Abstract:
Rift Valley fever (RVF) is a zoonotic, arthropod–borne RNA viral disease that may cause abortions
in pregnant ruminants and haemorrhage in humans. RVF vaccination is currently unstable and shortlasting warranting need for safe, specific and sensitive diagnostic tools for veterinary and surveillance
laboratories. The objectives were to culture RVF virus (antigen) in vitro using African monkey kidney
(Vero) cells; to identify the extracted antigen using Immunofluoresce antibody (IFA) test and to
optimize the antigen and RVF-positive serum sample (antibody) obtained from sheep (sample H2550)
using Indirect ELISA for designing an ELISA-based diagnostic kit. The experimental study was done
at KARI-Biotechnology Centre between August 2008 and December 2008. RVF virus was cultured
and sub-cultured in vitro using Vero cells and identified. Indirect ELISA, modelled as a titration
chequerboard, was done using the extracted antigen and antibody. The readings from the ELISA were
done at an optical density (OD) of 405nm. An OD of approximately 1 was sought, this being a
representation of the optimum concentrations of antigen and positive serum. The standardization study
revealed the optimum concentrations of the RVF antigen and positive serum (Sheep H2550) to be 1:80
and 1:27, respectively. Validation of optimized antibody and antigen concent.