Science (06/05/92) Vol. 256, No. 5062, P. 1387
A federally funded AIDS vaccine development program has incurred an
unfortunate and possibly costly setback that will prolong the time it
will take to test potential vaccines in chimpanzees. The problem could
also postpone the date of human trials expected to begin at the end of
next year. A critical stock of a single, well-characterized strain of
HIV that researchers around the world expected to use as a standard in
vaccine trials has been tainted by another strain of HIV, and now is
useless. The new stock, based on an HIV strain known as MN, was grown at
Duke University in Durham, N.C., as a replacement for a widely used
strain, called IIIB. MN was injected into three HIV-free unvaccinated
chimps in October 1991, but subsequently, researchers at the National
Cancer Institute-Frederick Cancer Research and Development Center found
no trace of it. The only virus the researchers found was one that looked
much like IIIB. It was determined that at the time the MN stock was
being prepared at Duke, other researchers working in the same lab were
conducting studies with a variant of the IIIB virus that had been
isolated from a chimp previously infected with a IIIB stock. It is
possible that a nearly undetectable amount of the chimp-adapted IIIB
virus must have contaminated the MN stock.