IAVI Report Vol. 2, no. 2

AIDS Vaccine Conference Report continued from page 5.Basic Science and Correlates
of Protection Research
Mary Klotman of the Mount Sinai School of Medicine reported what may be
a novel factor expressed by CD8 cells that can inhiit HIV.The presence of!:
such a factor (other than b-chemokines) has long been proposed by University
of California at San Francisco researcher Jay Levy. According to Klotman, the f
factor, named CAF 10, can inhibit a number HIV strains including IIIB, BA-I and
primary isolates.
While a number of studies have suggested that HIV-specific cellular immune
responses are found in seronegative partners of HIV-positive individuals, few have
reported HIV-specific antibodies in such individuals. At the conference, Mario Clerici
of the University of Milan reported that HIV antibodies (IgA) have been found in
the cervical swabs and/or urine of 93 percent of HIV-exposed, seronegative
individuals. In addition, he disclosed that when HIV peptides were added to the
blood of HIV-exposed seronegative and HIV-positive individuals, higher levels of
IL-2 and lower levels of IL- 10 were seen in the exposed seronegative individuals.
In his presentation, David Baltimore shared his personal views that while the
role of antibody remains unclear, he believes that CTL response may be more
important for protection. In presenting results from his own lab, conducted in
collaboration with Bruce Walker of Massachusetts General Hospital, Baltimore
suggested a possible way in which HIV-infected cells avoid "clearing" by CTLs.
Infection of cultured cells with HIV, he showed, downregulates MHC class I,
making cells resistant to CTL killing. Downregulation of MHC was associated
with the presence of the nef gene.
Summary
The conference demonstrated that an array of efforts are being made to
discover how the human immune system might effectively prevent HIV infection
or disease. However, definitive knowledge of the correlates of protection will
most likely arise when the first (even partially) effective vaccine is identified. At
this time, no Phase III efficacy studies have been initiated. Nevertheless, steady
progress is being made in understanding the immunogenicity of several candidate
vaccines in small animals and primates. In addition, promising new data suggest
that at least one candidate vaccine is capable of generating HIV-specific CTL
responses in humans and may have use against a broad number of HIV strains.
Evaluation of this candidate in different populations is an important step. In
addition, moving promising, novel designs into Phase I and then larger Phase II and
III trials appears to remain a slow point in the development pipeline at this time.*
Baltimore Interview continued from page 7
IAVI REPORT: Three years from now, how should we evaluate
whether your efforts have been successful?
BALTIMORE: The central issue, three years from now, will be
whether we have a more rigorous, broad-based research
program that is looking at a wider range of approaches and
candidate vaccines.
IAVI REPORT: You recently accepted the job of president of the
California Institute of Technology (Cal Tech).Will you still be able
to devote sufficient time to the AIDS vaccine position?
BALTIMORE: When I was interviewed by the trustees, the first

question I asked was whether I would be able to continue with the
commitment that I've made to the country and to the federal government in the area of AIDS vaccine research.They said they would
consider it an honor for Cal Tech if I would continue this work. *

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increase public and private support for such efforts. *