Development of an indirect ELISA for the detection of serum IgG antibodies against region IV of phase 1 flagellin of Salmonella enterica serovar Brandenburg in sheep.

Region IV of phase 1 flagellin (FliC) of Salmonella enterica serovar Brandenburg (S. Brandenburg) was expressed in Escherichia coli and purified by nickel chelate affinity chromatography. The purified recombinant protein was evaluated for its suitability as an antigen in an indirect ELISA for the detection of antibodies in sheep sera. A cut-off value of 0.1 was calculated using 80 serum samples collected from sheep with no previous history of S. Brandenburg. In the present study we show the results of ELISA with field sera collected from 81 sheep naturally infected with S. Brandenburg. The assay was able to detect antibodies belonging to the IgG class with a sensitivity of 93.8 %. Thus, indirect ELISA might be a suitable screening tool for serological monitoring of sheep flocks infected with S. Brandenburg.