- Genetically engineered pox viruses in cell cultures recombined
with natural viruses to create new viruses with unpredictable and potentially
dangerous characteristics.
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- In what may be the first experiment of its kind, scientists
infected cell cultures with two related viruses. One was a genetically
engineered poxvirus, (vaccinia virus (VIC) with a transgene from the influenza
virus). The other was a naturally occurring relative of the first virus,
isolated from Norwegian wildlife. Both were orthopoxviruses. The two viruses
interacted and created many new hybrid viruses by recombination. The characteristics
of some of the new viruses included traits not expressed in either parent
virus. Some viruses, for example, spread faster than either parent, while
others produced different, more serious cell culture changes. A single
virus multiplied into hundreds of thousands of viruses in a few hours,
with unpredictable consequences. Since the marker gene in the transgenic
virus was not present in some of the newly formed hybrid viruses, it would
not be possible to track transgenic viruses as the origin of the hybrids,
if they were found in the wild.
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- In a second series of experiments, various mammalian
cell lines were infected with avipoxviruses. In some cell lines, the avipoxviruses
were able to perform full multiplication. This was previously considered
to be impossible. The assumption that avipoxviruses were incapable of full
multiplication was used as a basis for safety claims of vaccines using
avipoxviruses.
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- Implications for human health
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- Orthoviruses are used for vaccinations of humans and
domestic animals, as non-target vaccinations for wildlife reservoirs of
human diseases (such as rabies in the wild), and for sterilization of mammals.
In 1999, for example, an orthopoxvirus engineered as a vaccine to combat
rabies was inoculated into chicken remnants (heads) and spread as bait
throughout the border between France and Belgium. Local mammals, including
the target animal, the red fox, then ate the chicken parts. Based on the
findings above, it is theoretically possible that if natural viruses similar
to the rabies vaccine also infected those mammals, they may have become
hosts to new transgenic hybrids. The hybrids might possibly threaten mammals,
humans, and the ecosystem.
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- Transgenic avipoxviruses are used as vaccines. Several
studies on avipoxviruses declare them safe, claiming that they do not multiply
in mammalian cells. This new finding contradicts that claim and calls into
question the safety of using these viruses in humans and other mammals.
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