Pullen J K, Anderson G W, Welkos S L, Friedlander A M
Bacteriology Division, U.S. Army Research Institute of Infectious Diseases, Fort Detrick, Frederick, Maryland 21702-5011, USA.
Infect Immun. 1998 Feb;66(2):521-7. doi: 10.1128/IAI.66.2.521-527.1998.
The V protein expressed by pathogenic Yersinia pestis is an important virulence factor and protective immunogen. The presence of linear B-cell epitopes in the V protein was investigated by using a series of 17 overlapping linear peptides. Groups of 10 mice were immunized intraperitoneally with 30 microg of each peptide on days 0, 30, and 60. Although the V protein-specific antibody response to the peptides varied, most of the peptides elicited high antibody titers. The immunized mice were challenged subcutaneously with 60 50% lethal doses (LD50) (1 LD50 = 1.9 CFU) of a virulent Y. pestis strain, CO92. None of the peptide-immunized mice survived challenge. The animals immunized with the V protein were completely protected against challenge. The immunogenicity of some of the V peptides was increased by conjugating them to keyhole limpet hemocyanin. Only one peptide (encompassing amino acids 1 to 30) conjugate demonstrated some protection; the others were not protective. In additional experiments, V peptides that reacted well with sera from mice surviving Y. pestis infection were combined and used to immunize mice. Although the combined peptides appeared to be very immunogenic, they were not protective. Therefore, the protective B-lymphocyte epitope(s) in the V protein is most likely to be conformational.
致病性鼠疫耶尔森菌表达的V蛋白是一种重要的毒力因子和保护性免疫原。利用一系列17种重叠线性肽研究了V蛋白中线性B细胞表位的存在情况。在第0、30和60天，每组10只小鼠腹腔注射30微克每种肽。虽然对这些肽的V蛋白特异性抗体反应各不相同，但大多数肽都能诱导出高抗体滴度。用60个50%致死剂量（LD50）（1个LD50 = 1.9 CFU）的强毒鼠疫耶尔森菌菌株CO92对免疫小鼠进行皮下攻击。肽免疫的小鼠在攻击后均未存活。用V蛋白免疫的动物对攻击具有完全保护作用。将一些V肽与钥孔戚血蓝蛋白偶联后，其免疫原性增强。只有一种肽（包含氨基酸1至30）偶联物表现出一定的保护作用；其他偶联物则没有保护作用。在另外的实验中，将与鼠疫耶尔森菌感染存活小鼠血清反应良好的V肽组合起来用于免疫小鼠。虽然组合肽似乎具有很强的免疫原性，但它们没有保护作用。因此，V蛋白中的保护性B淋巴细胞表位很可能是构象性的。
