Rapid Immunofiltration Assay as a Field Diagnostic Tool for Ovine Brucellosis

Abstract

This work describes the development of two rapid immunofiltration assays, enzymatic (ERIFA) and non-enzymatic (NERIFA), for the rapid detection of ovine anti-Brucella antibodies. Brucella abortus lipopolysaccharide and total bacterial extract were dotted separately as diagnostic antigens on a nitrocellulose filter-membrane of the individual assay unit along with a third dot of purified sheep IgG as an internal control. The assay's diagnostic performance was evaluated in comparison with a modified rose bengal test (mRBT) and an indirect enzyme-linked immunosorbent assay (ELISA) through usage of 590 serum samples from healthy, vaccinated, or infected sheep. The ERIFA and indirect ELISA were found to be significantly more sensitive than NERIFA, while mRBT was determined to be statistically equivalent to NERIFA. A perfect agreement (κ = 0.984) and a statistical equivalence to indirect ELISA suggest that the bi-antigenic ERIFA can be used as an "individual rapid ELISA" for screening ovine anti-Brucella antibody both in the field and in limited laboratory conditions.

Validation of Two Rapid Serological Tests for Human Brucellosis Detection

“…In the test, whole B. abortus antigen from Pendik Veterinary Control Institute was used and the result was evaluated after 24 hours of incubation at 37 ºC. The titre was accepted as serum dilution disclosing more than 50% agglutination [5,17,22,23] .…”

“…Two models of RIFA designated as enzymatic (ERIFA) and non-enzymatic (NERIFA) as described earlier for Mycoplasma gallisepticum infection detection in poultry and for brucellosis diagnosis in domesticated animals were used [21,22,27] . Both models were implemented on nitrocellulose (NC) membrane (Schleicher & Schuell, Germany) in the cassette.…”

“…Numerous commercial and home-made tests have been developed to identify brucellosis patients. Although, agglutination, complement fixation, globulin test, Brucellacapt, ELISA have been common [4,14,23,24,31] recently, immunochromatographic [20] and immunofiltration tests [21,22] are used as ancillary rapid and accurate tests.…”

“…Renovations in rapid test technology for brucellosis detection is on the development of membrane based field. In this respect, Lateral Flow (LFA) [36] and Rapid Immunofiltration tests (RIFAs) have been recently developed for brucellosis diagnosing in different species [21,22] . As the diagnostic performance of the RIFAs and ELISA were found to be statistically similar, these tests can be applied as "an individual quick test".…”

“…However, there are problems in interpretation of the results of these tests, especially for low titers obtained from healthy people who had the infection earlier in endemic areas [11,18] , also for early diagnosis or in patients with chronic brucellosis or recurrence [19] . Immunochromatographic lateral flow assays [20] and immunofiltration based test models known as enzymatic (ERIFA) and non-enzymatic (NERIFA) rapid immunofiltration assays [21,22] were suggested for rapid detection of Brucella-specific antibodies in different species in place of highly complicated and more expensive tests.…”