Source:http://linkedlifedata.com/resource/umls/id/C0178634
CSP: feline leukemia virus (FeLV) and feline sarcoma virus (FeSV) are both species of gammaretrovirus; FeLV causes leukemia, lymphosarcoma, immune deficiency, or other degenerative diseases in cats; FeSV is a recombinant feline leukemia viruses where part of the genome has been replaced by cellular oncogenes, unique to individuals and not transmitted naturally to other cats; FeSVs are replication defective and require FeLV to reproduce.