猪瘟兔化弱毒疫苗株适应家兔的关键基因定位

Classical swine fever (CSF), formerly called hog cholera, is a devastating disease of swine caused by classical swine fever virus (CSFV). The disease is controlled by vaccination with vaccines based on hog cholera lapinized virus (HCLV) strain (also known as C-strain), a very safe and efficacious vaccine against CSF. HCLV was derived from a highly virulent wild-type CSFV by passage for over 480 times in rabbits in China. However, the molecular basis of its adaptation to the rabbit remains unclear. Our previous study has demonstrated that the entire coding region of the viral genome of HCLV is required for its replication in the rabbit spleen. In this proposal, we will first generate two chimeric viruses, in which the regions coding for structural or nonstructural proteins of HCLV are replaced with the counterparts of the highly virulent CSFV Shimen (SM) strain, and evaluate the chimeras in rabbits with regards to fever response and viral replication in the spleen. Next, we will generate a series of chimeric viruses, in which individual protein genes of HCLV are replaced with the counterparts of the SM strain, and evaluate the phenotype of the chimeras in rabbits to pinpoint the exact gene(s) or region(s) of HCLV responsible for its adaptation to the rabbit. Finally, several chimeras containing the exact gene(s) or region(s) of HCLV based on the SM strain backbone will be constructed to verify the identified gene(s) or region(s). This project will precisely map the genetic determinants of the HCLV adaptation to the rabbit, and provide scientific data for elucidating the molecular mechanisms of the HCLV adaptation to the rabbit.

猪瘟兔化弱毒疫苗株（HCLV株）是我国学者将猪瘟病毒强毒株在兔体内连续传480余代后培育而成的一株非常安全和有效的疫苗。然而目前对其适应家兔的分子基础尚不清楚。我们前期的研究表明，HCLV株的编码区对于其在家兔脾脏中的复制是必需的。本项目拟以HCLV株为骨架，分别构建包含猪瘟病毒强毒石门株（SM株）结构蛋白和非结构蛋白编码区的嵌合病毒，比较嵌合病毒与HCLV株在家兔上的定型热反应和脾脏复制水平，以明确HCLV株适应家兔的关键编码区域；然后，构建一系列基于HCLV株基因组、包含SM株各蛋白基因的嵌合病毒，检测各嵌合病毒在家兔上的表型和复制特征，从而确定HCLV株适应家兔的关键基因；最后，构建以SM株为骨架、包含HCLV株关键基因或区域的嵌合病毒，验证HCLV适应家兔的重要基因或区域。本项目可望精确定位这株优异疫苗株适应家兔的关键基因（区域），为进一步阐明HCLV株适应家兔的分子机制奠定基础。

猪瘟兔化弱毒疫苗株（HCLV株）是我国学者将猪瘟病毒强毒株在兔体内连续传480余代后培育而成的一株非常安全和有效的疫苗。然而目前对其适应家兔的分子基础尚不清楚。我们前期的研究表明，HCLV株的编码区对于其在家兔脾脏中的复制是必需的。本项目分别构建了猪瘟病毒强毒石门株（SM株）和HCLV株结构蛋白或非结构蛋白编码区互换的嵌合病毒，比较嵌合病毒与HCLV株在家兔上的定型热反应和脾脏复制水平，确定结构蛋白Erns-E1-E2是HCLV株在适应家兔体的关键编码区域，而非结构蛋白编码区NS3-NS4B-NS5A-NS5B也影响病毒引起家兔定型热反应的能力；随后，构建一系列以SM株为骨架、包含HCLV株各蛋白基因及其不同组合的嵌合病毒，检测各嵌合病毒在家兔上的表型和复制特征，确定E2与Erns或E1共同决定HCLV株在家兔体上的适应性，而单个非结构蛋白不足以使HCLV株引起家兔的定型热反应。本项目精确定位了这株优异疫苗株适应家兔的关键基因，为进一步阐明HCLV株适应家兔的分子机制奠定了基础。

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