8: Mutations Flashcards
What is mutation?
- independent changes in the genetic material
- the source of evolution
What causes mutation?
failures in the NA replication
- Cell: 10^9
- DNA virus: 10^5
- RNa virus: 10^3
What are the type of mutations?
- spontaneous
- induced
What are the types of induced mutation?
- irradiation: UV, X-ray, atomic radiation
- mutagenic drugs: halogenated uridine
What are the different forms of mutation?
- point mutation
- sequence mutations
- substitution
- insertion
- deletion
- inversion (frame shift)
What are the results of mutation?
- silent mutation
- lethal mutation
- conditionally lethal mutation
- beneficial mutation
What is Silent mutation?
no phenotypic change
- untranslated region
- redundant translation code
- not important amino acid
What is Lethal mutation?
nonsense (stop) or missense (aa. change)
What is Conditionally lethal mutation?
- changes in the multiplication activity
- i.e: thermo-sensitive mutants
What is Beneficial mutation?
- rare
- accidental
What are the influences on the viral phenotype?
- antigenic change
- changes in host species specificity
- changes in organ specificity
- different tissue tropism (cell cultures
- virulence variants
- cytopathic effect, plaque formation
- temperature optimum
Antigenic change on the viral phenotype:
- escape mutants
- influenza - antigenic drift
Changes in host species specificity on the viral phenotype:
- feline panleucopena –> canine parvoenteritis
- SIV –> HIV
Changes in organ specificity on the viral phenotype:
- EHV1: abortion EHV4: rhinopneumonitis
- IBR: rhinotracheitis IPV. vulvo-vaginitis
Different tissue tropism (cell culture) on the viral phenotype:
Bovine Adenovirus - kidney/testicular cells
