Influenza strains are constantly mutating. Small changes to the genetic makeup of influenza strains are referred to as antigenic drift, while a major change is called antigenic shift. The antibodies created in response to having the flu in the past are unable to protect against the new strain.
Antigenic drift is a kind of genetic variation in viruses, arising by the accumulation of mutations in the virus genes that code for virus-surface proteins that host antibodies recognize. Antigenic drift occurs in both influenza A and influenza B viruses.
Furthermore, what increases the possibility of antigenic shift in influenza virus? 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. Evidence suggests that the 1918 influenza pandemic was the result of a direct jump from pigs to humans.
In respect to this, what does antigenic shift mean?
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.
Which is worse antigenic shift or drift?
When shift happens, most people have little or no immunity against the new virus. While influenza viruses change all the time due to antigenic drift, antigenic shift happens less frequently. Influenza pandemics occur very rarely; there have been four pandemics in the past 100 years.
What causes antigenic drift?
Antigenic drift, random genetic mutation of an infectious agent resulting in minor changes in proteins called antigens, which stimulate the production of antibodies by the immune systems of humans and animals. These mutations typically produce antigens to which only part of a population may be immune.
How does influenza mutate?
The influenza virus uses two methods to mutate and infect us every single winter. A gradual minor point mutation in the genes responsible for encoding HA and NA proteins on the surface of the influenza virus, called antigenic drift, may occur. These changes will cause us to fall ill with a new strain of the flu virus.
What is the difference between antigenic drift and antigenic shift in influenza viruses?
Antigenic Drift and Shift With the Flu Virus. Influenza strains are constantly mutating. Small changes to the genetic makeup of influenza strains are referred to as antigenic drift, while a major change is called antigenic shift. When the flu strain mutates, our immune system recognizes it as a new virus.
How many flu virus strains are there?
What happens when a virus mutates?
The genetic material inside the virus plays an enormous role in how quickly a virus mutates, which in turn can impact how the illness can spread in the population. This means mutations occur more slowly. Examples of DNA viruses such as smallpox. These viruses spread through human populations and were often fatal.
What is the difference between influenza A and B?
While the symptoms of influenza B mirrors those of A, the main difference between the two strains is who it can affect. This allows strains of A to be spread more rapidly than B, while also meaning strains of B cannot cause pandemics with symptoms likely less severe. Flu shots protect against both strains of influenza.
How many subtypes of influenza exist?
Subtypes of Influenza A Viruses Influenza A viruses are divided into subtypes on the basis of two proteins on the surface of the virus: hemagglutinin (HA) and neuraminidase (NA). There are 18 known HA subtypes and 11 known NA subtypes.
What is the usual incubation period for flu?
While the general incubation period for the flu is usually between one and four days, this period can vary from person to person. The average incubation period for the flu is two days . This means that, on average, people start to develop flu symptoms about two days after coming into contact with the influenza virus.
What is the best example of an antigenic shift?
An example of antigenic shift might be when an avian virus and a human virus simultaneously infect a cell in another species, for example a pig. This creates the potential for their genetic materials to be mixed creating a new and hybrid-type virus with increased virulence in humans.
Can you combine viruses?
Once a virus injects its DNA or RNA into a cell, it forces the infected cell to make new viruses. Sometimes, though, two different kinds of virus can infect the same cell. This can sometimes result in a new virus made up of parts of the other two. But this only happens in very special cases.
Do viruses get stronger?
Viruses tend to get stronger in cold, dry weather and can spread easily as people huddle inside for festive gatherings. Additionally, our immune systems tend to get weaker, thanks to all the drinking and fatty foods we consume this time of year.
What is an autoantigen?
An autoantigen is usually a normal protein or complex of proteins (and sometimes DNA or RNA) that is recognized by the immune system of patients suffering from a specific autoimmune disease.
Can a virus change over time?
Viruses are continuously changing as a result of genetic selection. They undergo subtle genetic changes through mutation and major genetic changes through recombination. Mutation occurs when an error is incorporated in the viral genome.
Why are pigs important intermediate animals in antigenic shifts?
Genetic reassortment in pigs allows for the generation of novel influenza viruses and further demonstrates that pigs can serve as intermediate hosts and therefore as “mixing vessels” for human, swine and avian influenza viruses.