Vaccination with experimental feline immunodeficiency virus vaccines, based on autologous infected cells, elicits enhancement of homologous challengeinfection

Cats were vaccinated with fixed autologous feline immunodeficiency virus (F IV)-infected cells in order to present viral proteins to the immune system of individual cats in an MHC-matched fashion. Upon vaccination, a humoral r esponse against Gag was induced. Furthermore, virus-neutralizing antibodies were detected in a Crandell feline kidney cell-based neutralization assay, but not in a neutralization assay based on primary peripheral blood mononu clear cells. Despite the induction of these FIV-specific responses, vaccina ted cats were not protected. Instead, accelerated virus replication was fou nd, an observation similar to what previous experiments using other vaccine candidates have shown, Here, the results of the present study are discusse d in the light of enhancement of lentivirus infections as a complicating fa ctor in lentivirus vaccine development.