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| | Influenza Virus |
 | | Antigenic drift is the term used to indicate minor antigenic variations in HA and NA of the influenza virus from the original parent virus, while major changes in HA and NA which make the new virions significantly different, are called Antigenic shift. | | | The antigenicity of NA on the surface of the influenza virus is also important in determining the subtype of the influenza virus isolates. | | | Genetic reassortment between human and non-human influenza virus has been suggested as a mechanism for antigenic shift. |
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http://www.angelfire.com/nj/inquisitivemind/influenza.html
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| | Antigenic Variation of Influenza Viruses, Influenza A Virus Antigenic Shift, Antigenic Drift |
| | The origin of antigenic shift has been a subject of intensive research but has yet to be resolved. | | | There are 3 theories as to how antigenic shift arise and they are not mutally exclusive: there is evidence for all 3 theories in past pandemics | | | Although many workers are convinced of the value of this technique, others have been disappointed with the specificity of the antisera and the level of background fluorescence that makes the test difficult to interpret. |
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http://virology-online.com/viruses/Influenza2.htm
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| | Document Title |
| | In antigenic drift it means both HA and NA changes and there is noimmunological experience. | | | In response to your question on viral structural changes; there are two types of antigenic changes, Antigenic shift and drift. | | | In antigenic drift either HA or NA changes. |
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http://www2.abc.net.au/science/284.shtm
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| | Re: Where does the flue come from every year? |
| | New influenza subtypes are detected by major antigenic changes within the HA and/or NA glycoprotein subtypes (antigenic shift). | | | The modern history of influenza began with its isolation from humans in 1933. | | | You may then ask, Why then do people get sick with the flu every couple of years, when there has been no major change in the HA or NA antigens? |
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http://www.madsci.org/posts/archives/jun2001/991966753.Vi.r.html
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| | Featured Bug: Influenza |
| | In contrast to antigenic drift, "antigenic shift" is characterized by major changes in surface antigens. | | | Drift is an ongoing process and is one way the virus evades the body's natural immune system. | | | Antigenic shift occurs only in influenza A viruses, and is associated with severe illness and worldwide pandemics. |
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http://microbiology.mtsinai.on.ca/bug/flu/flu-bug.shtml
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| | Lab News, Jan 1999b, Department of Laboratory Medicine at Yale |
| | Despite multiple re-infections with influenza virus, we remain susceptible to new assaults due to the remarkable ability of the virus to change itself and thereby elude our immune defenses. | | | With EIA, sample quality cannot be assessed, thereby giving rise to extreme variability in the sensitivity of results (5,6). | | | Antigenic shifts arise when human and animal (usually avian) influenza A strains co-infect a single host (such as swine), and a new recombinant strain emerges, now adapted for spread in mammals. |
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http://info.med.yale.edu/labmed/labnews/jan1999b.html
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| | Antigenic shift - Wikipedia, the free encyclopedia |
| | Because the human immune system has difficulty recognizing the new influenza strain, it may be highly dangerous. | | | 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) to evade the immune system. | | | Antigenic shift results when a new influenza A subtype to which most people have little or no immune protection infects humans. |
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http://en.wikipedia.org/wiki/Antigenic_shift
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| | 203ex1sg99 |
| | Describe how macrophages and monocytes are involved in antigen processing. | | | Know the two pathways for specific immune responses: B-cell and T-cell responses. | | | Describe the role of the O antigen in stimulating an immune response. |
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http://www.delta.edu/jahoward/203ex1sg2005.html
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| | ANTIGENIC DRIFT |
| | It is antigenic drift which complicates the development of an effective HIV (AIDS) vaccine. | | | A change that occurs on the molecular level to effect a change in the antigenicity of a bacteria or virus. | | | Antigenic drift occurs naturally and more rapidly in certain viruses (e.g. |
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http://www.medhelp.org/glossary/new/gls_0389.htm
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| | Orthomyxoviruses |
| | Minor changes are called antigenic drift and these are responsible for many epidemics. | | | The new variants are responsible for the process of antigenic shift. | | | These vaccines are given parenterally in the fall, primarily for those at risk (older persons or those with chronic disease). |
