VIRUSES. Name: Date: Per: Quiz and Test Dates:

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1 Name: Date: Per: VIRUSES Quiz and Test Dates: 4C Compare the structures of viruses to cells, describe viral reproduction, and describe the role of viruses in causing diseases such as HIV and influenza

2 IMPORTANT IDEAS ABOUT VIRUSES:

3 The Flu: How does it work and how can we prevent it? What is the Flu? Influenza, or flu, is a respiratory illness that is caused by a virus. Flu is highly contagious and is usually spread by the coughs and sneezes of a person who is infected. You can also catch flu from an infected person if you touch them (e.g. shaking hands). Adults are contagious one day before getting symptoms and up to 7 days after becoming ill. This means that you can spread the influenza virus before you even know you are infected. A flu epidemic, when a large number of people in one country are infected with flu, can last several weeks. According to the National Institutes of Health, between 5% and 20% of Americans get the flu each year. More than 200,000 people are hospitalized and 36,000 die annually because of flu in the United States. How do vaccines work? A vaccine contains a killed or weakened part of a germ that is responsible for infection. Because the germ has been killed or weakened before it is used to make the vaccine, it can not make the person sick. When a person receives a vaccine, the body reacts by making protective substances called "antibodies". The antibodies are the body's defenders because they help to kill off the germs that enter the body. In other words, vaccines expose people safely to germs, so that they can become protected from a disease but not come down with the disease. What does the seasonal influenza vaccine protect against? While there are many different flu viruses, a flu vaccine protects against the three or four viruses that research suggests will be most common. Three kinds of flu viruses commonly circulate among people today: Influenza A (H1N1) viruses, influenza A (H3N2) viruses, and influenza B viruses. All of the influenza vaccine is made to protect against the following three viruses: an A/California/7/2009 (H1N1)pdm09-like virus an A/Texas/50/2012 (H3N2)-like virus a B/Massachusetts/2/2012-like virus. Some of the flu vaccine also protects against an additional B virus (B/Brisbane/60/2008-like virus). How are the viruses selected to make flu vaccine? The influenza (flu) viruses selected for inclusion in the seasonal flu vaccines are updated each year based on which influenza virus strains are circulating, how they are spreading, and how well current vaccine strains protect against newly identified strains. Currently, 141 national influenza centers in 111 countries conduct year-round surveillance for influenza and study influenza disease trends.

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5 VIRUSES I. VIRUSES (Latin for poison) Viruses are not classified in any kingdom. A. General Characteristics 1. A virus is an infectious agent made up of a. they have no nucleus, no organelles, no cytoplasm or cell membrane b. viruses have either c. viruses with RNA that transcribes into DNA (using enzyme reverse transcriptase) are called Ex: RNA viruses have a high rate of mutations 2. Viruses are - - organism that depends entirely upon another living organism (host) for its existence in such way that it harms that organism. B. Examples: 1. Bacteriophage 2. Flu (influenza), HIV C. Replication (reproduction): How a virus spreads. *** A virus cannot reproduce by itself it must invade a cell and take over its activities. 1. Virus (bacteriophage) invading a bacterium (E. coli): 2. During Lysogenic Cycle, it is possible for viral DNA to separate from host cell DNA and cause cell to enter Lytic Cycle and replicate new viruses.

6 3. Virus invading an animal cell: Ex: Virus particle enters human cell by endocytosis Envelope of HIV contains marker proteins + carbs derived from host cell 4. Capsid of a virus bind to on cell surface and trick cell into allowing it inside 5. Because of this fit between virus and cell receptors, most viruses are for cells they infect Ex: Virus Cell D. Importance 1. Harmful a. causes disease, disease producing agent b. human diseases - DNA: RNA: c. viruses disrupt the body s normal equilibrium/balance (homeostasis) d. viruses can be with vaccines, but NOT treated with vaccines or antibiotics 2. Beneficial a. genetic engineering Use p.483 to compare viruses and living cells Receptor Sites Characteristic VIRUS CELL Structure Reproduction Genetic Material Growth and Development Obtain and use energy Response to Environment Change over time (evolve) How many characteristics of life do viruses possess? Are they then living?

