In our previous study, a Brucella suis WboA gene deleted vaccine strain (B. suis △ WboA) was constructed based on the B. suis S2 vaccine strain, but either the immunogenicity or pathogenicity of B. suis △ WboA was lower than its parental bacteria. To enhance the immune effect of B. suis A WboA, the immune program was optimized in sheep. In the present study, one year old female sheep were divided into four groups, including twice vaccination with B. suis △ WboA in 7-days interval at 2 dosage (group A) and 4 dosage (groupB), single vaccination with 1 dosage of B. suis A WboA (group C) and the perantal vaccine strain of S2 (group D), with a unvaccinated control (group D), and all groups were challenged with B. melitensis M28 virulent strain at 35 days post initial immunization. Antibody test results showed that the antibody titers of sheep from group A and group B were obviously higher than group C at 7 days and 21 days, but overall higher than that in group D post second immunization. However, the bacteria isolation from spleens showed that the bacteria load in group C was significant higher than that in other groups. These results demonstrated that sheep were efficiently protected against B. suis infection under the immunization program of twice injection via subcutaneous route in a 7-day interval at 4 dosges of B. suis △ WboA.%为优化猪种布氏杆菌WboA基因缺失株(B,suis△WboA)对绵羊的免疫条件,本研究采用1岁左右的成年雌性绵羊对B.suis△WboA的免疫剂量及免程序进行了比较研究.实验分5个组进行,其中A、B、C3个试验组分别以2倍剂量重复接种、4倍剂量重复接种和单剂量1次接种B.suis△WboA,D组单剂量1次接种猪种布氏杆菌S2疫苗株(B.suis S2),E组为空白对照组.各组羊首免后7d、21 d和35 d分别采血,测定血清抗体水平；在首免后35 d,分别采用布氏杆菌强毒菌M28株(B.melitensis M28),经腹股沟皮下注射攻毒.攻毒后28 d,分别取试验羊的脾脏分离攻毒菌株.所有试验羊,在实施攻毒前,其精神、食欲均正常.血清抗体测定结果表明,在二免7d、21 d后,A组和B组试验羊的抗体水平明显高于C组,而且均超过D组试验羊的抗体水平.攻毒后的细菌分离结果表明,攻毒后28 d,A组和B组试验羊的脾脏细菌分离数量明显低于C组试验羊,并且均低于D组试验羊的细菌分离水平.实验结果表明,B.suis△WboA的免疫剂量由单倍改为2倍或4倍,免疫程序由单剂量1次改为2倍或4倍剂量2次,可以明显提高免疫效果,并达到与亲本疫苗菌株B.suis S2的免疫水平.
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