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Journal of Virology, January 2007, p. 465-473, Vol. 81, No. 2
0022-538X/07/$08.00+0 doi:10.1128/JVI.00815-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
Christian M. Leutenegger,1
Gregg A. Dean,2
Jonathan D. Steckbeck,3
Kelly Stefano Cole,3 and
Ellen E. Sparger1*
Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California, Davis, California 95616,1 Department of Microbiology, Pathology, and Parasitology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina 27606,2 Department of Medicine, Infectious Diseases Division, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 152613
Received 20 April 2006/ Accepted 19 October 2006
A feline immunodeficiency virus (FIV) provirus with a vif gene deletion (FIV
vifATG
) that coexpresses feline gamma interferon (IFN-
) was tested as a proviral DNA vaccine to extend previous studies showing efficacy with an FIV-pPPR
vif DNA vaccine. Cats were vaccinated with either FIV
vifATG
or FIV-pPPR
vif proviral plasmid DNA or with both FIV-pPPR
vif DNA and a feline IFN-
expression plasmid (pCDNA-IFN
). A higher frequency of FIV-specific T-cell proliferation responses was observed in cats immunized with either FIV
vifATG
or FIV-pPPR
vif plus pCDNA-IFN
, while virus-specific cytotoxic-T-lymphocyte responses were comparable between vaccine groups. Antiviral antibodies were not observed postvaccination. Virus-specific cellular and humoral responses were similar between vaccine groups after challenge with a biological FIV isolate (FIV-PPR) at 13 weeks postimmunization. All vaccinated and unvaccinated cats were infected after FIV-PPR challenge and exhibited similar plasma virus loads. Accordingly, inclusion of plasmids containing IFN-
did not enhance the efficacy of FIV-pPPR
vif DNA immunization. Interestingly, the lack of protection associated with FIV-pPPR
vif DNA immunization contrasted with findings from a previous study and suggested that multiple factors, including timing of FIV-pPPR
vif inoculations and challenge, as well as route of challenge virus delivery, may significantly impact vaccine efficacy.
Published ahead of print on 1 November 2006.
Present address: Monogram Biosciences, Inc., 345 Oyster Point Blvd., South San Francisco, CA 94080.
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