1. discovery and structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... ·...
TRANSCRIPT
![Page 1: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/1.jpg)
Chapter 5. Viruses (at the threshold of life)
1. Discovery and Structure of viruses
What is virus ?
- virus : living things or not ? -> “organules” “molechisms”
- Golden age of microbiology (1880 - 1915)
-> increased understanding of infectious disease (tuberculosis, typhoid fever..)
-> industrial utilization of microbes
-> importance of microbes in environments
Yet unknown causation of some disease (measles, chickenpox, polio, hepatitis)
“ i ” d t f t k id tit f i f ti di“virus” was used to refer to unseen or unknown identity for infectious disease
- bacterium for tuberculosis d b i ?bacterium for tuberculosis- protozoan for malaria
caused by virus ?
The true nature of virus remained a mystery
![Page 2: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/2.jpg)
Chapter 5. Viruses (at the threshold of life)
1) Development of virology1) Development of virology
- 1892, Dmitri Iwanowski :
-> attempting to isolate bacterial cause of tobacco mosaic diseasep g
-> use filter to trap smallest known bacteria
-> filtered juice contained infectious agent -> called filterable virus
- 1898, Martinus Beijerinck , j
-> diluted filtered juice -> still infectious -> called contagious living fluid
- 1930s, Wendell M. Stanley : crystalization of tobacco mosaic virus
-> implies that TMV is chemical molecule> implies that TMV is chemical molecule
-> viral disease caused fever, a response by immune system or other symptom
- 1933, electron microscope 발명 -> TMV 전자사진
![Page 3: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/3.jpg)
Chapter 5. Viruses (at the threshold of life)
2) Structure of viruses2) Structure of viruses
- size : 27nm(poliovirus) ~ 250nm(smallpox virus)
- 500 or more viruses fit inside a single bacterial cellg
![Page 4: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/4.jpg)
Chapter 5. Viruses (at the threshold of life)
2) Structure of viruses2) Structure of viruses
- shape : helical, icosahedral, complex type
HIV
![Page 5: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/5.jpg)
Chapter 5. Viruses (at the threshold of life)
3) Component of viruses3) Component of viruses
- genome : core of nucleic acid
-> DNA or RNA, not both
-> long and helical, or folded
-> single molecule, occasionally segmented
- capsid : coat of protein -> consisted of capsomerescaps p capsom r s- nucleocapsid : combination of genome and capsid
- envelope : membrane-like envelope enclosing nucleocapsid
- no cytoplasmno cytoplasm
☞ spikes : projections on the envelope
-> contacting virus to its host
-> assist penetration into host cell
![Page 6: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/6.jpg)
Chapter 5. Viruses (at the threshold of life)
![Page 7: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/7.jpg)
Chapter 5. Viruses (at the threshold of life)
☞ 생물체로서의 미생물의 특징
- 성장을 위한 영양분의 흡수, 소화
소화산물의 배설- 소화산물의 배설
- 독립적 생식능력
- 환경변화에 대한 적응능력
생물계 구성원의 공통특징
- 자극에 대한 반응능력
☞ virus의 생화학적 특징- no chemistry going on within a virus
- no intake of nutrientno intake of nutrient
- no production of waste
- no increase or decrease in size
- no metabolism
- but, they replicate
-> programs a host cell biochemically to produce hundreds of copiesp g y p p
![Page 8: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/8.jpg)
Chapter 5. Viruses (at the threshold of life)2 Viral replication2. Viral replication
- virus : inert particle outside a host cell
-> becomes highly efficient replicating machine in the host cell
-> utilize metabolism of the cell-> utilize metabolism of the cell
-> produces multiple copies of itself in several stages
1) Stages of replication(1) attachment stage
- high degree of specificity for a certain host
- 1. protein molecule in envelope keys off receptor sites(lock) in the host cell
- 2. or viral tail attaches to receptor sites
- 3. or blending of viral envelope with host cell membrane
- 4. or by phagocytosis
![Page 9: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/9.jpg)
X 200,000
Viral attachmnet
X 70,000
![Page 10: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/10.jpg)
Chapter 5. Viruses (at the threshold of life)
(2) penetration stage
- nonenveloped virus is left outside the host cell, the genome passes into the cell
(3) uncoating stage
- within the cell, cellular protein removes the protein capsid from the viral genome
(4) synthesis stage
- viral proteins are synthesized from viral genome using cellular machinery
(5) assembly stage
- viral parts are combined to form new viral particles after synthesis is completed
(6) release stage
- viral envelope is built from cellular membrane
-> disrupt cell membrane => lytic cycle
![Page 11: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/11.jpg)
Replication of Enveloped virusReplication of Enveloped virusp pp p
![Page 12: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/12.jpg)
Cli k iClick to view animation.
animation
![Page 13: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/13.jpg)
Unenveloped virusUnenveloped virus
![Page 14: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/14.jpg)
Chapter 5. Viruses (at the threshold of life)
2) L tic and l s enic c cle2) Lytic and lysogenic cycle
- some times, virus enters a host cell but do not replicate immediately =>lysogeny- lysogenic cycle : y g y
-> virus incorporates its genes into the host genes and becomes part of it
-> multiply together with host genes => becomes provirus(oncogene)
![Page 15: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/15.jpg)
Chapter 5. Viruses (at the threshold of life)
Lytic and lysogenic cycleLytic and lysogenic cycle
![Page 16: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/16.jpg)
Chapter 5. Viruses (at the threshold of life)
Lysogenic and lytic cycleLysogenic and lytic cycle
Cli k i Cli k iClick to view animation.
Click to view animation.
animation
![Page 17: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/17.jpg)
Chapter 5. Viruses (at the threshold of life)3) Viriods and prions3) Viriods and prions
- Viriods : single-stranded molecules of RNA without protein coat
-> infect plants causing disease
- Prions : proteineous infectious particle
-> composed solely of protein, extremely stable
-> transformed from prion protein(PrP, harmless protein in itself in brain cell)
-> PrP : protect cells by helping rid of dangerous chemicals
-> prion : clump together -> block molecular traffic
3 Viruses and Cancer3. Viruses and Cancer- Cancer : results from uncontrolled reproduction of cells
-> grows into abnormal, functionless mass of cells => tumor- body’s response to the tumor
-> surrounding it with a capsule of connective tissue => benign-> outgrowth and break out of the capsule and spread => malignant
- Properties of cancer cell differing from normal cells
-> more rapid growth than normal cell
-> stick together less firmly than...
-> undergo dedifferentiation (reverting to an early stage to divide indefinitely
-> fail to exhibit contact inhibition -> not stop growing when contacted
![Page 18: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/18.jpg)
Chapter 5. Viruses (at the threshold of life)
Contact inhibitionContact inhibition
![Page 19: 1. Discovery and Structure of viruseswebbuild.knu.ac.kr/~app-mic/resources/lecture... · 2015-08-31 · -> diluted filtered juice -> still infectious -> called contagious living fluid-1930s,](https://reader033.vdocuments.us/reader033/viewer/2022041523/5e2fa7dc14cf952a052acedb/html5/thumbnails/19.jpg)
Chapter 5. Viruses (at the threshold of life)
☞ How viruses transform cells☞ How viruses transform cells
- oncogene : transforming genes normally reside in the chromosomal DNA of cells
-> not viral in origin but part of the genetic endowment
> over 60 oncogenes were identified-> over 60 oncogenes were identified
- proto-oncogene : fore-runners of oncogenes
-> can be converted to oncogenes by carcinogens including viruses