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DESCRIPTIONViral Genetics. Hsiao-Sheng Liu . The objectives. What kind of genetic changes are detected in viruses? The effects of viral genetic changes on viral virulence The application of viral mutants. What kind of genetic changes are detected in the virus?. A. Mutation - PowerPoint PPT Presentation
Viral GeneticsHsiao-Sheng Liu
The objectivesWhat kind of genetic changes are detected in viruses?The effects of viral genetic changes on viral virulenceThe application of viral mutants
What kind of genetic changes are detected in the virus?
A. Mutation Poor fidelity of viral polymerase: RNA-dependent RNA polymerase; RNA virus lack of genetic error-checking mechanism (one error per 1x10 nucleotides) Rapid replication rate3
A. MutationB. Recombination (Reassortment)
Attenuated virusViolent virusRecombinant virusHAHANANAHANAHemagglutininNeuraminidaseLipid bilayerMatrix proteinRibonucleoprotein
Antigen drift: gene mutationAntigen shift: gene recombination
C. Transcapsidation: Phenotype of A and genome of BD. Marker rescue
An example of viral genetic changes: SARS
Molecular analyses by RT-PCR:@ A 405 nucleotide segment of the coronavirus polymerase gene was amplified.
What kind of viral mutants may be generated?
MutantsLethal mutantPlaque mutantHost-range mutantAttenuated mutantTemperature sensitive mutant
What is the application of viral mutants?VaccineUnderstanding a mutated virus is the first step to find a vaccine
Why the virus is used for gene therapy?
1. Rapidly amplified in appropriate cell
2. Deliver the gene without producing infectious virus
What viruses are used for gene therapy?
Virus-mediated gene transfer in mammalian cells1. Retrovirus2. Adenovirus3. Adenovirus-associated virus4. Herpes simplex virus
What is the defective virus?
A. Defective Interfering viral particle (DI)B. Pseudovirion: Virus particle contains host nucleic acid
Web site for virologyGeneral virology: www.tulane.edu/~dmsander/garryfavweb.htmlTaxonomy of viruses: life.anu.edu.au/viruses/Ictv/index.htmlInfectious diseases: www.gen.emory.edu/medweb/medweb.id.html
Genetic change between viral particles