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http://www.cehs.siu.edu/fix/medmicro/ortho.htm
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| | Mechanism of Antigenic Variation |
| | Antigenic variation in influenza A comes in a multitude of forms, enabling it to effectively evade the immune system. | | | The 1957 Asian flu caused a high rate of mortality because the H2N2 subtype of the HA and NA antigens had not been seen by the immune systems of the vast majority of humans infected. | | | This is called antigenic shift, whereby a sudden dramatic change in the viral genome occurs. |
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http://www.brown.edu/Courses/Bio_160/Projects1999/flu/mechanism.html
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| | Infection Control Today: Is a Global Flu Pandemic Imminent? |
| | World health officials have been watching this growing threat, pondering the eventuality of an antigenic shift from animal to human, resulting in a recombinant strain of influenza to which no one is immune. | | | For this to happen, the novel subtype needs to have genes from human influenza viruses that make it readily transmissible from person to person for a sustainable period. | | | This reassortment process, or antigenic shift, results in a novel subtype different from both parent viruses. |
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http://www.infectioncontroltoday.com/articles/531feat1.html
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| | 14 Year Old Male |
| | The need for yearly changes in the vaccine is due to the distinctive ability of this virus, especially influenza A. to change over time. | | | Antigenic shift is defined as major changes in the antigenic structure of hemagglutinin or neuraminidase or both. | | | Yearly vaccination is recommended for individuals with chronic respiratory and cardiac disease, for those with immunodeficiencies, the elderly, and health care providers. |
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http://www.med.uc.edu/departme/molgen/malecas.htm
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| | Plans against influenza pandemics in Europe: history and principles |
| | All combinations are theoretically possible and lead to more radical changes than those associated with antigenic drift. | | | This new approach does not solve the problem of shift, which remains unpredictable and unavoidable in the short term. | | | Experimental culture models have shown that recombinations also take place in nature and have been responsible for pandemics. |
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http://www.eurosurveillance.org/em/v03n03/0303-223.asp
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| | genep4 |
| | There are several theories as to the way this may occur, all with varying degrees of supporting evidence. | | | This is probably the most likely theory for pandemic-causing antigenic shift. | | | There are 13 HA subtypes and 9 NA subtypes (see Virology). |
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http://www.portfolio.mvm.ed.ac.uk/studentwebs/session2/group21/genep4.htm
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| | [No title] |
| | However, by surveillance and by determining the cross-reactive antigens it might be possible to guide the immune response in the right direction. | | | Because of continuous antigenic change and ample availability of naive individuals in natural hosts, influenza viruses, unlike most other pathogens, have not evolved mechanisms to evade specific acquired immunity. | | | The most common serologic assay for diagnosis of swine influenza is the HI assay. |
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http://www.vetscite.org/publish/articles/000041/article.html
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| | Lecture |
| | These changes lead to new variants that are not recognized by the immune system of previously infected individuals. | | | Vaccines must also stimulate the appropriate branch of the immune system for response to a specific pathogen. | | | Antigenic shift: usually results from recombination events during a mixed infection; a mixed infection of 2 different influenza viruses yields progeny that are completely different from either of the parents, these drastic changes produce strains to which much of the human population lacks immunity. |
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http://www-personal.umich.edu/~mengk/micro/lecture23.htm
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| | Facts about influenza |
| | Clearly an effective vaccine must be of the same type which is thought likely to be common in the following influenza season. | | | The importance of these changes is that antibodies in the blood, which are responsible for protection against repeated infection with the virus, are less effective if the virus surface protein changes; the greater the change, the less effective is the antibody. | | | Minor changes are termed antigenic drift, while major changes in one or both of the surface proteins, is called antigenic shift. |
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http://www.amm.co.uk/newamm/files/factsabout/fa_flu.htm
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| | Ecological and immunological determinants of influenza evolution : Nature |
