Human Immunodeficiency Virus, better known as HIV, is the virus which causes AIDS. As its name suggests, HIV only affects humans. But other species have counterpart diseases; for example, cats can become infected with Feline Immunodeficiency Virus, or FIV, which causes AIDS in them. And a relatively new procedure, involving genes from monkeys and jellyfish, may provide hope for future cats in the war against FIV (and by extension, for people tackling HIV).

And as an intended side effect, the process makes the cats glow green, as seen above.

As reported by Reuters, the team of scientists working on the experiment injected the foreign genes into not-yet-fertilized feline eggs, and induced the eggs to incorporate the genes into its cells via a “harmless virus.” The monkey genes, researchers hoped, could cause cells to block FIV, thereby preventing a later AIDS infection. Further, a cat with the monkey gene-enhanced cells could pass that genetic improvement to its offspring. Unfortunately, while the theory behind that hope made sense, testing it proved difficult. The scientists needed to be able to check their experiment, and it would be difficult to see which cells came with the mutation induced by the harmless virus noted above. The solution: the jellyfish genes.

Jellyfish contain a protein which causes them to glow when exposed to blue light. This protein has been introduced into other animals a few times over the years in an effort to get these animals to fluoresce. In 2000, an artist introduced the protein into a rabbit named Alba, creating a green-glowing bunny and living piece of performance art. (Alba died in 2002, and there’s some question whether the protein actually worked in her case.) According to the BBC, in 2006, a team of Taiwanese scientists produced three green-glowing pigs. And commercially, there are glowing zebrafish known as GloFish available for purchase.

The FIV research team realized that, by including the proper jellyfish gene in the “harmless virus” carrying the monkey genes, they could easily identify the “infected” cats — simply by shining a blue light on them. If the cat glowed green, the cat carried the jellyfish genes; and because the jellyfish genes travelled with the monkey ones, the green hue meant that cat also had the monkey genes as well. And the green-glowing cats were showing a resistance toward FIV.

While researchers have hopes that advances in fighting FIV can help in the battle against HIV, that may not be true. As Science magazine notes, the two viruses “are different enough that cats can’t catch HIV and people can’t get FIV.” But it is probably a significant step in the right direction.

The full paper involving the green glowing cats is available here.

Bonus fact : Glowing foxes were almost used by the U.S. military in World War II. But they weren’t going to be infused with jellyfish genes — just slathered in paint. According to the book “Psychological Operations American Style” (excerpted here), foxes, “when illuminated,” were considered “a harbinger of bad times” by many Japanese. The Office of Strategic Services (a CIA predecessor), as a test, painted thirty foxes with glow-in-the-dark paint and released them in Manhattan’s Central Park. When New Yorkers reacted with fear and horror, the OSS decided to run a full-scale operation in Japan. But the war ended before the ghost foxes could be unleashed there.

From the Archives: Hug Me Dot: Want to know if you can hug a Mensa member? Look for a green dot.

Related: A 5-gallon fish tank made specifically for GloFish; it comes with 15 blue LEDs installed to enhance the fluorescence of the fish.

Image via Science magazine, originally here.