Goal
#4 |
To
conduct and support basic, preclinical, and clinical research to develop
a safe and effective preventive HIV vaccine. |
Objective
#1 |
Increase
scientific knowledge of host defense mechanisms leading to protection
against HIV infection and disease.
|
Description
|
More basic
knowledge is needed to define protective immune responses to HIV in order
to facilitate the development of vaccines and other immunologic strategies
to prevent and control HIV infection.
|
Action
Steps
|
- Develop
animal models that are practical and as much as possible are representative
of the spectrum of HIV infections and AIDS; models should be amenable
to use in evaluating protection by vaccines and, where this can be demonstrated,
determining the correlates of protective immunity.
- Determine
the mechanisms of immunologically mediated control of infection with
HIV and other related retroviruses, including the role of specific and
nonspecific immunity in inhibiting viral replication.
- Additional
basic knowledge is needed to determine: o factors, including persistence
of antigens, that favor establishment of memory and development of long-term
protective immunity;
-
the heterogeneity of specific responses to an immunogen within distinct
compartments of the immune system;
- factors
that promote development of particular effector cell types;
- mechanisms
resulting from exposure to HIV that interfere with induction or
propagation of vaccine-induced effector responses;
- mechanisms
of virus neutralization.
- Study
acutely infected individuals, exposed/uninfected humans (and other primates),
and rapid/nonprogressors to determine viral and host factors that impact
amounts of circulating virus and disease course; ensure that plasma,
PBMC, biopsy, autopsy, and other key patient and animal samples, including
CNS samples, are accessible to qualified laboratories.
- Define
and characterize viral B cell and T cell epitopes that induce protective
immunity; understand their structure and antigenicity and determine
whether and how their immunogenicity can be exploited in vaccine development;
and define epitopes in which substitutions cannot be tolerated by the
virus.
- Determine
whether infection with one strain of HIV or related retroviruses confers
protection against subsequent infection with a second strain; determine
the protective mechanism and timing.
- Understand
how and why HIV and related lentiviruses evade or escape from humoral
and cellular arms of the immune response.
- Explore
strategies to elucidate the obligate mechanisms for protective immunity
against HIV, including amplification of selected responses by passive
transfer of Ab or immune cells and subtraction by deletion of selected
components of the immune system.
- Study
chronic infection with attenuated viruses, such as SIV variants shown
to induce strong protection against virulent SIV strains in macaques,
to understand what properties of the virus and the immune system are
responsible for lack of disease induction and protection from challenge
with wild-type virus.
- Explore
the molecular epidemiology and serology of HIV-1 populations relevant
to vaccine trials and collect clinical material from these populations
for scientific analysis.
- Acquire
epidemiological information to assist in interpretation of these analyses.
- Develop
quantitative measures of HIV concentration in bodily fluids to determine
whether there is a relationship between HIV concentration and transmission
and to determine the effect of concurrent STDs on HIV shedding.
|
Objective
#2 |
Apply findings
from basic, epidemiologic, and clinical research to the design and evaluation
of vaccine strategies in laboratory studies and animal models, and foster
collaboration with industry in the research and development of candidate
vaccines.
|
Description
|
The identification
of viral antigens and vaccine delivery methods that elicit long-lasting
protective immune responses against a broad range of HIV isolates will
facilitate development of effective vaccines.
|
Action
Steps
|
- Support
the design and development of potential vaccines, including vaccines
composed of:
- whole-killed
HIV and genetically engineered, noninfectious HIV mutants that lack
the viral RNA genome or have a defect in a critical gene necessary
for replication but contain an array of HIV genes for expression
of antigenic proteins;
- live,
recombinant viral and bacterial vectors engineered to express one
or more HIV proteins;
- naturally
occurring and genetically engineered, live-attenuated strains of
HIV;
- synthetic
peptide candidates capable of inducing and boosting both cellular
and humoral immunity;
- DNA
coding for viral proteins; o agents that stimulate mucosal immune
responses;
- a
combination of the above agents and preparations;
- other
novel agents and preparations.
