antigenic shift

antigenic shift

n.

A sudden, major change in the antigenic structure of a virus, usually the result of genetic mutation.

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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.

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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.

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antigenic

having the properties of an antigen.

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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.

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shift

a change or deviation.

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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.

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

see macroreticulocyte.

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.