title: Clinical and immunologic aspects of FeLV-induced immunosuppression.
abstract: Cats exposed to the feline leukemia virus (FeLV) may mount an effective immune response and eliminate the virus, develop a non-viremic, latent infection or become persistently infected and shed the virus. Persistently infected cats commonly die of secondary opportunistic infections that result from FeLV-induced immunosuppression. The acquired immunosuppression is the most frequent and most devastating consequence of FeLV infection in the cat. Immunosuppression is targeted primarily to the cell-mediated immune system and has been attributed to the viral p15e envelope protein. The decreased IgG response and proliferative response to T cell mitogens is thought to be due to a defect in the helper cell function. As a result of T helper cell immunosuppression, infected cats may also have defective cytotoxic lymphocyte and activated macrophage functions which are regulated by their lymphokines. Research has shown that the virus causes a general suppression in the production of T cell-derived lymphokines, including gamma interferon and interleukin 2. A decrease in the function of polymorphonuclear leukocytes has also been reported and may contribute to deaths due to opportunistic infections in FeLV-positive cats. There are numerous parallels between the acquired immunodeficiency syndrome (AIDS) in man and the FeLV-induced immunodeficiency syndrome in cats. Frequent deaths due to opportunistic infections, lymphopenia, depressed cell-mediated immune responses to T cell-dependent antigens despite hypergammaglobulinemia and the presence of a long period of time between infection and the onset of clinical signs are just a few of the syndromes that are similar between the 2 retroviral diseases. A new strain of FeLV, FeLV-FAIDS has been associated with a naturally occurring immunosuppressive syndrome that is strikingly similar to AIDS in man. In addition, a T-lymphotropic retrovirus has recently been identified from cats with an immunodeficiency-like syndrome; this feline lentivirus disease is morphologically similar, but antigenically distinct from the human immunodeficiency virus, the cause of AIDS. Treatment for FeLV immunosuppression is primarily supportive. The development of a soluble tumor cell antigen vaccine has been shown to be efficacious in preventing FeLV infections.
authors.affiliation: College of Veterinary Medicine, University of Illinois, Urbana.
authors.forename: G K
authors.initials: GK
authors.lastname: Ogilvie
authors.forename: M B
authors.initials: MB
authors.lastname: Tompkins
authors.forename: W A
authors.initials: WA
authors.lastname: Tompkins
mesh_terms: D000163:Acquired Immunodeficiency Syndrome / Q000276:immunology; D000818:Animals; D002415:Cats; D004195:Disease Models, Animal; D007108:Immune Tolerance; D005256:Leukemia Virus, Feline; D007942:Leukemia, Experimental / Q000276:immunology* / Q000382:microbiology; D008214:Lymphocytes / Q000276:immunology; D009504:Neutrophils / Q000276:immunology