Chaudhari Atul A, Kim Sam Woong, Matsuda Kiku, Lee John Hwa
College of Veterinary Medicine and Bio-Safety Research Institute, Chonbuk National University, Jeonju, 561-756, Republic of Korea.
Avian Dis. 2011 Jun;55(2):165-71. doi: 10.1637/9512-083010-Reg.1.
In seeking to develop a safe fowl typhoid (FT) vaccine, a novel candidate lacking cpxR, lon, and asd Salmonella Gallinarum (SG) genes was constructed with the plasmid-containing araC::P(araBAD)::asd system. A balanced-lethal host-vector system based on the essential bacterial gene for aspartate beta-semialdehyde dehydrogenase (asd) was used to construct the SG mutant strain. A plasmid (p15A ori) with an araC::P(araBAD)::asd cassette was introduced into an auxotrophic mutant to prevent ex vivo survival. The safety, immunity, and protective properties of the SG mutant were evaluated. Inoculation of the mutant at 10(6) colony-forming units (CFU) did not result in recovery in feces and internal organs, whereas inoculation at 10(8) and 10(10) CFU resulted in moderate bacterial recovery from feces and organs. Birds immunized with the mutant were challenged with a virulent SG strain at day 14 postimmunization; significantly reduced mortality and induced plasma immunoglobulin (Ig)G and mucosal IgA responses were noted. Cellular immune responses as evaluated by a peripheral lymphocyte proliferation assay were also significantly induced. The balanced-lethal host-vector system for construction of SG mutants is an effective and improved approach for safe vaccine construction against FT.
为了研发一种安全的禽伤寒（FT）疫苗，利用含质粒的araC::P(araBAD)::asd系统构建了一种缺失cpxR、lon和asd基因的新型鸡沙门氏菌（SG）候选疫苗。基于天冬氨酸β-半醛脱氢酶（asd）这一必需细菌基因构建了一个平衡致死宿主-载体系统，用于构建SG突变株。将带有araC::P(araBAD)::asd盒的质粒（p15A ori）导入营养缺陷型突变体，以防止其在体外存活。对SG突变体的安全性、免疫性和保护特性进行了评估。以10⁶集落形成单位（CFU）接种突变体后，粪便和内脏器官中未检测到细菌恢复，而以10⁸和10¹⁰CFU接种则导致粪便和器官中有中度细菌恢复。在免疫后第14天，用强毒株SG对免疫突变体的鸡进行攻毒；结果显示死亡率显著降低，并诱导产生了血浆免疫球蛋白（Ig）G和黏膜IgA反应。通过外周淋巴细胞增殖试验评估的细胞免疫反应也得到了显著诱导。构建SG突变体的平衡致死宿主-载体系统是一种有效且改良的抗FT安全疫苗构建方法。
