A Brucella melitensis H38ΔwbkF rough mutant protects against Brucella ovis in rams

Table 3 Protective efficacy of vaccine candidates against a B. ovis PA experimental challenge in rams.

Vaccine (CFU dose)	No. infected animals/total (%)^a	No. infected organs/total (%)^b	No. severely infected animals (%)^a,c/no. severely infected organs (%)^b
Bov::CAΔwadB (1 × 10¹⁰)	11/14 (78.6)	41/112 (36.6)	4 (28.6)^d/11 (9.8)^d
Rev1::wbdRΔwbkC (2.5 × 10¹⁰)	7/14 (50.0)	30/112 (26.8)^d	5 (35.7)/13 (11.6)^d
H38ΔwbkF (2.5 × 10¹⁰)	2/14 (16.7)^e,f	6/112 (5.4)^e,f	1 (7.1)^e,f/2 (1.8)^e,f
Rev 1 (2 × 10⁹)	3/14 (21.4)^d	12/112 (10.7)^e	1 (7.1)^e/1 (0.9)^e
Unvaccinated	11/13 (84.6)	64/104 (61.5)	9 (69.2)/30 (28.8)

^aStatistical comparisons by Chi-square test (with Fisher-Yates correction when required). ^bStatistical comparisons by STEPBOOT MULTTEST (SAS); ^cseverely infected animals were those showing at least one organ sample with an infection level ≥ 3 (≥ 26 CFU/plate). ^dSignificant difference (P < 0.05) versus unvaccinated control; ^eHigh significant difference (P < 0.001) vs. unvaccinated control; ^fno significant (P > 0.05) versus Rev 1 vaccinated group.

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