Evaluation of Feline Monocyte-Derived Dendritic Cells Loaded with Internally Inactivated Virus as a Vaccine against Feline Immunodeficiency Virus

Retrovirus Center and Virology Section, Department of Experimental Pathology, University of Pisa,Via del Brennero 2, I-56127 Pisa

^* To whom correspondence should be addressed. Email: freer{at}biomed.unipi.it.

	Abstract

Dendritic cells are the only antigen-presenting cells that can present exogenous antigens to both helper and cytolytic T cells and prime Th1-type or Th2-type cellular immune responses. Given their unique immune functions, they are considered attractive "live adjuvants" for vaccination and immunotherapy against cancer and infectious diseases. The present study was carried out to assess whether reinjection of autologous monocyte-derived dendritic cells loaded with an aldithriol-2-inactivated primary isolate of feline immune deficiency virus (FIV) were able to elicit protective immune responses against the homologous virus in naïve cats. Vaccine efficacy was assessed by monitoring immune responses and, finally, by challenge with the homologous virus of both vaccinated, mock-vaccinated and normal cats. The outcome of challenge was followed by measuring cellular and antibody responses, viral and proviral loads and quantitating FIV by isolation and CD4⁺/CD8⁺ T cell count in blood. Vaccinated animals exhibited evident FIV-specific peripheral blood mononuclear cells proliferation and antibody titers in response to immunization, however, they became infected with the challenge virus at comparable rates as control animals.