Division of Swine Infectious Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, China.
Virol J. 2011 Aug 19;8:410. doi: 10.1186/1743-422X-8-410.
Nowadays, PRRS has become one of the most economically important infectious diseases of pig worldwide. To better characterize and understand the molecular basis of PRRSV virulence determinants, it would be important to develop the infectious cDNA clones. In this regard, HuN4-F112, a live-attenuated North-American-type PRRSV vaccine strain, could serve as an excellent model.
In the study, genomic sequence of HuN4-F112, an attenuated vaccine virus derived from the highly pathogenic porcine reproductive and respiratory syndrome virus (PRRSV) HuN4 strain, was determined and its full-length cDNA was cloned. Capped RNA was transcribed in vitro from the cDNA clone and transfected into BHK-21 cells. The supernatant from transfected monolayers were serially passaged in Marc-145 cells. The rescued virus exhibited a similar growth pattern to its parental virus in Marc-145 cells with peak titers at 48 h post-infection.
In conclusion, we rescued virus from an infectious cDNA clone of attenuated vaccine. It is possible in the future that a new attenuated PRRSV vaccine with broader specificity and good immunogenicity can be designed in vitro via an infectious cDNA clone platform coupled with validated information on virulence determinants.
如今，PRRS 已成为全球范围内对猪最具经济重要性的传染病之一。为了更好地描述和理解 PRRSV 毒力决定因素的分子基础，开发感染性 cDNA 克隆将非常重要。在这方面，HuN4-F112，一种源自高致病性猪繁殖与呼吸综合征病毒（PRRSV）HuN4 株的减毒活疫苗株，可以作为一个很好的模型。
在本研究中，测定了源自高度致病性猪繁殖与呼吸综合征病毒（PRRSV）HuN4 株的减毒活疫苗病毒 HuN4-F112 的基因组序列，并克隆了其全长 cDNA。从 cDNA 克隆体外转录加帽 RNA，并转染 BHK-21 细胞。转染单层细胞的上清液在 Marc-145 细胞中连续传代。拯救病毒在 Marc-145 细胞中的生长模式与其亲本病毒相似，感染后 48 小时达到峰值滴度。
总之，我们从减毒疫苗的感染性 cDNA 克隆中拯救了病毒。未来，通过感染性 cDNA 克隆平台结合对毒力决定因素的验证信息，有可能在体外设计出具有更广泛特异性和良好免疫原性的新型减毒 PRRSV 疫苗。
