Vaccination with a feline immunodeficiency virus multiepitopic peptide induces cell-mediated and humoral immune responses in cats, but does not confer protection

Cats were immunized with a 46-residue multiepitopic synthetic peptide of feline immunodeficiency virus (FIV) comprising immunodominant epitopes present in the third variable domain of the envelope glycoprotein, transmembrane glycoprotein (TM), and p24 Gag core protein, using Quil A as an adjuvant. All vaccinated cats developed a humoral response which recognized the synthetic peptide immunogen and the intact viral core and envelope proteins. A FIV Gag- and Env-specific effector cytotoxic T-lymphocyte response was also detected in the peripheral blood of vaccinated cats, which peaked at week 30. This response appeared to be major histo-compatibility complex restricted. Epitope mapping studies revealed that both the cellular and humoral im-mune responses were directed principally to a peptide within the TM glycoprotein, CNQNQFFCK. However, vaccination did not confer protection when cats were challenged with the Petaluma isolate of FIV at week 35. Determination of the fine epitope specificities involved in the protective immune response to immunosuppressive lenti-viruses is useful to the design of effective vaccines. The simi-larities between feline immunodeficiency virus (FIV) and hu-man immunodeficiency virus type 1 (HIV-1) and the diseases that they cause make FIV infection of domestic cats a valuabl