Viruses: An Introduction Biology 11 Mr. Andersen Click Here To Begin

New Recruit, You have been selected to become a member of the newly created Viral Emergency Response Team(VERT) for the Centers for Disease Control and Prevention. Here at the CDC, we pride ourselves on being the foremost authority on virology. As a condition of your acceptance into VERT, you must complete a training unit designed to enhance your knowledge of viruses and their effects on human health. On the next page you will find a list of training objectives as well as instructions on navigating the training unit. At the end of your training, you will be required to pass a short test of your viral knowledge. Good luck! Mr. Andersen, VERT Coordinator Initiate Training

Training Objectives: 1.Define what a virus is. 2.Identify criteria for classifying organisms as living. 3.Describe the basic structure of a virus. 4.Compare the lytic and lysogenic cycles. 5.Define and give example of viral specificity. 6.Describe the body’s basic lines of defense against viruses. 7.Examine ways to prevent the spread of viral disease. Navigational Tools: Launch Training Unit To navigate through your virus training, remember to use the arrow buttons found on the bottom corners of your screen. When using the virus training unit, clicking an underlined title will take you to information on that title.

Basic Structure of a Virus What is a Virus?Classifying Organisms as Living Viral Specificity Prevent Spread of Viral Disease Lines of Defense Lytic and Lysogenic Cycles Back to ObjectivesTake The Test Click On A Category To Find Out More

Classifying Organisms as Living All living things: 1.Are made up of one or more units called cells. 2.Reproduce. 3.Grow and develop. 4.Obtain and use Energy. 5.Respond to their environment. Are Viruses Alive? No, because we consider living things to be made up of cells and reproduce independently, both of which are qualities viruses do not have. However, when able to infect living cells, viruses can grow, reproduce, and even evolve. Return

What Is A Virus? A virus is a noncellular particle made up of genetic material and protein that can invade living cells. Viruses act as parasites on their host cell to carry out their functions of growth and reproduction. Viruses are responsible for many diseases including HIV /AIDS, HPV(Human papillomavirus), Avian Influenza, Swine Flu(H1N1 virus), rabies, mumps, and even the common cold! Return

Lytic and Lysogenic Cycles Lytic CycleLysogenic Cycle Click on either movie to view. Return

Viral Specificity Usually, specific viruses will infect specific organisms. For example, a plant virus cannot infect an animal. There are some viruses that will only infect humans. Others, such as rabies, infect all mammals and some birds. Still others infect species of animals that are closely related such as mice and rats. We call this viral specificity because each virus attacks specific hosts.

Basic Structure of a Virus Return Viruses can look very different from one and other but do share many common features. A typical virus is composed of nucleic acid(DNA or RNA) surrounded by a protein coat called a capsid. The capsid protects the core of nucleic acid which can contain several genes to several hundred genes. In addition, most viruses exhibit some form of spikes or fibers that allow the virus to attach itself to a host cell.

Lines of Defense 1. Primary line of Defense: Your skin and mucous membranes act as the primary line of defense against viral infection. Both are nonspecific defense mechanisms meaning that they do not differentiate between invaders. 2. Secondary line of Defense: If viruses make it past the skin and mucous membranes the second line of defense is an inflammatory response. This involves phagocytes, which are white blood cells, engulfing and destroying a virus. This is also a nonspecific defense mechanism. 3. Tertiary Line of Defense: The last line of defense envolves antibodies which are made by the body to defend against a specific invader. Antibodies bind to a specific virus and inhibit its ability to enter a cell. As one would expect, they are a specific defense mechanism. Return

Prevent Spread of Viral Disease Breaking the chain of Transmission: The most important aspect in controlling the spread of viral disease is to break the chain of transmission. This means to stop the virus from moving to new hosts. Several techniques have proved effective. 1.Sanitation and Disinfection: Sanitation is the hygienic means of promoting health through prevention of human contact with the hazards of wastes. Disinfection may be defined as: Cleaning an article of some or all of the pathogenic organisms which may cause infection. 2.Vaccines: A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains a small amount of an agent that resembles a microorganism. The agent stimulates the body's immune system to recognize the agent as foreign, destroy it, and remember it. 3.Anti Viral Drugs: Antiviral drugs are often nucleoside analouges, (fake DNA building blocks), which viruses incorporate into their genomes during replication. The life- cycle of the virus is then halted because the newly synthesized DNA is inactive. 4.Quarantine: Infected people are isolated from the rest of the community and those that have been exposed to the virus placed in quarantine. Return

In order to become a full member of the Viral Emergency Response Team, you will now have to demonstrate your new knowledge of viruses. You will be required to answer a series of 10 questions related to material in the Virus Training Unit. To answer a question, click on the best possible answer. In order to move through the test, each question must be answered correctly. Question #1Keep Training

Which answer best describes the definition of a virus? B. Noncellular particle containing genetic material. A. Living cell that can infect other cells. C. Type of bacteria that may cause disease. D. Phagocytic cell used by the body’s immune system.

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Which feature does not describe a living organism? B. Growth and Development. A. Reproduction. C. Contain DNA or RNAC. Contain DNA or RNA. D. Respond to their environment.

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Viral specificity refers a virus’s ability to? B. Grow specific features. A. Infect a particular host. C. Evolve. D. Respond to their environment.

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A typical viral capsid is made up of what? B. ProteinB. Protein. A. DNA or RNA. C. Lipids. D. Carbohydrates.

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The spikes or fibers found on a virus allow it to? B. Navigate through the blood. A. Bind to other viruses. C. Protect against antibodies. D. Attach to a host cell.

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Which line of the human body’s defense against viral attack is a specific defense mechanism? B. Primary A. Tertiary C. Secondary D. Quaternary

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_______ bind to a virus and inhibit its ability to enter a cell. B. Tail Fibers A. White blood cells C. Antibodies D. Antigens

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In which viral reproductive cycle does the viral DNA become part of the host cell’s chromosome? B. Lysogenic cycleB. Lysogenic cycle. A. Lytic cyle.

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In the lytic cycle, one infected host cell can generate how many new viruses? B. 10 to 20 A. 1 or 2 C. 100 to 200 D to 2000

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All are examples of ways to contain the spread of viruses except? B. Vaccines. A. Quarantine. C. Disinfection and Sanitation. D. Antibiotics.

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Congratulations on completing your training. You are now officially a member of the Viral Emergency Response Team for the Centers for Disease Control and Prevention. Thanks, Mr. Andersen VERT Coordinator RestartCredits

1. Miller and Levine. Biology. Prentice-Hall Inc Center for Disease Control and Prevention www.cdc.gov 3. Mayo Clinic www.mayoclinic.com 4. Wikipedia www.wikipedia.com