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DictionarySeeshiftantigenic shift
antigenic shift[‚an·tə¦jen·ik ′shift] (virology) An abrupt major change in the antigenicity of a virus; believed to result from recombination of genes. antigenic shift
shift [shift] a change or deviation.antigenic shift a sudden, major change in the antigenicity of a virus, seen especially in viruses" >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 drift" >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 release" >wheelchair pressure release.2. relocation of a patient's center of mass in order to allow movement; see also gait.an·ti·gen·ic shiftmutation, 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.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. |