Benjamin Franklin once advised a friend to take older women to bed because, figuratively speaking, "in the dark all cats are gray." Well, not these kittehs.

Researchers in the U.S. and Japan have developed green-glowing kittens with resistance to the feline version of AIDS, which may help work on AIDS research in humans.

In a study published in Nature Methods, researchers from the Mayo Clinic and Yamaguchi University took a genome approach to producing cats that are apparently resistant to feline immunodeficiency virus (FIV), a deadly condition that attacks infection-fighting T-cells as AIDS does.

The researchers including Mayo Clinic molecular biologist Eric Poeschla inserted genes into feline eggs before sperm fertilization. They added a gene for a rhesus macaque protein, known as a "restriction factor," that can prevent infection by FIV, and a jellyfish gene for tracking the cells that also makes the kitties glow a spooky green.