1. Viruses Viruses are insidious pathogens, they attack cells from the inside. They hijack your own DNA and use it against you. A virus cannot be treated with antibiotics, it can only run its course until your immune system kicks it out...Even then, the virus may lay dormant within the cells and come back at a later date Adenovirus - cause of the common cold

3. Viruses Virus – Latin for “_Poison__” Virus – Latin for “_Poison__” Russian Biologist Dmitri Ivanovski (1892) – Tobacco Mosaic Disease…not determined to be a virus until 1930…known as the first virus to be discovered!~ Russian Biologist Dmitri Ivanovski (1892) – Tobacco Mosaic Disease…not determined to be a virus until 1930…known as the first virus to be discovered!~

4. Characteristics of Viruses Scientist that studies viruses is called a virologist! Among the smallest biological particles (not cells) that are capable of causing harm in living organisms. Among the smallest biological particles (not cells) that are capable of causing harm in living organisms. Virus particles are called virions Virus particles are called virions 5000 influenza viruses can fit inside the head of a pin! 5000 influenza viruses can fit inside the head of a pin!

5. Properties of a Virus: no membranes, cytoplasm, ribosomes, or other cellular components no membranes, cytoplasm, ribosomes, or other cellular components they cannot move or grow they cannot move or grow they can only reproduce inside a host cell they can only reproduce inside a host cell they consist of 2 major parts - a protein coat, and hereditary material (DNA or RNA) they consist of 2 major parts - a protein coat, and hereditary material (DNA or RNA) they are extremely tiny, much smaller than a cell and only visible with advanced electron microscopes they are extremely tiny, much smaller than a cell and only visible with advanced electron microscopes

6. VIRUSES & CELLS CharacteristicVIRUSCELL Structure DNA or RNA core, capsid Reproduction Only within a host Genetic Code DNA or RNA Growth/DvpmtNO EnergyNO Response to Environment No Change over time Yes

7. Not Considered Living A virus is not a bacteria, fungus, protist, plant or animal. A virus is not a bacteria, fungus, protist, plant or animal. They do not carry out cellular functions. They do not carry out cellular functions. They do not grow or undergo division They do not grow or undergo division A virus can not replicate on their own – they need to infect a HOST and use the hosts organelles and enzymes to do this! A virus can not replicate on their own – they need to infect a HOST and use the hosts organelles and enzymes to do this!

8. How Are Viruses Named? 1. Nature of the nucleic acid (DNA or RNA) 2. Protein shell and symmetry 3. Geographic Origin 4. Year of Isolation 5. Named after the infected species (Swine Flu, Avian Flu..) 6. Named after a person (either a patient or a doctor) Example of an Influenza Virus

9. How are Viruses Classified? 1. Genetic Material DNA or DNA or RNA (retrovirus/mutates frequently) RNA (retrovirus/mutates frequently) But not both But not both 2. Capsid (Protein) Structure (95% of virus)  Helical (rod shaped)  Polyhedral (spherical)  Complex 3. Presence or absence of a membranous envelope surrounding the capsid **No envelope = naked virus Helical Marburg virus Polyhedral SV40 virus Complex bacteriophage

10. Virus Structure

11. Parasitic Nature Parasitic Nature Obligate intracellular parasites (they cannot exist independently) Specific to hosts (human, dog, some can cross species) Specific to hosts (human, dog, some can cross species) Specific to cells, the common cold is a virus that specifically attacks cells of the respiratory track (hence the coughing and sneezing and sniffling). HIV specifically attacks white blood cells This is a bacteriophage, a type of virus that attacks bacteria. It is recognizeable because it looks like the lunar landing spaceship. **Most widely studied virus!!! See animation http://www.youtube.com/watch?v=41aqxcxsX2w&feature= relatedhttp://www.youtube.com/watch?v=41aqxcxsX2w&feature= related

12. Viral Reproduction Lytic cycle = ACTIVE…reproduction occurs, cells burst Lysogenic cycle = DORMANT…reproduction does not immediately occur Virulent = viruses that undergo both cycles

13. Viral Replication – Lytic Cycle Infection See clip on desktop!!

14. Lytic (kills cells dead) Adsorption – (aka attachment) chemical attraction between the tail fibers and receptor proteins on the host cell (lock & key fit) Adsorption – (aka attachment) chemical attraction between the tail fibers and receptor proteins on the host cell (lock & key fit) Entry – release an enzyme to weaken the wall of bacterium & tail sheath contracts forcing a tube in. (like a needle) Entry – release an enzyme to weaken the wall of bacterium & tail sheath contracts forcing a tube in. (like a needle) Replication – enzymes degrate host DNA and stops making its molecules and begins using the viruses genome to make copies Replication – enzymes degrate host DNA and stops making its molecules and begins using the viruses genome to make copies Assembly – proteins spontaneously attach together Assembly – proteins spontaneously attach together Release - The newly assembled viruses are released from the host bacterial cell as the enzyme completes its degradation of the cell wall and the bacteria disintegrates. Release - The newly assembled viruses are released from the host bacterial cell as the enzyme completes its degradation of the cell wall and the bacteria disintegrates.

