virology lecture 2 (viral structure)
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TRANSCRIPT
Marilen M. Parungao-Balolong
Reference: Chapter 3 Carter And Saunders, 2007)
VIRAL STRUCTURE & CLASSIFICATIONS144 Lecture 2 (Virology)
http://www.virology.ws
Thursday, June 30, 2011
winfoin.com
SKILLS, VALUES, OUTPUTS
✤ Listening, Writing and Oral Communication Skills
✤ Critical Analysis and Organization of Ideas
✤ Appreciate Importance of Viral Structure
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
LECTURE OUTLINE
✤ Recall: Viruses Introduction
✤ Structure of Viruses
✤ Functional Anatomy
✤ Classification
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
REFERENCES
✤ Carter and Saunders, 2007 (Chapter 3)
✤ Gelderblom, 2010 (Chapter 41)
✤ (Bookshelf ID: NBK8174 PMID: 21413309)
✤ http://www.ncbi.nlm.nih.gov/books/NBK8174/
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
LECTURE OUTLINE
✤ Recall: Viruses Introduction
✤ Structure of Viruses
✤ Functional Anatomy
✤ Classification
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
VIRUSES: INTRODUCTION
✤ Viruses are small obligate intracellular parasites
✤ Contain either a RNA or DNA genome surrounded by a protective, virus-coded protein coat
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
VIRUSES: INTRODUCTION
✤ Viruses may be viewed as mobile genetic elements, most probably of cellular origin and characterized by a long co-evolution of virus and host
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
bio3400.nicerweb.net
Thursday, June 30, 2011
VIRUS: INTRODUCTION
✤ Propagation depend on specialized host cells supplying the complex metabolic and biosynthetic machinery of eukaryotic or prokaryotic cells
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
ncbi.nlm.nih.gov
Thursday, June 30, 2011
LECTURE OUTLINE
✤ Recall: Viruses Introduction
✤ Structure of Viruses
✤ Functional Anatomy
✤ Classification
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
virology.ws
medical-dictionary.thefreedictionary.com
Thursday, June 30, 2011
dvm5.blogspot.com
Reference: Chapter 3 Carter And Saunders, 2007)
Marilen M. Parungao-Balolong 2011
Thursday, June 30, 2011
CORONAVIRUS STRUCTURE: SARS
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
http://learn.genetics.utah.edu/archive/sars/index.html
Thursday, June 30, 2011
THE CORE: GENOME
✤ Except in helical nucleocapsids, little is known about the packaging or organization of the viral genome within the core
✤ SMALL VIRIONS:
✤ simple nucleocapsids
✤ containing 1 to 2 protein species
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Copyright © 1996, The University of Texas Medical Branch at Galveston.
Thursday, June 30, 2011
THE CORE: GENOME
✤ LARGE VIRIONS:
✤ nucleic acid genome complexed with basic protein(s)
✤ protected by a single- or double layered capsid or by an envelope
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Copyright © 1996, The University of Texas Medical Branch at Galveston.
Thursday, June 30, 2011
CHEMICAL COMPOSITION OF GENOME
✤ The genome of a virus may consist of DNA or RNA, which may be single stranded (ss) or double stranded (ds), linear or circular
✤ The entire genome may occupy either one nucleic acid molecule (monopartite genome) or several nucleic acid segments (multipartite genome)
✤ The different types of genome necessitate different replication strategies
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
INTRODUCTION TO VIRUS STRUCTURE
✤ TYPES OF VIRION STRUCTURE
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
TYPES GENOMESGENOMESGENOMESGENOMES
dsDNA ssDNA dsRNA ssRNA
Icosahedral (naked)
Icosahedral (Enveloped)
Helical (naked)
Helical (Enveloped)
Thursday, June 30, 2011
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
http://www.mansfield.ohio-state.edu/~sabedon/017vrgnm.gif
Thursday, June 30, 2011
VIRUS GENOMES
✤ dsDNA✤ encode their genes in the same kind of
molecule as animals, plants, bacteria and other cellular organisms
✤ ssDNA, dsRNA, ssRNA✤ unique to viruses
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
ARRANGEMENT OF GENOME
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
GENOME EXAMPLEssDNA, linear ParvovirusdsDNA, linear Poxvirus
ssDNA, circular Phage X174dsDNA, circular Baculoviruses
ssRNA, linear Tobacco Mosaic VirusdsRNA, linear Reovirus
ssRNA, circular Hepatitis D virus
Note: there are no viruses known with circular dsRNA genomes
Thursday, June 30, 2011
USUALLY....
