《微生物学》（英文版） 2 Virus General Properties of Viruses

Virus General Properties of Viruses Virus have both an extracellular and an intracellular state. a virus is a submicroscopic particle containing nucleic acid surrounded by protein and occasionally containing other macromolecular components In this extracellular state, the virus particle, also called the virion, is metabolically inert and does not carry out respiratory or biosynthetic functions. The virion is the structure by which the virus genome is carried from the cell in which it has been produced to another cell where the viral nucleic acid can be introduced. In the intracellular state virus replication occurs: the virus genome is produced, and the components that make up the virus coat are synthesized When a virus genome is introduced into a host cell and reproduces, the process is called infection

Virus General Properties of Viruses Virus have both an extracellular and an intracellular state. A virus is a submicroscopic particle containing nucleic acid surrounded by protein and occasionally containing other macromolecular components. In this extracellular state, the virus particle, also called the virion, is metabolically inert and does not carry out respiratory or biosynthetic functions. The virion is the structure by which the virus genome is carried from the cell in which it has been produced to another cell where the viral nucleic acid can be introduced. In the intracellular state, virus replication occurs: the virus genome is produced, and the components that make up the virus coat are synthesized. When a virus genome is introduced into a host cell and reproduces, the process is called infection

General Properties of viruses viruses differ from living cells in at least three ways: (1)their simple, acellular organization (2)the absence of both dna and rna in the same virion 3)their inability to reproduce independently of cells and carry out cell division as prokaryotes and eukaryotes do

(1) their simple, acellular organization (2) the absence of both DNA and RNA in the same virion (3) their inability to reproduce independently of cells and carry out cell division as prokaryotes and eukaryotes do. viruses differ from living cells in at least three ways: General Properties of Viruses

lucleic Acid Type Nucleic Acid Structure Virus Examples Single-Stranded Linear single strand Parvoviruses Circular single strand oX174, M13, fd phage Double-Stranded Linear double strand Herpesviruses(herpes simplex viruses, stein-Barr virus) adenoviruses, T coliphages, lambda ph Linear double strand with single chain breaks T5 coliphage Double strand with cross-linked ends Vaccinia, smallpox QⅢ Closed circular double strand Polyomaviruses(SV-40), papillomaviruses, PM2 phage, cauliflower mosaic RNA Single-Stranded Linear, single stranded, positive strand Picornaviruses (polio, rhinoviruses), togaviruses RNA bacteriophages, TMV, and most plant viruses Linear, single stranded, negative strand Rhabdoviruses(rabies), paramyxoviruses Linear, single stranded, segmented, positive strand Brome mosaic virus (individual segments in separate virions Linear, single stranded, segmented, diploid Retroviruses(Rous sarcoma virus, human two identical single strands), positive strand Immuno deficiency vi Irus Linear, single stranded, segmented, negative strand Paramyxoviruses, orthomyxoviruses (influenza) Double-Stranded Linear, double stranded, segmented Reoviruses, wound- tumor virus of plants, toplasmic polyhedrosis virus of insects, phage 6, many mycoviruses Types of Viral Nucleic Acids

Types of Viral Nucleic Acids

SSDNA Caulimoviridae Caulimovirus Geminiviridae ②② SbCMV-like Mastrevirus &ese Nanovirus Diagrammatic dsRNA SSRNA(-) ssRNA (+ Bromoviridae Sequiviridae|③ Description of Tombusviridae Bunyaviridae Luteoviridae Bromovirus Reoviridae movin a Families and Phytoreovirus Oryzavirus Rhabdoviridae Umbravirus Cytorhabdovirus Tenuivirus 命自 Nucleorhabdovirus Ophiovirus Alfamovirus Comoviridae Idaeovirus 参念 SSRNA(RT) Genera of Pseudoviridae Tobamovirus Tobravir Virus that 命B自 Ourmiavirus a fuom Infect Plants Benyvirus RT Stands for Varicosavirus Calis,Tithovwu, wiu reverse Potyviridae ● LJ Closteroviridae 100nm transcriptase

A Diagrammatic Description of Families and Genera of Virus That Infect Plants. RT stands for reverse transcriptase

dsDNA SSDNA A Iridoviridae Circoviridae Poxviridae Asfarviridae Chordopoxvininae Lymphocystivirus Diagrammatic Parvoviridae dsDNA (RT) Parvoviridae Polyomaviridae Description of Hepadnaviridae Herpesviridae Papillomaviridae Adenoviridae the families dsRNA SSRNA () SSRNA(RT) and genera of Rhabdoviridae Retroviridae Reoviridae Orthomyxoviridae Viruses that Orthoreovirus Metavirus Aquareovirus @◎ Infect Paramyxoviridae Bornaviridae Arenaviridae Bunyaviridae Bunyavirus Ⅴ ertebrates.RT Nairovirus Birnaviridae Phlebovirus aquabirnavirus Filoviridae ssRNA(+) stand for ② Nodaviridae Caliciviridae HEV-like Betanodavirus Togaviridae reverse Picornaviridae 100nm Astroviridae Flaviviridae Coronaviridae Arteriviridae transcriptase

