Viral cross-species DNA is actually pretty common. It is one of those reasons I have a sad laugh at anti-GMO activists who claim that doesn't happen in nature when in fact, it happens all the time.
Not really. Though some anti-GMO concerns are unfounded to a large degree (based on ignorance, not information) there is a great deal of evidence that it is foolish to trust Monsanto and the government lackeys who rubber stamp their excursions into experimental science disguised as mundane industrial applications of practicality.
Here are a few of responsible objections:
1) DNA is not fully understood. There is evidence that telomeres once thought to be inert are actually active on the DNA molecule, and that there is an additional dimension of "language" in the encoding that we have not been reading. In essence, this suggests that while we have been playing two-dimensional chess with DNA, Nature has been playing in 3-D. This means expressions of active proteins and other manifestations of DNA in the environment are potentially being invoked without any notion whatsoever of the nature or magnitude of the effects on the organism or on the larger biosphere.
2) Ordinary DNA mutation happens at an infinitely slower pace in nature than in genetic engineering. The changes that are being manifested through guided, purposeful DNA modification would generally not normally occur in less than a period of centuries or millennia. It is not possible to monitor nor predict peripheral effects of rapid changes to the DNA of living things in the environment. Even worse, once introduced, it is impossible to recall changes - they become permanent. Once introduced, those changes are eternal. Living organisms cannot be "edited" from the biosphere the way programming errors are debugged from software.
3) Multinational corporations do not have a good track record on responsible stewardship of technology. Dr. Michael Crichton spent much time in the last years of his life speaking on the topic of licentiousness of multinational corporations in regard to technology (medical, pharmaceutical and otherwise) and the dangers of making assumptions about manageability of often inconceivably complex homeostatic systems. Jurassic Park and other works by Crichton dramatize this issue by demonstrating how the hubris of money-incentivized corporations enabled by willing governments greedy for power and tax revenue, encourage the public to turn a blind eye to reckless behavior on the parts of wielders of new technology who essentially bribe or intimidate people into silence about problems / dangers because of avarice and ambition.