✤ FUNGI VIRUSES
✤ dsRNA
✤ PLANT VIRUSES
✤ ssRNA
✤ PROKARYOTIC VIRUSES
✤ dsDNAMarilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
sdnhm.org
http://www.whmsoft.net
topnews.in
Thursday, June 30, 2011
POINTS TO REMEMBER...
✤ Some linear molecules may be in a circular conformation as a result of base pairing between complimentary sequences at their ends
✤ Example:✤ DNA in Hepadnavirus✤ RNA in Influenza virions
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
virology.ws
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
medical-dictionary.thefreedictionary.com
Take note of the nucleocapsid and envelope
THE CAPSID: PROTEIN CORE
Thursday, June 30, 2011
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
THE CAPSID: PROTEIN CORE
Structure of adenovirus. The icosahedral capsid structure of adenovirus is made up of three proteins, hexon, penton base, and fiber. A cross-sectional view of the viral capsid. Some proteins are associated with viral DNA, whereas others are associated with hexon and are involved in the formation of the capsid.
Thursday, June 30, 2011
MORPHOLOGY : Helical
✤ Helical morphology is seen in nucleocapsids of many filamentous and pleomorphic viruses
✤ Helical nucleocapsids consist of a helical array of capsid proteins (protomers) wrapped around a helical filament of nucleic acid
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
The helical structure of the rigid tobacco mosaic virus rod
Copyright © 1996, The University of Texas Medical Branch at Galveston.
Thursday, June 30, 2011
MORPHOLOGY : Helical
✤ In the replication of viruses with helical symmetry, identical protein subunits (protomers) self-assemble into a helical array surrounding the nucleic acid, which follows a similar spiral path
✤ Nucleocapsids form rigid, highly elongated rods or flexible filaments
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
MORPHOLOGY : Helical
✤ Details of the capsid structure are often discernible by electron microscopy
✤ NOTE: Helical nucleocapsids are characterized by length, width, pitch of the helix, and number of protomers per helical turn
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Fragments of flexible helical nucleocapsids (NC) of Sendai virus, a paramyxovirus, are seen either within the protective envelope (E) or free, after rupture of the envelope
Copyright © 1996, The University of Texas Medical Branch at Galveston.
Thursday, June 30, 2011
MORPHOLOGY
✤ Icosahedral morphology is characteristic of the nucleocapsids of many “spherical” viruses
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
MORPHOLOGY
✤ Lines through opposite vertices define axes of fivefold rotational symmetry: all structural features of the polyhedron repeat five times within each 360° of rotation about any of the fivefold axes
✤ Lines through the centers of opposite triangular faces form axes of threefold rotational symmetry; twofold rotational symmetry axes are formed by lines through midpoints of opposite edges.
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Icosahedral models seen, left to right, on fivefold, threefold, and twofold axes of rotational symmetry
Copyright © 1996, The University of Texas Medical Branch at Galveston.
Thursday, June 30, 2011
MORPHOLOGY
✤ Viruses were first found to have 532 symmetry by x-ray diffraction studies
✤ Electron microscopy with negative-staining techniques
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Adenovirus after negative stain electron microscopy
Copyright © 1996, The University of Texas Medical Branch at Galveston.
