Rift Valley fever virus (RVFV) is a vector-borne virus that causes high neonatal mortality in livestock and deadly haemorrhagic
fever in humans. In this paper, we describe the generation of
monoclonal antibodies (mabs) against all three structural
proteins of RVFV (
glycoproteins Gn and Gc and
nucleocapsid protein NP). After immunization of BALB/c mice with individual
recombinant proteins, a total of 45 clones secreting ELISA-reactive
monoclonal antibodies against NP, Gn and Gc
epitopes were obtained. Twelve clones were directed to NP, 28 to Gn, and 5 to Gc. Western blot analysis revealed that most of the mabs were reactive to linearized
epitopes on recombinant as well as native virus
proteins. Six mabs against NP, 21 against Gn and all mabs against Gc also detected conformational
epitopes, as shown by indirect immunofluorescence on RVFV-infected cells. All of the mabs were evaluated for their use in a competition
enzyme-linked
immunosorbent assay (ELISA) for the detection of a RVFV
infection. Several mabs were identified that competed with polyclonal rabbit serum, and one of them - mab Gn123, raised against Gn
protein - was selected for a proof-of-principle study with field sera from a recent
Rift Valley fever outbreak. The novel Gn-based competition ELISA demonstrated high performance, offering a promising alternative and addition to serological assays based on
nucleocapsid protein.