Ugalde Juan Esteban, Comerci Diego José, Leguizamón M Susana, Ugalde Rodolfo Augusto
Instituto de Investigaciones Biotecnológicas, Universidad Nacional de General San Martín, Consejo Nacional de Investigaciones Científicas, Buenos Aires, Argentina.
Infect Immun. 2003 Nov;71(11):6264-9. doi: 10.1128/IAI.71.11.6264-6269.2003.
Brucella abortus S19 is the vaccine most frequently used against bovine brucellosis. Although it induces good protection levels, it cannot be administered to pregnant cattle, revaccination is not advised due to interference in the discrimination between infected and vaccinated animals during immune-screening procedures, and the vaccine is virulent for humans. Due to these reasons, there is a continuous search for new bovine vaccine candidates that may confer protection levels comparable to those conferred by S19 but without its disadvantages. A previous study characterized the phenotype associated with the phosphoglucomutase (pgm) gene disruption in Brucella abortus S2308, as well as the possible role for the smooth lipopolysaccharide (LPS) in virulence and intracellular multiplication in HeLa cells (J. E. Ugalde, C. Czibener, M. F. Feldman, and R. A. Ugalde, Infect. Immun. 68:5716-5723, 2000). In this report, we analyze the protection, proliferative response, and cytokine production induced in BALB/c mice by a deltapgm deletion strain. We show that this strain synthesizes O antigen with a size of approximately 45 kDa but is rough. This is due to the fact that the deltapgm strain is unable to assemble the O side chain in the complete LPS. Vaccination with the deltapgm strain induced protection levels comparable to those induced by S19 and generated a proliferative splenocyte response and a cytokine profile typical of a Th1 response. On the other hand, we were unable to detect a specific anti-O-antigen antibody response by using the fluorescence polarization assay. In view of these results, the possibility that the deltapgm mutant could be used as a vaccination strain is discussed.
流产布鲁氏菌S19是预防牛布鲁氏菌病最常用的疫苗。尽管它能诱导出良好的保护水平,但不能用于怀孕母牛,由于在免疫筛查过程中会干扰感染动物和接种疫苗动物的区分,因此不建议再次接种,而且该疫苗对人类具有致病性。由于这些原因,人们一直在不断寻找新的牛用候选疫苗,这些疫苗可能具有与S19相当的保护水平,但没有其缺点。先前的一项研究对流产布鲁氏菌S2308中与磷酸葡萄糖变位酶(pgm)基因破坏相关的表型进行了表征,以及光滑脂多糖(LPS)在HeLa细胞毒力和细胞内增殖中的可能作用(J. E. 乌加尔德、C. 齐贝纳、M. F. 费尔德曼和R. A. 乌加尔德,《感染与免疫》68:5716 - 5723,2000)。在本报告中,我们分析了δpgm缺失菌株在BALB/c小鼠中诱导的保护、增殖反应和细胞因子产生情况。我们表明,该菌株合成大小约为45 kDa的O抗原,但为粗糙型。这是因为δpgm菌株无法在完整的LPS中组装O侧链。用δpgm菌株接种诱导的保护水平与S19诱导的相当,并产生了增殖性脾细胞反应和典型的Th1反应细胞因子谱。另一方面,我们使用荧光偏振测定法无法检测到特异性抗O抗原抗体反应。鉴于这些结果,讨论了δpgm突变体用作疫苗接种菌株的可能性。