1989 Volume 42 Issue 10 Pages 715-720
Immunogenicity of the cell culture-adapted RC·EHL strain of rabies·Evirus, as well as the efficacy and administration method of an inactivated vaccine prepared from this strain were investigated. The cross-neutralization test revealed that anti-RC·EHL, anti-CVS and anti-HF-TC sera neutralized the respective homologous viruses with the highest titer, and that anti-RC·EHL serum neutralized the CVS strain with a higher titer than the HF-TC strain. The minimum effective neutralizing antibody titers, which were determined in dogs injected with the experimental vaccine, were 11.3 when assayed with the RC·EHL strain and approximately 4 when assayed with the HF-TC strain. The minimum effective neutralizing antibody titers determined in guinea pigs were higher to some extent than those in dogs. These results were comfirmed by the passive immunization test performed in guinea pigs. There were no significant differences in neutralizing antibody titers measured at 2 or 4 weeks post-inoculation (PI) when dogs or cats were vaccinated subcutaneouly with 0.5, 1.0, and 2.0 ml, subcutaneously and intramuscularly with 1.0 ml, or subcutaneously with 1.0 ml of undiluted and 2-, 4-, or 8-fold diluted vaccine. Dogs inoculated subcutaneously with 1.0 ml of the vaccine produced a neutralizind antibody titer of 29.3 at 1-month PI, when assayed with the HF-TC strain, then the titer gradually declined to 5.4 at 12-month PI. Dogs inoculated twice with the vaccine at a 1-, 6-or 12-month interval developed the maximum neutralizing antibody titers of 313.3, 368.1 or 340.3, respectively, whereas dogs inoculated twice with the vaccine at a 24-month interval did not produce any amnestic immune response. These results indicated that the inactivated vaccine prepared from the RC·EHL strain induced immunity lasting for 12 months and elicited a high amnestic immune response by re-vaccination within 12 months of the first vaccination.
