a new, mutated virus by hybrid medical animation on vimeo, the home for high quality videos and the people who. Based on the relationship of antigenic distance to genetic differences between viruses, we developed a model to interpret measured antigenic data and predict the properties of viruses that have not been characterized antigenically and explore the models value in predicting the future composition of influenza virus populations. Modeling influenza antigenic shift and drift with lego bricks ncbi.268 1144 1260 1468 214 1482 1453 34 1091 41 1416 592 1080 542 524 1147 663 124 711 544 1111 59 823 582 311 1401 1356 124 1231 87 700 1261 1031 589 517 1241