antigenic shift


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Related to antigenic shift: Antigenic drift

shift

 [shift]
a change or deviation.
antigenic shift a sudden, major change in the antigenicity of a virus, seen especially in influenza viruses, resulting from the recombination of the genomes of two different strains; it is associated with pandemics because hosts do not have immunity to the new strain. See also antigenic drift.
chloride shift the exchange of chloride and carbonate between the plasma and the erythrocytes that takes place when the blood gives up oxygen and receives carbon dioxide. It serves to maintain ionic equilibrium between the cell and surrounding fluid.
mediastinal shift a shifting to one side of the tissues and organs of the mediastinum; see also mediastinal shift.
shift to the left
1. a change in the blood picture, with a preponderance of young neutrophils.
2. an increased oxygen affinity of hemoglobin.
shift to the right
1. a preponderance of older neutrophils in the blood picture.
2. a decreased oxygen affinity of hemoglobin.
weight shift
1. the frequent movement of a paralyzed or partially paralyzed patient to redistribute the patient's weight and prevent impairment of circulation, which leads to pressure sores. One variation is the wheelchair pressure release.
2. relocation of a patient's center of mass in order to allow movement; see also gait.

an·ti·gen·ic shift

mutation, that is, sudden change in molecular structure of RNA/DNA in microorganisms, especially viruses, which produces new strains; hosts previously exposed to other strains have little or no acquired immunity to the new strain; antigenic shift is believed to be the explanation for the occurrence of new strains of influenza virus, which occur by recombination or genetic reassortment of two different viral strains in a given host, and is associated with large-scale epidemics.

antigenic shift

a sudden, major change in the antigenicity of a virus, seen especially in influenza viruses, resulting from the recombination of the genomes of two different strains; it is associated with pandemics because hosts do not have immunity to the new strain. Compare antigenic drift.

an·ti·gen·ic shift

(an'ti-jen'ik shift)
Mutation, i.e., sudden change in molecular structure of RNA/DNA in microorganisms, especially viruses, which produces new strains of the microorganism; hosts previously exposed to other strains have little or no acquired immunity to the new strain.

antigenic shift

major changes in surface ANTIGENS caused by the reassortment of GENES between different INFLUENZA VIRUSES. This may involve the mixing of genes from influenza viruses of humans and of animals, such as pigs or ducks. Typically this phenomenon results in a sudden change, approximately every 10 to 15 years, in the predominant type of influenza virus, causing PANDEMICS in humans.

antigenic

having the properties of an antigen.

antigenic competition
the immune response to an antigen may be reduced if an unrelated antigen is administered simultaneously or shortly before. These may be between different molecules (intermolecular) or different determinants on the same molecule (intramolecular).
antigenic drift
point mutations in genes resulting in antigenic change. See also orthomyxoviridae.
antigenic mimicry
similarities between sequences found in microbial proteins and host proteins which may result in cross-reacting immune responses and autoimmune disease.
antigenic shift
genetic reassortment between two subtypes of a viral species resulting in a new subtype with completely different antigenicity. See also orthomyxoviridae.

shift

a change or deviation.

antigenic shift
see antigenic shift.
chloride shift
see chloride shift.
shift to the left
an alteration in the distribution of leukocytes in the peripheral blood in which there is an increase in the numbers of immature neutrophils, primarily band forms but metamyelocytes or more immature cells may also be present; usually in response to an infection.
Enlarge picture
Canine blood smear showing a shift to the left with a segmented neutrophil (left) with toxic vacuolation and a metamyelocyte (right) with two Döhle bodies. By permission from Willard MD, Tvedten H, Small Animal Clinical Diagnosis by Laboratory Methods, Saunders, 2003
shift red cell
shift to the right
an alteration in the distribution of leukocytes in the peripheral blood in which there is an increased number of mature neutrophils but no immature cells are present.
References in periodicals archive ?
Influenza pandemics result from Influenza A undergoing antigenic shift, creating a new virus capable of being transmitted between humans.
Comparison of influenza viruses (a) Characteristic Influenza A Influenza B Genome Negative-strand RNA, Negative-strand RNA, eight segmented genes eight segmented genes Sequence High Moderate variability in HA and NA Mode of antigen Antigenic drift and Antigenic drift only variation antigenic shift Hosts Humans, avian, swine, Humans only equine, marine mammals Epidemiology Epidemic, pandemic Epidemic, nonpandemic (a) RNA, ribonucleic acid; HA, hemagglutinin; NA, neuraminadase.
Mutations also happen due to antigenic shifts similar to Influenza virus A.
The concept is based on identifying alternative influenza antigens that are not as susceptible to antigenic shift and drift.
Conditions favorable for the emergence of antigenic shift have long been thought to involve humans living in close proximity to domestic poultry and pigs.
After an interpandemic interval >35 years, any antigenic shift may again seriously affect young adults, including many pregnant women.
World health authorities fear that if the avian influenza virus undergoes antigenic shift with a human influenza virus, the new subtype created could be both highly contagious and highly lethal in humans.
A more drastic antigenic change, termed antigenic shift, occurs if a new HA subtype is introduced into the pool of human virus strains by reassortment of genes between animal and human strains or by direct transmission of strains from an animal reservoir to humans, as has occurred recently with strains of H5N1, H7N7, and H9N2 (1).
The need for a new vaccine was apparent (7), but early reports consistently described the disease as mild (8), and the US epidemic was over before the A2/Hong Kong virus was recognized as an antigenic shift (9,10).