They can’t hunt in the dark anymore, but at least they won’t get AIDS. U.S. scientists have engineered a small battalion of glow-in-the-dark cats that are resistant to feline immunodeficiency virus, or FIV, which causes AIDS in cats. The green glow actually has nothing to do with the FIV resistance, but there’s a reason for turning Puss into a haunted-house character. Scientists in Minnesota inserted into the cats some monkey genes that create cells that block FIV, but they also wanted to track the modified cells easily, so they inserted jellyfish genes that make the altered cells glow in the dark. The team hopes to study these spooky kitties to help find a cure for HIV.