15. LYSOGENIC CYCLE See clip on desktop!!!

16. Viral Replication – Lysogenic Cycle Infection The host cell makes copies of the virus indefinately The host cell makes copies of the virus indefinately The virus integrates its DNA into the DNA of the host cell, and the viral genetic information replicates along with the host cell’s DNA. The virus integrates its DNA into the DNA of the host cell, and the viral genetic information replicates along with the host cell’s DNA. Unlike lytic viruses, lysogenic viruses DO NOT lyse the host cell right away. (it can remain inactive for a long period of time) Unlike lytic viruses, lysogenic viruses DO NOT lyse the host cell right away. (it can remain inactive for a long period of time) The viral DNA embedded in the host’s DNA is called a prophage and it can remain in the host for many years before becoming active. The viral DNA embedded in the host’s DNA is called a prophage and it can remain in the host for many years before becoming active.

17. What Organisms and Host Cells Do Viruses Infect? Infection by viruses Infection by viruses viruses infect bacteria, plants, animals and other living organisms in order to reproduce viruses infect bacteria, plants, animals and other living organisms in order to reproduce a given virus usually infects a limited number of species. a given virus usually infects a limited number of species. within a host organism, usually only a limited number of cell types are susceptible to infection by a given virus within a host organism, usually only a limited number of cell types are susceptible to infection by a given virus Host range Host range array of host cells that a particular virus can infect array of host cells that a particular virus can infect determined by a “lock-and-key” fit between the virus and a receptor on the surface of a host cell protein determined by a “lock-and-key” fit between the virus and a receptor on the surface of a host cell protein Ex: HIV, for example, only will enter cells that have a surface protein molecule called CD4. These molecules are found only on white blood cells. Thus, HIV will only infect white blood cells and not lung cells or other cell types. Ex: HIV, for example, only will enter cells that have a surface protein molecule called CD4. These molecules are found only on white blood cells. Thus, HIV will only infect white blood cells and not lung cells or other cell types.

18. Emerging Viruses: Emerging Viruses: illnesses not previously known illnesses not previously known AIDS, West Nile Virus, SARS, Ebola, Bird Flu AIDS, West Nile Virus, SARS, Ebola, Bird Flu Could be genetic code mutations of known viruses…protein coat changes that are unrecognizable to host’s immune system Could be genetic code mutations of known viruses…protein coat changes that are unrecognizable to host’s immune system Could be viruses exposed when new areas were developed Could be viruses exposed when new areas were developed Could have jumped species (avian flu, swine flu) Could have jumped species (avian flu, swine flu)

19. How do our bodies fight viruses? Functions of the Immune System: Functions of the Immune System:Recognition: Antibodies (proteins that bind to the surface of a virus) recognize an infected cell and attach. Antibodies (proteins that bind to the surface of a virus) recognize an infected cell and attach.Destruction: Leukocytes move in to destroy the infected cells Leukocytes move in to destroy the infected cells Also known as White Blood Cells that come from the bone marrow Also known as White Blood Cells that come from the bone marrow Goal is to recognize foreign substances (not healthy cells) Goal is to recognize foreign substances (not healthy cells)Memory: Once infected, memory cells recognize the virus if it enters the cell again! Once infected, memory cells recognize the virus if it enters the cell again!

