Comparison of BP26, Omp25 and Omp31 and a Multiepitope-Based Fusion Protein in the Serological Detection of Canine Brucellosis

Figures & data

Table 1 Optimization of Antigen Concentration and Serum Dilution for iELISA

Antigen	Maximum P/N Value	OD450 (mean±SD) (Positive Serum)	OD450 (mean±SD) (Negative Serum)	Antigen Coating Concentration (ug/mL)	Serum Dilution
Fusion protein	4.33	0.5689±0.1408	0.1321±0.0700	2.5	1:25
Omp31	17.49	1.7582±0.5520	0.1005±0.0531	0.625	1:50
BP26	4.67	1.7408±0.4470	0.3725±0.1471	1.25	1:50
Omp25	3.22	0.7593±0.1204	0.2360±0.0595	1.25	1:50

Figure 1 Dotplot of iELISAs using the fusion protein, Omp31, BP26 and Omp25 as antigens to detect canine brucellosis-positive and brucellosis-negative sera.

Figure 2 ROC analysis of the fusion protein, Omp31, BP26 and Omp25 in detecting canine brucellosis.

Table 2 Predictive Values for Positive and Negative Calculated at Different Cutoff Values

Cutoff Value	Positive		Negative		PPV (%)	NPV (%)	Accuracy (%)
	TP	FN	TN	FP
>0.4855 (Fusion protein)	33	1	62	0	100.0	98.41	99.0
>0.4130 (Omp31)	33	1	59	3	91.67	98.33	95.8
>0.6565 (BP26)	26	8	61	1	96.30	88.41	90.6
>0.2165 (Omp25)	32	2	47	15	68.09	95.92	82.3

Abbreviations: TP, true positives; TN, true negatives; FP, false positives; FN, false negatives; PPV, positive predictive value (TP/TP+FP)×100; NPV, negative predictive value (TN/TN+FN) ×100; Accuracy, (TP+TN)/(TP+FN+TN+FP)×100.

Table 3 Cross-Reaction of Rabbit Sera with Fusion Protein, Omp31, BP26 and Omp25 by iELISA

Pathogens	Fusion Protein		Omp31		BP26		Omp25
	OD450	S/N	OD450	S/N	OD450	S/N	OD450	S/N
Yersinia enterocolitica O9	0.0464	0.65	0.8049	1.23	0.1243	0.70	0.1718	0.73
Escherichia coli O157	0.0483	0.68	0.7268	1.11	0.1641	0.93	0.2452	1.04
Escherichia coli H7	0.0876	1.23	0.6445	0.99	0.1048	0.59	0.1383	0.59
Salmonella	0.1241	1.75	0.8290	1.27	0.1276	0.72	0.7337	3.11
Listeria monocytogenes	0.0715	1.01	0.6399	0.98	0.4041	2.28	0.5808	2.46
Vibrio parahaemolyticus	0.1269	1.79	1.390	2.12	0.1846	1.04	1.4998	6.36
Vibrio cholerae	0.0591	0.83	1.053	1.61	0.1750	0.99	0.2848	1.21
Negative	0.0710	–	0.6543	–	0.1771	–	0.2357	–