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.

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.

Implications for human health

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.

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.

Contact

New findings: Terje Traavik PhD, +47 9581 7537, terjet@genok.org

Further discussion: Jeffrey Smith in KL, 012-333-7495