Yes, if you are prepared for medical expenses and the fact that the cat will have a shortened life span. FeLV+ cats can live with dogs, and other FeLV+ cats. They cannot be left outdoors, and cannot live with cats that are not FeLV+ even if those cats are vaccinated. At best, the vaccine is only 80% effective in preventing the disease. FeLV cats need an owner who takes them to the vet just as soon as the slightest sign of illness appears - a weepy eye, sneezing, diarrhea - the cat has a weak immune system and something that would be harmless for another cat can become very serious in one that is FeLV+. They also need quality foods to help support the immune system. So if you have no other cats, are prepared to deal with potential vet expenses and are willing to keep the cat indoors and indoors only, then go ahead, as long as you have no other cats. But some people do adopt more than one FeLV+ cat - no harm in that.