ViroBlogy

I am rather troubled by this article, because although it is obviously well-researched, it erects a house of cards from some rather flimsy initial premises.

The first is that the gene VI 3′ fragment, included as part of constructs for the 35S promoter, is in fact expressed in ANY of the transgenic plants it appears in: there is NO proof of this.

The second is that this same fragment encodes a polypeptide which has any/all of the functions associated with the full length protein: again, there is NO proof of this, although a throwaway statement is made that hints that it does.

The third is that the polypeptide fragment, IF expressed at all, would have deleterious effects in animals / humans: again, there is no conclusive proof of this at all, despite extensive toxicity trials.

There are other problems with the piece, including the statements:

“In general, viral genes expressed in plants raise both agronomic and human health concerns (reviewed in Latham and Wilson 2008).”

Sorry, this is not GENERALLY taken to be the case at all!

“This is because many viral genes function to disable their host in order to facilitate pathogen invasion. Often, this is achieved by incapacitating specific anti-pathogen defenses. Incorporating such genes could clearly lead to undesirable and unexpected outcomes in agriculture.”

Really? It has been clearly demonstrated that the anti-host function works in very different hosts, meaning this last sentence is true? Where?

“Furthermore, viruses that infect plants are often not that different from viruses that infect humans. For example, sometimes the genes of human and plant viruses are interchangeable, while on other occasions inserting plant viral fragments as transgenes has caused the genetically altered plant to become susceptible to an animal virus (Dasgupta et al. 2001).”

Oooooh…the taurine excreta value is high in this one…while an argument can be made that certain viruses of plants and of animals have a common origin, and are not THAT different in a long-term evolutionary sense, there are NO viruses that have been shown to infect both plants and mammals – NONE.

As for Dasgupta et al., what they showed was that flockhouse virus – an insect virus which replicates in plant cells but does not spread in plants – CAN spread in plants IF these are expressing CERTAIN plant virus-derived movement proteins. Which, I will note, are NOT components of any DNA in released GM plants of which I am aware.

And replication does not = “susceptible”: it means the virus CAN replicate and spread, NOT that it causes disease. I note that there are many viruses which replicate in both an insect and a plant, and others that replicate only in a plant but can be spread by an insect, and yet others which replicate in an insect only but can survive in plants as a reservoir. I note further that there are NO examples which can do any of these things in a plant and a mammal.

So – an interesting article, as I said, but one that is unnecessarily alarmist.