Efficient expression of the envelope protein of feline immunodeficiency virus in a recombinant feline herpesvirus type 1 (FHV-1) using the gC promoter of FHV-1

We constructed two recombinant feline herpesvirus type 1 (FHV-1) expressing the envelope (Env) protein of feline immunodeficiency virus (FIV). One rec ombinant, designated dlTK-env, has the whole FIV env gene inserted at a thy midine kinase (TK) deletion site. The second recombinant, designated dlTK(g Cp)-env, has a cassette containing a partial FIV env gene fused with the si gnal sequence of the gC protein of FHV-1 (under the control of the gC promo ter) inserted at the same site. Growth kinetics of both the recombinants in Crandell feline kidney (CRFK) cells were similar to that of the parent str ain of FHV-1. By indirect immunofluorescence assays and immunoblot analyses , we confirmed the expression of the FIV Env protein in CRFK cells infected with both recombinants. Enzyme-linked immunosorbent assays showed that the maximum Env expression level achieved by dlTK(gCp)-env was more than four times higher than that observed for dlTK-env. Flow cytometric analyses reve aled that the Env protein produced by both recombinants was efficiently exp ressed on the cell surface. The dlTK(gCp)-env reported here may thus be a p romising candidate for a live recombinant vaccine to protect against FIV in fection. (C) 2000 Elsevier Science B.V.. All rights reserved.