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.
Likewise, 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.
Similarly, 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.
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.
Why does influenza mutate so quickly?
Because flu viruses mutate quickly, flu vaccines have to be redesigned every year. The MIT researchers found that to mutate rapidly, flu viruses use a group of proteins called chaperones in infected cells in the host (a person or animal with the flu).
What is the structure of the influenza virus?
Structurally, the influenza virus is spherical in shape. It is covered in an envelope made of a lipid bilayer with spikes of glycoproteins called haemagglutinin and neuraminidase. These proteins enable the virus to effectively bind with a host cell.
How many flu virus strains are there?
What are the two major antigens on the viral structure that can mutate and change?
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. Antigenic shift may occur as well.
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 does antigenic variation mean?
Antigenic variation or antigenic alteration refers to the mechanism by which an infectious agent such as a protozoan, bacterium or virus alters the proteins or carbohydrates on its surface and thus avoids a host immune response. It is related to phase variation.
What does it mean to be antigenic?
: any substance (such as an immunogen or a hapten) foreign to the body that evokes an immune response either alone or after forming a complex with a larger molecule (such as a protein) and that is capable of binding with a product (such as an antibody or T cell) of the immune response.
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 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.
Why does flu virus change every year?
Flu epidemics reoccur every year because of the the way the virus is built and how it interacts with the human immune system. The viruses are highly changeable, acquiring genetic variations, called mutations, even within a single season.
How do new flu strains arise?
New influenza strains of influenza virus arise continually as a result of two mechanisms that alter the genetic code in the viral RNA. These mechansims are referred to as genetic drift and genetic shift. Genetic Shifts result from reassortment of genetic material between vastly different strains of influenza viruses.
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.
What does antigenic drift mean?
Antigenic drift is a mechanism for variation in viruses that involves the accumulation of mutations within the genes that code for antibody-binding sites. The immune system recognizes viruses when antigens on the surfaces of virus particles bind to immune receptors that are specific for these antigens.