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).
Why does antigenic drift happen?
Antigenic drift is a kind of genetic variation in viruses, arising from
the accumulation of mutations in the virus genes that code for virus-surface proteins that host antibodies recognize
.
What is the process of antigenic drift?
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).
What is antigenic shift vs drift?
Antigenic drift vs. shift.
Antigenic drift creates influenza viruses with slightly modified antigens
, while antigenic shift generates viruses with entirely new antigens (shown in red).
What enzyme causes antigenic drift?
Antigenic drift is a feature of not only the
hemagglutinin (HA)
, but also of neuraminidase (NA).
What is an example of antigenic drift?
The emergence of a new
strain of influenza A
due to antigenic drift can cause an influenza epidemic or pandemic. Antigenic drift is also known to occur in HIV (human immunodeficiency virus), which causes AIDS, and in certain rhinoviruses, which cause common colds in humans.
Can antigenic drift be predicted?
These data have now generated explicit predictions on when specific mutations in the HA gene may result in antigenic drift and reduce vaccine efficacy.
What is genetic drift and shift?
A small change to the genetic makeup of influenza strains is referred to as antigenic drift, while a major change is called
antigenic shift
.
What happens during antigenic shift?
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.
What is the incubation period for flu?
The incubation period of influenza is
2 days long on average
but may range from 1 to 4 days in length.
Why is antigenic drift a problem for the immune system?
When antigenic drift occurs,
the body’s immune system may not recognize and prevent sickness caused by the newer influenza viruses
.
How is antigenic drift beneficial for viruses?
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
.
Was h1n1 antigenic shift or drift?
The CDC believes that this virus resulted from
antigenic shift
, which as noted above is a process through which two or more influenza viruses can swap genetic information by infecting a single human or animal host.
Is neuraminidase A enzyme?
Neuraminidase, also called sialidase, any
of a group of enzymes that cleave sialic acid
, a carbohydrate occurring on the surfaces of cells in humans and other animals and in plants and microorganisms.
How long does it take for virus to mutate?
So the more a virus spreads, the more opportunities it has to replicate, the higher its fixation rate will be, and the more the virus will evolve, Duffy says. For SARS-CoV-2, scientists estimate that one mutation becomes established in the population
every 11 days or so
.
Is drift or antigenic shift worse?
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.
