CTU Las Vegas was a Domestic Unit of the Counter Terrorism Unit. The unit was based Las Vegas, Nevada.
Day 3
During Day 3, CTU Las Vegas secured a vial of the Cordilla Virus.
AS with CTU Seattle, CTU Denver and CTU Phoenix, it is assumed that CTU Las Vegas found the vial of the virus but no-one actually said that a CTU branch found it. Again, Las Vegas is quite a large city so it is assumed they would have a Domestic Unit.