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Prepared by Max Darnell - AP225 Fall 2011


Image Courtesy Graham Colm, Sept 20, 2008

Viruses are very small biological constructs which contain either DNA or RNA. As they lack cellular machinery and rely on an infected cell to actually replicate their viral genomes, there is debate as to whether viruses should be considered "living." A virus consists of three main parts.

1) Genetic Material - This can be either DNA or RNA. Upon a viral infection, the virus inserts its genome into the host cell, where it is processed by various polymerases.

2) Protein capsid - this is a simple protein "shell" which envelops the genetic material and gives the virus structure.

3) Coat - there may exist certain proteins or lipids on the surface of the virus that identify the virus and aid in receptor binding to the cell surface. These surface modifications to the virus can induce an immune response in the host organism.

The figure below is a schematic of a bacteriophage (virus that infects bacteria) inserting its DNA .

Applications/Connections to Soft Matter

In medicine, viruses are modified and then used as vaccines, where they elicit an immune response and confer immunological "memory" without being infectious. In molecular biology, viruses are used as a means of delivery for genetic material. There are currently a number of clinical trials using viruses as the delivery vehicle for gene therapy.

Image from Angela Belcher Lab

There is growing interest, however, in viruses as a nanotechnology building block.


Alberts, B., Johnson, A., Lewis, J., Raff, M., Roberts, K., & And Walter, P. (2008). Molecular Biology of the Cell. (Bruce Alberts, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, & P. Walter, Eds.) Garland Press.

Blum AS, Soto CM, Wilson CD et al. (2005). "An Engineered Virus as a Scaffold for Three-Dimensional Self-Assembly on the Nanoscale". Small 7: 702.

Neltner, B., Peddie, B., Xu, A., Doenlen, W., Durand, K., Yun, D. S., Speakman, S., et al. (2010). Production of hydrogen using nanocrystalline protein-templated catalysts on m13 phage. ACS nano, 4(6), 3227-3235.

Keyword in references:

Phase Diagram and Effective Shape of Semiflexible Colloidal Rods and Biopolymers