Abstract
Background:
Brucellosis is prevalent and significantly endemic cause of abortion of goat. Among the various diagnostic methods used for the confirmatory diagnosis of the causing agent, the standard polymerase chain reaction (c-PCR) method is more accurate and appropriate for diagnosing Brucella spp. infection in goats than serological tests such as RBPT and ELISA. The current study compared molecular and serological tests to the diagnosis of Brucella spp.

Aim:
This study used the enzyme-linked immunosorbent assay (ELISA) and the Rose Bengal Plate Test (RBPT) on blood serum to determine prevalence of brucellosis in goats in Tikrit, Iraq. In addition, standard polymerase chain reaction (c-PCR) was conducted on whole blood samples for Brucella spp. detection of investigation the kind to Brucella spp. using the technique of multiplex polymerase chain reaction (m-PCR) and to comparative the c-PCR methodology with RBPT and indirected enzyme-linked immunosorbent as approaches to illness diagnosis.

Methods:
This study inspected 40 aborted goats of different ages gathered from various areas of Tikrit, Iraq, from November 2023 to March 2024. Molecular analysis included collection of 1 ml blood sample from the jugular vein in an anticoagulant EDTA-coated plastic tube, as well as 2-4 ml blood in an anticoagulant-free glass gel tube. In order to detection Brucella antibodies at the serum using the Rose-Bengal plate test (RBPT) and indirect ELISA test, these tubes were centrifuged for five minutes at 3000 rpm. Meanwhile, PCR was used on the complete blood samples to identify Brucella species.

Results:
Using RBPT and ELISA of blood serum and the traditional PCR test, the overall prevalences of brucellosis in abortion goats were 40% (16), 35% (14) and 45% (18) out of 40, respectively. The multiplex PCR method used to primary identification of Brucella spp. showed that prevalence of B. melitensis was 27.5% (11 out of 40), with positive band in 731 bp and B. Abortus was 12.5% (5 of 40), with the positive bands at 498 bp, indicating the prevalence of Brucella spp. According to Kappa value of 0.218, the present researh revealed difference between RBPT and the c-PCR technique in the diagnosis of Brucella spp. at abortion goat, and accuracy, specificity, and sensitivity of RBPT were 87.5%, 83.3%, and 40%, respectively, when comparative to technique of c-PCR. Accorded to Kappa value of 0.216, the present study also found an similarity between ELISA and the c-PCR technique at the accuracy, specificity, sensitivity and of ELISA were 81.2, 95%, and 95%, respectively, when comparative with the technique of c-PCR. The study concluded that Brucellosis is widespread and important for inducing abortion in goats in Tikrit city, and the technique of c-PCR is more dependable and suitable for detection Brucella spp. infection of goats than RBPT and ELISA.

Conclusion:
The study concluded that B. mentensis and B. abortus are important causes to abortion of goats in some areas of Tikrit city. The tests of serologically used in this study were the RBPT most sensitive, whereas the indirect ELISA test was the most specific, and the technique of c-PCR was more dependable and suitable for detection Brucella spp. infection of goats than the serological tests RBPT and ELISA.

Key words: Molecular; Serological; Goat brucellosis.