A genetically engineered chimeric vaccine against porcine circovirus type 2 (PCV2) is genetically stable in vitro and in vivo

• Published in: Vaccine 2008-08, Vol.26 (33), p.4231-4236
• Main Authors: Gillespie, J, Juhan, N.M, DiCristina, J, Key, K.F, Ramamoorthy, S, Meng, X.J
• Format: Article
• Language: English
• Subjects: Allergy and Immunology; Amino Acid Substitution - genetics; Animals; Applied microbiology; Biological and medical sciences; Capsid Proteins - genetics; Cell Line; Circovirus - genetics; Feces - virology; Fundamental and applied biological sciences. Psychology; Genetic stability; Lung - virology; Lymph Nodes - virology; Microbiology; Miscellaneous; Mutation; Palatine Tonsil - virology; Porcine circovirus; Porcine circovirus type 2 (PCV2); Porcine circovirus-associated disease (PCVAD); Selection, Genetic; Serial Passage; Swine; Vaccine; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies (general aspects); Vaccines, Attenuated - genetics; Viral Vaccines - genetics; Virology; Virulence
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2008.05.051

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.