Table 1.

Efficacies of Brucella abortus strain RB51 vaccination strategies in protecting against experimental challenge at midgestation with 10⁷ CFU of B. abortus strain 2308

Vaccination strategy	Rate (%) of abortion or infection (no. aborted or infected/total)a
	Abortion	Infection
		Uterineb	Mammaryc	Fetald	Remaining maternal tissuese
Hand RB51f	67 (2/6)	66 (4/6)	83 (5/6)	100 (6/6)	83 (5/6)
Dart RB51g	57 (4/7)	57 (4/7)	100 (7/7)	100 (7/7)	94 (6/7)
Booster RB51h	0 (0/5)*	40 (2/5)*	80 (4/5)	100 (5/5)	40 (2/5)*
Control	83 (5/6)	100 (6/6)	100 (6/6)	100 (6/6)	100 (6/6)

^a*, mean significantly different (P < 0.05) from that for the control treatment group.

^bPlacentome, vaginal swab, and/or internal iliac lymph node.

^cMammary tissues (4 quarters), milk, and/or supramammary lymph node.

^dFetal lung, liver, spleen, gastric contents, bronchial lymph node, or rectal swab.

^eAny maternal tissue except mammary gland, placentome, milk, supramammary lymph node, or internal iliac lymph node.

^fThe vaccination dose was 1.1 × 10¹⁰ CFU.

^gThe vaccination dose was 2.2 × 10¹⁰ CFU.

^hThe initial vaccination dose was 1.1 × 10¹⁰ CFU, and the booster vaccination dose was 2.2 × 10¹⁰ CFU.