title: A genetically engineered chimeric vaccine against porcine circovirus type 2 (PCV2) is genetically stable in vitro and in vivo.
abstract: A vaccine against porcine circovirus type 2 (PCV2), designated PCV1-2 chimera, was recently developed by replacing the capsid gene of the non-pathogenic PCV1 with that of PCV2. The PCV1-2 chimera virus is attenuated in pigs but induces protective immunity against PCV2. In this study, the genetic stability of the PCV1-2 chimera was evaluated for its potential use as a live vaccine. The PCV1-2 chimera virus was serially passaged 11 times in PK-15 cells and 3 times in pigs. The PCV1-2 chimera virus used in this study contained a tracking marker mutation in the capsid gene (F to V at amino acid position 79). Sequence analyses of the PCV1-2 chimera virus after 11 serial passages in PK-15 cells did not reveal any sequence change including the marker mutation. Similarly, there is no change in the genomic sequence of the PCV1-2 chimera virus recovered from pigs during 3 serial in vivo passages. Under in vivo selection pressure, however, the introduced tracking marker mutation in the PCV1-2 chimera quickly mutated (V79F) and restored to its original sequence after one passage in pigs, and remained stable in subsequent 2 passages in pigs. The results indicate that the PCV1-2 chimera virus is genetically stable, and thus should be a good vaccine candidate.
authors.affiliation: Center for Molecular Medicine and Infectious Diseases, Department of Biomedical Sciences and Pathobiology, Virginia-Maryland Regional College of Veterinary Medicine, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0342, USA.
authors.forename: J
authors.initials: J
authors.lastname: Gillespie
authors.forename: N M
authors.initials: NM
authors.lastname: Juhan
authors.forename: J
authors.initials: J
authors.lastname: DiCristina
authors.forename: K F
authors.initials: KF
authors.lastname: Key
authors.forename: S
authors.initials: S
authors.lastname: Ramamoorthy
authors.forename: X J
authors.initials: XJ
authors.lastname: Meng
mesh_terms: D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D036022:Capsid Proteins / Q000235:genetics; D002460:Cell Line; D017925:Circovirus / Q000235:genetics*; D005243:Feces / Q000821:virology; D008168:Lung / Q000821:virology; D008198:Lymph Nodes / Q000821:virology; D009154:Mutation; D014066:Palatine Tonsil / Q000821:virology; D012641:Selection, Genetic; D012692:Serial Passage; D013552:Swine; D014613:Vaccines, Attenuated / Q000235:genetics; D014765:Viral Vaccines / Q000235:genetics*; D014774:Virulence
chemical_list: D036022:Capsid Proteins; D014613:Vaccines, Attenuated; D014765:Viral Vaccines