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Chapter 5

HLTB21H3 Chapter Notes - Chapter 5: Luc Montagnier, Chemokine Receptor, Robert Gallo


Department
Health Studies
Course Code
HLTB21H3
Professor
Caroline Barakat
Chapter
5

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Chapter 5- A Modern Plague, AIDS
Aids stalks the continent of Africa, but isn’t confined to it
It is a global disease and the 1st pandemic of the 21st century
It is a deadly disease for which there is NO cure or vaccine
The threat of polio and smallpox are nonexistent because of effective vaccines, and
diphtheria, whooping cough are rare because children are immunized with DPT shot
Aids transcends economies, and according to the WHO it afflicts 15 million people
worldwide and occurs in both developed and less developed countries
Worldwide estimated that 12.9 million were infected, 20 years later 30-40 million people
were infected and 18 million died from AIDS
since 1999, 15000 new infections every day
A Look Back
Aids began as most epidemics do with small number of cases, fewer # of deaths and
almost geometric increase in # of cases and deaths
virus that causes AIDS is called “human immunodeficiency virus [HIV]
1981, center for disease control [CDC] began receiving increased numbers of requests for
pentamidine, drug used to treat an unusual type of pneumonia
Dr. Micheal Gottlieb; Caused by fungus “Pneumocytis carinii
Usually found in leukemia, or adults with lymphomas or immunosuppressive drugs
He found them in young, male homosexuals
GRID was used to name the syndrome, which collected all the characteristics of the
disease for gay related immune deficiency
2 labs found causative agent for GRID, Luc Montagnier and Robert Gallo: a virus
named HLTV II and LAV,
o today both known to be same virus
virus renamed human immunodeficiency virus [HIV] and the disease complex it
produced was called “acquired immunodeficiency disease” [AIDS]
HOW are they related?
o HIV is a virus, an entity
o Virus such as HIV is spherical in shape, resembling a 20 sided soccer ball,
o Cannot be seen with naked eye, or light microscope, but only with electron
microscope which magnifies 100,000x
o Viruses aren’t cells, but are able to reproduce themselves by taking over the
machinery of living cell
o Ultimate parasite
o Composed of DNA or RNA, and viral nucleic acid is packaged within a protein
wrapper called the core, then outer virus coat or capsid then layer; envelope partly
of host origin
o In the case of HIV the genetic material is in the form of RNA, NOT DNA
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o In order for virus to use the machinery of eukaryotic host cell, it must subvert the
cell’s machinery to copy viral RNA to DNA
o Information is written as: RNADNARNAprotein, basically flow of info is in
reverse of what is typically found in cells; retroviruses
HIV discovered
Discovery began more than a century ago [1884] with development of porcelain
filter by Charles Chamberland, who worked in the lab of Louis Pasteur; the
infectious agent had to be smaller than bacterium which is a VIRUS
AIDS described in 1891, 2 years later Luc and Gallo discovered the retrovirus
responsible for destruction of lymphocytes [HIV]
Upon virus replication, the host immune system was crippled, leading to clinical
syndrome of AIDS
Hitchings and Elion were chemist-pharmacologists who had produced active
compounds against smallpox
When pandemic of AIDS began, burroughs-wellcome had a wide array of antitumor
compounds
One was AZT, 1964, it became the first line of treatment for AIDS
Both received Nobel prize,
HIV’s Target: the Immune System
Chemokines are soluble chemical messengers that attract or activate other white cells
especially the T and B lymphocytes and macrophages
To be activate, these white cells must have on their surface a receptor for the
chemokine
One chemokine receptor called alpha is an entry cofactor for the invasion of T cells by
HIV,
Another called beta is an entry factor for the invasion of macrophages by HIV and it
activates monocytes, lymphocytes, basophils and eosinophils
T lymphocytes, the cells that can be infected with HIV
The glyproteins of the HIV capsid resemble lollipops; the stick is called gp41 and the
candy ball gp120
o The function of the 2 viruses is to bind and anchor HIV to the surface of the
cell, CD4 on surface allows for docking of gp120, which changes its shape so
that it can bind and then a fusion takes place, with entry of HIV
o If person has mutation in the chemokine receptor that individual would not
be susceptible to HIV because the virus cannot enter the T CELL
o Only 1% of Caucasians have this trait and it is absent from western and
central Africans and Asians
o CCR5 acts as a receptor for HIV also as well as smallpox virus
o People with 2 normal CCR5 genes can easily contact HIV, those with one copy
of the mutation can be infected but will develop AIDS more slowly, and HIV
will never affect those with 2 copies of delta-32 gene
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