| | Intense selection from the host immune system drives antigenic change in influenza A and B, resulting in continuous replacement of circulating strains with new variants able to re-infect hosts immune to earlier types. | | | Another enigma is the replacement of existing strains during a global pandemic caused by 'antigenic shift'—the introduction of a new avian influenza A subtype into the human population | | | However, given the high transmissibility and mutation rate of influenza, the constancy of genetic diversity within lineages over time is paradoxical. |
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http://www.nature.com/doifinder/10.1038/nature01509
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| | Barnyard blues |
| | But it's also got a faster, more threatening way to change its stripes: "antigenic shift." | | | This all must seem totally irrelevant, but there's a kicker: After a shift or a reassortment, the human immune system will have no antibodies to the new strain, and therefore no power to fight it. | | | Because the genes determine the surface proteins, these proteins (antigens) will be different, and the human immune system will not recognize the new hybrid. |
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http://whyfiles.org/049flu/main3.html
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| | CH10 |
| | Alternately, maybe we should try to generate a TH1 T-cell response instead of a TH2 response. | | | Impairment of macrophage function - cell death does not occur, but altered chemotaxis and and antigen processing has been observed in infected macrophages. | | | T-cell function, especially of memory T-cells, is likely affected well before you see a drastic drop in circulating CD4+ T-cells. |
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http://members.aol.com/HUImmuno/BIO513/CH10.html
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| | Additional Details about Influenza Epidemics. |
| | Several trivia points which might be interesting are | | | Hemagglutinin is also often the source of major antigenic Shift. | | | (The World Health Organization and our own CDC maintain a large worldwide surveillance system to detect and characterize new strains as quickly as possible.) Mostly the change is slow, and is referred to as antigenic "Drift." Researchers have developed the ability to stay mostly ahead of Drift. |
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http://www.ryebrookobgyn.com/pateduc/influ2.htm
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| | INFLUENZA VACCINATION: A CALL FOR ACTION |
| | Antigenic shift occurs only with influenza A, and refers to a major change in either or both antigens, with a change in the subtype of the virus. | | | Vaccination decreases the incidence of influenza, and is associated with significant reductions in use of healthcare services, absenteeism from work due to illness, hospitalizations for management of lower respiratory tract complications, and deaths among persons with underlying risk factors. | | | Antigenic variations in these antigens result in the well-known influenza-related phenomena: antigenic drift and antigenic shift. |
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http://www.kfshrc.edu.sa/annals/176/97-248R.html
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| | INFLUENZA |
| | When a new subtype of virus appears after antigenic shift that can cause both illness in humans and can also spread easily from person to person, an influenza pandemic (worldwide epidemic) can occur. | | | The viruses that are isolated from patients are characterised antigenically and the HA gene is partially sequenced to assess the extent of antigenic drift from the vaccine strains. | | | Influenza activity is monitored using proxy indices such as monitoring school absenteeism, utilization of pharmaceuticals related to respiratory infections and also mortality data. |
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http://www.scienceinafrica.co.za/2002/june/flu.htm
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| | Gnostical Turpitude: Influenza Genetics: or, Poultry's Revenge |
| | Major antigenic shift is the result of coinfection of a human cell by both human and animal influenzaviruses. | | | Progeny virii carrying hemagglutinin and neuraminidase derived from the animal virus (novel antigens that allow the virus to escape immune system detection) and internal proteins from the human virus (which allow it to efficiently attack a human host) are capable of spreading in the human population. | | | New flus develop through two major pathways: minor antigenic shift and major antigenic drift. |
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http://gnosticalturpitude.org/archives/000021.html
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| | Untitled Document |
| | This diagram displays the process of antigenic shift which was responsible for the three major influenza pandemics in history. | | | These strains of influenza are dramatically different than any humans have encountered before, and therefore the immune system is incapable of responding until after the body has been irreparably compromised. | | | This is the reason for development of new flu vaccines each year, and your doctor's recommendation that you receive one. |
