Document 0740
 DOCN  M95A0740
 TI    Recombinant FeLV vaccine: long-term protection and effect on course and
       outcome of FIV infection.
 DT    9510
 AU    Hofmann-Lehmann R; Holznagel E; Aubert A; Ossent P; Reinacher M; Lutz H;
       Department of Internal Veterinary Medicine, University of Zurich,;
       Switzerland.
 SO    Vet Immunol Immunopathol. 1995 May;46(1-2):127-37. Unique Identifier :
       AIDSLINE MED/95343521
 AB    The efficacy and the long-term protection of a recombinant feline
       leukemia virus (FeLV) vaccine were determined in 30 specified pathogen
       free cats for over 3 years. At the same time, in order to specify the
       effects of feline immunodeficiency virus (FIV) on the immune system, one
       half of the cats (n = 15) were previously infected with the Swiss
       isolate FIV Zurich 2. The second half of the animals (n = 15) served as
       non-infected controls. Eighteen (nine FIV-negative, nine FIV-positive)
       vaccinated and 12 (six FIV-negative, six FIV-positive) non-vaccinated
       cats were intraperitoneally challenged with FeLV A. Seventeen of 18
       vaccinated cats were protected against persistent viremia, while ten of
       12 non-vaccinated controls became infected. An increase of antibodies
       against FeLV SU was found in all protected cats after the challenge
       exposure. No difference in vaccine efficacy was found between
       FIV-negative and FIV-positive animals. The whole group of cats was
       observed for over 3 years. There were no further vaccinations during
       this period. CD4+ and CD8+ cell subsets, clinical outcome and time of
       survival of the cats were recorded. FIV-negative and FIV-positive
       animals were kept in two different rooms. However, FeLV-negative and
       FeLV viremic cats were housed together in both rooms in order to imitate
       a natural FeLV exposure situation. Anti-recombinant FeLV SU antibodies
       were measured by enzyme-linked immunosorbent assay. Although a
       continuous decline of antibodies was found in FeLV vaccinated cats, they
       remained protected against constant FeLV challenge for over 3 years. FIV
       infection had a stronger effect on the depression of the CD4+:CD8+ ratio
       than FeLV infection. Within the group of FIV-positive cats, the
       FeLV-vaccinated animals had significantly better survival rates as well
       as better clinical and laboratory parameters. FIV- and FeLV-coinfected
       cats showed the lowest CD4+:CD8+ ratio, mainly caused by decreased CD4+
       lymphocyte counts. CD8+ lymphocytes with strong fluorescence (CD8(high))
       disappeared and cells with weak fluorescence (CD8(low)) appeared
       instead. Prevention of coinfection by immunizing FIV-positive cats
       against FeLV infection improved the clinical outcome and prolonged the
       cat's life expectancy.
 DE    Animal  Antibodies, Viral/BLOOD  Cats  CD4-CD8 Ratio/VETERINARY
       CD4-Positive T-Lymphocytes/IMMUNOLOGY  CD8-Positive
       T-Lymphocytes/IMMUNOLOGY  Enzyme-Linked Immunosorbent Assay  Feline
       Acquired Immunodeficiency Syndrome/IMMUNOLOGY/MORTALITY/  *PREVENTION &
       CONTROL  Female  Flow Cytometry/VETERINARY  Immunodeficiency Virus,
       Feline/*IMMUNOLOGY  Leukemia Virus, Feline/*IMMUNOLOGY  Male  Specific
       Pathogen-Free Organisms  Support, Non-U.S. Gov't  Survival Analysis
       Vaccination/*VETERINARY  Vaccines, Synthetic/IMMUNOLOGY  Viral
       Vaccines/*IMMUNOLOGY  Viremia/IMMUNOLOGY/PREVENTION &
       CONTROL/*VETERINARY  JOURNAL ARTICLE

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