Protein blocks HIV, other deadly viruses

US researchers say they identified a protein with broad virus-fighting properties that potentially could be used as a weapon viruses such as HIV and Ebola. Su-Yang Liu, a student, and Genhong Cheng, a professor at the David Geffen School of Medicine at the University of California, Los Angeles, said the novel anti-viral property of the protein, cholesterol-25-hydroxylase, is an enzyme that converts cholesterol to an oxysterol called 25-hydroxycholesterol, which can permeate a cell's wall and block a virus from entering. The cholesterol-25-hydroxylase enzyme is activated by interferon, an essential antiviral cell-signaling protein produced in the body, the researchers said. "Anti-viral genes have been hard to apply for therapeutic purposes because it is difficult to express genes in cells," Liu said in a statement. "Cholesterol-25-hydroxylase produces a natural, soluble oxysterol that can be synthesized and administered. Also, our initial studies showing that 25HC can inhibit HIV growth in vivo should prompt further study into membrane-modifying cholesterols that inhibit viruses." The discovery is particularly relevant to efforts to develop broad-spectrum antivirals against an increasing number of emerging viral pathogens, Liu said. The findings were published in the journal Immunity.