What is meant by 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.
What is an example of antigenic drift?
A minor change to a flu virus is known as antigenic drift. Both influenza A and B viruses undergo antigenic drift. As the virus replicates, these changes in antigenic drift happen continually. Over time, these small changes accumulate and result in a new strain that is not recognized by the immune system.
Is Regensortment an antigenic shift?
Antigenic shift occurs when a nonhuman influenza virus directly infects human hosts or when a new virus is generated by genetic reassortment between nonhuman and human influenza viruses.
Is influenza antigenic shift or drift?
Influenza viruses constantly change through a process called antigenic drift. This is the random accumulation of mutations in the haemagglutinin (HA), and to a lesser extent neuraminidase (NA) genes, recognized by the immune system. It is most pronounced in influenza A viruses.
Does pandemic cause antigenic drift?
Type A viruses undergo both antigenic drift and shift and are the only flu viruses known to cause pandemics, while flu type B viruses change only by the more gradual process of antigenic drift.
Do all viruses antigenic drift?
All influenza viruses experience some form of antigenic drift, but it is most pronounced in the influenza A virus. Antigenic drift should not be confused with antigenic shift, which refers to reassortment of the virus’ gene segments.
What contributes to antigenic shift in influenza viruses?
The influenza viruses are characterized by segmented, negative-strand RNA genomes requiring an RNA-dependent RNA polymerase of viral origin for replication. The particular structure of the influenza virus genome and function of its viral proteins enable antigenic drift and antigenic shift.
Which is worse antigenic shift or drift?
Because the genes in the resulting virus are dramatically different, this is called antigenic shift. Antigenic shift is more concerning than antigenic drift. Antigenic shift can produce a version of influenza virus that no person’s immune system has antibodies to protect against.
How can antigenic drift be prevented?
Vaccination. Influenza vaccine is directed at the currently circulating antigenic types of seasonal influenza A and B and influenza A/H1N1 and A/H3N2. Because of antigenic drift, it is necessary to vaccinate on a yearly basis to prevent seasonal influenza A and B.
What enzyme is responsible for antigenic drift?
The hemagglutinin (H) and neuraminidase (N) undergo small changes in structure called antigenic drift on a yearly basis, which allows the virus to partially evade humans’ past immune response and cause yearly epidemics. Larger changes in the H and N, called antigenic shift, occur infrequently.
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