Glow in Dark Cats Help Finding a Cure for HIV?
A study published in the 11th September issue of Nature Methods has attracted media attention about a potential decisive step in finding a cure against HIV. Beyond the magic trick of creating green glowing cats under a UV light, what are the findings and how can they have potential implications in the search of an HIV cure?
It is almost an headline in many newspapers: cats will help humans cure HIV.
Mayo Clinic researchers have developped a gene-based immunization strategy to fight feline AIDS induced by FIV (1).
The technique is called gamete-targeted lentiviral transgenesis. The authors actually microinjected lentiviral vectors into oocytes to make future kittens express 2 genes:
-a gene coding for a restriction factor known to block cell infection by FIV in macaques (TRIMCyp);
-a jellyfish gene for "tracking" purposes that makes the offspring cats glow green. Consequently, the fluorescent cats will be those expressing the restriction factor.
Twenty-two embryo transfer procedures resulted in 5 pregnancies, 5 births and 3 live kittens.
The level of genomic transduction was high. The percentage of green fluorescent protein positive cells varied from 15 to 80% in cats. Detailed organ examination in the 2 kittens that died showed abundant expression of the inserted genes in different organs.
Although these experiments are original and interesting we would like to counterbalance the publicity made in the media for several reasons:
-FIV is not HIV;
-More advanced strategies knocking out CCR5 expression with zinc finger nucleases are already tested in humans and are more realistic than gene therapy performed before birth;
-it is not known if a single restriction factor is sufficient to protect cells, and if long-term selection of escape viral variants will occur;
-the use of lentiviral vectors in human has safety issues;
-it is not known if this gene therapy will protect cats against an FIV challenge and what the level of protection would be: hard to speculate about an HIV cure in humans. Don't put the cart before the horse...
In conclusion, this study brings some "light" about the feasability of creating transgenic cats but is far from having practical consequences for our HIV-infected patients.
1. Wongsrikeao P, Saenz D, Rinkoski T, Otoi T, Poeschla E. Antiviral restriction factor transgenesis in the domestic cat. Nature Methods 2011 Sep 11. doi: 10.1038/nmeth.1703. [Epub ahead of print]
Key words: HIV cure, HIV eradication, glow in dark cats, towards HIV cure, towards an HIV cure