© Elsevier, 2011.Principles of Molecular Virology Virus Particles Why do viruses make particles to contain the genome? Symmetry allows particles to assemble.

© Elsevier, 2011.Principles of Molecular Virology

Virus ParticlesVirus Particles

• Why do viruses make particles to contain the genome?

• Symmetry allows particles to assemble using only

the information contained within the particle

• The main types of virus particle –

– helical

– icosahedral

– complex structures


Virus Particles Virus Particles


Capsid Symmetry & Virus ArchitectureCapsid Symmetry & Virus Architecture

• 1957: Fraenkel-Conrat and Williams - when mixtures

of purified tobacco mosaic virus (TMV) RNA and coat

protein are incubated together, virus particles form

• Forces that drive the assembly of virus particles

include hydrophobic and electrostatic interactions

• Rarely are covalent bonds involved in holding

together subunits


Helical Capsids - TMVHelical Capsids - TMV

P = µ x p


Bacteriophage M13Bacteriophage M13


Rhabdovirus particleRhabdovirus particle


Icosahedral (Isometric) CapsidsIcosahedral (Isometric) Capsids


Triangulation numberTriangulation number


Geminivirus - twinned icosahedraGeminivirus - twinned icosahedra


Picornavirus ParticlePicornavirus Particle


Eight-strand antiparallel Eight-strand antiparallel -barrel-barrel


Proteolytic processing of Proteolytic processing of picornavirus capsid proteinspicornavirus capsid proteins


Budding of enveloped virus particlesBudding of enveloped virus particles


Envelope proteinsEnvelope proteins


Complex Virus Structures - Complex Virus Structures - Poxvirus particlePoxvirus particle


Assembly pathway of bacteriophage T4Assembly pathway of bacteriophage T4


Baculovirus particlesBaculovirus particles


MimivirusMimivirus


Assembly of tobacco mosaic Assembly of tobacco mosaic virus (TMV) particlesvirus (TMV) particles


SummarySummary

• There are a number of repeated structural patterns

found in many different virus groups

• Virus particles are not inert structures

• Virus particles are designed to interact with host cell

receptors to initiate the process of infection


Further ReadingFurther Reading

Brown, J.C., Newcomb, W.W. and Wertz, G.W. (2010) Helical Virus Structure: The Case of the Rhabdovirus Bullet. Viruses 2: 995-1001

Cherwa, J.E. and Fane, B.A. (2009) Complete Virion Assembly with Scaffolding Proteins Altered in the Ability To Perform a Critical Conformational Switch. J Virol. 83 (15): 7391–7396

Hemminga, M.A., et al. (2010) Viruses: incredible nanomachines. New advances with filamentous phages. Eur Biophys J. 39(4): 541-550

Hutchinson, E.C. et al. (2010) Genome packaging in influenza A virus. J Gen Virol 2010 91: 313-328.

Ivanovska, I.L. et al. (2004) Bacteriophage capsids: tough nanoshells with complex elastic properties. Proceedings of the National Academy of Science USA, 101: 7600–7605

Klug, A. (1999) The tobacco mosaic virus particle: structure and assembly. Philos Trans R Soc Lond B Biol Sci. March 29; 354 (1383): 531–535

Mannige, R.V. and Brooks, C.L. (2010) Periodic Table of Virus Capsids: Implications for Natural Selection and Design. PLoS ONE 5(3): e9423

Maurer-Stroh, S. and Eisenhaber, F. (2004) Myristoylation of viral and bacterial proteins. Trends in Microbiology, 12: 178–185

McKenna, R. et al. (1992) Atomic structure of single-stranded DNA bacteriophage φX174 and its functional implications. Nature, 355: 137–143

Roberts, K.L. and Smith, G.L. (2008) Vaccinia virus morphogenesis and dissemination. Trends in Microbiology 16(10): 472-479

Rohrmann, G.F. (2008) Baculovirus Molecular Biology. NCBI Bookshelf

Xiao C, et al. (2009) Structural Studies of the Giant Mimivirus. PLoS Biol 7(4): e1000092

© Elsevier, 2011.Principles of Molecular Virology Virus Particles Why do viruses make particles to contain the genome? Symmetry allows particles to assemble.

Documents

assembly of virus particles

helical virus structure

tobacco mosaic virus

virus particles form

vaccinia virus morphogenesis

capsid subunits

bacteriophage capsids

entire particle