7 HIV: Evolving Menace Viruses are tiny, but they pack a big punch. Viruses spread and multiply fast, causing some of the most common and contagious diseases in the world. If you ve ever had a rash, flu, or warts, you ve probably hosted a few viruses. Actually, you ve hosted a few billion. Once a virus sets up residence in an organism, it doesn t stay solo for long. One type of virus, HIV, can make 10 billion new viruses in a single day. A virus consists of a small amount of genetic material inside a protein case. The genetic material of some viruses, such as herpes viruses, is DNA, while the genetic material of other viruses, like HIV, is RNA. DNA and RNA store information for making proteins, which in turn build a complete organism. Whether it contains DNA or RNA, a virus is basically a recipe for making more viruses. But a virus can t make new copies by itself; it needs the equipment of a living cell. Viruses attach themselves to cells and dump their genetic material inside. The virus takes over the cell s machinery, which then starts turning out copies of viruses instead of its own products. The new viruses bud from the cell and go on to infect other cells. To viruses, your cells are nothing more than giant copy machines for making more viruses. Luckily, your body is equipped with an infection-fighting army called the immune system. The immune system is made up of many different kinds of cells. There are T cells that alert the body to viruses and organize an attack, and other T cells that kill off the infected cells. There are B cells that produce proteins called antibodies that lock on to the virus and prevent it from attaching to a cell. And there are cells that clean up the mess. Your immune army is able to recognize and respond to virus invasions almost as fast as the viruses multiply. For example, it takes only a few days to recover from colds or flu. It happens naturally. Some viruses, however, are so dangerous or deadly it isn t safe to let the immune system attack them naturally. You ve probably received vaccines (usually shots) to protect you against highly contagious childhood diseases like polio, measles, mumps, and whooping cough. A vaccine is made of dead or weakened viruses. It boosts the immune system by stimulating your cells to create antibodies that can recognize and block the viruses before they attach to a cell. The vaccine prepares your body to recognize the infection if it should recur. In other words, your body becomes immunized against that particular virus. But not all viruses are vaccine friendly. For example, there are more than 200 types of cold viruses, too many for a single vaccine to handle. Other viruses, such as influenza, quickly evolve into new versions that may be resistant to last year s vaccine. Every year scientists need to predict the type of flu that will be widespread that year and develop a flu vaccine that targets that particular version. And you re likely to need a different vaccine the following year. One of the deadliest viruses to emerge in recent years is HIV. It causes the disease called AIDS. HIV stands for Human Immunodeficiency (im-you-no-dee-fishin-see) Virus. HIV invades the body s immune system, the

8 very system that protects you from viruses and other invaders. Specifically, HIV targets the immune system s T cells. T cells organize the immune system response team. HIV is able to attach to a T cell through the interaction of its surface proteins with the T cell s receptor, like a key in a lock. Once the virus attaches to the cell, it fuses with the cell to deliver its genes inside. People whose T cells become infected with HIV may not know it at first, but their immune system is gradually being destroyed, leaving them defenseless against deadly diseases such as pneumonia and tuberculosis. Even normally mild diseases like colds and flu may become deadly as the immune system collapses from HIV infection. This weakened condition is called AIDS (Acquired Immune Deficiency Syndrome). AIDS is always fatal. But with the proper drugs, people can live for many years with HIV infection. HIV was discovered in the 1980s. In 20 years, the virus has spread to people in every country in the world. Today, about 40 million adults and children are infected with HIV, over 20 million have died from the disease, and the numbers keep rising. Increasingly, the victims are young women in their childbearing years. They often pass the virus to their babies. As HIV races around the world, scientists are racing to stop it. One of these scientists is Charles Wood, a virologist (virus expert) at the University of Nebraska. Wood heads a team of scientists that is tracking the evolution of HIV in mothers and their infants. The team investigates how the virus evolves as it passes from mother to child, and how it changes in response to the immune system. Charles Wood studies these things to try to understand effective ways to block HIV s spread. It s not clear yet who will win this race, HIV or us. Read on and find out why. HIV not only multiplies rapidly, it also mutates rapidly. This means that new viruses are not exact copies. They have genetic variations, or mutations. Scientists call these different viruses strains. The strains are like a swarm of bees, each slightly different. The body s immune system (or a drug treatment) blocks many of the new strains and greatly reduces the number of viruses. But some of the viruses escape and produce new strains. Each time the immune system or treatment tries to eliminate the viruses, some of the new viruses escape, and the different strains build up into another swarm. This is typical behavior for viruses. What is unusual about HIV is that it infects the immune cells themselves. With each new swarm, HIV is simultaneously destroying the immune system, leaving the body defenseless against all kinds of disease. Charles Wood is the director of the Nebraska Center for Virology at the University of Nebraska. He studies how HIV is transmitted from mothers to infants. Photo courtesy David Fitzgibbon University of Nebraska-Lincoln Charles Wood s research takes him to a laboratory in Zambia, a country in Africa. HIV is one of the greatest threats to women and children in Zambia and in the rest of the developing world. In tracking the evolution of HIV from mother to child, Wood first identifies the strains of HIV in the mother on the day she has her baby. He then looks at what happens when the virus travels to its new host, the newborn baby.