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http://www.mtholyoke.edu/%7Edebrough/geneticdrift.html
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| | Orthomyxoviruses |
| | Unlike most viral diseases, early therapy of type A influenza can be accomplished with amantadine hydrochloride. | | | When an antigenic shift occurs, the vaccines then in stock may be of no value. | | | A prototype, called the "Asian flu," developed, and, because there was no known antibody immunity, the disease spread rapidly within a year, causing major pandemics in most parts of the world. |
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http://www.innvista.com/health/microbes/viruses/orthomy.htm
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| | Influenza: Introduction of the Neuraminidase Inhibitors |
| | The other mechanism of antigenic variation is referred to as antigenic shift. | | | People who have contracted the flu do not have protective immunity for life because of changes in these 2 viral antigens that elicit the immune response in humans. | | | It is thought that 2 or more amino acid changes in 2 or more of the 5 main antigenic sites on hemagglutinin are sufficient to result in a significant antigenic change. |
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http://www.p-e-g.de/Research_News/03092000-15.html
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| | BioEd Online: Flu Prevention: Hot Topic in Biology |
| | Foreign molecules, such as these proteins, that stimulate an immune response, are called antigens. | | | Antibodies made by the host immune system in response to the previous subtypes will not recognize the new subtype Antigenic shift was responsible for the emergence of the "Hong Kong" flu in 1968, which was caused by subtype H3N2. | | | Slight changes in these antigenic proteins allow the virus to escape detection by the immune system. |
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http://www.bioedonline.org/hot-topics/flu.cfm
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| | Swine Flu Epidemics |
| | Scientists believe that these changes are due to the recombination of influenza viruses from different sources, such as if an influenza from a swine was mixed with an influenza from a person, which could create an new strain that has swine-type hemagglutinin and human-type neuraminidase. | | | For example, the swine flu of 1918 was named H1N1, while a later strain of influenza which was found to have changed its hemagglutinin molecules was named H2N1, and an even later influenza was found to have changed both its surface molecules (double antigenic shift), and was named H2N2. | | | It is common for a major outbreak to occur after a shift, and even more likely after a double shift, because the antibodies in the population are useless against these new forms of disease. |
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http://www.haverford.edu/biology/edwards/disease/viral_essays/warnervirus.htm
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| | Influenza |
| | This may have offered some protection for many individuals as only a "partial disguise" was created by the antigenic shift. | | | This would allow people who were in their sixties and older in 1968 to be protected to some degree by way of their supposed exposure to the similar virus when they were much younger. | | | This is why they must invade our bodies in order to continue to exist. |
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http://www.stemrich.com/hci/influenza/facts.htm
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| | veshland: 2003 Flu: Shift vs. Drift. Treatment. |
| | This is different than an antigenic shift, where a completely new strain is introduced into the population, presumably from a change of a complete gene, and presumably when a strain jumps from an animal vector to a human vector. | | | People do seem to be deriving benefit from it. | | | We may be due for one, especially in light of the recent transgenic viruses we have had earlier this year like monkeypox. |
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http://www.veshman.com/mt/archives/000097.php
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| | Orange County Fire Authority |
| | Briefly review symptoms and management of dehydration, febrile seizures and respiratory distress in children. | | | This antigenic shift results in a virus different from those seen in previous years with no immunity in humans. | | | These antibodies then neutralize the antigen and prevent or minimize the effect of the antigen on the body. |
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http://www.ucihs.uci.edu/emergmed/_ems\flu.htm
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| | Will This Year's Flu Shot Work? |
| | Shift variants are flu bugs that have managed to change one or both of their two kinds of surface molecules. | | | Shift variants aren't always as bad as feared. | | | Instead, a drift variant called type A Victoria caused much more illness and death in the 1976-1977 flu season. |
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http://my.webmd.com/content/article/77/95576.htm
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| | influenza |
