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Published on: June 19, 2014
Vaccination against feline immunodeficiency virus using fixed infected cells
E J Verschoor1, A L van Vliet, H F Egberink
1Department of Infectious Diseases and Immunology, Veterinary Faculty, University Utrecht, The Netherlands.
Insights
Vaccinating cats with feline immunodeficiency virus (FIV)-infected cells induced antibodies but did not prevent infection. However, a few cats showed resistance, suggesting potential avenues for FIV vaccine development.
Area of Science:
- Veterinary Virology
- Immunology
- Feline Health
Background:
- Feline immunodeficiency virus (FIV) poses a significant threat to cat populations worldwide.
- Developing an effective FIV vaccine remains a critical challenge in veterinary medicine.
Purpose of the Study:
- To evaluate the immunogenicity and efficacy of whole-cell vaccines derived from FIV-infected feline cells in cats.
- To assess the development of anti-FIV antibodies and neutralizing antibody responses post-vaccination and challenge.
Main Methods:
- Feline kidney and thymocyte cell lines, infected or uninfected with FIV, were fixed and formulated with an adjuvant for vaccination.
- Eighteen specific pathogen-free cats received three vaccinations, followed by challenge with the FIV-UT113 strain.
- Antibody titers, including neutralizing antibodies, were measured, and viral loads were assessed post-challenge.
Main Results:
- Vaccination with FIV-infected cells elicited significant anti-FIV antibody responses in 80% of cats.
- Neutralizing antibodies were detected at the time of challenge in vaccinated cats.
- Despite vaccination, 15 out of 18 cats became viremic within 5 weeks post-challenge.
- Three cats (two vaccinated with infected cells, one with uninfected cells) remained resistant to infection for 6 months and upon rechallenge.
Conclusions:
- Whole-cell FIV vaccines can induce antibody responses but show limited efficacy in preventing viremia.
- A subset of cats demonstrated resistance to FIV infection, irrespective of vaccination status, suggesting innate or pre-existing immunity.
- Further research into the mechanisms of resistance observed in a small number of cats is warranted for FIV vaccine development.
Abstract:
Crandell feline kidney cells and feline thymocytes, either feline immunodeficiency virus (FIV) infected or uninfected, were fixed with paraformaldehyde and used to vaccinate cats. The cells were mixed with a 30:70 water/mineral oil emulsion containing 250 micrograms ml-1 N-acetyl-D-glucosaminyl-beta-(1-4)-N-acetyl-muramyl-L-alanyl-D-isoglutam ine. Eighteen specific pathogen-free cats were vaccinated three times with 3-week intervals and challenged 21 days after the final boost with a low dose of the homologous FIV-UT113 strain. Eight out of ten cats that had received FIV-infected cell vaccines developed significant anti-FIV antibody titres to the envelope and core antigens. Neutralizing antibodies were detectable at the moment of challenge in the sera of these animals. Within 5 weeks after challenge 15 out of 18 cats became viraemic. Three animals, two that had been vaccinated with FIV-infected thymocytes and did not develop antibody, and one that had received an uninfected thymocyte preparation, remained uninfected for 6 months. Upon rechallenge of the three animals, two again resisted infection; these cats had been immunized with the infected and the uninfected thymocyte preparations, respectively.
