There is very little research that i can find concerning disenfecting your saw to prevent the spread of OW. Perhaps it would be a good idea if you were pruning a diseased tree but you dont seem to be. You are worried about pruning an oak and then it becoming infected. Since this is the case then i would avoid pruning when the fungal mats are forming and the nitidulid beetles are the most active, during the fall and spring. This being about the hottest part of the summer you could perform the pruning and to be safe immediately paint all wounds if any.