Study questions (All topics) -2

Study questions (All topics)

1.   What were some of the important events in the development of virology as an independent science? Who contributed the critical ideas and experimental evidence that led to an understanding that viruses are pathogens unlike any other?
2.  Explain each of the following terms related to types of viruses: (1) covirus (2) satellite virus (3) virusoid (4) viroid (5) defective virus (6) helper virus
3.  Explain each of the following terms: a) Multicomponent virus, b) Segmented genome, c) +, -, ambisense, d) Matrix, e) Core/nucleocapsid, f) Envelope, g) Spikes, h) Capsid, i) Non-structural capsid protein, j) Provirus/prophage, k) Prion, k) Interference/DI particle
4. Explain the officially-recognized system for the nomenclature and classification of viruses. What are some of the popular but unofficial competing systems? Use examples to illustrate your answer.
5. What are some of the problems and pitfalls associated with trivial, historical or non-systematic nomenclature of viruses?
6. Explain the key feature of the Baltimore system and give an example.
7. Explain each of the following terms: a) Suffixes of the ICTV system, b) Order of presentation, c) Polythetic class, d) Virus orders, e) Conservative approach
8. How could you best define a virus species? How does a virus species differ from an animal or plant species as a unit of classification?
9. Explain the term `one-step growth curve’ as it relates to viruses and why is it important? Diagram a typical one-step growth curve, label the parts and explain what they mean. How does one-step growth differ from the growth of a cell?
10. What is a Poisson distribution and how is it used in the study of viruses?
11. Explain the following terms: Direct virus particle counts, Hemagglutination assay, Dilution endpoint,  ID50 or LD 50,  m.o.i., primary culture, cell line, cell strain, Hela cells, Transforming viruses, Cytopathic effect or CPE, Syncytium, Titrate/titer, infectious unit, plaque, PFU, Burst size, “eclipse” or “latent” phase, Systemic/localized infection of plants
12. What sorts of methods would you use to assay a plant, animal or bacterial virus? What type of results would you expect to see and how would you interpret them?
13. Explain the following terms in relation to viruses:

• Reassortment
• Recombination
• Deletion
• Insertion
• Substitution
• Missense/nonsense
• Resistance
• Selection

14. What are the important structural features of the `typical’ icosahedral virion? Use a diagram, if necessary, to illustrate and describe the most important components of the particle. Explain how the different features might vary from one type of virus to another.
15. What are the major experimental approaches used for the study of virus structure? For each of the methods, you cite, provide a brief explanation of how it works.
16. What are some important features of the icosahedron and what are its evolutionary advantages? Why is the icosahedron the preferred basic shape of viruses with cubic symmetry?
17. Explain the following terms as they relate to viral structure (you should be able to relate these to a diagram of an icosahedron or to an image of a virion):

(a) icosahedron

(b) icosadeltahedron

(c) face

(d) facet

(e) vertex

(f) edge

(g) triangulation number,T

(h) pseudotriangulation number, P

(i) morphological subunit or capsomere

(j) 60T

(k) quasi-equivalence

(l) beta-barrel

(m) structural subunit

(n) domain

(o) surface lattice

(p) hexamer and pentamer

(q) phage HK97

18. Two overall principles may be said to govern the morphology of viruses (Genetic Economy; Equivalence or Quasi-equivalence). Explain what these principles mean and describe how they relate to the structure of viruses.
19. What are the three major types of symmetry associated with viral particles and what shape do the respective particles assume? Which two of the three types are most commonly found? Provide examples of viruses of these two types. What are the advantages and disadvantages associated with these two types of symmetry? 5) What are the two major types of symmetry associated with viral particles and what shape do the respective particles assume? Which two of the two types are most commonly found? Provide examples of viruses of these two types. What are the advantages and disadvantages associated with these two types of symmetry?
20. Why is the icosahedron the preferred basic shape of viruses with cubic symmetry? What are some important features of the icosahedron and what are its evolutionary advantages?
21. What are some examples of viruses with structurally complex capsids and what makes these capsids complex?
22. What is an infectious DNA clone of a virus and why is it considered the “holy grail” of virology?
23. Names that you should recognize in virology

Caspar and Klug

Watson and Crick

Beijerinck

Iwanowski

Mayer

Loeffler and Froesch (sp?)

Stanley Prusiner

Ellis and Delbruck