Comparison of a recombinant nucleocapsid IgG indirect ELISA with an IgG sandwich ELISA for the detection of antibodies to Rift Valley fever virus in small ruminants.

Serological tests are widely used for Rift Valley fever (RVF) surveillance, disease control, and monitoring of immunological responses after vaccination. In recent years, several enzyme-linked immunosorbent assay (ELISA) formats have been developed for the detection of antibodies to RVF virus, but limited comparisons of their diagnostic sensitivities are available for specifically-targeted animal populations. This article describes the comparison of the commercially-available RVF recombinant nucleocapsid IgG indirect ELISA with the IgG sandwich ELISA in field-collected serum samples from 1262 domestic small ruminants in Mozambique. The agreement between the two tests measured by Cohen's kappa value was high (0.99 in goats and 0.92 in sheep), but the IgG sandwich ELISA was slightly more sensitive than the recombinant nucleocapsid IgG indirect ELISA in detecting the IgG response in sheep and goats naturally exposed to RVF virus.