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Viruses
Characteristics of viruses?
- Smallest known infectious agent
- Measured in nanometers (10-9), 1000x smaller than bacteria
- Also known as nucleoproteins
- Have hollow protein head containing DNA or RNA.
- Head is also called a capsid or nucleocapsid.
- All living organisms have both DNA and RNA, virus only have either DNA or RNA
- Too small to be seen with regular light microscope.
- Will not grow on agar plates or broth tubes.
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Viruses
Living organism characteristics of viruses?
- Are reproduced at a very rapid rate, 1-50k in 1-2hrs (done by host cell)
- Have genetic DNA or RNA
- Can change or mutate (done by host cell)
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Viruses
Non-living characteristics of viruses?
- Have no cell structure
- Have no cytoplasm (hollow)
- Have few, if any, enzymes.
- Carry out no chemical reactions.
- Obligate intracellular parasite.
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Types of Species specific viruses?
- Animal viruses - infect animal cells
- Plant viruses - infect plant cells
- Bacterial viruses (phage) - infect bacterial cells
- Fungal viruses (phage) - infect fungal cells
- Protozoal viruses (phage) - infect protozoal cells
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Types of Tissue specific viruses?
- Dermatotropic viruses - skin
- Pneumatotropic viruses - lungs
- Hepatropic viruses - liver
- Neurotropic viruses - neurons
- Lymphotropic viruses - infects lymphocytes (HIV)
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3 types of virus shapes?
- Icosahedral
- Helical or cylindrical
- Complex shaped virus "The Bug"
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2 catagory types of medications used to treat viruses?
- Attacks viral DNA or blocks its replication.
- Blocks formation of viral proteins.
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Examples of medications used to treat viruses?
- AZT, ddI, ddC, Retrovin, Amantadine, Idoxuridine, Methisazone
- 1. Used against HIV, influenza, severe herpes, smallpox, chickpox
Protease inhibitors; Norvir, Inverase, Saquinovir, Acyclovir
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2 main immune system responses to viruses?
- Neutralizing antibodies.
- Interferons
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Viruses; Immune Response
Mechanism of Neutralizing antibodies?
- Proteins made by the immune system against specific viruses
- Antibodies attach to the protein receptors on the capsid of the virus and prevent viral attachment to a host cell.
- Antibodies are specific.
- Antibodies are kept in the body forever.
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Viruses; Immune Response
Mechanism of Interferons?
- Antiviral proteins made by virus infected cells in the body.
- Interferons pass into surrounding cells and prevent viral take over and replication in the adjacent cells.
- Interferons are non-specific.
- Interferons are short-term.
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