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Therapeutic vaccination in healthy FeLV positive cats

Helfer-Hungerbuehler AK, Spiri AM, et al. No benefit of therapeutic vaccination in clinically healthy cats persistently infected with feline leukemia virus.Vaccine. 33 (2015):1578-1585.

Therapeutic vaccination is a possible treatment for some infectious diseases. Use of the FeLV vaccine in cats naturally infected with the virus was examined by these investigators. As they state,” By vaccinating persistently FeLV-infected cats and presenting FeLV antigens to the immunesystem of the host, e.g., in the form of recombinant and/or adjuvanted antigens, we intended to shift the balance toward an advantage of the host so that persistent infection could be overcome by the infected cat.” 

To examine this possibility, two commercially available FeLV vaccines were tested in six FeLV-persistently infected cats. Unfortunately, no reduction in viral load nor increase in life expectancy were detected with either vaccine. While some cats developed antibodies in response to the vaccination, they were not protective. Thus, vaccination of cats persistently infected with FeLV with a FeLV vaccine offers no advantage, and cannot be recommended. (MK)

See also:
Hoffman-Lehmann R, Cattori V, et al. How molecular methods change our views of FeLV infection and vaccination. Vet Immunol Immunopathol. 2008 May 15;123(1-2):119-23.