Antigenic drift involves the accumulation of a series of minor genetic mutations. Antigenic shift involves “mixing” of genes from influenza viruses from different species.
What is antigenic shift in viruses?
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.
How likely is antigenic shift occur in influenza viruses?
The influenza virus is another pathogen that can be the cause of a pandemic. Flu pandemics occur roughly every 40 years, at times when there is an antigenic shift in the virus.
What contributes to antigenic shift in influenza viruses?
Antigenic shift refers to the emergence of a novel influenza virus in humans, due to direct introduction of an avian strain or to a new strain produced by recombination and reassortment of two different influenza viruses.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 is the difference between recombination and reassortment?
Reassortment only occurs in segmented RNA viruses, whereas recombination stricto sensu occurs in virtually all RNA viruses. The formation of a hybrid RNA sequence after inter-molecular exchange of genetic information between two nucleotide sequences results specifically from the latter.
What is an example of an antigenic shift?
An example of a pandemic resulting from antigenic shift was the 1918-19 outbreak of Spanish Influenza. This strain was originally the H1N1 avian flu, however antigenic shift allowed the viral infection to jump from pigs to humans, resulting in a large pandemic which killed over 40 million people.
What is shift and 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.What is the meaning of Antigenic?
(AN-tih-jen) Any substance that causes the body to make an immune response against that substance. Antigens include toxins, chemicals, bacteria, viruses, or other substances that come from outside the body.
Why does antigenic drift occur?Antigenic drift: A subtle change in the surface glycoprotein (either hemagglutinin or neuraminidase) caused by a point mutation or deletion in the viral gene. This results in a new strain that requires yearly reformulation of the seasonal influenza vaccine.
Article first time published onWhy does antigenic drift happen?
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 does hemagglutinin mean?
hemagglutinin, any of a group of naturally occurring glycoproteins that cause red blood cells (erythrocytes) to agglutinate, or clump together. These substances are found in plants, invertebrates, and certain microorganisms.
Is influenza spread through droplet transmission?
People with flu can spread it to others up to about 6 feet away. Most experts think that flu viruses spread mainly by droplets made when people with flu cough, sneeze or talk. These droplets can land in the mouths or noses of people who are nearby or possibly be inhaled into the lungs.
What is phenotypic mixing in viruses?
Phenotype mixing is a form of interaction between two viruses each of which holds its own unique genetic material. The two particles “share” coat proteins, therefore each has a similar assortment of identifying surface proteins, while having different genetic material.
What is recombination of a virus?
Viral recombination occurs when viruses of two different parent strains coinfect the same host cell and interact during replication to generate virus progeny that have some genes from both parents.
What is the reassortment of chromosomes and genetic information?
Reassortment is the mixing of the genetic material of a species into new combinations in different individuals. Several different processes contribute to reassortment, including assortment of chromosomes, and chromosomal crossover.
What is the process of 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 the difference between antigen and epitope?
An epitope (also known as the antigenic determinant) is that part of the antigen to which antibodies bind. While the antigen evokes the antibody response in the host, the antibody doesn’t bind to the entire protein, but only to that segment called the epitope.
What is the other name of antigenic determinant?
An epitope, also known as antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. The epitope is the specific piece of the antigen to which an antibody binds.
What viruses have antigenic drift?
Antigenic drift occurs in both influenza A and influenza B viruses. (Confusion can arise with two very similar terms, antigenic shift and genetic drift. Antigenic shift is a closely related process; it refers to more dramatic changes in the virus’s surface proteins.
What is the role of hemagglutinin in influenza infections?
The hemagglutinin(HA) of influenza virus is a major glycoprotein and plays a crucial role in the early stage of virus infection: HA is responsible for binding of the virus to cell surface receptors, and it mediates liberation of the viral genome into the cytoplasm through membrane fusion.
What is a glycoprotein and what does it do?
Glycoproteins are molecules that comprise protein and carbohydrate chains that are involved in many physiological functions including immunity. Many viruses have glycoproteins that help them enter bodily cells, but can also serve to be important therapeutic or preventative targets.
What is the structure of hemagglutinin?
The hemagglutinin molecule is actually a combination of three identical proteins (shown here as gray, green, and purple) that are bound together to form an elongated cylindrical shape. Hemagglutinin consists of a globular head and a stem. The globular head consists of three chains, Chains A, C, and E.
Where is hemagglutinin located in a virus?
Hemagglutinin (HA) or Haemagglutinin (BE) is an antigenic glycoprotein found on the surface of the influenza viruses. It is responsible for binding the virus to the cell that is being infected.
What is the difference between droplet transmission and airborne transmission?
They may also fall on surfaces and then be transferred onto someone’s hand who then rubs their eyes, nose or mouth. Airborne transmission occurs when bacteria or viruses travel in droplet nuclei that become aerosolized. Healthy people can inhale the infectious droplet nuclei into their lungs.
Is influenza airborne or droplet?
Traditionally, influenza viruses have been thought to spread from person to person primarily through large-particle respiratory droplet transmission (e.g., when an infected person coughs or sneezes near a susceptible person).
What type of virus is influenza What are the various modes of transmission through which it can be acquired?
Influenza viruses are believed to be spread between humans through a number of modes of transmission, including primarily through inhalation of respiratory droplets containing infectious virus, and possible contact of respiratory secretions containing infectious virus with mucous membranes.
What is genotypic mixing?
The genotype is commonly mixed up with the phenotype which describes the end result of both the genetic and the environmental factors giving the observed expression (e.g. blue eyes, hair color, or various hereditary diseases).
What is phenotypic masking?
A gene’s phenotype is considered ‘fully masked’ if no observable defect is found upon single-gene knockdown, but phenotype masking is revealed upon double gene knockdown (E–F).
What is phenotyping mixing?
phe·no·typ·ic mix·ing a nongenetic interaction in which virus particles released from a cell that is infected with two different viruses have components from both the infecting agents, but with a genome from one of them.
