Diagnostic performance of RFLP-PCR and sarcosine based indirect ELISA versus immunoassays in Brucella infected and vaccinated small ruminants

This study was carried out for evaluation of the diagnostic performance of different serological assays; buffered acidified plate antigen test (BAPAT), rose bengal plate test (RBPT), immunochromatographic assay (ICA), rivanol test (RivT), indirect ELISA using two types of coating antigens (smooth lipopolysaccharide; S-LPS and N-lauroylsarcosine-extracted antigens; SE) and complement fixation test (CFT). Relative sensitivity and specificity of various techniques were estimated. The traditional serological tests failed to distinguish the vaccinated from naturally infected animals. Using iELISA with extracted antigens (SE) as a coating antigen was a more accurate test to differentiate the naturally infected animals from vaccinated animals. Application of restriction fragment length polymorphism polymerase chain reaction (RFLP-PCR) on sera samples from seropositive animals, Rev-1 vaccinated sheep and Brucella field strain infected sheep and goats revealed that there were samples identified as B. melitensis biovar 3 field strain and other samples identified as B. melitensis Rev-1 vaccinal strain. The obtained results established that restriction fragment length polymorphism-polymerase chain reaction can differentiate between animals infected with Brucella field strains from animals vaccinated with the Rev-1 vaccine.