Report from the AIDS/Poliovirus Advisory Committee

CONFIDENTIAL
September 18, 1992
Report from the AIDS/Poliovirus Advisory Committee
We have been asked by the Wistar Institute to evaluate the probability that
the hypothesis raised by Tom Curtis in an article published in the Rolling Stone
magazine of March 19, 1992 under the heading, "The origin of AIDS" may be correct.
Briefly stated, the article suggests that the crucial event in the origin of the AIDS
epidemic was the extensive clinical trial of a live, attenuated poliovirus vaccine
conducted by Dr. H. Koprowski and colleagues in Congo in 1957. Since this vaccine
was grown in primary monkey kidney cell cultures, and there is evidence to suggest
that human immunodeficiency virus (HIV, the etiological agent of AIDS) may have
originated from a simian immunodeficiency virus (SIV) ancestor, Mr. Curtis
suggested that contamination of these monkey kidney cultures with SIV or an SIVlike virus could have led to the inadvertent inoculation of this virus, together with
the attenuated poliovirus, into the mouths of the vaccinated individuals.
Subsequent evolution of this virus in infected individuals could have led to the
emergence and spread of the currently predominant HIV strains. The timing of
these clinical trials, and the general belief that HIV appeared first in central Africa,
lend superficial support to this hypothesis.
In evaluating the credibility of this hypothesis, we have taken the approach of
assessing the probability that each step in this postulated mode of transmission
would have occurred successfully to allow HIV or a close progenitor to enter the
human population during the Congo poliovirus vaccine trials.
1) Contamination of the vaccine with SIV or similar viruses (hereafter
referred to as SIV). SIV does not multiply in or infect epithelial or fibroblastic cells
from monkey kidneys and neither does HIV. However, poliovirus for the vaccine
was grown in primary cultures that could have contained a low number of
lymphocytes and macrophages, known to harbor SIV in vivo and to support the
replication of SIV in culture. Thus, the possibility of the presence of a small amount
of SIV particles in these culture supernatants cannot be discounted. Such cell
culture-derived contamination could have taken place at any time during
propagation of the attenuated virus stocks, including the preparation of "seed" virus

from which the lots actually used in the field were derived by subsequent passages
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