1. BELL WORK (Buff Binder): DRAW and LABEL the two virus pictures below, using the terms CAPSID, GENETIC MATERIAL, ENVELOPE, and SPIKES.
GENETIC MATERIAL
ENVELOPE
CAPSID
SPIKE
CAPSID
GENETIC MATERIAL

2. Set up your page for today…
Date:
Title: Viral Cycles
Essential Question: How does a virus reproduce?
Yes, Cornell notes please!

3. Why are most viruses harmful?
Virus invades cell
When your cells make viruses instead of operating normally, YOU get sick
Virus forces cell to make copies of virus
Eventually, so many copies are made that the cell explodes,
releasing all of the new viruses

4. TWO viral reproduction cycles
LYSOGENIC CYCLE = very long
Symptoms may not appear for weeks, months, or even years.
LYTIC CYCLE = very short
Symptoms appear very quickly.

5. Let’s look at the lysogenic cycle…

7. HIV

8. Virus “hides” for a while inside host cells before becoming active
Lysogenic Cycle
Virus “hides” for a while inside host cells before becoming active
Steps:
Attach to cell
Inject virus DNA/RNA
Integrate virus DNA/RNA into cell DNA
Wait
Remove from virus from cell DNA
Become active (lytic cycle)

9. Lysogenic Cycle
- Viruses

10. Now let’s see the lytic cycle…

12. Lytic Cycle

13. Lytic Cycle
Viruses enter cells & immediately multiply, leading to quick cell death.
Steps:
Attach to cell
Inject DNA/RNA
Produce (replicate) virus parts
Assemble new virons
Release viruses to infect other cells

14. - Viruses
Lytic Cycle

15. Spread of influenza virus
Respiratory aerosoles can be generated from the respiratory tract by various means – from speaking to sneezing.
During a sneeze, millions of tiny droplets of water and mucus are expelled at about 200 miles per hour (100 metres per second). The droplets initially are about micrometres diameter, but they dry rapidly to droplet nuclei of 1-4 micrometres, containing virus particles or bacteria. This is a major means of transmission of several diseases of humans.

16. ATTACH INJECT PRODUCE INTEGRATE ASSEMBLE WAIT RELEASE REMOVE
to the cell
INJECT
DNA/RNA
PRODUCE
virus parts
INTEGRATE
into cell’s DNA
ASSEMBLE
new virions
(become active)
WAIT
RELEASE
viruses
REMOVE
viral DNA

17. Lysogenic Cycle
Lytic Cycle

18. Transmission of Viruses
Respiratory transmission
Influenza A virus
Faecal-oral transmission
Enterovirus
Blood-borne transmission
Hepatitis B virus
Sexual Transmission
HIV
Animal or insect vectors
Rabies virus
·         As with many infections viruses can be transmitted between susceptible individuals by a variety of means. The details provided related mainly to viruses infecting humans.
·         Many animal viruses do not remain infectious for very long outside the host.
Ø     Respiratory: Influenza A virus (and rhinovirus). Transmission in the form of aerosols during coughing and sneezing. The viruses are fairly sensitive to drying and their transmission is highest when individuals are in close contact.
Ø     Faecal-oral: Enteroviruses (e.g. poliovirus) A lot of viruses are excreted in faeces following high levels of replication in the gut.
Ø     Blood borne: Hepatitis B (and HIV). Transferred through contaminated blood products or via shared needles with drug abuse.
Ø     Sexual transmission: (HIV)
Animal/insect vector: Rabies. In many instances the virus infection is a specific pathogen of the animal and is not normally transmitted to humans by any other means.

19. Think-Pair-Share
Are viruses alive?
(Justify your answer)

20. Viruses have both living and nonliving characteristics.
Living characteristics of viruses:
They reproduce at a fantastic rate, but only in living host cells.
They can mutate.
They contain DNA or RNA

21. Viruses are NOT alive because they DO NOT have ALL of the characteristics of life.

22. Use for microorganisms in society

23. Case Study: Ebola What is the general structure of Ebola?
What type of reproductive cycle does it probably go through?
How is it transmitted?
What are the treatment options?

24. Ebola Virus Prototype Viral Hemorrhagic Fever Pathogen
Filovirus: enveloped, non-segmented, negative- stranded RNA virus
Severe disease with high case fatality
Absence of specific treatment or vaccine
>20 previous Ebola and Marburg virus outbreaks
2014 West Africa Ebola outbreak caused by Zaire ebolavirus species (five known Ebola virus species)

25. Figure. Ebola virus disease (EVD) cumulative incidence
Figure. Ebola virus disease (EVD) cumulative incidence* — West Africa, January 21, 2015
* Cumulative number of reported EVD cases to WHO

26. 2014 Ebola Outbreak Reported Cases in Guinea, Liberia, and Sierra Leone
This graph shows the cumulative reported cases in Guinea, Liberia, and Sierra Leone provided in WHO situation reports beginning on March 25, 2014 through the most recent situation report on January 21, 2015.

