Transcript The Aids Vaccine

The Aids Vaccine
Research and Development
What is HIV?
 -Human Immunodeficiency Virus that leads to AIDS,
Acquired Immunodeficiency Syndrome
 It is an RNA retrovirus. The RNA enters the cell, and the
reverse transcriptase makes DNA out of the RNA. The DNA
enters the nucleus as a provirus, and becomes part of the
cell’s chromosomal DNA. This DNA can create more
viruses that will infect more cells in the body.
 Damages and destroys the white blood cells that run the
body’s Immune system, breaking down its defenses and
leaving it open to infections from other diseases.
What is the difference between
HIV and AIDS?
 -HIV is the ground state for the virus,
infected individuals can live for as much as
10 years without feeling an effect.
 -AIDS is the later state of the virus, when the
CD4+ T cell count drops below 200, in a
healthy person it exceeds 1000.
How is it Spread?
 -The HIV virus is carried in blood, semen, vaginal
fluid, breast milk and to a far lesser extent saliva
 -It is spread most commonly through unprotected
sex, needle sharing, breastfeeding by an infected
parent.
 -It is a growing epidemic in areas of the world
where healthcare and education are
underdeveloped.
What does it do?
 The HIV virus targets T Cells in the immune
system. These cells protect the body from
infection.
 Our immune system is constantly under attack, a
healthy person has no problem warding off most
infections.
 When enough T Cells have been killed, the immune
system can no longer function properly. The body
is vulnerable to all kinds of diseases and eventually
dies due to it’s inability to defend itself against
diseases as common as colds.
What is the Rate of Infection, and How
Many People are Currently infected with it?
 At the end of 2000, 36.1 million people lived with Aids, 21.8 million
are already dead.
 In Sub-Saharan Africa 10% of adults are infected.
 The Aids epidemic in Africa has created a generation of orphans, many
of whom also become infected.
 A full course of medication for Aids costs $15,000 a year, more than
most developing villages can spend on healthcare for the entire
community.
 Aids is spreading rapidly through Central Asia, partly from the drug
trade, and partly from unsafe sexual practices.
 95% of all infections are in underdeveloped countries
What medications are used to control
HIV?
 The first group are nucleoside reverse transcriptase
inhibitors (RT) that stop the virus from replicating itself.
Some examples are AZT and ddl, dideoxyinosine.
 Non-Nucleoside reverse transcriptase drugs include
Nevirapine and Delavirdine. These drugs prevent the
reverse transcriptase enzyme from being able to change the
RNA of the HIV virus into DNA in the cell.
 Protease inhibitors stop the viral reproduction at an early
stage, some examples are ritonavir, saquinivir and nelfinavir.
Vaccine Types
 Most vaccines contain a dead or mostly killed
version of a virus. This is not possible in the Aids
vaccine, because even a small amount of the virus
can be infect the host and kill them.
 “Sub unit” vaccines contain a small part of the
virus, that the immune system can learn to
recognize and kill without placing the subject in
danger of infection.
Immunity
 The first kind of immunity is antibody
immunity, this attacks and kills the virus in
the liquid parts of the body.
 The second kind is cell mediated immunity,
which simply kills the infected cells.
Vaccine
HIV vaccines approaches
recombinant protein (gp120)
synthetic peptides (V3)
naked DNA
live-recombinant vectors
(viral, bacterial)
whole-inactivated virus
live-attenuated virus
1
UNAIDS–97098 1 August 1998
Naked Genetic Material in
Plasmids
 These are bacterial plasmids that have a
piece of the HIV genetic material in them.
They are injected into the cell in an attempt
to create immunity. Similar experiments
with mice and the influenza virus have
shown that immunity is created. The cell
learns to recognize and kill the plasmids
without being exposed to any harm itself.
Recombinant Proteins
 The envelope for the Aids virus is formed by
gp 160, a protein. Gp 120, which is part of
gp 160 and gp 160 itself are used to make
recombinant subunit vaccines. These are
vaccines in which only part of the protein
envelope is injected into the subject in order
to stimulate antibodies.
Whole, Inactivated Virus
 The virus is injected whole, but dead, in a
more traditional form of vaccination, in an
attempt to create antibodies to a nonpathonogenic form of the Aids virus.
Live, Attenuated Virus
 The genetic material inside the virus is killed,
but the protein envelope remains intact and
whole. The virus is then harmless, and the
immune system can be trained to recognize
and kill the protein shell.
Keys To The Vaccine
 People who are repeatedly exposed, such as
prostitutes in developing countries, yet do
not develop HIV.
 People who have long term HIV infections,
whose T Cell counts remain high, or have a
decrease in T Cells that does not effect their
health.
Difficulties in Developing a
Vaccine
Human trials are difficult and the ethics surrounding
them are extremely complicated.
There are 3 main types of Aids, type M, which has 9
subtypes, type N and type O. Most successful viral
vaccines only have to protect against a few forms of
the virus. Unless a common type is found, the
vaccine would have to be a combination of several
viral subgroups.
Treatment and Prevention
 Education-People in underdeveloped countries are
being educated about Aids risks.
 Condoms are being distributed more commonly
among high risk groups, such as prostitutes.
 Aids Vaccine is being developed
 In an effort to make them affordable, Aids drugs are
being made generically.
 Political leaders in underdeveloped countries are
starting to speak out about the epidemic.
Bibliography
 HIV Vaccine Handbook: Community Perspectives on Participating in
Research, Advocacy, and Progress, edited by Bill Snow. Washington,
D.C., AIDS Vaccine Advocacy Coalition, 1999.
 David Gold, Sam Avrett, HIV Vaccines are moving slowly into human
trials, 1999
 The Village Voice, Aids in Africa, 1999, by Mark Schoofs
 National Institute of Health, National Institute of Allergy and Infectious
diseases, Aids Vaccine.
 UNAIDS, United Nations Aids Initiative
 International Aids Vaccine Initiative Research Newsletter., Feb 14, 2002,
Berna Biotech teams with IAVI, Gallo lab, Uganda to test AIDS vaccine
designed for developing countries
 Aids Treatment news, Aids.org. Information on Medication available.
 WHO, World Health Organization, World Health Report 2001.