virology lec 1:2012

VIROLOGYMarilen M. Parungao-Balolong

(Reference: http://pathmicro.med.sc.edu/book/virol-sta.htm)

Thursday, January 19, 2012

http://pathmicro.med.sc.edu/book/virol-sta.htm

http://pathmicro.med.sc.edu/book/virol-sta.htm

REMAINING CALENDAR


TOPICS TO COVER

• CLASSIFICATION

• REPLICATION

• DIAGNOSTICS

• PUBLIC HEALTH VIRUSES

• EMERGING & RE-EMERGING VIRUSES


PLENARY REPORTS• CLASS MUST HAVE 6 GROUPS

(7-8 PEOPLE EACH GROUP)

• A TOPIC WILL BE ASSIGNED & TO BE REPORTED FORMALLY IN CLASS

• FOCUS: ADVANCES IN DIAGNOSTICS

• 3 GROUPS PER MEETING (MARCH 9 & 16)


TOPICS• ADVANCES IN LABORATORY DIAGNOSTICS

(THEN & NOW)

• INFLUENZA (AH1N1 @ SEASONAL FLU)

• INFLUENZA (AVIAN FLU)

• DENGUE

• HIV

• HEPATITIS A/B/C

• SARS


VIROLOGYINTRODUCTION


INTRODUCTION• VIROLOGY

• scientific study of viruses and the disease they cause

• VIRUSES

• an infective agent typically consists of nucleic acid in a protein coat

• too small to be seen by light microscopy

• multiply within living cells of host (obligate parasite)

• filterableParungao-Balolong 2011-2012


VIRUSES•Contain DNA or RNA

•Contain a protein coat (capsid)

• Some are enclosed by an envelope

• Some viruses have spikes

•Most viruses infect only specific types of cells in one host

•Host range is determined by specific host attachment sites and cellular factors

Parungao-Balolong 2011Thursday, January 19, 2012

VIRUSES

Parungao-Balolong 2011Thursday, January 19, 2012

RELATIVE SIZES & TOOLS

Parungao-Balolong 2011-2012

Jane Flint Principles of Virology, 2004


ARE THEY ALIVE?

• Viruses challenge the way we define LIFE:

• they do not respire

• they do not display irritability

• they do not move

• they do not “grow”

• WHAT THEY DO: they reproduce and adapt to new hosts

Parungao-Balolong 2011-2012Thursday, January 19, 2012

STRATEGIES FOR SURVIVAL

• Genomes are packaged inside a particle (transmission)

• Genome contains all information needed for infection cycle (attachment to release)

• Establishment in a host population


NATURE OF VIRUSES• Viruses are Small Particles


• Viruses Have Genes

• virus use host cell proteins

• virus code efficiently

• multifunctional


NATURE OF VIRUSES


• Viruses are Parasites


NATURE OF VIRUSES


DOWN MEMORY LANE...

• Dmitri Iosifovich Ivanowsky (1892)

• Martinus Beijerink (1898)

• Filterable agent: Tobacco Mosaic Virus


OTHERS FOLLOWED...

• Freidrich Loeffler & Paul Frosch (1898)

• Foot & Mouth Disease Virus


THE THIRD PARTY..• Walter Reed (1899)

• Yellow fever: transmission by insect vectors


LINKS TO CANCER???

• VIRUSES AND ONCOGENESIS

• Ellerman and Bang (1908)

• Chicken leukemia

• Peyton Rous (1911)

• Rous Sarcoma virus


AND THEN, THERE WERE THE PHAGES

•Bacteriophages Era

• Frederick Twort (1915)

• discovery of phages

• Felix D’ Herelle (1917)

• role in immunityParungao-Balolong 2011-2012


AND THE REST IS HISTORY

• Wendell Stanley (1935): crystallization of TMV

• Delbruck (1940s): modern molecular biology and virology

• Lwoff (1949): discovery of lysogeny

• Enders et al., (1949): poliovirus and tissue culture/plaque assays

• 1980s: Immunology and PCR technology was Parungao-Balolong 2011-2012


WHY DO WE STUDY VIROLOGY?

• Some Viruses Cause Disease


Common Cold

Rabies

HIVSmallpox




Pepper Mottle Virus

Cauliflower Mosaic Virus

Tobacco Mosaic Virus

Rice Tungro Virus

Papaya Ringspot Virus





Foot & Mouth Disease

Classical Swine Fever

Avian Flu

Porcine Reproductive & Respiratory Syndrome (PRRS)

Ebola





AH1N1



• Some Viruses are Useful

• Phage Typing of Bacteria

• e.g. Salmonella spp.

• classified into strains on the basis of the spectrum of phages to which they are susceptible

• advantage: EpidemiologyParungao-Balolong 2011-2012




• Sources of Enzymes

• RNA polymerase (T7 phage)

• Genetic Pesticides

• gene from baculovirus against worms





• Gene Vector for Protein Production

• baculovirus, adenovirus

• vaccine component

• Gene Vector for Treatment of Genetic Diseases

• retrovirus

• immunodeficient casesParungao-Balolong 2011-2012



• Virus Studies Have Contributed to Knowledge

• Hershey and Chase experiment (T2 phage)





• Characterization of enhancers (genes of Simian SV 40)

• Characterization of transcription factors and localization of protein signal (genes of Simian SV 40)





• Discovery of introns (adenovirus)

• Role of cap structure at 5’ end of eukaryotic mRNA (vaccinia and reovirus)

• discovery of internal ribosomal entry site (RNA of poliovirus)

• discovery of RNA pseudoknot (turnip yellow mosaic virus)




NEXT MEETINGSTRUCTURE, CLASSIFICATION & REPLICATION


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