DEVELOPMENT OF POLYVALENT RECOMBINANT VACCINES FOR CATS.

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The aim of the present studies is to develop polyvalent recombinant (rec) vaccines which are superior to safeness, inexpensiveness and effctiveness to cats, and to put the vaccines to practical use. The following results are obtained.1.We succeeded in the attenuation of thymidine kinase (TK) deficient mutant (C7301dlTK) of feline herpesvirus type 1 (FHV-1) in cats and the construction of a recombinat FHV-1 (C7301dlTK-Cap) inserted a precursor capsid gene of feline calicivirus (FCV) into the TK deletion locus of the C7301dlTK.Cats vaccinated with C7301dlTK-Cap and then challenged with virulent FHV-1 and FCV were protected to a significant degree against the manifestations of the illness caused by both viruses. However, immune presponse to FCV was weak.2.Therfore to improve further on the recombinat FHV-1, we constructed an improved recombinant FHV-1 (dlTK (gCp) -Cap) carring a putative FHV-1 gC promoter sequence on the upstream of the FCV precursor capsid gene of the C7301dlTK-Cap. Growth kinetics of the dlTK (gCp) -Cap in cell cultures was similar to those of C7301dlTK and C7301dlTK-Cap. A strong expression of FCV immunogenic antigen by dlTK (gCp) -Cap was confirmed by indirect immunofluorescence and enzime-linked immunosorbent assays. In addition, one vaccination with dlTK (gCp) -Cap protected cats more effectively against subsequent virulent FCV challenge than that with C7301dlTK-Cap.3.We constructed a recombinat FHV-1 expressing Gag protein of feline immunodeficiency virus (FIV), in which a cDNA encoding the Gag protein of FIV was inserted at the TK deletion site of C7301ddlTK,and was designated as C7301ddlTK-gag. Growth kinetics of the reconbinat viruses in Crandell feline kidney cells was similar to that of the parent C7301 strain. By immunoblot analysis, C7301ddlTK-gag was confirmed to express the FIV Gag precursor protein in the cells.