1. Viruses
&
Human Health‏
June 23, 2009
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2. Viral diseases are difficult to treat because:
No drug is available to kill viruses in the body
2. Some viruses are lysogenic  can remain dormant for years (hide inside cells)
ex. a) Herpes Simplex Virus I (HSV I)
(cold sores)
b) HIV
some viruses are oncoviruses
cause cells to become cancerous
onco = tumour
(AIDS)
(genital warts)
(cervical cancer)
ex. Human Papiloma Virus (HPV)
November 21, 2018
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3. Protection Against Viral Diseases
 vaccines: only true protection against viral diseases,
it is preventative
people are given a dead or weakened form
of the virus
builds up an army of WBC’s & antibodies to
kill the living virus immediately before it
can reproduce
ex. polio vaccine,
hepatitis B vaccine
antiviral agents:
drugs given after infection to
slow the reproduction of the virus
ex. Valtrex – helps heal and decrease pain
(herpes)
November 21, 2018
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4. Viral Uses In Medicine 1. Viral Vectors
Viruses can be used for gene therapy as “carriers”
Viral core is removed &
desired human gene is added
Virus is mixed with living
cells
Virus attaches to human host
cell & injects the human gene
i.e. acts like a microscopic
hypodermic needle
(Dr. John Bell) OHRI (Ottawa Health Research Institute): University of Ottawa professor
success with mice injected cancer cells : also trials in humans that didn’t respond to conventional cancer treatments (chemotherapy & radiation) tumours receded wthin weeks
cancer cells give off hormones that inhibit immune response
also found that viruses stimulated response & person was immune to that form of cancer for life
November 21, 2018
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5. SOME EXTRA INFO ON HIV…
November 21, 2018

6. Worldwide HIV Distribution
Note: Total exceeds 100 percent due to rounding.
Source: UNAIDS, 2006 Report on the Global AIDS Epidemic, 2006.
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7. Structure of HIV
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8. AIDS HIV (Human Immunodeficiency Virus) virus that causes AIDS
RNA core (retrovirus)
can only infect helper T cells (type of white blood cell)
cannot survive outside the body because
glycoprotein membrane around its capsid dries
out (membrane picked up as it buds off white
blood cell)
can only be transmitted from 1 bodily fluid to another
ex blood to blood: needles, transfusions,
toothbrushes
2. semen & vaginal secretions
breast milk
November 21, 2018
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9. Transmission of AIDS (Worldwide)‏
HIV in Body Fluids
Semen
11,000
Vaginal
Fluid
7,000
Blood
18,000
Amniotic
4,000
Saliva 1
Average number of HIV particles in 1 mL of these body fluids
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10. Life Cycle of HIV
Lysogenic Cycle
HIV+
Lytic Cycle
AIDS
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11. virus is in its lysogenic cycle (dormant)
HIV positive:
virus is in its lysogenic cycle (dormant)
patient is not sick, but is a carrier of the virus
can infect others
AIDS (Acquired Immunodeficiency Syndrome)
patient has symptoms of the disease
(begins when HIV enters the lytic cycle)
WBC’s are being destroyed
Early symptoms:
night sweats, diarrhea, cold symptoms
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12. AIDS Associated Disease
Late Symptoms
Gastrointestinal: Cause most of illness and death of late AIDS
Symptoms:
Wasting (extreme weight loss)‏
Abdominal pain
Infections of the mouth and esophagus
Respiratory: 70% of AIDS patients
develop serious respiratory problems
Bronchitis
Pneumonia
Tuberculosis
Lung cancer
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13. More AIDS Associated Disease
Skin Disorders: 90% of AIDS patients develop skin or mucous membrane disorders
Herpes
Thrush
Eye Infections: % patients develop eye conditions.
Dry eye syndrome
November 21, 2018
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14. The ultimate fate of a patient with AIDS
patient dies from other infections due to a lack of immune response
ex. pneumonia
cancer
November 21, 2018
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15. Transmission of AIDS (Worldwide)‏
Why so may cases of homosexual AIDS cases in US?
-1st case of AIDS in US came from a traveling salesman, homosexual;
- then spread by homosexual drug users & then to heterosexual drug users etc.
became HIV+ in Africa, then went to Jamaica, then west coast US; caused epidemic in the male homosexual population
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16. “When you have sex with someone, you are
having sex with everyone they have ever had
sex with.”
Former US Surgeon General
C. Everett Koop
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17. Drug Therapy
Reverse Transcriptase Inhibitors: Competitive enzyme inhibitors. Example: AZT, ddI, ddC
Protease Inhibitors: Inhibit the viral proteases. Prevent viral maturation
Problem with individual drug treatments: Resistance
Drug Cocktails: A combination of:
One or two reverse transcriptase inhibitors
One or two protease inhibitors
Drug cocktails have been very effective in suppressing HIV replication and prolonging the life of HIV infected individuals, but are not considered to be a cure
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18. Homework Read ‘Sex Slaves for Science’ article Answer questions 1 – 11
November 21, 2018

19. Viral Uses In Medicine help kill cancer cells
Oncolytic viruses used in targeted cancer treatment
Choose a nonpathogenic virus that can infect human cells is chosen ex. Vaccinia (cowpox)
Allow this virus to attack human tumour cells
After reproducing, viruses released kill host cancer
cell i.e. lytic cycle
New viruses infect neighbouring tumour cells
Also stimulate immune system, bringing WBC’s in to
help kill cancer cells
Note: cancer  is caused by a mutated ‘stop’ gene
 results in uncontrollable cell division
Viral Uses In Medicine
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20. November 21, 2018
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21. AIDS History 1950s: Blood samples from Africa have HIV antibodies
1976: First known AIDS patient died
1980: First human retrovirus isolated (HTLV-1)‏
1981: First reports of “Acquired Immuno-
deficiency Syndrome”
1983: Virus first isolated in France (LAV)‏
1984: Virus isolated in the U.S.
1985: Development and implementation of
antibody test to screen blood donors
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22. History - continued 1986: Consensus name Human Immunodeficiency
Virus (HIV-1)‏
Related virus (HIV-2) identified
1992: AIDS becomes the leading cause of death
among adults ages in the U.S.
1997: Mortality rates of AIDS starts to decline due
to the introduction of new drug cocktails
2005: World Health Organization (WHO) predicts
up to 40 million infected individuals
More than 22 million have already died
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23. HIV Prevalence Worldwide
Source: UNAIDS, 2006 Report on the Global AIDS Epidemic, 2006
Adults Ages with HIV
15.01% %
5.01% %
1.01% - 5.0%
0.51% - 1.0%
0.0% - 0.5%
Not available
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