Effect of dual-subtype vaccine against feline immunodeficiency virus infection

Abstract

Dual-subtype feline immunodeficiency virus (FIV) vaccine, consisting of inactivated cells infected with subtypes A (Petaluma strain) and D (Shizuoka strain), was developed and tested for its vaccine efficacy against FIV infection in specific pathogen free (SPF) cats. Animals were monitored for proviral DNA by FIV-specific PCR and for FIV-specific antibody profiles by ELISA and virus-neutralization assays. In addition, blood from challenged cats was inoculated into naive SPF cats to confirm the viral status of the vaccinated cats. All cats immunized with Petaluma vaccine alone were protected against homologous Petaluma challenge, but only one of four cats was protected against heterologous Shizuoka challenge. More importantly, all cats immunized with the dual-subtype vaccine were protected against both Petaluma and Shizuoka challenges. These results suggest that a multi-subtype vaccine approach may provide the broad-spectrum immunity necessary for vaccine protection against strains from different subtypes.

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

“…Finally, the FC MBM vaccine was seen to absorb neutralizing antibodies from infected cat sera in vitro more efficiently than inactivated whole FIV vaccines (23). These findings, in conjunction with the observation that day-of-challenge FIV neutralizing titers of FC MBM -vaccinated cats correlated with protection (23), made it feasible that the superior protective efficacy of this and similar cell-based vaccines tested by other groups (3,16,27,67,68) relative to the ones composed of cell-free virions was due to viral epitopes rendered immunologically functional by FIV interaction with cell surfaces (designated here as interaction dependent [ID]). …”

“…One vaccine (FC PLB ) was "conventional" in that it was composed of fixed massively infected cells similar to other previously tested cell-based FIV vaccines (3,16,27,31,38,67,68). The others were variations around the feasibility of producing immunogens enriched in ID epitopes and consisted of cells fixed after adsorption of internally inactivated FIV particles onto the cell surface in the presence or absence of two peptide inhibitors of virus entry.…”

Patterns of Feline Immunodeficiency Virus Multiple Infection and Genome Divergence in a Free-Ranging Population of African Lions

“…This parallels laboratory vaccine trials for FIV-Fca and SIV and HIV vaccine trials in simian models, where vaccines may be successful against homologous challenge but ineffective against heterologous challenges. For example, in domestic cat a single subtype vaccine is protective against homologous challenge but ineffective against heterologous challenge with a different subtype (19). Additionally, a dual-subtype vaccine was completely protective against homologous challenge but only partially protective against heterologous challenge (40).…”

Neutralization sensitivity and accessibility of continuous B cell epitopes of the feline immunodeficiency virus envelope

“…Thus, naive primates have been protected from challenge with HIV-1, HIV-2 and SIV by the administration of purified antibodies or the transfer of sera from animals immunized with virus subunit vaccines or with attenuated virus strains (reviewed in Norrby & Matthews, 1993). Similarly, cats have resisted challenge with FIV after receiving the sera of immunized cats (Hohdatsu et al, 1993) and maternal antibodies from either vaccinated or infected queens protected kittens from FIV infection (Pu et al, 1995). Nevertheless, certain subunit vaccines of FIV have augmented or accelerated infection after challenge (Hosie et al, 1992) and the demonstration that such enhancement may be extended to naive animals upon passive transfer of plasma from immunized cats strongly suggests that antibodies mediated the enhanced infection observed in vivo (Siebelink et al, 1995a).…”