This article is from the Feline Leukemia (Cats) FAQ, posted to rec.pets.cats newsgroup. Maintained by Erin Miller with numerous contributions by others.
No. As of July 1992, all of the vaccines which are approved for sale in the United States are incapable of causing a positive FeLV test result. (Sorry, but I don't have figures for vaccines in other countries. If anyone does, feel free to append them onto this FAQ.)