This type of genetic mutation is called “antigenic drift.” Influenza viruses can change through antigenic drift, which is a process in which mutations to the virus genome produce changes in the viral H or N. Drift is a continuous ongoing process that results in the emergence of new strain variants.
What does drift“antigenic mean?
How the Flu Virus Can Change: “Drift” and “Shift”. 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.
What is antigenic shift in the flu?
Another type of change is called “antigenic shift.” Shift is an abrupt, major change in a flu A virus, resulting in new HA and/or new HA and NA proteins in flu viruses that infect humans. Antigenic shift can result in a new flu A subtype.
How does the influenza virus change over time?
Antigenic Drift One way influenza viruses change is called “antigenic drift.” These are small changes (or mutations) in the genes of influenza viruses that can lead to changes in the surface proteins of the virus: HA (hemagglutinin) and NA (neuraminidase).
What happens when a virus shifts from one type to another?
When shift happens, most people have little or no protection against the new virus. While influenza viruses are changing by antigenic drift all the time, antigenic shift happens only occasionally. Type A viruses undergo both kinds of changes; influenza type B viruses change only by the more gradual process of antigenic drift.
What is antigenic drift and antigenic shift pertaining to influenza?
shift. Antigenic drift creates influenza viruses with slightly modified antigens, while antigenic shift generates viruses with entirely new antigens (shown in red). Source: Wikipedia Commons and USDA.
Why does antigenic shift only occur in influenza A?
Antigenic shift, however, occurs only in influenza A because it infects more than just humans. Affected species include other mammals and birds, giving influenza A the opportunity for a major reorganization of surface antigens.
How does antigenic shift occur in influenza A virus?
Abstract. Human influenza A viruses evolve rapidly by antigenic shift and antigenic drift. Antigenic shift occurs by gentic reassortment between currently circulating human viruses and influenza viruses of other origin and by re-emergence of a previously circulating virus.
What is antigenic drift in influenza?
Antigenic drift: A subtle change in the surface glycoprotein (either hemagglutinin or neuraminidase) caused by a point mutation or deletion in the viral gene. This results in a new strain that requires yearly reformulation of the seasonal influenza vaccine.
What is the result of antigen drift in viruses?
Antigenic drift refers to the evolutionary accumulation of amino acid substitutions in viral proteins selected by host adaptive immune systems as the virus circulates in a population. Antigenic drift can substantially limit the duration of immunity conferred by infection and vaccination.
What is antigenic shift explain its ability to cause pandemics and how likely is this to occur?
Antigenic shift refers to the complete replacement of the HA or NA with a novel HA or NA. These viruses are “new” viruses to which the population has no specific immunity. When such a new virus is introduced into a population, a severe, worldwide epidemic, or pandemic, of influenza can result.
Why does antigenic drift occur?
Antigenic drift is a natural process whereby mutations (mistakes) occur during replication in the genes encoding antigens that produce alterations in the way they appear to the immune system (antigenic changes) (Figure 1).
How does antigenic shift work?
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.
How does antigenic variation occur?
Antigenic variation can occur by altering a variety of surface molecules including proteins and carbohydrates. Antigenic variation can result from gene conversion, site-specific DNA inversions, hypermutation, or recombination of sequence cassettes.
What happens during antigenic shift quizlet?
Antigenic shift leads to the generation of a novel virus strain to which no one on Earth would be immune. It occurs when two strains of flu virus infect the same cell. Reassortment can occur, generating a chimeric virus that may have new pairings between the HA and N genes. The new virus may then jump to humans.
What fact about the influenza virus allows the dramatic antigenic shift that generates novel strains?
What fact about the influenza virus allows the dramatic antigenic shift that generates novel strains? C. transmission is through a mosquito vector.
What is the antigenic shift?
Antigenic shift is a more major change in the influenza virus. This shift typically occurs when a human flu virus crosses with a flu virus that usually affects animals (such as birds or pigs).
What is the name of the virus that changes the surface proteins of the virus?
A minor change to a flu virus is known as antigenic drift. Both influenza A and B viruses undergo antigenic drift. These mutations in the virus’s genes can lead to changes in its surface proteins hemagglutinin (HA) and neuraminidase (NA). Known as antigens, these are recognized by the immune system, prompting an immunological response ...
How does the bird flu spread?
This can happen in three ways: 1 1 A human flu virus infects an animal, such as a pig. The same pig also gets infected by a flu virus from another animal, such as a duck. The two flu viruses mix and mutate, creating a completely new type of flu virus that can then spread to humans. 2 A strain of bird flu passes to humans without undergoing any type of genetic change. 3 A strain of bird flu passes to another type of animal (such as a pig) and is then passed on to humans without undergoing a genetic change.
What happens when a virus crosses with a virus?
This shift typically occurs when a human flu virus crosses with a flu virus that usually affects animals (such as birds or pigs). When the viruses mutate, they shift to create a new subtype that is different from any seen in humans before. This can happen in three ways: 1 . A human flu virus infects an animal, such as a pig.
Can a pig get the flu?
