title: AIDS vaccination studies using an ex vivo feline immunodeficiency virus model: failure to protect and possible enhancement of challenge infection by four cell-based vaccines prepared with autologous lymphoblasts.
abstract: Immunogenicity and protective activity of four cell-based feline immunodeficiency virus (FIV) vaccines prepared with autologous lymphoblasts were investigated. One vaccine was composed of FIV-infected cells that were paraformaldehyde fixed at the peak of viral expression. The other vaccines were attempts to maximize the expression of protective epitopes that might become exposed as a result of virion binding to cells and essentially consisted of cells mildly fixed after saturation of their surface with adsorbed, internally inactivated FIV particles. The levels of FIV-specific lymphoproliferation exhibited by the vaccinees were comparable to the ones previously observed in vaccine-protected cats, but antibodies were largely directed to cell-derived constituents rather than to truly viral epitopes and had very poor FIV-neutralizing activity. Moreover, under one condition of testing, some vaccine sera enhanced FIV replication in vitro. As a further limit, the vaccines proved inefficient at priming animals for anamnestic immune responses. Two months after completion of primary immunization, the animals were challenged with a low dose of homologous ex vivo FIV. Collectively, 8 of 20 vaccinees developed infection versus one of nine animals mock immunized with fixed uninfected autologous lymphoblasts. After a boosting and rechallenge with a higher virus dose, all remaining animals became infected, thus confirming their lack of protection.
authors.affiliation: Retrovirus Center and Virology Section, Department of Biomedicine, University of Pisa, Pisa, Italy.
authors.forename: Simone
authors.initials: S
authors.lastname: Giannecchini
authors.forename: Patrizia
authors.initials: P
authors.lastname: Isola
authors.forename: Olimpia
authors.initials: O
authors.lastname: Sichi
authors.forename: Donatella
authors.initials: D
authors.lastname: Matteucci
authors.forename: Mauro
authors.initials: M
authors.lastname: Pistello
authors.forename: Lucia
authors.initials: L
authors.lastname: Zaccaro
authors.forename: Daniela
authors.initials: D
authors.lastname: Del Mauro
authors.forename: Mauro
authors.initials: M
authors.lastname: Bendinelli
mesh_terms: D016915:AIDS Vaccines / Q000008:administration & dosage / Q000276:immunology; D000163:Acquired Immunodeficiency Syndrome / Q000517:prevention & control; D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000956:Antigens, Viral / Q000276:immunology; D002415:Cats; D004195:Disease Models, Animal; D016181:Feline Acquired Immunodeficiency Syndrome / Q000517:prevention & control*; D005260:Female; D007117:Immunization, Secondary; D016089:Immunodeficiency Virus, Feline / Q000276:immunology* / Q000502:physiology; D007963:Leukocytes, Mononuclear / Q000276:immunology / Q000637:transplantation / Q000821:virology*; D008213:Lymphocyte Activation; D012367:RNA, Viral / Q000097:blood; D014182:Transplantation, Autologous; D014611:Vaccination; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology
chemical_list: D016915:AIDS Vaccines; D000914:Antibodies, Viral; D000956:Antigens, Viral; D012367:RNA, Viral; D014765:Viral Vaccines