27. EVD Cases and Deaths* Reporting Date Total Cases Confirmed Cases
Total Deaths
Guinea
19 Jan 15
2,873
2,542
1,879
Liberia
20 Jan 15
8,524
3,136
3,636
Sierra Leone
10,362
7,909
3,153
United Kingdom
29 Dec 14 1
Nigeria**
15 Oct 14 20 19 8
Spain**
27 Oct 14
Senegal**
United States**
24 Oct 14 4
Mali**
23 Nov 14 7 6
TOTAL
21,794
13,620
8,683
Updated case counts available at
*Reported by WHO using data from Ministries of Health
**The outbreaks of EVD in Senegal, Nigeria, Spain, the United States, and Mali have ended.

28. Ebola Virus Transmission
Virus present in high quantity in blood, body fluids, and excreta of symptomatic EVD-infected patients
Opportunities for human-to-human transmission
Direct contact (through broken skin or unprotected mucous membranes) with an EVD-infected patient’s blood or body fluids
Sharps injury (with EVD-contaminated needle or other sharp)
Direct contact with the corpse of a person who died of EVD
Indirect contact with an EVD-infected patient’s blood or body fluids via a contaminated object (soiled linens or used utensils)
Ebola can also be transmitted via contact with blood, fluids, or meat of an infected animal
Limited evidence that dogs become infected with Ebola virus
No reports of dogs or cats becoming sick with or transmitting Ebola

29. Transmission
Burial ceremonies in which mourners have direct contact with the body of the deceased person can also play a role in the transmission of Ebola.
Burial (n) 葬禮
Mourner (n) 送葬者、參加喪禮的人
非洲有個習慣是親人要幫死去的家屬洗身體，包括消化道，如此又會增加人傳人的風險。

30. EVD Cases (United States)
EVD has been diagnosed in the United States in four people, one (the index patient) who traveled to Dallas, Texas from Liberia, two healthcare workers who cared for the index patient, and one medical aid worker who traveled to New York City from Guinea
Index patient – Symptoms developed on September 24, 2014 approximately four days after arrival, sought medical care at Texas Health Presbyterian Hospital of Dallas on September 26, was admitted to hospital on September 28, testing confirmed EVD on September 30, patient died October 8.
TX Healthcare Worker, Case 2 – Cared for index patient, was self-monitoring and presented to hospital reporting low-grade fever, diagnosed with EVD on October 10, recovered and released from NIH Clinical Center October 24.
TX Healthcare Worker, Case 3 – Cared for index patient, was self-monitoring and reported low-grade fever, diagnosed with EVD on October 15, recovered and released from Emory University Hospital in Atlanta October 28.
NY Medical Aid Worker, Case 4 – Worked with Ebola patients in Guinea, was self- monitoring and reported fever, diagnosed with EVD on October 24, recovered and released from Bellevue Hospital in New York City November 11.
Information on U.S. EVD cases available at

31. EVD Cases (United States)
During this outbreak, five health workers and one journalist have been infected with Ebola virus while in West Africa and transported to hospitals in the United States. Five of these patients have recovered.
One of the health workers died on November 17 after being transported from Sierra Leone to Nebraska Medical Center.

32. Detection of Ebola Virus in Different Human Body Fluids over Time

33. Signs & Symptoms Early symptoms of Ebola look like flu, including:
Fever
Headache
Muscle aches
Sore throat
Weakness
Diarrhea
Diarrhea (n) 腹瀉
Rash (n) 疹子
As the disease gets worse:
Bleeding inside and outside of the body
Rash
Trouble breathing

34. Clinical Manifestations by Organ System in West African Ebola Outbreak
General
Fever (87%), fatigue (76%), arthralgia (39%), myalgia (39%)
Neurological
Headache (53%), confusion (13%), eye pain (8%), coma (6%)
Cardiovascular
Chest pain (37%),
Pulmonary
Cough (30%), dyspnea (23%), sore throat (22%), hiccups (11%)
Gastrointestinal
Vomiting (68%), diarrhea (66%), anorexia (65%), abdominal pain (44%), dysphagia (33%), jaundice (10%)
Hematological
Any unexplained bleeding (18%), melena/hematochezia (6%), hematemesis (4%), vaginal bleeding (3%), gingival bleeding (2%), hemoptysis (2%), epistaxis (2%), bleeding at injection site (2%), hematuria (1%), petechiae/ecchymoses (1%)
Integumentary
Conjunctivitis (21%), rash (6%)
WHO Ebola Response team. NEJM. 2014

35. Examples of Hemorrhagic Signs
Hematemesis
Gingival bleeding
Bleeding at IV Site

36. Common Viral Diseases
Unlike with bacterial diseases, there are currently no medications that can cure viral infections.

37. Treatment and Prevention of Virus Infections
Antivirals
Vaccines and immunisation
Antivirals
Vaccines and immunisation

38. Antiviral Targets Attachment/Entry Nucleic acid replication
Virus protein processing
Virus maturation
Attachment/Entry
Picornaviruses
Nucleic acid replication
Human immunoideficiency virus (AZT)
Herpes simplex virus (Acyclovir)
Virus protein processing
HIV (Protease inhbitors)
Virus maturation
Influenza A virus (Neuraminidase blockers)
Problems of antivruals
Dificuly in finding a virus specific site against which to direct the antivrial
As with the use of antiiotics – resistant mutant scan be readily generated that are resistant to antiirals – this is particuarly a problem with those against HIV where the drug has to be used for prolonged periods of time.

39. Problems with Antivirals
Finding a virus-specific target.
Creating resistant variations (natural selection)