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Topic: Antigenic shift

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Antigenic drift

Influenza

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	Antigenic Shift & Drift
		The antigenic variability of the influenza virus is determined by these glycoproteins, which undergo two changes, antigenic shift and antigenic drift.
		Antigenic shift occurs as a result of reassortment of the genes for hemagglutinin or neuraminidase.
		Antigenic shift is represented by the shift from H7N7 to H3N8.
	www.vetmed.ufl.edu /courses/vem5141/fall2003/students/groups_topics/10/Antigenic_Shift_Drift.htm (452 words)

	Antigenic drift - Wikipedia, the free encyclopedia
		Antigenic drift refers to mutations in the influenza virus that cause changes in the virus's surface proteins over time.
		Antigenic drift has been responsible for heavier than normal flu seasons in the past, like the outbreak of influenza A Fujian(H3N2) in the 2003 - 2004 flu season.
		Antigenic drift is not the same as antigenic shift, which is a major change in the surface proteins on the virus.
	en.wikipedia.org /wiki/Antigenic_drift (203 words)

	Antigenic shift - Wikipedia, the free encyclopedia
		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.
		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 drift occurs in all types of influenza including influenza A, B and C. Antigenic shift, however, occurs only in influenza A because it infects more than just humans.
	en.wikipedia.org /wiki/Antigenic_shift (716 words)

	Influenza Virus
		The antigenicity of NA on the surface of the influenza virus is also important in determining the subtype of the influenza virus isolates.
		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.
		Antigenic drift (minor changes) occurs due to accumulation of point mutations in the gene which results in changes in the amino acids in the proteins.
	www.angelfire.com /nj/inquisitivemind/influenza.html (2022 words)

	Types of Flu
		Antigenic drift produces new virus strains that may not be recognized by antibodies to earlier influenza strains.
		The other type of change is called "antigenic shift." Antigenic shift is an abrupt, major change in the influenza A viruses, resulting in a new influenza virus that can infect humans and has a hemagglutinin protein or hemagglutinin and neuraminidase protein combination that has not been seen in humans for many years.
		Antigenic shift results in a new influenza A subtype.
	www2.hawaii.edu /~nagahisa/html/types_of_flu.html (495 words)

	Featured Bug: Influenza (Site not responding. Last check: 2007-11-01)
		In contrast to antigenic drift, "antigenic shift" is characterized by major changes in surface antigens.
		Antigenic shift occurs only in influenza A viruses, and is associated with severe illness and worldwide pandemics.
		Antigenic shift originate from the genetic recombination of strains of virus from two different species, and is facilitated by the segmentation of the RNA genome.
	microbiology.mtsinai.on.ca /bug/flu/flu-bug.shtml (1421 words)

	Orthomyxoviruses (Site not responding. Last check: 2007-11-01)
		Antigenic drift is due to mutations in the RNA that leads to changes in the antigenic character of the H and N molecules.
		Antigenic shift is due to rearrangement of different segments of the viral genome that produces major changes in the antigenic character of the H and N molecules.
		Antigenic shift usually occurs in animal hosts and is responsible for producing both epidemics and pandemics.
	www.cehs.siu.edu /fix/medmicro/ortho.htm (711 words)

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		Should a new strain develop with new antigens on its surface, this strain of the same microorganism likely will be able cause infection, and once again the virus will begin to spread through the population.
		Antigenic shift can occur in influenza A because its genome is encoded in eight segments of RNA.
		Should antigenic shift occur in H5N1, the result could be a virus that could be passed from human to human easily.
	courses.washington.edu /conj/immune/flu.htm (1150 words)

	INFLUENZA
		Antigenic shift is an abrupt, major change due to gene reassortment and results in an influenza A virus with new haemagglutinin and/or neuraminidase proteins.
		Due to the antigenic drift of the virus, monitoring the antigenicity of the viruses in circulation each year is necessary to identify any new variant strains so that influenza vaccines can be updated annually with closely matching strains.
		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.
	www.scienceinafrica.co.za /2002/june/flu.htm (1711 words)

