Response of feral cats to vaccination at the time of neutering.

Objective: To determine whether administration of inactivated virus or modified-live virus (MLV) vaccines to feral cats at the time of neutering induces protective serum antiviral antibody titers.

Design: Prospective study.

Animals: 61 feral cats included in a trap-neuter-return program in Florida.

The influence of homologous vs. heterologous challenge virus strains on the serological test results of rabies virus neutralizing assays.

The effect that the relatedness of the viral seed strain used to produce rabies vaccines has to the strain of challenge virus used to measure rabies virus neutralizing antibodies after vaccination was evaluated. Serum samples from 173 subjects vaccinated with either purified Vero cell rabies vaccine (PVRV), produced from the Pittman Moore (PM) seed strain of rabies virus, or purified chick embryo cell rabies vaccine (PCECV), produced from the Flury low egg passage (Flury-LEP) seed strain of rabies virus, were tested in parallel assays by RFFIT using a homologous and a heterologous testing system. In the homologous system, CVS-11 was used as the challenge virus in the assay to evaluate the humoral immune response in subjects vaccinated with PVRV and Flury-LEP was used for subjects vaccinated with PCECV.