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17 Cards in this Set
- Front
- Back
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Characteristics of Viruses
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Contain:
-DNA or RNA -Capsid: protein coat -Envelope -Most viruses infect only specific types of cells in one host -Host range is determined by specific host attachment sites and cellular factors |
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Structure of Viruses
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Contain:
-DNA or RNA -Capsid: protein coat -May contain an envelope |
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Morphology of Viruses
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-Nonenveloped Polyhedral Virus
-Enveloped Helical Virus -Helical Virus -Complex Virus |
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Taxonomy of Viruses
and scientific naming |
-Family names end in -viridae
-Genus names end in -virus -Viral species: a group of viruses sharing the same genetic information and ecological niche (host). Common names are used for species. -Subspecies are designated by a number EXAMPLE Family: Herpesviridae Genus: Herpes virus Species: Human herpes virus 1, HHV 2, HHV4 EXAMPLE Family: Retroviridae Genus: Lentivirus Species: Human Immunodeficiency Virus 1, HIV 2 |
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Viral Cultivation Methods
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-Viruses must be grown in living cells
1)Bacteriophage plaques 2) Inoculated embryonated egg |
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Methods for Viral Identification
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-Cytopathic effects
-Serological tests: ---detect antibodies against viruses in a patient ---use antibodies to identify viruses in neutralization tests, viral hemagglutination, and Western blot -Nucleic acids ---RFLPs ---PCR |
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Compare and contrast
Lytic cycle & Lysogenic cycle |
-Lytic cycle: phage causes lysis and death of host cell
-Lysogenic cycle: prophage DNA incorporated in host DNA |
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Lytic Cycle
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1. Attachment
-----phage attaches by tail fibers to host cell 2. Penetration -----phage lysozyme opens cell wall, tail sheath contracts to force tail core and DNA into cell 3. Biosythesis -----production of phage DNA and proteins 4. Maturation -----assembly of phage particles 5. Release -----phage lysozyme breaks cell wall |
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Lysogenic Cycle
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1. Attachment
-----phage attaches by tail fibers to host cell 2. Penetration -----phage lysozyme opens cell wall, tail sheath contracts to force tail core and DNA into cell 3b. Prophage -----phage DNA recombines with host DNA, lysis genes repressed 4b. Latency -----prophage replicates with host DNA 5. Lytic event -----prophage may exise and intiate the lytic cycle |
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Multiplication of animal viruses
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1. Attachment
-----viruses attaches to cell membrane 2. Penetration -----by endocytosis or fusion 3. Uncoating -----by viral or host enzymes 4. Biosynthesis -----production of nucleic acid and proteins 5. Maturation -----nucleic acid and capsid proteins assemble 6. Release -----by budding (enveloped viruses) or rupture |
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Role of reverse transcriptase in the multiplication of retroviruses
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RNA---->DNA
(instead of DNA-->RNA) |
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Oncogenic Viruses
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-Activated oncogenes transform normal cells into cancerous cells
-Transformed cells have increased growth, loss of contact inhibition, tumor specific transplant, and T antigens -The genetic material of oncogenic viruses becomes integrated into the host cell's DNA |
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Viral Cultivation Methods
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-Viruses must be grown in living cells
1. Bacteriophage plaques 2. Inoculated embryonated egg |
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Define: Latent Viral Infections
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Virus remains in asymptomatic host cell for long periods
--cold sores, shingles |
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Define: Persistent Viral Infections
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Disease processes occurs over a long period, generally fatal
--subacute sclerosing panencephalitis (measles virus) |
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Structure of Prions
& their method of infection |
-Infectious proteins
-PrPc, normal cellular prion protein on cell surface ----may function in regulating cell death ----PrpSc, scrapie protein, accumulate in brain cells forming plaques ----common in animals >scrapie in sheep & goats >bovine spongiform encephalopathies (BSE) aka mad cow disease >wasting disease (in deer) >humans-Creutzfeldt-Jakob Syndrome (CJS) |
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Herpes Simplex Viruses
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-Humans susceptible to 2 varieties
-HSV-1- usually lesions on the oropharynx, cold sores, fever blisters (occur early in childhood) -HSV-2- lesions on the genitalia, possibly oral >>occurs in ages 14-29 >>can be spread without visible lesions |
