Immunogenicity and efficacy of an in-house developed cell-culture derived veterinarian rabies vaccine.

The efficiency of an inactivated tissue culture rabies vaccine produced on BHK-21 cells, according to an in-house developed process, was evaluated and compared to a commercial cell-tissue culture vaccine (Rabisin). Fifteen experimental dogs from local common breed were duly conditioned during a quarantine period, then vaccinated via the subcutaneous route with 1 ml of either the tissue culture vaccine developed in-house or the commercial vaccine Rabisin. The immune response of each dog was monitored for 162 days. Serum-neutralizing antibodies titers to rabies virus were determined by the rapid fluorescent focus inhibition test (RFFIT) which confirmed the strong response of dogs to both vaccines except one dog in the Rabisin group. The dogs were then challenged in the masseter muscle with a rabies street virus of canine origin. All vaccinated dogs except the single dog in the Rabisin group that failed to respond to the vaccine, survived the challenge. In contrast, 80% of animals in the control non-vaccinated group, developed rabies and died. A field vaccine trial was also conducted: 1,000 local dogs living in field conditions received one subcutaneous dose of the locally developed vaccine. Serum neutralizing antibody titers to rabies virus was determined by RFFIT at days 0, 60 and 360. Mean rabies neutralizing antibody titers were equal to 0.786, 3.73 and 1.55 IU/ml, respectively. The percentage of dogs with a neutralizing rabies antibody titer higher than the 0.5 IU/ml mandated WHO threshold, was 30%, 91.4% and 87.5% at day 0, 2 months and 1 year post-vaccination, respectively. These data demonstrate the efficiency of the in-house developed vaccine produced on BHK-21 cells in both experimental and field conditions and support its use in dog mass vaccination campaigns.