9 To stay ahead of the evolving virus, scientists need to predict which parts of the virus are likely to change and evade recognition by the body s immune system, and which parts are likely to remain unchanged. Wood is hopeful: If we can understand the evolution of HIV, where the virus is going, and why it is going there, we ll win. Wood and his team are collaborating with other scientists on a vaccine to give HIV-infected mothers before they give birth. The vaccine is designed to create antibodies that tie up all the viruses so that none are able to infect the baby. But what about a vaccine for the baby? Try your hand at creating one that works. In this activity you ll meet the virus, HIV, investigate what happens when it infects a newborn, work on a vaccine to save the baby, and discuss the evolutionary race between humans and HIV. Zambia is in central Africa. SMM Lonnie Broden illustration Women and children with AIDS - awareness pins at a clinic in Zambia. Photo courtesy John West

10 Name Pd HIV: Evolving Menace 1. Name 2 diseases caused by viruses: and. 2. A virus is simple, made up of and. 3. The genetic material in a virus can be either or. 4. A virus uses a cell like a giant, hijacking the cell s machinery to make more viruses. 5. Your system fights infection with many different kinds of cells: organize and attack invading viruses. produce antibodies that prevent the virus from invading a cell. 6. Vaccines, made of or viruses, boost the immune system to make that fight the virus. 7. The virus that causes AIDS is. It attacks the immune system, specifically. 8. Because the immune system is being destroyed by HIV, even may be deadly. 9. HIV has spread around the world, currently infecting people. have died from the disease. 10. A major problem for scientists is that HIV not only multiplies rapidly, but it also rapidly, making it extremely difficult to make a vaccine against this deadly virus.

11 Name: Dr. Virus, M.D. Date: Pd. Patient A: While traveling in Turkey, the 52-year-old patient was bitten by an aggressive wild dog. Upon return to the US, the patient showed mental confusion, fever, and difficulty in swallowing. Patient B: The 15-year-old student was sent to the nurse s office because he couldn t stay awake in biology class, opening his eyes only to cough and sneeze on his lab partner. The nurse found he had a fever, headache, and his entire body ached. Patient C: The 5-year-old girl was sent home from a birthday party at the park when it was discovered that, while hanging upside down from the monkey bars, her stomach was covered with small, red, blistered bumps. The rash was very itchy, and she also had a fever and cough. Patient D: The 35-year-old man went to the emergency room, complaining of extreme shortness of breath. For a few weeks he had had a fever, fatigue, and aching muscles. The patient had recently moved to Katy from the high desert of New Mexico, where he had lived in an old cabin that he had renovated. Patient E: The 24-year-old addict was brought to the emergency room because of an overdose. Her skin and the whites of her eyes were yellow, her urine was dark, and she had pain in her abdomen and joints. She mentioned sharing needles with another addict. Patient F: The 3-year-old was sent home from daycare because his head was very congested, he had a continuously runny nose, and he was sneezing on the other 3-year-olds. He had no fever but complained of his body aching. Patient G: The 16-year-old had been extremely tired for weeks and could barely climb the stairs to bed at night. The doctor found she had a high fever, a very sore throat, swollen glands, and the upper left part of her abdomen was tender to touch. Patient H: The 5-year-old boy was brought to the emergency clinic with muscle pain and loose, floppy arms and legs. He had been suffering from a fever and headache for 10 days previously. The family had recently immigrated from India to Texas. Patient I: The 30-year-old patient complained of a history of swollen lymph nodes, a fever and chills that had lasted for weeks, and weight loss over the past several months. He said he used intravenous drugs many years ago. Patient J: The 50-year-old woman had a painful rash of blisters, in a distinct band wrapping around her right side. She was currently undergoing chemotherapy for ovarian cancer. SOME VIRAL DISEASES AND THEIR SYMPTOMS: Chicken Pox Common Cold Hantavirus Hepatitis B HIV/AIDS Influenza (flu) Mononucleosis (mono) Polio Rabies Shingles red, itchy rash, small liquid-filled blisters, fever, headache, cough infection of upper respiratory tract; include runny nose, sore throat, cough, watery eyes, sneezing, and congestion fatigue, fever, chills, muscle aches, shortness of breath, fluid in lungs; virus found in rodent droppings; found in Four Corners area of western US liver infection; abdominal pain, dark urine, joint pain, nausea, fatigue, jaundice (yellowing of skin and eyes) attacks immune system; fever, fatigue, swollen lymph glands, rash, weight loss, persistent fever over weeks; transmitted by unprotected sex or contact with infected blood respiratory infection; fever > 100 F, chills and sweats, headache, cough, aching muscles, fatigue, congestion fatigue, weakness, sore throat, fever, swollen lymph nodes and tonsils, headache, swollen spleen fever, sore throat, headache; pain, stiffness, and spasms in limbs, back, and/or neck; loss of reflexes, paralyzed limbs; present in Afghanistan, India, Nigeria, Pakistan fever, headache, agitation, anxiety, confusion, difficulty swallowing, hallucinations; transmitted through saliva of an infected animal pain, burning, red rash, fluid-filled blisters, often in a band pattern on one side of chest; especially in patients with weakened immune systems; caused by chicken pox virus

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13 Name Dates Period BIOLOGY WARM-UPS All warm ups will be taken up after each test for a quiz grade. Date: Date: Date: (Over)

14 Date: Date: Date: