Brushing a dog that bites can be quite scary. If you have a dog who bites you may not have a groomer who is willing to touch your dog. This might mean you're stuck brushing your dog all the time and you could potentially be bitten.
Outside of the obvious muzzle you can put on your dog to keep him from biting, one thing you can do is retrain your dog to not bite. If he's biting when he's being brushed, then it's likely because he doesn't enjoy brushing, he's fearful of the brush, or he's been abused before. Though there could be other reasons your dog is upset and bites during brushing, you can retrain him to be tolerant and well-mannered during brushing.
If your dog bites, he probably bites for a reason. Typically this is for protection or out of fear. Either way, he's your little guy and spending some extra time showing him he is safe with nothing to worry about will go a long way. Also, rewards for good behavior, even if they are short bouts of good behavior, will go a long way in retraining your dog.