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Chapt 6: Viruses - Coggle Diagram
Chapt 6: Viruses
Structure
Genetic Material
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Types: ssDNA (few) Parvoviridae- Parvovirus, dsDNA (many) Herpesviridae- Simplexvirus (HHV1 & 2), +ssRNA (many) Picornaviridae- Enterovirus- polio, Rhinovirus- cold, -ssRNA (many) Filoviridae- Filovirus- Ebola, dsRNA (few) Reociridae- Rotavirus- gastroenteritis
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Envelope: may be present around the outside of the capsid (some viruses): Consists of part of the host cell membrane along with proteins coded for by the virus
Surface Spikes: carb and protein complexes that project from the envelope surface. attachment to host cells and determine virulence and identification
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Human DNA viruses:
Pixviridae- smallpox, cow pox
Poxviridae- smallpox, cow pox
Herpesviridae- cold sores, genitcal herpes, mono, chickenpox, mono
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Yellow Fever
Flavivirus (ss RNA, envelope): Mexico, South America, Africa)
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Diagnosis based on clinical signs, rise in antibody titer or isolation of the virus from blood. No specific TMT
PVT: Vaccine- attenuated yellow fever 17D strain or Dakar Stain. Mosquiot control: drain standing water, insecticides, insect repllants, mosquito netting
Morphology (shape)
Polyhedral (icosahedral): 20 equilateral triangles. Ex: poliovirus, adenovirus
Helical: Ex: Filovirus (ebola), Rabies
Enveloped: Herpesviridae- dsDNA with envelope. Cold sores, genital herpes, monoculeosis, chicken pox, shingles
Complex (bacteriophages): dsDNA, enveloped, very large virus, Ex: T-bacteriophage
Host Range & Attachment
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Phage therapy: widely experimented within Eastern Europe. Treatment that uses bacteriophages to target and kill bacteria
Background
1886- Adolf Mayer: Demonstrated that TMD could be transmitted from an affected plant to a health plant
1892- Dimitri Iwanoski: Filtered the sap of the infected plants through a porcelain filter. The filtered fluid was still able to transmit the disease (filterable agent)
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Viral Diseases
Influenza
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Signs/symptoms:
chills, fever, headache, general muscle aches
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Three major groups:
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C- common, but seldom, causes disease symptoms
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Prevention: Vaccines, vector control
Antigenic Variation
Antigenic Drift: small mutations in the antigenic makeup of the influenza virus, seasonal changes. high mutations rates are characteristics of RNA viruses
Antigenic Shift: major genetic change in the H and/or N portions, antibodies formed against one strain will usually not be protective following an entigenic shift, can cause pandemics
Impacts: vaccine development. Identify and guesstimate the new strains of circulating virus. Takes months to develop, usually in October for elderly, hospital workers, etc, 70-90% effective
Replication
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Animal viruses
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Biosynthesis: DNA replication occurs in the nucelus of the host cell. Capsid and proteins are synthesized in the cytoplasma then transported to the nucleus where assembly will take place.
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