One way flu viruses change is called “antigenic drift.” Drift consists of 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 is an example of an antigenic drift?
The process of antigenic drift is best characterized in influenza type A viruses. The viral coats, or outer surfaces, of these viruses contain two major antigenic glycoproteins—hemagglutinin (H) and neuraminidase (N)—which differ between influenza A subtypes (e.g., H1N1, H3N2, H5N1).
What causes antigenic drift?
20 Antigenic drift is caused by point mutations in the HA and NA genes that are driven by immune pressure and the infidelity inherent in the replication of RNA genomes.
What is antigenic shift vs drift?
Antigenic drift involves the accumulation of a series of minor genetic mutations. Antigenic shift involves “mixing” of genes from influenza viruses from different species.
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 is antigenic shift and antigenic drift in influenza?
Influenza strains are constantly mutating. A small change to the genetic makeup of influenza strains is referred to as antigenic drift, while a major change is called antigenic shift.
Can antigenic drift cause a pandemic?
Antigenic shift results in a new influenza A subtype that is so different from previous subtypes in humans that most people do not have immunity to the new virus. An antigenic shift can lead to a worldwide pandemic if the virus is efficiently transmitted from person to person.
What flu antigens are involved in 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.
How often does antigenic drift occur?
Since the late nineteenth century, four occurrences of antigenic shift have led to major influenza pandemics. Although influenza viruses constantly and gradually change by antigenic drift, antigenic shift happens only occasionally.
Is antigenic shift unique to influenza?
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.
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.
What is difference between antigen drift and antigenic shift?
Difference Between Antigenic Drift and Antigenic Shift Definition. Antigenic drift refers to a mechanism for variation by viruses, which involves the accumulation of mutations within the antigen-binding sites while antigenic shift refers to a sudden shift in Mechanism. Degree of Antigenic Change. Result in. Frequency of Occurrence. Host variation. Treatment. Occurrence. Give Rise to. Conclusion.
What does antigenic variation mean?
Antigenic variation is a shift in surface antigens on an infectious organism to help the organism evade the immune systems of potential hosts.
What is drifting in genetic drift?
Genetic drift. The genetic drift pertains to the process of change in the frequency of an allele (gene variant) in a population over time. The change is caused by chance or random events (e.g. a disastrous event in a habitat) rather than by natural selection.