- Evaluate
the efficacy of vaccine strategies in animal models of HIV and related
lentiviruses. To accomplish this:
- test
vaccine strategies in animal models that most closely mimic the
HIV infection in humans;
- determine
the effect of vaccine formulation and regimen as well as the nature,
timing, and route of vaccine challenge on the characteristics and
effectiveness of the vaccine-induced immune response;
- define
the impact of different vaccine approaches on kinetics of immune
responses, kinetics and localization of viral replication, disease
progression, and biologic characteristics of breakthrough virus
including transmissibility;
- conduct
long-term follow-up of vaccinated animals that become chronically
infected to determine the impact of vaccination on disease progression;
- develop
assays to distinguish between infection and serological responses
due to immunization.
- Support
design and development of methods to improve or modulate immune responses
(qualitatively or quantitatively), including:
- novel
adjuvants and presentation methods;
- vaccines
incorporating cytokines or other biologically active molecules;
- establishment
of physical or biological reservoirs for long-term antigen presentation;
- other
novel strategies.
- Encourage
development of candidate vaccines of suitable antigenic types and possessing
stability and route of administration characteristics appropriate for
international as well as domestic use.
- Characterize
and evaluate the potential negative side effects of candidate vaccines,
including production antibodies enhancing neurotoxicity and oncogenicity.
- Develop
better in vitro methodologies to measure immune responses to primary
viral isolates.
- Develop
infrastructure, and address scientific, legal, and regulatory issues
to foster and encourage participation by, and collaboration with, industry
and other agencies in the research, development, production, and clinical
testing of candidate vaccines.
|
Objective
#3 |
Select
candidate vaccines or concepts suitable for Phase I and Phase II trials
and conduct these trials.
|
Description
|
Suitable
candidate vaccines need to be selected and evaluated in Phase I and Phase
II trials to determine safety and immunogenicity.
|
Action
Steps
|
- Support
the conduct of Phase I and Phase II coordinated clinical trial that
will determine long-term and short-term safety and compare immunologic
responses to preventive vaccine candidates; include a broad range of
humoral, cell-mediated, and mucosal immune parameters.
- Develop
a mechanism to evaluate the suitability of vaccine candidates for entry
into Phase I and Phase II trials; evaluation criteria should include
originality and intrinsic value of the concept and animal model data.
- Develop
strategies at the local and national levels to reduce social and economic
risk to volunteers in Phase I and Phase II trials to facilitate broad
participation.
- Design
and conduct Phase II trials using promising HIV vaccines that are also
genetically or immunologically related to HIV isolates circulating in
the proposed trial population and of an appropriate size to facilitate
decisions regarding efficacy trials.
- Analyze
immune responses in vaccines and appropriate controls.
- Isolate
and characterize virus and follow clinical course and immune responses
of vaccines who become HIV-infected.
- Study
viral isolates from participants in HIV vaccine trials and selected
controls to explore the possible effects of vaccination on the characteristics
of transmitted viruses.
- Conduct
behavioral research on trial participants to establish whether their
risk behavior has been influenced by participation in a vaccine trial,
with emphasis on individuals who become infected while participating.
- Closely
coordinate the evaluation of research findings on prophylactic AIDS
vaccines with preclinical research and immunotherapeutic interventions.
|
Objective
#4 |
Identify
mechanisms of protective immunity to HIV in newborns and infants and support
the development of safe and effective immunologic strategies for preventing
or controlling HIV infection in this population.
|
Description
|
Distinct
approaches and infrastructure are needed to achieve protection of newborns
and infants because of the unique nature of their immune responses and
modes of exposure to HIV.
|
Action
Steps
|
- Determine
what viral, immunologic, and non-immunologic host factors influence
transmission of HIV-1 from mother to infant;
- Compare
virus isolates that are and are not transmitted from mother to infant;
- Seek
maternal and infant immune responses that might prevent transmission
to infants.
- Develop
and maintain domestic and international infrastructure necessary to
enroll mothers and infants in prospective long-term follow-up vaccine
trials and other interventions.
- Determine
the safety and immunogenicity of various HIV vaccines and adjuvants
in relevant animal models of maternal-fetal and maternal-infant transmission
to evaluate safety, immunogenicity, and efficacy of candidate vaccines.
