Brass knuckles are in the game, but don't seem configured yet, and are doing no damage what so ever. (could be multiple melee weapons which are like this)
*P.S* You can still abuse the melee exploit very hard (blocking glitch, while attacking, take no damage), and I believe this, hit reg, and FPS should be fixed before Stable*
Infected wise, whenever they are attacking you, they loop behind you then start attacking you, making melee look buggy, awkward/frusterating.
Infected can sometimes warp through walls, and have trouble jumping small fences (may run around it, but not jump.)
Sometimes, when you encounter infected, they will aggro, but they'll stay still/non-moving for awhile, unless you don't have your camera looking at them?
Infected are also still endlessly crawling in some situations (like a monkey) and go through structures/terrain/environment, when in this "endless crawl" mode.