A Diagrammatic Description of the Families and Genera of Viruses That Infect Vertebrates. RT stand for reverse transcriptase

dsDNA SSDNA 念 Maior Myoviridae, isometric head Bacteriophage Inoviridae Families and Myoviridae, elongated head enera Siphoviridae 和 Podoviridae The Myoviridae are Lipothrixvinidae SNDv-like viruse the only family with Inoviridae contractile tails lasmaviridae Corticoviridae Plasmaviridae are pleomorphiC Fusellovinidae Tectiviridae have RL rudiviridae distinctive double dsRNA SSRNA capsids whereas the corticoviridae have Cystoviridae Levivinidae complex capsids 100nm containing lipid

Major Bacteriaophage Families and Genera. The Myoviridae are the only family with contractile tails. Plasmaviridae are pleomorphic. Tectiviridae have distinctive double capsids, whereas the corticoviridae have complex capsids containing lipid

Viruses can exist in two phases extracellular and intracellular Virion, the extracellular phase, posses few if any enzymes and can not reproduce independently of living cells. In the intracellular phase, viruses exist primarily as replicating nucleic acids that induce host metabolism to synthesize virion components; eventually complete virus particles or virions are released

Virion, the extracellular phase, posses few if any enzymes and can not reproduce independently of living cells. In the intracellular phase, viruses exist primarily as replicating nucleic acids that induce host metabolism to synthesize virion components; eventually complete virus particles or virions are released. extracellular and intracellular Viruses can exist in two phases

Hosts and size Three main classes -animal viruses. bacterial viruses (bacteriophages), and plant viruses The particular host range of a virus is determined by the virus's requirements for its specific attachment to the host cell and the availability within the potential host of cellular factors required for viral multiplication Virus particles(virions) vary widely in size and shape. Viruses are smaller than cells, ranging in size from 0.02 to 0.3 um. A common unit of measure for viruses is the nanometer which is 1000 times smaller than 1 um and 1 million times smaller than 1 mm. Smallpox virus, one of the largest viruses, is about 200 nm in diameter(a bit smaller than the size of the smallest bacteria); poliovirus, one of the smallest, is only 28 nm in diameter (about the size of a ribosome)

Hosts and size Three main classes - animal viruses, bacterial viruses (bacteriophages), and plant viruses. The particular host range of a virus is determined by the virus's requirements for its specific attachment to the host cell and the availability within the potential host of cellular factors required for viral multiplication. Virus particles (virions) vary widely in size and shape. Viruses are smaller than cells, ranging in size from 0.02 to 0.3 μm. A common unit of measure for viruses is the nanometer, which is 1000 times smaller than 1 um and 1 million times smaller than 1 mm. Smallpox virus, one of the largest viruses, is about 200 nm in diameter (a bit smaller than the size of the smallest bacteria); poliovirus, one of the smallest, is only 28 nm in diameter (about the size of a ribosome)

The comparative sizes of several viruses and bacteria 225 no Hacterachase MIs H.Ern MOnr x TUnn e 24 nm Totacromasie vius Bacterin 2n x 18 n b实m(k3xm ●3nm poliovirus wacana viru 3. nm x 20nm x ICD nm Pe-nerete ot bleed ell L crit il r emic hater

The comparative sizes of several viruses and bacteria:

Structure of viruses Most viruses are too small to be seen under light microscope. All viruses consists of an rNa or dNa core genome surrounded by a protein coat id capsic The combined viral genome and capsid is called the nucleocapsid. .The nucleic acid of a virus is surrounded by a protein coat called the capsid .Each capsid is composed of protein subunits called capsomeres .In some viruses, the capsid is covered by an envelope, which usually consists of some combination of lipids, proteins, and carbohydrates. .Depending on the virus, envelopes may or may not be covered by spikes, which are carbohydrateprotein complexes that project from the surface of the envelope

• Most viruses are too small to be seen under light microscope. • All viruses consists of an RNA or DNA core genome surrounded by a protein coat capsid. • The combined viral genome and capsid is called the nucleocapsid. •The nucleic acid of a virus is surrounded by a protein coat called the capsid •Each capsid is composed of protein subunits called capsomeres. •In some viruses, the capsid is covered by an envelope, which usually consists of some combination of lipids, proteins, and carbohydrates. •Depending on the virus, envelopes may or may not be covered by spikes, which are carbohydrateprotein complexes that project from the surface of the envelope. Structure of viruses