Thursday, June 30, 2011
MORPHOLOGY
✤ PROTOMERS:
✤ structural polypeptide chains
✤ arranged in oligomeric clusters (capsomeres)
✤ readily delineated by negative staining electron microscopy
✤ form the closed capsid shell
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Adenovirus after negative stain electron microscopy
Copyright © 1996, The University of Texas Medical Branch at Galveston.
Thursday, June 30, 2011
THE CAPSOMERES
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
pc.maricopa.edu
Thursday, June 30, 2011
CAPSOMERES & ENVELOPE
✤ The number and arrangement of the capsomeres are useful in identification and classification
✤ Many viruses also have an outer envelope
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Envelope of Herpesvirus
biologie.uni-hamburg.de
Thursday, June 30, 2011
CAPSID & ENVELOPE
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
pc.maricopa.edu
Thursday, June 30, 2011
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
THE ENVELOPE
✤ Envelope consists of a lipid bilayer with proteins (usually glycoproteins) imbedded in it
✤ Lipids derived from host cell
✤ Proteins encoded by the virus
✤ Envelope is important in determining host cell specificity & some aspects of cell penetration are affected by it
Thursday, June 30, 2011
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
ENVELOPED VIRUSES
Thursday, June 30, 2011
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
COMPLEX VIRUSES
Thursday, June 30, 2011
LECTURE OUTLINE
✤ Recall: Viruses Introduction
✤ Structure of Viruses
✤ Functional Anatomy
✤ Classification
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
bbc.co.uk
Thursday, June 30, 2011
STRUCTURE IN RELATION TO FUNCTION
✤ Core
! ! ! a.! DNA or RNA
! ! ! b.! Contains genetic
information
! !
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
ncbi.nlm.nih.gov
Thursday, June 30, 2011
STRUCTURE IN RELATION TO FUNCTION
✤ Capsid
! ! ! a.! Outer protein coat
! ! ! b.! Functions
! ! ! ! 1).!Protects core
! ! ! ! 2).!Shape of the virus
! ! ! ! 3).!Attachment to host
cell membrane (by means of
spikes)Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
sparknotes.com
library.thinkquest.org
Thursday, June 30, 2011
STRUCTURE IN RELATION TO FUNCTION
✤ Envelope
✤ Membrane around capsid - enveloped virus
✤ Not all viruses have envelope
✤ If lack envelope - naked virus!
✤ Composed of:
✤ Bilayer of phospholipids and proteins
✤ Derived from host bell membrane during viral multiplicationMarilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
microscopicblog.blogspot.com
Thursday, June 30, 2011
STRUCTURE IN RELATION TO FUNCTION
✤ Functions :
✤ Protection from drying (enhances transmission)
✤ Makes virus more susceptible to chemical agents that dissolve lipids
✤ Attachment to host cell membrane (by means of spikes)
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
wpro.who.int
me-you-and-virus.blogspot.com
Thursday, June 30, 2011
LECTURE OUTLINE
✤ Recall: Viruses Introduction
✤ Structure of Viruses
✤ Functional Anatomy
✤ Classification
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
✤ Viruses are grouped on the basis of size and shape, chemical composition and structure of the genome, and mode of replication
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
PLANT VIRUSES
Marilen M. Parungao-Balolong 2011 Reference: Chapter 13 TortoraMicrobiology
Thursday, June 30, 2011
CLASSIFYING ENVELOPED VIRUS BASED ON SHAPE...
✤ Sphere (eg. Influenza virus)
✤ Bullet (e.g. Rabies virus)
✤ Rod (e.g. Baculovirus)
✤ Thread (e.g Ebola virus)
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011
CLASSIFYING VIRUS BASED ON GENOME...
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
antiviralintelistrat.com
Thursday, June 30, 2011
Date
END OF LECTURE 2
Marilen M. Parungao-Balolong 2011 Reference: Chapter 3 Carter And Saunders, 2007)
Thursday, June 30, 2011