| | Although, many factors are involved with the spread of influenza viruses, a lot of attention has been focused on the idea of their antigenic changeability. | | | The Spanish Flu of 1918 is an example of an epidemic where no vaccine is helpful and it spreads around the world faster than any research laboratory could isolate, prepare and then make accessible to the public as a vaccine. | | | Antigenic shifts are more dramatic changes, and the virus strains appear more different antigenically from previously seen strains. |
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http://www.goshen.edu/bio/Biol206/Biol206LabProject/Influenza/brookejodi/ANTIGE~1.HTM
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| | David Zage's Influenza Antigenic Drift Page |
| | Only influenza A can change by antigenic shift and is responsible for world pandemics and high mortality rates. | | | The changes in the antigens allow influenza to evade the immune systems of the host and make a yearly vaccination a necessity. | | | Currently, there are three subtypes circulating, two of which are classified as type A and one type B. Another way influenza evades the immune system of the host is through antigenic shift. |
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http://www.cs.bsu.edu/homepages/dmz/david/drift.html
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| | [No title] |
| | Antigenic variation within the serotype is thought to occur as a result of antibody pressure existing in the population. | | | The severity of the epidemic is dependent on the degree of antigenic variation. | | | Antigenic drift occurs more regularly than antigenic shift. |
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http://www.pitt.edu/~super1/lecture/lec0652/017.htm
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| | BioS 353 |
| | Antigenic shift is a sudden major change in antigenic type. | | | Molecular analyses have shown that both the 1957 and 1968 pandemic viruses were a result of the reassortment of a human strain with an avian strain. | | | Some of these changes will be neutral and some will be favored ("disfavored" changes will not accumulate in the population). |
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http://www.lehigh.edu/~jas0/V10.html
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| | A Flu or Two! |
| | By studying the viruses that are found in frozen bodies, scientists can learn more about the course of antigenic shifts and, in the future, develop a vaccine if a similar outbreak occurs. | | | Antigenic shift can also occur when a virus that was unable to produce an infection in people previously makes a leap from another host animal. | | | The link to Quizville has been deleted because it lead to a site that is not appropriate for children. |
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http://www.suite101.com/article.cfm/science_for_kids/33122
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| | Influenza Genetics! (>")> |
| | Only small children who have not developed the antibodies against it have any trouble, and then only once will the strain show itself before the immune system recognizes it. | | | This rapid shifting of genetic material is what gives influenza A its incredible virulence. | | | Thus, with massive populations of un-vaccinated people with limited access to health care, the largest and most destitute countries of the world (China, India, much of Eastern Europe and Asia, and most of the third-world nations to name a few) are rapidly becoming hotbeds of infection. |
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http://www.rpi.edu/~schwab2/genetics.html
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| | Vaccines |
| | The other way that flu viruses can change is by a mechanism referred to as "antigenic shift." Antigenic shift is an abrupt, major change in the influenza A viruses, resulting in a completely new influenza A subtype. | | | One way is called "antigenic drift." These are small changes in the proteins on the surface of the virus that happen over time. | | | Influenza B viruses circulate widely only among humans and are not divided into subtypes. |
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http://www.taxtyranny.ca/images/HTML/Vaccines/Vaccines37.html
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| | News in Science - Flu survives by creating sacrificial mutations - 27/03/2003 |
| | The model looked at 'antigenic drift' which is the ability of the virus to alter its antigen - the part of the virus the body's immune system sees. | | | The researchers think that mathematical models can now give an integrated and detailed description of evolution by looking at patterns of disease and patterns of sequence evolution. | | | The last two major antigenic shifts in flu were in 1957 (when it became the Asian flu) and 1968 when the Hong Kong version evolved. |
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http://www.abc.net.au/science/news/stories/s816361.htm
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| | more.html |
| | Antigenic Drift: is one or more random point mutations that add up into small molecular changes. | | | Antigenic Shift: is the genetic recombination of diiferent strains. | | | "Original Antigenic Sin": This phrase describes the phenomenon that greatest amount of anitbodies that are stimulated by an influenza infection are antibodies specific to the strain of influenza of your first infection. |
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http://www.stanford.edu/group/virus/orthomyxo/more.html
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