|| Checking for direct PDF access through Ovid
To evaluate the immunogenicity and efficacy of an inactivated dual-subtype feline immunodeficiency virus (FIV) vaccine.Specific-pathogen-free cats were immunized with dual-subtype (subtype A FIVPet and subtype D FIVShi) vaccine and challenged with either in vivo- or in vitro-derived FIV inocula.Dual-subtype vaccinated, single-subtype vaccinated, and placebo-immunized cats were challenged with in vivo-derived heterologous subtype B FIVBang [10–100 50% cat infectious doses (CID50)], in vivo-derived homologous FIVShi(50 CID50), and in vitro- and in vivo-derived homologous FIVPet(20–50 CID50). Dual-subtype vaccine immunogenicity and efficacy were evaluated and compared to single-subtype strain vaccines. FIV infection was determined using virus isolation and proviral PCR of peripheral blood mononuclear cells and lymphoid tissues.Four out of five dual-subtype vaccinated cats were protected against low-dose FIVBang (10 CID50) and subsequently against in vivo-derived FIVPet (50 CID50) challenge, whereas all placebo-immunized cats became infected. Furthermore, dual-subtype vaccine protected two out of five cats against high-dose FIVBang challenge (100 CID50) which infected seven out of eight single-subtype vaccinated cats. All dual-subtype vaccinated cats were protected against in vivo-derived FIVPet, but only one out of five single-subtype vaccinated cats were protected against in vivo-derived FIVPet. Dual-subtype vaccination induced broad-spectrum virus-neutralizing antibodies and FIV-specific interferon-γ responses along with elevated FIV-specific perforin mRNA levels, suggesting an increase in cytotoxic cell activities.Dual-subtype vaccinated cats developed broad-spectrum humoral and cellular immunity which protected cats against in vivo-derived inocula of homologous and heterologous FIV subtypes. Thus, multi-subtype antigen vaccines may be an effective strategy against AIDS viruses.