A human flu virus infects an animal, such as a pig. The same pig also gets infected by a flu virus from another animal, such as a duck. The two flu viruses mix and mutate, creating a completely new type of flu virus that can then spread to humans.
How does drift affect the flu?
This process allows influenza viruses to change and re-infect people repeatedly through their lifetime and is the reason the influenza virus strains in vaccine must be updated each year.
What is the term for the genetic shift that enables a flu strain to jump from one animal species to another?
The genetic change that enables a flu strain to jump from one animal species to another, including humans, is called antigenic shift . Antigenic shift can happen in three ways:
How do viruses change?
Influenza viruses can change through antigenic drift, which is a process in which mutations to the virus genome produce changes in the viral H or N. Drift is a continuous ongoing process that results in the emergence of new strain variants.
How do viruses escape from person A?
Mutant viruses that arise in person A can escape antibodies by replacing one critical amino acid in this antigen region.
When was gene sequencing not possible?
Of course, says Dr. Yewdell, gene sequencing was not possible in the mid-1950s, when the nature of the gene was first elucidated, and until very recently, sequencing was expensive and time-consuming. "Now, with automated gene sequencers, sequencing of dozens of isolates is easily done overnight," he says.
What did the findings of the mice show?
The findings in mice, using a strain of seasonal influenza virus first isolated in 1934, also suggest that antigenic drift might be slowed by increasing the number of children vaccinated against influenza. Scott Hensley, Ph.D., Jonathan W. Yewdell, M.D., Ph.D., and Jack R. Bennink, Ph.D., led the research team, ...
What is the NIH?
NIH is the primary federal agency conducting and supporting basic, clinical, and translational medical research, and is investigating the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov. NIH…Turning Discovery Into Health®.
Do viruses detach from infected cells?
Also, newly formed viruses must detach from infected cells before they can spread to the next uninfected cell. Viruses that have mutated to be highly adherent to the lung cell receptors may have difficulty completing this critical step in the infection cycle.".
What is an antigenic shift?
This antigenic shift results in a much greater population of susceptible individuals in whom more severe disease is possible. Such an antigenic shift can result in a virulent strain of influenza that possesses the triad of infectivity, lethality, and transmissibility and can cause a pandemic.
What happens when you reassort an avian strain with a mammalian strain?
The reassortment of an avian strain with a mammalian strain may produce a chimeric virus that is transmissible between mammals; such mutation products may contain H or N proteins that are unrecognizable to the immune systems of mammals.
How many genes are in a viral genome?
Segmentation of the viral genome, which consists of 10 genes on 8 RNA molecules, facilitates genetic reassortment. Because pigs have been susceptible to both human and avian influenza strains, many experts believe ...
What is the difference between antigenic drift and antigenic shift?
Antigenic shift is a genetic variation which results from the genetic material exchange between two or more closely related strains of influenza virus. This is the key difference between antigenic drift and antigenic shift. Both these processes create viral particles which are more virulent than preexisting viruses.
What is antigenetic drift?
Antigenetic drift is a genetic variation occurring in the viral genome due a development and accumulation of point mutations in the genes that encode H and N . Antigenetic shift is a variation occurs in the viral genome due to gene reassortment between two or more viral strains. Development of the Genetic Change.
How do H and N antigens work?
H and N antigens of the influenza virus bind to the host cell receptors and make a successful infection to cause the disease. H and N antigen structures can be easily recognized by the host defense systems which destroy the viral particles to prevent the disease occurrence. However several genetic variations of influenza viral particles limit the chance of destroying the viral antigens which enter the host body by the host immune system. Antigenic drift is such kind of a genetic variation common in influenza virus. It happens due to gradual development and accumulation of a point mutation in the genes of H and N. As a result of this point mutation, viral particles acquire the capability of changing the H and N antigen structures which cannot be recognized by the host cell antibodies or vaccines. Therefore, the mutations of these H and N coding genes allow the viral particles to escape from the host immune systems and spread the disease.
What are the two types of genetic variations that occur in the influenza virus?
Antigenic shift and antigenic drift are two types of genetic variations that occur in influenza virus. These variations make it difficult to prevent common diseases associated with influenza virus by vaccines or the natural immunity system. Main two types of glycoproteins (antigens) named hemagglutinin (H) and neuraminidase (N) ...
What is the viral genome?
Viral genome codes glycoproteins ( antigens) which are important for attaching to the host organism and include viral genome to replicate within the host organism . Influenza virus is one type of virus responsible for the common cold associated diseases among humans and other animals.
What are the two glycoproteins that are modified by the virus?
Main two types of glycoproteins (antigens) named hemagglutinin (H) and neuraminidase (N) located at the outer surface of the virus are modified by the viral genes as a result of antigenic drift or antigenic shift. The key difference between antigenic drift and antigenic shift is that antigenic drift is a genetic variation ...
Is antigenic shift rare?
Antigenic shift is a rare process. Nature of the Disease. This can lead to an epidemic among the population such as H3N2. This can lead to a pandemic in the population such as H1N1, Spanish flu, and Hong kong flu.
