病毒的大小. Fungus. From: Principles of Virology. 3 rd ed, S.J. Flint et al.

Transcription

1 Lecture 2- 病毒的結構與分類

2 病毒的大小 Fungus From: Principles of Virology. 3 rd ed, S.J. Flint et al.

3 From: Principles of Virology. 3 rd ed, S.J. Flint et al. 病毒的大小

4 病毒的特色 病毒介於生物與非生物之間 病毒是絕對性的細胞內寄生體 (Obligate intracellular parasites) 基因核酸成分不是 DNA 就是 RNA 病毒有 metastable 特性 (i.e., stable and unstable) Protect the genome (stable) Come apart quickly on infection (unstable)

5 主要微生物比較 Virus Bacteria Fungi ( 黴菌 ) Protozoa( 原蟲 ) 寄生蟲 核酸 DNA or RNA DNA and RNA DNA and RNA DNA and RNA DNA and RNA 核膜 no no Yes Yes Yes 細胞外壁 no Yes no Some no 複製 within host cell within and outside host cell With and outside host cell With and outside host cell Outside host cell

6 病毒的結構 病毒顆粒 (the particle; the virion) From: ecometrex

7 病毒的結構 - 名詞定義 Capsid = protein shell (box) Nucleocapsid = nucleic acid + capsid Envelope = lipid membrane which surrounds some virus (viral membrane) Virion = Infectious viral particle From: ecometrex

8 Capsid Mimivirus Parvovirus Adenovirus Phycodnavirus Size of viral genomes From: Fundamentals of Molecular Virology. N.H. Acheson

9 病毒的 Capsid 結構 立方對稱 (Cubic Symmetry) 螺旋對稱 (Helical Symmetry) 複雜結構 (Complex Structure)

10 病毒的 Capsid 結構 立方對稱 (Cubic Symmetry) 均為二十面體 (icosahedral) 每一面為等邊三角形 From: Principles of Virology. 3 rd ed, S.J. Flint et al. From: 臨床病毒學. 劉建榮

11 Viral Capsid From:

12 病毒的 Capsid 結構 From: Principles of Virology. 3 rd ed, S.J. Flint et al.

13 Build your own virus

14 Capsid 結構 - 二十面體 (icosahedral) From: 臨床病毒學. 劉建榮 From:

15 病毒的 Capsid 結構 -2 螺旋對稱 (Helical Symmetry) From: Fundamentals of Molecular Virology. N.H. Acheson

16 病毒的 Capsid 結構 -3 立方對稱 vs. 螺旋對稱 From: Principles of Virology. 3 rd ed, S.J. Flint et al.

17 電子顯微鏡下的病毒 From: Fundamentals of Molecular Virology. N.H. Acheson

18 腺病毒 (Adenovirus)

19 乳突狀病毒 (Papilomavirus)

20 B 型肝炎病毒 (Hepatitis B virus) From:

21 Virus 的命名 Viral Nomenclature By diseases By the sites in the body that are affected or isolated By the geographic location By name of scientists By imagination Examples Poliovirus, rabies virus Rhinovirus, adenovirus Sendai virus, Sapporo virus (Japan) Coxsackievirus (New York) Nipah virus (Malaysia) Epstein-Barr virus Dengue (evil spirit), influenza ( influence of bad air )

22 Dengue Fever

23 Viruses vs. Living cells Cell Virus Nucleic acid DNA and RNA DNA or RNA Proteins and glycoproteins Yes Reproduction Yes Needs host Yes Polysaccharides; ions Yes No Lipid Yes Only found in enveloped viruses Cultivation Growth on cell-free media Can t grow on cell-free media

24 簡單, 是最終極的細膩 Simplicity is the ultimate sophistication

25 Steve Jobs Stanford Commencement Speech 2005

26 Molecular Machine in a Cell 轉錄 (Transcription) DNA mrna 轉譯 (Translation) mrna amino acid From: Word wizards Inc.

27 Viral Protein Structure protein= capsid Gene: VP-1, VP-2,. Non-structure protein (NS) Eg. RNA dependent RNA polymerase Gene: NS-1, RdRp From: Principles of Virology. 3 rd ed, S.J. Flint et al.

28 Enveloped Virus The envelope is derived from host cell membranes Plasma membrane Golgi Endoplasmic reticulum Nuclear membrane Exit host cell by budding No lyses of host cell From: Fundamentals of Molecular Virology. N.H. Acheson

29 Interactions of Capsids with Envelope From: Principles of Virology. 3 rd ed, S.J. Flint et al.

30 Structure of Viral Glycoprotein From: Principles of Virology. 3 rd ed, S.J. Flint et al.

31 From: 臨床病毒學. 劉建榮 Enveloped Virus

32 Non-enveloped virus Exit from host cells by lyses Cell dies Eg. Hepatitis A virus From: Principles of Virology. 3 rd ed, S.J. Flint et al.

