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Confidence

Confidence. The Hot Zone. General Features of Viruses #1. Obligate Intracellular Parasites Very small (ultramicroscopic) Non-cellular Not Alive Protein Coat Capsid Envelopes. General Features of Viruses #2. Utilization of Host Cell Machinery Host Range Genome DNA or RNA but NOT both

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Confidence

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  1. Confidence

  2. The Hot Zone

  3. General Features of Viruses #1 • Obligate Intracellular Parasites • Very small (ultramicroscopic) • Non-cellular • Not Alive • Protein Coat Capsid • Envelopes

  4. General Features of Viruses #2 • Utilization of Host Cell Machinery • Host Range • Genome • DNA or RNA but NOT both • Single stranded or double stranded • Enzymes (Polymerases)

  5. Virus Replication (5 Basic Steps) • Adsorption • Penetration • Replication • Maturation • Release

  6. Viral Replication (5 basic steps)

  7. Bacteriophage Multiplication Cycle • Lytic Cycle

  8. Lysogenic Cycle Movie

  9. DNA Viruses

  10. RNA Viruses

  11. Consequences of Infection *Cytopathic Effect (CPE) *Latency *Transformation Oncogenic viruses

  12. Animal Viruses------DNA • Pox Enveloped Large/complex virus SMALLPOX

  13. Animal Viruses------DNA • Herpes • latency & recurrent infections • “Herpes is Forever” • Large, enveloped virus • complications of latency & recurrent infections become more severe with age, cancer chemotherapy, etc • Among the most common & serious opportunists among AIDS patients Herpes Simplex Virus Herpes simplex virus can enter both neuronal and skin cells but achieves latency only in neurons

  14. Herpes Simplex Virus-1 Latency in trigeminal nerve ganglion

  15. Herpes Cure? “There is no treatment that can cure herpes, but antiviral medications can shorten and prevent outbreaks during the period of time the person takes the medication.  In addition, daily suppressive therapy for symptomatic herpes can reduce transmission to partners.” (from CDC fact sheet) Treatment parody http://www.youtube.com/watch?v=jLBTXe1R3VE

  16. Herpes: Varicella-Zoster (Chicken Pox/Shingles) Early symptoms are acute pain and redness of dermatome followed by rash Chickenpox Shingles

  17. Epstein-Barr Virus (EBV) • infects lymphoid tissue & salivary glands • transmission – direct oral contact & contamination with saliva • by mid-life 90-95% of all people are infected. • causes mononucleosis – sore throat, high fever, cervical lymphadenopathy • Because of great sanitation in U.S. 70% of college-age Americans have never had the infection…so a very vulnerable population for mono • Long incubation period (30-50 day incubation) • most cases of infection are asymptomatic

  18. Animal Viruses------DNA • Parvo Single-stranded DNA virus Very small nonenveloped virus Important disease in domestic animals-causes distemper in cats, enteric disease in dogs, fatal cardiac infection in puppies

  19. Parvoviruses • B19 variety causes fifth disease, (erythema infectiosum), rash of childhood • Child may have fever & rash on cheeks • Severe fatal anemia can result if pregnant woman transmits virus to fetus “slapped face” rash of fifth disease. Parvovirus B19

  20. Papillomavirus Plantar wart Common wart Genital wart

  21. Papillomavirus • papilloma – benign, squamous epithelial growth or wart • caused by 40 different strains of HPV (nonenveloped DNA virus) • Common warts (seed warts) – on fingers, etc • plantar warts – on soles of feet • genital warts – prevalent STD • transmissible through direct contact or contaminated fomites, autoinnoculation(self-spread) • Incubation – 2 weeks to more than a year • For most people the virus goes away on its own

  22. Genital warts • most common STD in US? • over 6 M new cases each year • 20+ million carriers (U.S.) of one of the 5 types of HPV associated with genital warts • strong association with cervical & penile cancer • CDC estimates sexually active people have a 50% chance of catching HPV during a lifetime

