Mayo Clinic researchers have developed a genome-based immunization strategy to fight feline AIDS and illuminate ways to combat human HIV/AIDS (photo courtesy of the Mayo Clinic)
Somewhere in Minnesota sits a litter of fluorescent green kittens that may be immune to AIDS. No, this is not a science fiction plot, but a research project at the Mayo Clinic that is investigating the potential of gene therapy to prevent infection with the viruses that cause AIDS.
Cats can be infected with a virus called FIV, the feline counterpart to HIV, and can also develop AIDS. Rhesus monkeys can’t be infected with either virus thanks to proteins they naturally express. One, known as TRIMCyp, blocks the virus from entering their cells.
The team of researchers at the Mayo Clinic and collaborators in Japan made a virus to use as a vector—a biological mechanism used to transfer genetic information into a cell—to deliver the gene for TRIMCyp. They then injected the virus into egg cells taken from a cat. The eggs went through the process of in vitro fertilization before being transferred to a surrogate cat mother, who gave birth to a litter of adorable kittens. The baby cats were completely normal – healthy and playful just like any other – except that they might be resistant to FIV infection. And they glowed green.
Making cats fluoresce might seem like a nice party trick, but the reason these cats glow is to provide a noninvasive visual marker of successful gene expression. Certain jellyfish are fluorescent because of a naturally occurring green fluorescent protein, or GFP. The gene for this protein was delivered along with that for TRIMCyp in the same viral vector, which means that a green cat also expresses the FIV-blocking monkey protein.
After making these green cats, the big question is whether TRIMCyp can block FIV infection. So far, experiments have shown that immune cells taken from the blood of the transgenic cats are resistant to FIV infection, and future studies will reveal whether this leads to protection of the cats themselves. (Read more about the cats here).