title: Generation of an infectious clone of HuN4-F112, an attenuated live vaccine strain of porcine reproductive and respiratory syndrome virus.
abstract: BACKGROUND
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Swine Infectious Diseases, Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, China.
authors.forename: Shanrui
authors.initials: S
authors.lastname: Zhang
authors.forename: Yanjun
authors.initials: Y
authors.lastname: Zhou
authors.forename: Yifeng
authors.initials: Y
authors.lastname: Jiang
authors.forename: Guoxin
authors.initials: G
authors.lastname: Li
authors.forename: Liping
authors.initials: L
authors.lastname: Yan
authors.forename: Hai
authors.initials: H
authors.lastname: Yu
authors.forename: Guangzhi
authors.initials: G
authors.lastname: Tong
mesh_terms: D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D019318:Porcine Reproductive and Respiratory Syndrome / Q000517:prevention & control*; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics*; D012367:RNA, Viral / Q000235:genetics; D017422:Sequence Analysis, DNA; D012692:Serial Passage; D013552:Swine; D014162:Transfection; D014613:Vaccines, Attenuated / Q000235:genetics; D014765:Viral Vaccines / Q000235:genetics*
chemical_list: D018076:DNA, Complementary; D012367:RNA, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines