AIDS Vaccines: the basics
CindraFeuer
AVAC: Global Advocacy for HIV Prevention
20 April 2010
The HIV Research Catalyst Forum
Baltimore, Maryland
April 2010
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AIDS Vaccine Presentation Overview
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What is a vaccine?
How would an AIDS vaccine work?
Where are we in the search?
How to get involved?
April 2010
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What is a vaccine?
• A substance that teaches the
immune system how to protect
itself against a virus or bacteria
• No effective AIDS vaccine
available today
• AIDS vaccines cannot cause HIV
• No vaccine is 100% effective. Most
vaccines licensed in the US 70%95% effective.
April 2010
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Why the interest in an AIDS vaccine?
• Need for a range of HIV prevention methods
(There’s no silver bullet)
• Proven prevention options have slowedHIV’s
spread but thousands of people continue to get
infected daily
• Vaccines are one of the world’s most effective
public health tools
• Cost-effective (administered once)
April 2010
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Types of AIDS vaccines
• Preventive Vaccines:
– Designed for people who are not infected with HIV
– Reduces risk of infection or viral load set point after
infection
• Therapeutic Vaccines:
– Designed for people who are living with HIV
– Uses the body’s immune system to control HIV in the
body
April 2010
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How does a vaccine work?
• By teaching the body to recognize and fight
invaders
– Subunit—small amount of virus or copy of virus in the
form of vaccine
– Body reacts by creating antibodies or killer cells
– Upon viral infection, antibodies and killer cells are there
waiting to attack
April 2010
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How a preventive AIDS vaccine would work
• Humoral
– Antibodies
– Y-shaped proteins that
look for HIV to stop it
from infecting cells
– Adaptive immune
system
April 2010
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How preventive vaccines would work (con’t)
• Cellular immunity
– White blood cells or CTL
– White blood cells that
look for HIV-infected
cells and kill them
April 2010
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How an HIV vaccine might work
HIV
PREVENT
ESTABLISHED
INFECTION?
*****
C
A
Vaccine
Administered
B
HAART
A. Lower Initial Peak of Viremia
B. Lower Set Point
April 2010
C.Delay
Progression
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How are most vaccines made?
• Live attenuated
vaccines(examples:
measles, mumps, and
rubella)
• Whole killed virus
vaccines (example:
influenza and rabies)
April 2010
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How are AIDS vaccines made?
• Recombinant vaccines
• Do not contain HIV
• DNA vaccines
• Vector vaccines
April 2010
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Developing an AIDS vaccine is difficult
• Numerous modes of transmission
• HIV kills the very immune cells uses in defending the
body against HIV
• HIV makes many copies of itself and mutates, making
itself unrecognizable to the immune system
• Mutation leads to different subtypes of the virus through
out the world
April 2010
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Vaccine research in perspective
Duration between discovery of microbiologic cause of selected infectious diseases and development of a vaccine
Virus or bacteria
Year cause
discovered
Year vaccine
licensed
Years elapsed
Typhoid
1884
1989
105
HaemophilusInfluenzae
1889
1981
92
Malaria
1893
None
–
Pertussis
1906
1995
89
Polio
1908
1955
47
Measles
1953
1995
42
Hepatitis B
1965
1981
16
Rotavirus
1973
1998
25
HPV
1974
2007
33
HIV
1983
None
–
Source: AIDS Vaccine Handbook, AVAC, 2005
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Timeline of results from AIDS vaccine efficacy trials
April 2010
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Thai prime-boost AIDS vaccine trial
April 2010
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The Thai trial: RV144
• First glimpse of evidence a vaccine has a
protective effect
• 31.2 % (modest effect)
• Not for licensure
• Research ongoing
April 2010
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Ongoing vaccine trials
• About two dozen safety and
immunogenicity studies
• HIV Vaccine Trials Network (HVTN 505)
April 2010
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HVTN 505
• Phase II, uses a DNA prime/rAd5 boost (T cellbased)
• Currently recruiting circumcised MSM at sites
across the US
• Parts of this vaccine regimen are similar to the
vaccine used in Step and Phambili
• Reduce viral load in individuals who receive the
vaccine and go on to become infected with HIV
April 2010
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HVTN 505 continued
• Not expected to prevent HIV infection
• Not on the path to licensure
• Better understand and develop T cell-based
vaccines
• Like in all prevention research studies, all
participants will receive the best available
prevention services
• Results expected 2013
More information about HVTN 505: www.hopetakeaction.org
Get involved: www.bethegeneration.org; www.hvtn.org/about/sites/html; www.vaccineforall.org
April 2010
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What is needed now?
• Vaccination to protect against infection, mitigate
infection and prevent transmission to others
• Focus investigation to better understand the Thai
trial result
• Ensure diversity of approaches beyond the Thai
trial, exploring novel directions for vaccine design
• More community involvement
April 2010
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What can you do?
• Join a Community Advisory Board
• Ask your local AIDS organizations if they are
aware of or involved in vaccine research
• Support trial volunteers and recognize their
contribution to the fight against HIV/AIDS
• Volunteer to be in a clinical trial
April 2010
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Stay informed
• Join the Advocates Network
• AVAC publications: Px Wire, Anticipating and
Understanding Results series, AVAC Report
• Attend events (AVAC calendar)
AVAC: Global Advocacy for HIV Prevention www.avac.org
International AIDS Vaccine Initiative www.iavi.org
HIV Vaccine Trials Network www.hvtn.org
Global HIV Vaccine Enterprise www.hivvaccineenterprise.org
April 2010
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The search must go on
“... they are ill discoverers that think there is no land
when they can see nothing but sea.”
— Francis Bacon (1561-1626)
April 2010
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