The efficacy of three feline leukaemia virus (FeLV) vaccines was compared. Kittens were immunised with either a recombinant subunit vaccine, Leucogen, or one of two inactivated virus vaccines, Leukocell 2 or Leucat. On subsequent challenge by intraperitoneal inoculation of FeLV of subgroup A (FeLV-A), only Leucogen gave significant protection. In a second experiment, kittens vaccinated with Leucogen were protected against oronasal challenge with a phenotypic mixture of FeLV of subgroups A, B and C, These results indicate that a recombinant vaccine, containing only the protein moiety of the surface glycoprotein of FeLV-A, can provide better protection than the inactivated virus vaccines tested against challenge with virus of the same subgroup, and can also protect against challenge by all three subgroups of FeLV.
