Viruses: The Tiniest Pests

1. Viruses: The Tiniest Pests 1

2. In this computer rotation we will be studying how viruses are pests Before you view the power point, write down 2 things you already know about viruses. Write this answer on question #1 on your Virus worksheet 2

3. Size of a Virushttp://www.cellsalive.com/howbig.htm Click on the site above and compare the sizes of two of the following with the Rhinovirus. • Rhinovirus • E. coli bacteria • Red blood cell • White blood cell • Ragweed pollen • Dust mite • Human hair 3

4. General Characteristics of Viruses Viruses are infectious agents with both living and nonliving characteristics. We will explore the following 3 characteristics: 1. Living characteristics of viruses 2. Nonliving characteristics of viruses 3. Criteria used to define a virus 4

5. Living characteristics of viruses 1. Living characteristics of viruses a. They reproduce at a fantastic rate, but only in living host cells. b. They can mutate. 5

6. Nonliving characteristics of viruses a. They are acellular, that is, they contain no cytoplasm or cellular organelles. b. They carry out no metabolism on their own and must replicate using the host cell's metabolic machinery. In other words, viruses don't grow and divide. Instead, new viral components are synthesized and assembled within the infected host cell. c. Vast majority of viruses possess either DNA or RNA but not both. 6

7. Criteria used to define a virus a. The vast majority of viruses contain only one type of nucleic acid: DNA or RNA, but not both. b. They are totally dependent on a host cell for replication. (They are strict intracellular parasites and cannot reproduce outside a living host cell.) c. Viral components must assemble into complete viruses (virions) to go from one host cell to another. 7

8. How viruses Attack: http://www.youtube.com/watch?v=TVLo2CtB3GA&feature=related 8

9. Virus Film clip: Shape and Structure http://www.youtube.com/watch?v=7iVm1uEIyP0&feature=related 9

10. These viruses invade humans, animals, plants and other microorganisms. Viruses are very specific to the type of cell they invade. For instance, a cold virus does not attack the human foot, ear or nose cells. It does attack the cells that line the respiratory system. TheHIV virus does not attack the elbow, skull or brain cells, but it does attack the T4 cells of the immune system. 10

11. Types of Viruses There are thousands of known viruses. Today we will be exploring the following viruses: • HIV • HPV (Human Papillomavirus) • West Nile • Ebola • Flu 11

12. HIV Virus 12

13. Symptoms and Transmission of HIV Virus Symptoms of HIV How it is transmitted Only specific fluids (blood, semen, vaginal secretions, and breast milk) from an HIV infected person can transmit HIV. These specific fluids must come in contact with a mucous membrane or damaged tissue or be directly injected into the blood-stream (from a needle or syringe) for transmission to possibly occur. Within a few weeks of infection • Fever • Headache • Sore throat • Swollen lymph glands • Rash Years later • Swollen lymph nodes — often one of the first signs of HIV infection • Diarrhea • Weight loss • Fever • Cough and shortness of breath These are all common symptoms of many illnesses, but with HIV infection, they last much longer than usual, for two weeks or longer. 13

14. HPV Virus Genital Warts 14

15. Symptoms and Transmission of HPV Symptoms of HPV How HPV is Transmitted HPV is passed on through genital contact, most often during vaginal and anal sex. HPV may also be passed on during oral sex and genital-to-genital contact. HPV can be passed on between straight and same-sex partners—even when the infected partner has no signs or symptoms • Genital warts: a small bump or group of bumps in the genital area. They can be small or large, raised or flat, or shaped like a cauliflower. Health care providers can diagnose warts by looking at the genital area during an office visit. Warts can appear within weeks or months after sexual contact with an infected partner—even if the infected partner has no signs of genital warts. If left untreated, genital warts might go away, remain unchanged, or increase in size or number. These strains of HPV will not turn into cancer. • Other strains of HPV can result in cancers, but they are not the same strains that cause genital warts. 15

16. West Nile Virus 16

17. Symptoms and Transmission of West Nile Virus Symptoms of West Nile How West Nile is Transmitted The main route of human infection with West Nile virus is through the bite of an infected mosquito. Mosquitoes become infected when they feed on infected birds, which may circulate the virus in their blood for a few days. The virus eventually gets into the mosquito's salivary glands. During later blood meals (when mosquitoes bite), the virus may be injected into humans and animals, where it can multiply and possibly cause illness. • Symptoms include fever, headache, tiredness, and body aches, occasionally with a skin rash (on the trunk of the body) and swollen lymph glands. While the illness can be as short as a few days, even healthy people have reported being sick for several weeks. 17

18. Ebola Virus 18

19. Symptoms and Transmission of Ebola Virus Symptoms of Ebola How Ebola is Transmitted We still don't know how primates contract filoviruses in nature. The secondary cases of filovirus infection have been from contact with contaminated blood, organs, semen or other bodily secretions. Ebola can also be transmitted through the handling of ill or dead chimpanzees. In humans, Ebola is transmitted by contact with infected bodily fluids and/or tissues. There is evidence of a possible respiratory route of transmission of Ebola in nonhuman primates (3). But humans may be resistant to the airborne/aerosol transmission of Ebola (may not have the right receptors). • Ebola symptoms typically begin to develop within four to six days of being infected. Symptoms of Ebola commonly include fever, sore throat, vomiting, weakness, stomach pain, a dry, hacking cough, and internal or external bleeding. • Death usually occurs during the second week of Ebola symptoms, most often as a result of massive blood loss. 19

20. Flu Virus 20

21. Symptoms and Transmission of Influenza Flu and Cold Virus Symptoms of Influenza Flu? How is Influenza Flu Transmitted? Influenza can be highly contagious, particularly among persons without pre-existing antibodies against influenza, such as young children during the inter-pandemic phase influenza and anyone during a pandemic. Roughly 50% of all infections are however asymptomatic; asymptomatic infection is especially common in children. The influenza virus is transmitted in most cases by droplets through the coughing and sneezing of infected persons, but it can be transmitted as well by direct contact. • Fever • Aches • Chills • Tiredness • Sudden onset • Coughing • Sneezing • Sore throat 21