猪链球菌保守的转录因子PrlP通过N端的XRE结构域调控致病力，但其调控致病性的分子机制并不清楚。本研究拟（1）应用CHIP-Seq技术，并结合细菌单杂交技术和EMSA技术鉴定PrlP的XRE结构域结合的靶序列。（2）随后，基于鉴定的靶序列，对照猪链球菌的基因组序列，筛选候选靶基因；并对prlp基因缺失菌株的表达谱进行分析，鉴定PrlP直接调控的靶基因。通过敲除靶基因分析菌株致病性等表型，确定其调控毒力的关键靶基因。再应用RNA-Seq分析靶基因缺失菌株的表达谱，解析其间接调控毒力的靶基因。（3）最后，在prlp基因缺失菌株的基础上回补表达PrlP调控的关键靶基因，通过动物感染试验分析其表型，解析PrlP是通过调控哪个（些）基因来实现毒力调控的分子机制，并绘制PrlP调控致病力的调控网络（或通路）。这不仅有助于深入理解猪链球菌致病的分子机理，而且也将为PrlP发展为新药靶标提供重要依据。

The virulence of Streptococcus suis (S. suis) could be regulated by XRE family regulator PrlP, which is mediated by its N’- XRE domain. However, the mechanism for virulence regulation remains to be elucidated. The present project would firstly identify the binding sequence of PrlP XRE domain through CHIP-Seq thenology, which would be further confirmed by bacterial one-hybrid reporter system and EMSA technology. In addition, the project would identify the PrlP-directly regulated genes by screening the genome sequences with the identified binding sequence and by the analysis of the expression profile of the isogenic prlp mutant; and then the PrlP-directly regulated genes invovled in the virulence of S. suis were also identified based on the analysis of the virulence of the constructed traget genes mutants. Furthermore, the project would further identify PrlP-indirectly regulated genes based on the RNA-Seq analysis of the expression profile of the PrlP-directly regulated gene mutants. At last, the project would further evaluate the virulence of the complemented PrlP-directly or -indirectly regulated genes in isogenic prlp mutant, and confirm the PrlP-directly or -indirectly regulated genes through which, PrlP contributes to the virulence. Therefore, the present project would construct the regulatory signaling or regulatory network for PrlP to the viulence of S. suis, which would contribute to the understanding of pathogenesis of S. suis, and also contribute to the development of drug target against S. suis diseases.