20. How Can Viral Diseases Be Prevented and Treated? Good hygiene Good hygiene Avoid contact with contaminated food, water, fecal material or body fluids. Avoid contact with contaminated food, water, fecal material or body fluids. Wash hands frequently. Wash hands frequently. Vaccines Vaccines Stimulate natural defenses with in the body. Stimulate natural defenses with in the body. Contain a component of or a weakened or killed virus particles. Contain a component of or a weakened or killed virus particles. Are developed for many once common illnesses such as smallpox, polio, mumps, chicken pox. Are developed for many once common illnesses such as smallpox, polio, mumps, chicken pox. Not available for all viruses. Not available for all viruses. Anti-viral drugs (but not antibiotics) Anti-viral drugs (but not antibiotics) Available for only a few viruses. Available for only a few viruses. There are two FDA-approved antiviral drugs recommended by CDC. The brand names for these are Tamiflu® (generic name oseltamivir) and Relenza® (generic name zanamivir). There are two FDA-approved antiviral drugs recommended by CDC. The brand names for these are Tamiflu® (generic name oseltamivir) and Relenza® (generic name zanamivir). Used to relieve symptoms Used to relieve symptoms Other antivirals block the viruses at various stages of their life cycle, such as blocking cell receptors, preventing attachment or preventing viral repication after the virus has entered the cell. Other antivirals block the viruses at various stages of their life cycle, such as blocking cell receptors, preventing attachment or preventing viral repication after the virus has entered the cell.

21. Some parents are opting out of immunizations due to fears about vaccine safety. In response, government agencies are producing commercials to encourage parents to get their child vaccinated. Discuss: 1. What are the risks of vaccines? Are they safe? 2. Would you have your own child vaccinated? 3. Should the government force immunizations?

22. RV = rotovirus; DTaP = diptheria, tetanus, pertussis (whooping cough); Hib = haemophilus influenza type B; PCV = pneumococcal vaccine; IPV = inactivated polio virus; MMR = measles, mumps, rubella, RV = rotovirus; DTaP = diptheria, tetanus, pertussis (whooping cough); Hib = haemophilus influenza type B; PCV = pneumococcal vaccine; IPV = inactivated polio virus; MMR = measles, mumps, rubella,

23. Retroviruses -- RNA viruses that have a DNA stage Retroviruses -- RNA viruses that have a DNA stage Human Immunodefiency Virus - causes AIDS Human Immunodefiency Virus - causes AIDS Retrovirus (RNA inside a protein coat) Retrovirus (RNA inside a protein coat) Reverse Transcriptase makes DNA from the virus RNA Reverse Transcriptase makes DNA from the virus RNA DNA inserts into host DNA DNA inserts into host DNA Proteins are assembled from the DNA code Proteins are assembled from the DNA code Viruses assembled from the proteins Viruses assembled from the proteins Viruses released from the cell Viruses released from the cell (Link) HIV Animation - how virus infects cellsHIV Animation - how virus infects cells

24. What we know about HIV.....

25. Developing a vaccine for AIDS is difficult because it is a RETROVIRUS. RNA mutates easily and each individual virus can be slightly different from the others. In fact, different viruses can exist within the same person.

26. HSV1 vs HSV2

29. Human Papilloma Virus – 14yo boy

30. http://www.youtube.com/watch?v=6E1zh6ukc OU

32. Polio Virus Six countries (Afghanistan, Egypt, India, Niger, Nigeria, and Pakistan) still have polio circulating

34. Now Let’s Check Your Knowledge!! Mini Virus Quiz

35. VIRUS MINI QUIZ 1. THE PRIMARY FUNCTION OF ALL VIRUSES IS TO REPLICATE!!

36. MINI QUIZ… 2. WHAT IS THE TYPICAL/COMMON VIRUS THAT STUDENTS STUDY WHEN LEARNING ABOUT VIRUSES? T4 Bacteriophage

37. MINI QUIZ… 3. IN ORDER FOR A VIRUS TO REPLICATE IT NEEDS TO BE IN A…. HOST CELL

38. MINI QUIZ… 4. VIRAL REPRODUCTION THAT KILLS THE HOST CELL IS CALLED THE Lytic CYCLE!

39. MINI QUIZ… 5. WHEN VIRAL DNA IS EMBEDDED INTO A HOST CELL’S DNA IT FORMS A…. PROPHAGE

40. MINI QUIZ… 6. ANOTHER NAME FOR INFLUENZA IS…. FLU VIRUS

41. MINI QUIZ… 7. 3 WAYS VIRUSES CAN BE TREATED/PREVENTED ARE…. 1. Hygiene 2. Vaccines 3. AntiVirals

42. MINI QUIZ… 8. SCIENTISTS THAT STUDY VIRUSES ARE CALLED VIROLOGISTS

43. MINI QUIZ… 9. 2 WAYS THAT VIRUSES CAN BE TRANSMITTED ARE…. -- droplets in the air -- via food or water -- via mosquitoes, ticks other animals -- physical contact

44. MINI QUIZ… 10. A VIRUS THAT HAS ONLY A CAPSID SURROUNDING IT’S GENETIC INFORMATION AND NO ENVELOPE IS CALLED A…. NAKED VIRUS.