33 Enveloped vs. Non-enveloped Virus Envelope Non-envelope Outer coating Lipid membrane from host cell Viral matrix and glycoprotein Stability Less stable (lysed by gastric acid) Exit from host cell Budding Host cells are not destroyed Infection Can become chronic infection Example Hepatitis B Herpes viruses Naked More stable in the environment Not lysed by gastric acid Rupture of host cell Cell dies Acute infection Hepatitis A, adenovirus Norovirus, Rotavirus

34 Viral Genome Viral genome can be DNA virus Double strand (ds) or single strand (ss) RNA virus Double strand (ds) Single strand (ss) (+) strand or (-) strand Linear Circular Segmented Gapped

35 DNA genome Double-stranded DNA (dsdna) Adenoviridae Herpesviridae Papillomaviridae Polyomaviridae Poxviridae From: Principles of Virology. 3 rd ed, S.J. Flint et al.

36 DNA genome Gapped DNA Partially doublestranded Gap must be filled to produce perfect duplexes eg. Hepatitis B virus From: Principles of Virology. 3 rd ed, S.J. Flint et al.

37 DNA genome Single-stranded DNA (ssdna) mrna can be made only from dsdna template DNA synthesis must precede mrna production From: Principles of Virology. 3 rd ed, S.J. Flint et al.

38 RNA Genome Cells have no RNA-dependent RNA polymerase that can replicate RNA or make mrna from RNA Two strategies of RNA viruses to solve this Virus contain RNA genome and RNA-dependent RNA polymerase (RdRp), i.e., bring RdRp into cells Reverse transcription of RNA to ds DNA

39 RNA Genome dsrna Includes (+) strand and (- ) strand RNA (-) strand RNA is copied into mrnas by RdRp eg. Reoviridae Rotavirus From: Principles of Virology. 3 rd ed, S.J. Flint et al.

40 RNA Genome (+) Strand RNA The most plentiful viruses on earth Can be translated directly into protein by host ribosomes The genome is replicated in two steps (+) strand is copied into (-) strand (-) strand is then copied into (+) strand The largest RNA virus: corona virus (31 kb) From: Principles of Virology. 3 rd ed, S.J. Flint et al.

41 RNA Genome (+) Strain RNA with DNA intermediate Convert (+) RNA into a dsdna By viral RNA-dependent DNA polymerase (reverse transcriptase) dsdna mrna and RNA genome Retrovirus, HIV From: Principles of Virology. 3 rd ed, S.J. Flint et al.

42 RNA Genome (-) Strand RNA Cannot be translated directly into protein Must be copied to make (+) strand RNA Viral RNA-dependent RNA polymerase (RdRp) Cell has no RdRp Virus contains RdRp and bring it into cell to survive From: Principles of Virology. 3 rd ed, S.J. Flint et al.

43 Classification of Viruses Baltimore classification 1970 由 David Baltimore 提出 根據病毒 mrna pathway 分六大類 From: Principles of Virology. 3 rd ed, S.J. Flint et al.

44 From: youtube Baltimore Classification

45 病毒的分類依據 Nucleic acid: DNA 或 RNA Capsid 對稱性, 形狀 有無包膜 (envelope) 病毒顆粒大小

46 病毒的分類依據 Nucleic acid 種類 DNA or RNA 有無 envelope Enveloped or non-enveloped Genomic organization Single strand (ss) vs. double strand (ds) Linear vs. circular Continuous vs. segmented Morphology Symmetry, shape, size

47 病毒的分類 DNA viruses Non-enveloped Enveloped SS (Linear) ds (Linear) ds (Circular) ds (Linear) Ds (circular) Parvovirus adenovirus B 19 微小病毒 感冒 Papillomavirus Polyoma virus 子宮頸癌 Herpesvirus poxvirus 泡疹水痘 hepadnavirus B 型肝炎

48 病毒的分類 RNA viruses Non-enveloped Enveloped SS (+) Astrovirus Caliciviruses picornavirus ds Rotavirus Reovirus SS (+) SS (-) Retroviruses HIV Togavirus Coronavirus Flavivirus Linear Segmented 腸胃炎腸病毒 A 型肝炎 腸胃炎 C 型肝炎 E 型肝炎 Rhbdovirus Paramyxovirus 狂犬病麻疹 Arenavirus Bunyaviruse Orthomyxovirus 流感

49 International Committee on Taxonomy of Viruses (ICTV) Level of Taxonomy, ICTV 2011 Level No. Suffix Example Order ( 目 ) 6 -virales Mononegavirales ( 單股反鏈病毒目 ) Family ( 科 ) 94 -viridae Paramyxoviridae ( 副黏液病毒科 ) Subfamily ( 亞科 ) 22 -virinae Paramyxovirinae ( 副黏液病毒亞科 ) Genus ( 屬 ) 395 -virus Morbillivirus ( 麻疹病毒屬 ) Species ( 種 ) 2480 Measles virus ( 麻疹病毒 )

50 ICTV Level Suffix Example Order ( 目 ) -virales Mononegavirales Family ( 科 ) -viridae Rhabdoviridae ( 桿狀病毒科 ) Subfamily ( 亞科 ) -virinae Genus ( 屬 ) -virus Lyssavirus Species ( 種 ) Rabies virus

51 Life Cycle of Viruses From: Fundamentals of Molecular Virology. N.H. Acheson

52 From: Principles of Virology. 3 rd ed, S.J. Flint et al.