  23. HPV Vaccine • For girls and women 9-26 years of age • Three doses • Initial • 2 month booster • 6 month booster • For prevention only…not a treatment

  24. Animal Viruses------RNA • Paramyxoviruses • Measles • Mumps

  25. How Iowa Got The Mumps How Iowa Got the Mumps • In 2006 Iowa got the mumps. Over 2000 individuals got mumps infection in the first half of 2006 (in a normal year there are on average 5 cases per year) • Probably originated … in the UK? 26

  26. Influenza

  27. Animal Viruses------RNA • Orthomyxoviruses INFLUENZA • Influenza A (circulates in many species) • Influenza B (circulates widely only in man) • Influenza C (mild illness…not thought to cause epidemics) • Antigenic Drift (small changes that happen continually over time) • Antigenic Shift (abrupt major change in the virus)

  28. Shift and Drift Yearly variations in the “Seasonal Flu” are the result of antigenic drift.

  29. Vaccination for “seasonal flu” • There are two types of vaccines: • The "flu shot"— an inactivated vaccine (containing killed virus) that is given with a needle, usually in the arm. • The nasal-spray flu vaccine— a vaccine made with live, weakened flu viruses that do not cause the flu (sometimes called LAIV for “live attenuated influenza vaccine” or FluMist®). LAIV (FluMist®) is approved for use in healthy* people 2-49 years of age who are not pregnant. • Each vaccine contains three influenza viruses-one A (H3N2) virus, one regular, seasonal A (H1N1) virus, and one B virus. The viruses in the vaccine change each year based on international surveillance and scientists' estimations about which types and strains of viruses will circulate in a given year. • About 2 weeks after vaccination, antibodies that provide protection against influenza virus infection develop in the body. • Seasonal flu peaks in the U.S. in Jan and Feb

  30. Influenza type A • acute, highly contagious respiratory illness • seasonal, pandemics • among top 10 causes of death in US • respiratory transmission • binds to ciliated cells of respiratory mucosa • causes rapid shedding of cells, stripping the respiratory epithelium, severe inflammation • fever, headache, myalgia (muscle pain), pharyngeal pain, shortness of breath, coughing • treatment: amantadine, rimantadine, zanamivir & oseltamivir • annual vaccine

  31. 2009 H1N1…”swine flu”

  32. Animal Viruses------RNA • Orthomyxoviruses INFLUENZA Is an Avian Flu pandemic on the way??

  33. Avian Flu

  34. Avian Flu

  35. Avian Flu

  36. Avian Flu Why would “Bird Flu” be a big deal? Pandemic viruses appear as the result of antigenic shift, which causes new combinations of proteins on the surface of the virus. If the new virus spreads easily from person to person a pandemic can result.

  37. Avian Flu • Culling of infected Poultry

  38. NOVA Science NOWPandemic flu video (2006) http://www.pbs.org/wgbh/nova/sciencenow/3302/04.html

  39. More RNA Animal Viruses Togaviruses(Flavivirus subcategory) • Dengue • Yellow Fever • West Nile

  40. Dengue American countries with laboratory-confirmed hemorrhagic fever (red shaded areas), prior to 1981 and from 1981 to 1997. Distribution of Aedes aegypti (red shaded areas) in the Americas in 1970, at the end of the mosquito eradication program, and in 1997

  41. Dengue

  42. West Nile Virus-1999-2001

  43. West Nile Virus-2002

  44. West Nile Virus – 2004 (march 3rd)

  45. West Nile Virus – 2005 (Jan 11Th)

  46. West Nile Virus - Life Cycle

  47. Animal Viruses------RNA • Picorna(a nonenveloped small RNA virus) Polio (generally fecal-oral transmission, also shed in throat. Spread by contact with infected person or drinking water) Hepatitis A (fecal-oral transmission) Foot and Mouth Disease Virus (FMDV) (foreign animal disease…object of extreme surveillance)

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