ATTENUATION OF THE NYCBH VACCINE STRAIN OF VACCINIA

第一阶段的研究确定了使用分子 从减毒稳定的NYCBH疫苗株衍生的方法 免疫效力没有改变的突变体。在此阶段II建议书中选择 在强毒NYCBH-IH分离株中产生的突变株将被研究 测定其毒力参数和免疫保护能力。一个 正常和免疫低下人群毒力参数的穷尽研究 小鼠将包括，颅内和鼻腔LD50，生长和 接种现场的传播情况，以及麻点的程度 在结痂的皮肤上形成。突变体的免疫保护能力 将根据他们提供保护免受外国入侵的能力进行评估 通过表达单一的中和抗原而引起的病原体。 上述研究是为了方便实验而在 一株高毒力的NYCBH实验室分离物。这一信息将是 用于在提纯的低毒菌斑中产生特定突变 从为NIH生产的惠氏疫苗种子库(NYCBH-W)中分离出 在良好的制造规范下。NYCBH-W突变体将被评估 用于毒力参数，以及提供对 通过表达单一中和抗原的外来病原体。这 数据将用于设计第一代候选疫苗(S) 含有单一突变的。随后，突变的组合将 用于确定第二代候选疫苗(S)。

The Phase I studies established the feasibility of using molecular approaches to derive from the NYCBH vaccine strain, stable attenuated mutants of unaltered immune efficacy. In this Phase II proposal selected mutants generated in the virulent NYCBH-IH isolate will be studied to determine their virulence parameters and immune protective capacity. An exhaustive study of virulence parameters in normal and immunocompromised mice will include, intracranial and intranasal LD50s, growth and dissemination from the site of inoculation, and the extent of pock formation on scarified skin. The immune protective capacity of mutants will be assessed by their ability to confer protection against a foreign pathogen by the expression of a single neutralizing antigen. The studies described above were performed for experimental convenience in a high virulence laboratory isolate of NYCBH. This information will be used to create specific mutations in a low virulence plaque purified isolate form the Wyeth vaccine seed stock (NYCBH-W) produced for the NIH under good manufacturing practice. The NYCBH-W mutants will be assessed for virulence parameters, and ability to confer protection against a foreign pathogen by the expression of a single neutralizing antigen. This data will be used to design first generation vaccine candidate(s) containing single mutations. Subsequently, combinations of mutations will be used to conform second generation vaccine candidate(s).