Biological Nanomachines: Viruses

What are Viruses? Extremely efficient and well-designed to enter the body, travel through blood- stream, then attach, invade and infect cells Scientists are interested in viruses for both their efficient biological function & their architecture & self-assembling behavior

How Big is a Virus? A typical virus is 20 to 250 nm in length A bacterium is huge (2 or 3 mm) compared to a virus

Viral Anatomy Viruses do not have a brain, sensory receptors, reproductive system or independent movement Able to perform purely through architectural and biochemical design Solving the mysteries of virus design & function gives clues on how to build artificial nanomachines

Are Viruses Living or Nonliving? Cannot answer because scientists have not clearly defined what it means to be living! Does genetic material or needing food mean it is alive? More complicated than simple molecules or complex proteins yet much simpler than a single-celled organism

Are Viruses Living or Nonliving? Made of proteins & nucleic acids –Nucleic acids (RNA or DNA) packed in a “box” made of proteins Some have a lipid membrane Evolve & mutate Ability to reproduce using host cell Does not require food to exist How would you define a virus?

Why are Some Viruses Harmful? Viruses can infect bacteria, plants & animals (humans included!) The same virus does not infect a dog or plant that infects a human Bacteriophage Common Cold Virus

Are All Viruses Dangerous? Viral infections can range from a wart to Ebola (very serious), but viruses can be used to help cure diseases as well! Modify the virus to be a gene vector Gene Therapy: This vector arrives at the target cell and alters the cell’s DNA by inserting the gene into the cell’s genetic material –Example: insert an insulin gene into a diabetic patient’s cells to produce insulin again

What Makes Something a Virus? Shared Characteristics: –Parasites that invade cells –Has DNA or RNA that are gene codes for reproduction of virus AND other reprogramming of the host cell –Direct the synthesis of new viruses within the cell to infect new cells

Virus Structure Viruses are covered by a protein coat known as a capsid 2 kinds of Virus Shapes: 1) Helical capsids –Filament-shaped structure with RNA in the center (e.g. Tobacco Mosaic Virus)

Virus Structure cont. 2) Icosahedral capsids –Most common shape (e.g. pinkeye or common cold) –DNA or RNA found at core Enveloped Viruses (helical or icosahedral capsids) –Viruses that have a lipid coating –Common in animal viruses (e.g. Herpes & HIV) HIV Common Cold Virus

Future Technology using Viruses Exploring ways to use viruses as tiny vessels to deliver –Deliver drug therapy (cancer patients –Repair faulty or mutated DNA –Act like tiny sensors Able to do this because –Viruses are have very specific bonding to a specific host cell Hope to cure diseases using this gene therapy –Diabetes, cystic fibrosis or Parkinson’s disease