AIDS Vaccines: the basics
CindraFeuerAVAC: Global Advocacy for HIV Prevention20 April 2010The HIV Research Catalyst ForumBaltimore, Maryland
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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?
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• 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.
What is a vaccine?
Why the interest in an AIDS vaccine?
April 2010 www.avac.org/presentations
• 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)
Types of AIDS vaccines
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• 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
How does a vaccine work?
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• 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
How a preventive AIDS vaccine would work
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• Humoral– Antibodies
– Y-shaped proteins that look for HIV to stop it from infecting cells
– Adaptive immune system
How preventive vaccines would work (con’t)
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• Cellular immunity– White blood cells or CTL– White blood cells that
look for HIV-infected cells and kill them
How an HIV vaccine might work
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HIVHIVPREVENT ESTABLISHED INFECTION?
*****
VaccineAdministered
AA. Lower Initial Peak of Viremia
AA
BB. Lower Set Point
BB
C.C.Delay Progression
CC
HAART
How are most vaccines made?
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• Live attenuated vaccines(examples: measles, mumps, and rubella)
• Whole killed virus vaccines (example: influenza and rabies)
How are AIDS vaccines made?
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• Recombinant vaccines
• Do not contain HIV• DNA vaccines• Vector vaccines
Developing an AIDS vaccine is difficult
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• 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 throughout the world
Vaccine research in perspective
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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 –
Duration between discovery of microbiologic cause of selected infectious diseases and development of a vaccine
Source: AIDS Vaccine Handbook, AVAC, 2005
Timeline of results from AIDS vaccine efficacy trials
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Thai prime-boost AIDS vaccine trial
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The Thai trial: RV144
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• First glimpse of evidence a vaccine has a protective effect• 31.2 % (modest effect)• Not for licensure• Research ongoing
Ongoing vaccine trials
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• About two dozen safety and immunogenicity studies
• HIV Vaccine Trials Network (HVTN 505)
HVTN 505
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• Phase II, uses a DNA prime/rAd5 boost (T cell-based)
• 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
HVTN 505 continued
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• 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 2013More information about HVTN 505: www.hopetakeaction.orgGet involved: www.bethegeneration.org; www.hvtn.org/about/sites/html; www.vaccineforall.org
What is needed now?
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• 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
What can you do?
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• 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
Stay informed
April 2010 www.avac.org/presentations
• 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.orgInternational AIDS Vaccine Initiative www.iavi.orgHIV Vaccine Trials Network www.hvtn.orgGlobal HIV Vaccine Enterprise www.hivvaccineenterprise.org
The search must go on
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“... they are ill discoverers that think there is no land when they can see nothing but sea.”
— Francis Bacon (1561-1626)