	CDC - Avian Influenza (Flu) \| Influenza Viruses
		Antigenic drift refers to small, gradual changes that occur through point mutations in the two genes that contain the genetic material to produce the main surface proteins, hemagglutinin, and neuraminidase.
		Antigenic drift produces new virus strains that may not be recognized by antibodies to earlier influenza strains.
		Antigenic shift can occur either through direct animal (poultry)-to-human transmission or through mixing of human influenza A and animal influenza A virus genes to create a new human influenza A subtype virus through a process called genetic reassortment.
	www.cdc.gov /flu/avian/gen-info/flu-viruses.htm (1304 words)

	Antigenic Variation of Influenza Viruses, Influenza A Virus Antigenic Shift, Antigenic Drift
		The appearance of a new influenza virus subtype is paralleled by the disappearance of the old subtype (an exception occurred in recent times, when 2 virus subtypes have circulated concurrently) The HA antigen is always involved in antigenic shift as it is responsible for eliciting virus-neutralizing antibodies.
		Antigenic drift is thought to arise through natural mutation, and selection of new strains takes place by antibody pressure in an immune or partially immune population.
		Epidemics due to new virus strains arising due to antigenic drift is not as great as for those showing antigenic shift, since partial immunity is present in persons with cross- reacting antibody induced by previous infection.
	virology-online.com /viruses/Influenza2.htm (3799 words)

	[No title]
		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.
		The term antigenic shift is specific to the influenza literature; in other viral systems, the same process is called reassortment or viral shift.
		Antigenic drift is the natural mutation over time of known strains of influenza to evade the immune system.
	www.pitt.edu /~super1/lecture/lec21431/016.htm (118 words)

	Gnostical Turpitude: Influenza Genetics: or, Poultry's Revenge
		Minor antigenic shift is simply the random mutation of the hemagglutinin and neuraminidase genes.
		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.
	gnosticalturpitude.org /archives/000021.html (473 words)

	AVIAN FLU - THE IMMINENT PLAGUE: Antegenic Drift/Shift
		Antigenic drift is the minor mutation of the surface glycoproteins, namely hemagglutinin (HA) and neuraminidase (NA) of the influenza virus.
		Antigenic drift occurs over a long period of time and it is a gradual process.
		This process of antigenic shift in influenza viruses has been hastened by species which are capable of being infected by different types of the influenza virus.
	library.thinkquest.org /05aug/01349/sb3.html (695 words)

	University of Miami School of Medicine - Glossary - Antigenic shift
		Antigenic shift: A sudden shift in the antigenicity of a virus resulting from the recombination of the genomes of two viral strains.
		Antigenic shift is seen only with influenza A viruses.
		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 influenzaviruses for a long time.
	www.med.miami.edu /glossary/art.asp?articlekey=26115 (126 words)

	Influenza
		The H and N antigens are essential for the virulence of the virus: the H antigen is involved in attachment and the N antigen is probably involved in penetration and the eventual release of the virus.
		Both the H and N antigens of the virus are recognized by the immune mechanisms of the host and antibody raised against these antigens either by infection or vaccination is protective.
		Antigenic shift is an abrupt, major change in the influenza A viruses, resulting in new hemagglutinin and/or new neuraminidase proteins in influenza viruses that infect humans.
	www.bact.wisc.edu /themicrobialworld/Influenza.html (2228 words)

	Influenza - MSN Encarta
		Called antigenic drift, this process accounts for most of the changes in influenza viruses that occur from one year to the next.
		This type of change is called antigenic shift and results in a new subtype of the virus.
		This strain has the ability to infect humans but has antigens on its surface that are unfamiliar to the human immune system.
	encarta.msn.com /encyclopedia_761557270/Influenza.html (1313 words)

