Screening and identification of T helper 1 and linear immunodominant antibody-binding epitopes in the spike 2 domain and the nucleocapsid protein of feline infectious peritonitis virus.

The antibody-dependent enhancement (ADE) of feline infectious peritonitis virus (FIPV) infection has been recognized in experimentally infected cats, and cellular immunity is considered to play an important role in preventing the onset of feline infectious peritonitis (FIP). In the present study, we synthesized eighty-one kinds of peptides derived from the spike (S)2 domain of type I FIPV KU-2 strain, the S2 domain of type II FIPV 79-1146 strain, and the nucleocapcid (N) protein of FIPV KU-2 strain. To detect the T helper (Th)1 epitope, peripheral blood mononuclear cells (PBMCs) obtained from FIPV-infected cats were cultured with each peptide, and Th1-type immune responses were measured using feline interferon (fIFN)-γ production as an index.

Identification of cytosine-phosphorothioate-guanine oligodeoxynucleotide sequences that induce interferon-γ production in feline immune cells.

Unmethylated CpG-ODN are known to enhance Th1-type immune response. However, optimal sequences of CpG-ODN for activating Th1-type immune cells vary among species. It is necessary to identify the effective CpG-ODN sequences in each species.

Serological differentiation of FIV-infected cats from dual-subtype feline immunodeficiency virus vaccine (Fel-O-Vax FIV) inoculated cats.

Feline immunodeficiency virus (FIV) vaccine, Fel-O-Vax FIV, was released for sale in the US in 2002. The antibodies of vaccinated cats interfere with serological assays by currently available FIV diagnostic kits. In this study, we investigated whether it is possible to distinguish serologically cats vaccinated with Fel-O-Vax FIV from cats experimentally or naturally infected with FIV.

Dual-subtype vaccine (Fel-O-Vax FIV) protects cats against contact challenge with heterologous subtype B FIV infected cats.

Fel-O-Vax FIV is a dual-subtype vaccine consisting of inactivated whole viruses of subtype A (Petaluma strain) and subtype D (Shizuoka strain). The efficacy of this vaccine against heterologous subtype A strain challenge was demonstrated, but it is unclear whether the result reflects efficacy in the field. In this study, we evaluated the efficacy of this vaccine against contact challenge by exposing both vaccinated and unvaccinated control animals with cats infected with Aomori-2 strain belonging to subtype B, a subtype prevalent in many regions of the world.