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First Multigene, Multiclade HIV-1 Vaccine Trial Opens

First Multigene, Multiclade HIV-1 Vaccine Trial Opens

BETHESDA, Maryland—The first clinical trial of an HIV-1 vaccine based on
multiple genes from three subtypes, or clades, of the virus began November
13, 2002, when researchers at the National Institute of Allergy and
Infectious Diseases (NIAID) vaccinated three healthy volunteers. Researchers
expect to enroll 50 participants in the 12-month phase I study. The DNA
vaccine contains modified material from four genes from clades A, B, and C,
which cause about 90% of HIV infections worldwide.

The new vaccine was developed at NIAID’s Dale and Betty Bumpers Vaccine
Research Center (VRC), located on the grounds of the National Institutes of
Health (NIH). The phase I trial will be conducted at NIH, with Barney S.
Graham, MD, PhD, serving as the lead investigator.

"This trial begins a process that we hope will culminate in a globally
effective HIV vaccine," said VRC head Gary Nabel, MD, PhD. "The first step is
to develop a multiclade vaccine. If our candidate elicits an effective immune
response and proves safe in clinical testing, we will include additional
components in subsequent trials in hopes of boosting this response.
Ultimately, we aim to build a potent vaccine designed to prevent HIV

The vaccine, currently designated VRC-HIVDNA009-00-VP, contains parts of
three HIV genes—gag, pol, and nef—from clade B, the HIV subtype that
predominates in Europe and North America. The fourth component is derived
from an HIV gene called env, which codes for a protein on the virus’s
outer coat that enables the virus to recognize and attach to human cells.

The new vaccine is the first to combine a modified env from clades
A and C, the most common cause of AIDS in Africa, with the env from
clade B. Because the vaccine’s components have been modified, they cannot
reconstitute into and infectious virus, but they can stimulate an immune

The new vaccine was tested in mice, guinea pigs, rabbits, and rhesus
monkeys prior to its use in humans and produced good immune responses with no
ill effects, Dr. Graham told ONI in an interview.

The development of an effective HIV vaccine has been stymied by both the
existence of the various subtypes and by the virus’s ability to mutate
rapidly and thus evade the body’s immune defenses. "Any HIV vaccine must hit
a constantly moving target," Dr. Nabel said. "Essentially, we are trying to
enlarge that target through a multiclade vaccine."


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