Report from the AIDS/Poliovirus Advisory Committee

CONFIDENTIAL
in the Congo trials or at best lots prepared at the same time in the same laboratory.
If these can be found, they can be tested by attempting recovery of infectious virus or
by reverse transcriptase-polymerase chain reaction (RT-PCR). Virus infectivity is
almost certain to have been lost, since these samples have been stored for 35 years,
possibly subjected to cycles of freezing and thawing, etc. Thus, a negative result will
be inconclusive. PCR amplification would have to be performed after reverse
transcription, using primers bracketing conserved regions in the SIV/HIV genomes.
Again, a negative result may not be conclusive and a positive result will not identify
the virus type. Thus cloning and sequencing of the PCR products would be
required. Finally, the significance of the presence of SIV sequences only distantly
related to HIV-1 may be difficult to evaluate.
It has also to be considered that attenuated poliovirus vaccine was universally
prepared in monkey kidney cells at that time and even at much later times
(including today). Thus a thorough analysis would require that a number of vaccine
lots used during the late 50's and early 60's should also be tested. Millions of
individuals were vaccinated in Russia and Eastern Europe during those times with
vaccines prepared similarly. There is no evidence that the AIDS epidemic began in
these parts of the world. What if a significant percentage of the polio vaccines used
there were also found to be positive for SIV-like viruses?
In conclusion, testing of the vaccines will be laborious, expensive and may be
inconclusive.

-5 -