NATS 1670 Lecture Notes - Lecture 18: Aspirin, Fetus, Reassortment
23 Apr 2016
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Document Summary
The virus from last year is not going to be the same for this year, therefore vaccine is not useful: antigenic drifts in influenza virus is induced by high mutations rate, rna virus consists of 8 segments. Rna dependent rna polymerase is not linked to a significant proofreading mechanism. Antigenic drift: in influenza types a, b and c, high mutation rate in rna viruses causes gradual changes. Minor antigenic change: immune response no longer protects fully, sporadic outbreaks, limited epidemics, why we need a new vaccine each year (graph), last year virus is going to be different. Epidemic more causes in a specific region with greater frequency. Pandemic infection that takes place southern and northern hemisphere: antigenic shifts, haemagglutinin (ha)h3n2, h5n1neuraminidase (na, influenza type a only, major antigenic change. New subtype (>15% different) of ha or/and na proteins: pre-existing antibodies do not protect. No preexisting immunity: may lead to pandemics.
