NAVS was discouraged by a headline news story this week that raved about “green-glowing cats” as a new research tool for studying human diseases like AIDS. Researchers generated genetically-modified cats expressing a gene thought to protect them from feline immunodeficiency virus (FIV), the cat form of HIV. At the same time, the cats were genetically engineered to express a “reporter gene” that allowed any genetically-modified cells to glow green under black light to help the researchers identify the animals that had been genetically modified.
The public seemed fascinated at the sight of a green-glowing cat, but let’s stop for a moment and assess its relevance as a model for human disease, in this case, AIDS. Scientifically, there are so many problems I see with this model system that I’m not even sure where to begin! Assuming that the gene given to the cats could also protect humans from infection, the technical approach used in this study to deliver the genes to the cats cannot be applied to humans. This difference alone makes it hard to extrapolate findings from this model system to the human situation.
Here is why: in this study, the new genes were delivered to the cat before it was even conceived! Female egg cells were genetically modified before they were fertilized to generate these altered cats. We would not use that same approach for gene delivery in humans. Another practical thing to consider is while there are similarities in the biological behavior of HIV and FIV, they are different viruses, each of which is highly variable, which further complicates matters. Most importantly, we are not cats! We are genetically very different from cats, and we know that subtle genetic differences between people can have big consequences. Developing disease treatments for human beings in glowing green cats is as ridiculous as it sounds. I am puzzled why researchers wouldn’t choose to focus their efforts on developing more relevant model systems to study human disease.
The good news is that some scientists have expressed concern with extrapolating findings from this animal model to humans. Perhaps Helen Sang and Bruce Whitelaw, biologists at the Roslin Institute at the University of Edinburgh, stated it best when they said “…the uses of genetically modified cats as models for human diseases are likely to be limited...” The need for the development of more human-relevant models cannot be overstated.
For more information see: New model organism could be the cat’s meow for studying human disease
Also see: Green-glowing cats are new tool in AIDS research
- Dr. Pam Osenskowski, Director of Science Programs