	Calgary Health Region
		Antigenic drift occurs constantly among influenza A viruses, which is why we see new strains every year.
		Antigenic shift usually occurs in two ways: either as a sudden “adaptive” change when a normal virus reproduces, or from an exchange of genes between a human strain of influenza A virus and an animal strain.
		Influenza A viruses have undergone antigenic shift three times in the last century, resulting in pandemics with large numbers of both disease and death.
	www.calgaryhealthregion.ca /pandemic/whatis3.htm (497 words)

	more.html (Site not responding. Last check: 2007-11-01)
		"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.
		Antigenic Shift: is the genetic recombination of diiferent strains.
		Shift is one reaon why the virus can spread throughout the world so quickly.
	www.stanford.edu /group/virus/orthomyxo/more.html (222 words)

	Blogger: Email Post to a Friend
		Antigenic drift produces new virus strains that may not be recognized by the body's immune system.
		The other type of change is called "antigenic shift." Antigenic shift is an abrupt, major change in the influenza A viruses, resulting in new hemagglutinin and/or new hemagglutinin and neuraminidase proteins in influenza viruses that infect humans.
		While influenza viruses are changing by antigenic drift all the time, antigenic shift happens only occasionally.
	www.blogger.com /email-post.g?blogID=9286418&postID=110202904786921907 (668 words)

	Plans against influenza pandemics in Europe: history and principles
		Antigenic variations of surface glycoproteins are an important factor in viral mechanisms of escape from immune defences.
		For an antigenic shift to occur, infection of the same cell by two viruses is necessary.
		The antigenic composition of influenza vaccine is updated annually to cope with the incessant drift of viral antigens.
	www.eurosurveillance.org /em/v03n03/0303-223.asp (1626 words)

	Lecture (Site not responding. Last check: 2007-11-01)
		Antigenic drift: usually results from mutation; in the case of influenza, mutations frequently occur in the 2 envelope proteins (hemagglutinin and neuraminidase) resulting in changes in the antigenic structure of the virions.
		Antigenic drift in epidemic influenza viruses from year to year requires continual updating of the strains used to produce immunizing vaccines.
		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.
	www-personal.umich.edu /~mengk/micro/lecture23.htm (592 words)

	There are three subtypes of infl
		Antigenic drift happens frequently, usually annually; antigenic shift happens only occasionally, perhaps every 20 - 40 years.
		Antigenic shift is an infrequent, yet sudden, major change that produces a novel influenza virus, i.e., a virus subtype not previously circulating among the human population.
		Antigenic shift can occur in a number of ways, one of which is through a process called genetic reassortment.
	cns.miis.edu /flu_watch/about_human_influenza.htm (815 words)

	14 Year Old Male
		Antigenic drift is believed to be due to point mutations in the RNA genome.
		Antigenic shift is defined as major changes in the antigenic structure of hemagglutinin or neuraminidase or both.
		Antigenic shift occurs as result of genetic reassortment, in which genomic RNA segments are exchanged between viruses, leading to major changes in the antigenic structure of the virus.
	www.med.uc.edu /departme/molgen/malecas.htm (827 words)

	INFLUENZA VACCINATION: A CALL FOR ACTION
		Antigenic variations in these antigens result in the well-known influenza-related phenomena: antigenic drift and antigenic shift.
		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.
		These vaccines are multivalent, and are updated every year to include viruses that are antigenically similar to the strains of the three distinct groups of influenza viruses that are circulating worldwide.
	www.kfshrc.edu.sa /annals/176/97-248R.html (1632 words)

	Avian Flu Overview (Site not responding. Last check: 2007-11-01)
		Antigenic shift allows for large amounts of new genetic information to be acquired by the avian flu from the human flu virus when they are exposed to each other.
		Antigenic drift is responsible for small changes in the genetic properties of the virus.
		It is theoretically possible for an avian flu virus to accumulate enough mutations through antigenic drift to gain the ability to infect humans easily, without antigenic shift or an intermediate host involved, but this generally requires a specific series of mutations to happen.
	www.nawabirds.org /fluoverview.htm (1587 words)

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