Cats as Experimental Animals for Human Diseases

Posted by Pete Shanks on September 15th, 2011

Mice have been the mammals of choice for research for years, because they are quite similar to humans genetically, as well as being convenient and cheap. But there are limitations to the work, and sometimes mutations to a common gene have different results in mice and humans. So the publication in Nature of research that created genetically modified cats, with the ultimate goal of studying human disease, is worth noting.

That the disease most specifically targeted is AIDS doubtless helped generate interest. So too did the, by now routine, inclusion of jellyfish genes that make fluorescent proteins. Yes, these were glow-in-the-dark cats. (At least under a particular kind of light.) All the headlines said something like "Glowing transgenic cats could boost AIDS research."

Cats can suffer from a form of AIDS that seems to be similar to the human version, and is caused by feline immunodeficiency virus (FIV, as opposed to HIV; monkeys have SIV, for simian). FIV can also infect at least some monkeys, but rhesus macaques carry a gene that seems to confer protection. The idea of the transgenic research was to see if that gene, introduced to cats, would protect cats against the disease. This is a very long way from human applications, but clearly could be of interest.

So far, scientists have barely begun to answer that question, but they have succeeded in transferring the gene into cats, with the marker jellyfish gene, by using a new technique. The genes of interest were added to a lentivirus, which was introduced into an oocyte. The egg was then fertilized and implanted in a surrogate. The results were better than cloning rates, though still limited: 3 surviving kittens (2 others died shortly after birth) from 22 attempts, which led to 12 fetuses, at least 10 of which carried the foreign genes. The surviving cats seem to be healthy, and one has confirmed that the genetic modification was inheritable by fathering 8 transgenic second-generation kittens. Blood samples, though not yet tests with the grown cats, suggest that they may have some resistance to FIV.

Mice are still more convenient to work with, and monkeys are more like humans. But working with cats may have advantages. The Nature article refers to testing "the potential of restriction factors for HIV gene therapy and to build[ing] models of other infectious and noninfectious diseases." The New Scientist extrapolated this to "help[ing] researchers develop and test similar approaches to protecting humans from infection with HIV," which would imply human germline genetic engineering. That may not be what the researchers intend, but how these techniques are used bears watching.

Previously on Biopolitical Times:

Posted in Animal Technologies, Inheritable Genetic Modification, Pete Shanks's Blog Posts


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