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89 Cards in this Set
- Front
- Back
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Virus particles composed of either RNA or DNA that is encased by capsid |
Virions |
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Protein coat encasing the virions |
Capsid |
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If the virus is enveloped its capsid os surrounded by what material |
Lipoprotein coat |
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Other naturenof nature of virus (3) |
Replicate in living cells Obligate intracellular parasites Lack a system that generates ATP |
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Give 9 virus with their sizes |
Mimivirus 450nm Herpes simplex 150nm Rabies 125nm HIV 110nm Influenza 100nm Adenovirus 75nm T2 bacteriophage 65nm Poliomyelitis 30nm Yellow fever 22nm |
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Example of protein molecule and size |
Hemoglobin molecule 15nm |
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What are the components of virus |
External coating Capsid and envelope Core Rna and dna Nucleocapsid |
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Termed when virus has no envelope |
Naked virus |
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Compomemt of nucleocapsid |
Capsid and nucleic acid |
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Structural units of capsid |
Capsomers |
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Aggregates of viral-specific polypeptides |
Capsid or capsomer? |
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Classification of capsid and example |
Main classification : helical, icosahedral and complex Examples Naked helical virus: tobacco mosaic virus Enveloped helical virus: imfluenza virus Icosahedral : Adenovirus Complex : T4 bacteriophage |
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Functions of viral capsid |
Protects the viral genome Site of receptors necessary for naked virus to Initiate infection Site of antigenic determinants important in some serologic testing |
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Composition of viral envelope |
Viral-specific glycopeptides and host-cell-derived lipids and lipoproteins |
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Viral envelope contain molecules necessary to |
Initiate infection Act as stimulus to antibody production Serve as antigen in serologic testing Basis of ether sensitivity of a virus |
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Viral genome can be? |
DNA or RNA linear or circular Single stranded or double stranded Segmented or non-segmented Criteria for viral classification Viral specific-enzymes |
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Small hydrophobic virus encoded proteins that oligomerize at host cell membranes |
Viroporins |
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Function in enveloped and non enveloped virus |
Budding of enveloped proteim Cellular lysis of nin enveloped virus |
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Form hydrophilic pores which disrupts normal cell physiology |
Viroporins |
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Enumerate the taxonomy of virus |
Order: virales (herpesvirales) Family: viridae (herpesviridae) Subfamily: virinae (alphaherpesviridae) varicellovirus) Genus: virus (varicellovirus)Species: common name (varicella-zoster virus) Species: common name (varicella-zoster virus) |
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Basis for taxonomy of virus |
Type of genome Strands of genome Capsid morphology Presence and absence of envelope |
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Double stranded DNA virus |
Asfarviridae Poxviridae Iridoviridae Polyomaviridae Papillomaviridae Herpesviridae Adenoviridae |
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Single stranded DNA virus |
Parvoviridae Circoviridae |
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dsDNA (RT) |
Hepadnaviridae |
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All dna are (circular,linear ) except |
Linear Papillomaviridae and hepadnaviridae |
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All dna virus are double stranded except |
Parvoviridae |
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All dna viruses are (naked,enveloped ) except |
Naked
Herpesviridae, poxviridae and hepadnaviridae |
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All dna viruses are (icosahedral, polyhedral) except |
Polyhedral Poxviridae |
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All dna virus replicate in (nucleus,nucleolus,cytoplasm) except |
Nucleus Poxviridae (cytoplasm) |
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dsRNA |
Reoviridae Picobirnaviridae |
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ssRNA (-) |
Orthomyxoviridae Rhadbdoviridae Paramyxoviridae Bornaviridae Arenaviridae Filoviridae Bunyaviridae |
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SsRNA (+) |
Hepeviridae Calcilivirdae Astroviridae Picornaviridae Coronaviridae Arteriviridae Togaviridae Flaviviridae |
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ssRNA (RT) |
Retroviridae |
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All rna viruses are single stranded except |
Reoviridae |
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All rna viruses are (naked,enveloped ) except |
Enveloped Reoviridae Picornavirodae |
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All rna viruses are (helical,complex,icosahedral ) except |
Helical Retroviridae,Picornaviridae and togaviridae |
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All rna virises replicate in cytoplasm excep |
Retroviridae and orthomyxoviridae |
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Viral replication |
Only occurs in living cells May lead ro the death of the host or may occur without apparent damage to the host cell Involves many host-cell enzymes and functions |
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Steps of virus replication (8) |
1.Adsorptoon 2.Penetration 3.Uncoating (releasing of nucleic acid) (Replication and translation ) 4.early mrna and protein 5. Duplication of nucleic acid Duplication of nucleic acid 6.late mrna and protein 7. Assembly and intracellular accumulation Release 8. Release by lysis or budding |
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Attachment to the host cell |
Adsorption |
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Direct Penetration of the membrane Envelope-membrane fusion Endocytocis |
Penetration |
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Loose of capsid exposing the genome |
Uncoating |
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Location of uncoating in Rna Dna |
Rna: cytoplasm Dna: nucleus |
