The feline leukemia virus pol gene (FeLV-pol) encodes a reverse
transcriptase (enzyme that "converts", i.e., reverse transcribes,
RNA into DNA). A portion of the FeLV-pol gene that is not expressed
is used together with the glycoprotein (FeLV-env) and the complete
nucleoprotein (FeLV-gag) genes of the feline leukemia virus in
vaccines to help preventing the disease in cats.