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Dive into the world of virology, understanding viruses from their structure-dynamics-function relationships to self-assembly and viral life cycles. Explore principles of viral capsid architecture, including symmetry, subunits, and assembly processes. Discover the dynamic nature of virus capsids and their interactions with host cells. Engage in practical exercises using VIPERdb to analyze virus structures and conserved regions. Enhance your knowledge of viral capsids through interactive movies and hands-on alignment tasks. Unravel the secrets of viral diversity and host interactions in this comprehensive introduction to structural and molecular virology.
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Introduction to Structural and Molecular Virology Yaroslav Daniel Bodnar University of Illinois at Urbana-Champaign
Viruses Highlight Some Big Ideas • Structure-Dynamics-Function relationships. • A systems perspective: Understanding of complex function by looking at its components. • Self-assembly gives rise to complex forms in biological systems. • Using a simplified model system to understand a broad range of more complex phenomena.
A Few Surprises • Mutual symbiosis between Polydnaviruses and parasitic wasps. • Oncolytic Virotherapy: Seneca Valley Viruses
Wendell M. Stanley1946 Nobel Prize in ChemistryCrystallized Tobacco Mosaic Virus andSystematically Investigated its Biochemistry
A Trip Inside of HPV PLAY MOVIE 1 (HPV Density Map)
What the nucleocapsid and other accessory viral proteins need to do? • Protect viral genome: needs to be fully enclosed. • Needs to be inert outside the cell and move freely in-search of a new host. • Needs to be a dynamic structure: • Change (“activate”) in response to a specific stimulus. • Occurs in a series of “programmed” stages.
Symmetry of Viral Capsids Icosahedral Helical
AsymmetricSubunit • Each subunit consists of four proteins. • Capsid proteins interact by highly specific, flexible non-covalent contacts. • Long terminal extensions and loops make each viral capsid unique.
Repeat the Asymmetric Subunit to “Tile” the Surface of the Capsid
“Quasi-Equivalence” is a Necessary Property of Enclosed Surfaces
Triangulation Numbers • How many equilateral triangles can fit on one face? • The size of each capsid protein must stay approximately the same. • How do you make a larger capsid? ...Increase the triangulation number!
You can make viruses in a test tube! Play Movie 3 (Virus Self-Assembly)
Play movie at: http://www.molecularmovies.com/movies/gp41_061008.html
VIPERdb Exercise 1:(http://viperdb.scripps.edu/) • Explore VIPERdb. Be sure to visit viruses of different families and T-numbers. While you surf, write down the T-number, excess surface charge, and average radius of each virus. Some search suggestions include: • Picornaviruses: • POLIO: Poliovirus (Type 1; Mahoney strain) • POLIO: Poliovirus/Receptor Complex • COMMON COLD: Human Rhinovirus 16 • COMMON COLD: Human rhinovirus 16 with Receptor • Hepadnaviruses: • HEPATITIS: Human Hepatitis B Viral Capsid • Papillomaviruses: • HPV (CERVICAL CANCER): Human Papilloma Virus 16 L1 Capsid
Did you find a relationship between the T-number and the size of the viruses? Why may this be? • Clue: Most virus capsid proteins are approximately the same size. • Did you notice a trend in the charge of virus capsids? Do they tend to be positively or negatively charged? Why does this make sense? • Clue: Remember that virus capsids are essentially “molecular containers.” What do they contain? What is the charge of the contents?
VIPERdb Exercise 2 • Load 6 to 10 viruses from the same family into STRAP and perform a multi-sequence alignment. • Choose one of the viruses from above and list several of the most highly conserved regions. • Why do you think that these conserved regions are important? What do you think they do? Use structural information and other information available on VIPERdb to support your answer. • Suppose you want to identify regions of your virus that interact with antibodies. How can you use VIPERdb to do this? • Hint: Different strains (or serotypes) of a virus are characterized by which antibodies bind to them. This means that different strains of the same virus will differ in the regions you're interested in.