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Copies genome and produce proteins |
Replication and translation |
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Viruses to form Virions |
Assembly or maturation |
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Release in naked and envelope |
Naked: lysis Enveloped: budding |
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Where does dna virus replication happens |
Nucleus except for poxviruses |
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Regulates dna virus transcription |
DNA-dependent RNA polymerase |
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Regulates poxviruses t4wnscription |
Virion-associated RNA polymerase |
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Location of dna viruses translation |
Cytoplasmic polysomes |
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Occurs after the synthesis of the early protein |
Genome replication |
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Genome replication is done by ___ and supplied by ____ |
DNA- dependent DNA polymerase
Host cell (Adenovirus ) Virus specific (herpesvirus) |
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Location of dna virus assembly |
Nucleus |
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Imefficient process of virslvproteins lead to formarion of -___ |
Iclusion bodies |
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Three different viral genome of rna viruses |
Messenger (positive-sense) polarity Antimessenger (negative-sense) polarity Ambisense |
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Single stranded and able to act as messenger |
Messenger (positive-sense ) polarity |
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Example of messenger rna viruses |
Picornaviruses and Retroviruses |
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Single stranded and a complementary to mRna |
Antimessenger (negative-sense ) polarity |
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Example Antimessenger rna viruses |
Orthomyxoviruses and Paramyxoviruses |
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Single stranded and with portions of messenger and Antimessenger polarity |
Ambisense |
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Example of ambisesne |
Arenaviruses |
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Rna viruses transcription involves |
Viral-specified RNA-dependent rna polymerase |
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Rna viruses transcription involves viral-specified RNA depemdemt RNA polymerase except |
Retroviruses which uses host cell, DNA-Dependent RNA polymerase |
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Negative-sense viruses (orthomyxoviruses and Paramyxoviruses ) uses ? |
Virion -associated enzyme (transcriptase) |
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Results into synthesis of a large polyprotein that is subsequently cleaved into individual viral polypeptides |
Translation ( happens in cytoplamic polysomes) |
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Viruses involved in translation |
Picornavirus amd retrovirus |
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Genome replication occurs where Except Done by_ except for_ |
Cytoplasm Orthomyxoviruses amd retrovirus Viral-specific replicase enzyme ; retrovirus |
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All ssRna genomes require __ |
Replicative intermediate RNA structure |
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Which has a higher mutation rate? Rna or dna? |
RNA |
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Viral entry to a host |
Through the mucosa of the RT, GIT or GUT By directvirus injection into the bloodstream via a needle or insect bite |
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Asymptomatic or subclinical infection |
No clinical symptoms are evident Can Stimulate Humoral or cellular immunity |
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Symptimatic/Clinical infection |
Results from Direct or indirect viral effects Diseases does not always follow infection and therefore is not accurate index or viral infection |
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Viral attachment proteins |
May react with specific antibodies and become imcapable of interaction with cellular receptor sites Can be inactivated by pH, enzymes and other host biochemical factors |
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Decreased with attenuated strains of virus Genetically determined |
Viral virulence |
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Tendency of a virus to infect and replicate in a cell |
Cell tropism |
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Cellmtropism, ismdetermimed by |
Interaction of VAPs and cellular receptor site Cell's ability to provide other components such as substrates and enzymes |
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Cellular responses to virsl infectiom |
Cytopathic effects Cytolysis Inclusion body formation Chromosomal aberrations Transformation Interferon synthesis |
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Tyoe of infection that is too few cells are infected to cause clinical symptoms |
Inapparent infections |
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Clinical manifestations are observed for a short period of time after a short incubatiom period |
Acute infections |
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Acute infectiom may be |
Localized or disseminated |
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Comtinuing presence of the infection for an extended period |
Persistent infections |
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Persistently infected individual are known as |
Carriers |
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True or false Constant viral antigenic stimulstion leads to low antibody titers for some antigens |
False ( high antinody titers) |
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Virus persists in the body in a noninfectious form |
Latent infection |
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Can periodically reinactivate |
Latent infections |
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On what phase does antibody production occurs in latent infection |
Initial infection and during recurrence |
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Prolonged incubation period lasting months or years |
Slow infection |
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Slow infection do not cause clinical symptoms during incubation but can produce some infectious agents (true or false ) |
True |
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Slow infectiom is mostly associated with |
Chronic progressive Fayal viral diseases of the CNS |
