From what I've read, K-wing virus is typically transmitted by varroa, not tracheal mites. No smoke, or opening the inner cover is unrelated. The fact that the colony made it thru winter is a good sign. If they're light on stores, you may need to feed them until the spring flow. Once the colony starts to build up in the spring, the K-wing may resolve itself, but you'll have to monitor the mite levels and treat, if necessary.