1. Viral Genetics

2. The objectives What genetic changes are detected in viruses? The effects of viral genetic changes on viral virulence. The application of viral mutants

3. What may cause genetic changes of the virus?

4. 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 rate 3

6. A. Mutation B. Recombination (Reassortment)

7. Attenuated virus Violent virus Recombinant virus HA NA HA NA Hemagglutinin Neuraminidase Lipid bilayer Matrix protein Ribonucleoprotein

8. Antigen drift: gene mutation Antigen shift: gene recommbination

9. Antigen

10. NP: nucleoprotein

11. A.Mutation B.Recombination (Reassortment) C. Transcapsidation: Phenotype of A and genome of B D. Marker rescue

12. An example of viral genetic changes: SARS

13. Molecular analyses by RT-PCR: @ A 405 nucleotide segment of the coronavirus polymerase gene was amplified.

15. What kind of viral mutants may be generated?

16. Mutants Lethal mutant; Plaque mutant; Host-range mutant; Attenuated mutant; Temperature sensitive mutant

17. What is the application of viral mutants? Vaccine Understanding a mutated virus is the first step to find a vaccine

18. Why the virus is used for gene therapy?

19. 1. Rapidly amplified in appropriate cell 2. Deliver the gene without producing infectious virus

20. What viruses are used for gene therapy?

21. Virus-mediated gene transfer in mammalian cells 1. Retrovirus 2. Adenovirus 3. Adenovirus-associated virus 4. Herpes simplex virus

22. What is the defective virus?

23. A. Defective Interfering viral particle (DI) B. Pseudovirion: Virus particle contains host nucleic acid

24. Web site for virology General virology: www.tulane.edu/~dmsander/garryfavwe b.html Taxonomy of viruses: life.anu.edu.au/viruses/Ictv/index.html Infectious diseases: www.gen.emory.edu/medweb/medweb.i d.html

25. Genetic change between viral particles

28. H5N1