- Select
and evaluate antibody and/or cellular preparations in passive or passive/active
HIV prevention studies.
- Establish
criteria for advancement of candidates in Phase I, Phase II, and Phase
III clinical trials in children.
- Conduct
Phase I, Phase II, and Phase III clinical trials in children for the
most promising candidates that meet established criteria.
|
Objective
#5 |
Identify
appropriate domestic and international population and develop infrastructure
and collaborations with government, communities, and industry necessary
for ensuring adequate performance of Phase III efficacy trials.
|
Description
|
Preparation
for HIV vaccine efficacy trials requires development of an infrastructure
and a series of studies and planning activities to ensure their feasibility.
|
Action
Steps
|
- Develop
domestic and international sites with access to populations at high
risk for acquiring HIV infection, where vaccine or other prevention
research activities may be feasible.
- Establish
linkages with communities or community organizations where efficacy
trials might be conducted to optimize education, recruitment, and follow-up
activities and to help address community concerns related to AIDS vaccine
efficacy trials.
- For
international trials, work closely with national (host) governmental
and regulatory authorities, collaborating institutions, vaccine manufacturer(s),
and the World Health Organization to plan and conduct vaccine efficacy
trials adhering to the highest ethical and scientific standards.
- Carry
out appropriate epidemiologic studies that determine the risk profiles
and infection rates of various populations in the United States and
worldwide in order to identify those groups most likely to be the participants
in vaccine trials.
- Maintain
the necessary laboratory infrastructure at designated sites for conducting
domestic and international vaccine efficacy trials.
- Acquire
and analyze HIV isolates from recent seroconverters representative of
potential efficacy trial populations so that genetic and antigenic information
about virus circulating in the population can be obtained.
- Evaluate
other biomedical and behavioral interventions that could prove of benefit
in decreasing the incidence of HIV infection in the populations identified
for future vaccine efficacy trials and assess their potential impact
on the evaluation of vaccine efficacy.
- Conduct
behavioral research in populations at high risk for HIV infection to
determine, for example, appropriate risk-reduction interventions and
to estimate risk behavior and recruitment, adherence, and retention
strategies pertinent to the design and execution of a successful efficacy
trial, especially for populations that have been historically underrepresented
in clinical trials.
- Determine
possible adverse social, economic, or legal consequences of participation
in clinical trials, and develop strategies for mitigating potential
harm.
- Determine
optimal methods of achieving informed consent for vaccine efficacy trials.
- Prepare
for adequate long-term follow-up of individuals participating in vaccine
clinical trials where it will be necessary to determine the longevity
of immune response, the correlates of immune protection, long-term safety,
the impact of participation on risk-taking behavior, and the possible
positive or negative effects of vaccine immunization against disease
progression and HIV transmission.
- Encourage
linkage between vaccine preparedness studies in high-risk populations
and other research activities including research on TB and STDs; and
integrate research on vaccines against opportunistic infections as appropriate.
|
Objective
#6 |
Select
suitable vaccine candidates and support efficacy trials when appropriate
criteria are met.
|
Description
|
Conduct
HIV vaccine efficacy trials of the most promising candidate vaccines in
well-characterized, high-risk populations to identify effective vaccines
for the control of HIV infection.
|
Action
Steps
|
- Establish
criteria with concurrence of an advisory group that has the requisite
scientific, public health, government and community expertise.
- Conduct
large-scale efficacy trials of preventive vaccine candidates that have
proven promising, safe, and immunogenic in Phase II trials and that
meet appropriate criteria;
- Evaluate
HIV vaccine candidate efficacy against infection and disease;
- Evaluate
additional virologic, immunologic, and behavioral outcomes, particularly
correlates of protective immunity;
- Ensure
that trials are conducted with the highest regard for social and
ethical standards.
|
Resources
|
FY95
|
FY96
|
FY96
|
$
100.4 million
|
$
109.5 million
|
$
116.1 million
|
Populations
Served
|
All populations.
|
Constituency
Involvement
|
Researchers,
clinicians, community and patient representatives, and NIH-affiliated
advisory councils and committees.
|