Chimeric infectious DNA clones, chimeric porcine circoviruses and uses thereof
View Patent ↗The present invention relates to infectious DNA clones, infectious chimeric DNA clones of porcine circovirus (PCV), vaccines and means of protecting pigs against viral infection or postweaning multisystemic wasting syndrome (PMWS) caused by PCV2. The new chimeric infectious DNA clone and its derived, avirulent chimeric virus are constructed from the nonpathogenic PCV1 in which the immunogenic ORF gene of the pathogenic PCV2 replaces a gene of the nonpathogenic PCV1, preferably in the same position. The chimeric virus advantageously retains the nonpathogenic phenotype of PCV1 but elicits specific immune responses against the pathogenic PCV2. The invention further embraces the immunogenic polypeptide expression products.
1. A process for the production of an immunogenic polypeptide product, said process comprising: growing, under suitable nutrient conditions, prokaryotic or eucaryotic host cells transfected with a chimeric nucleic acid molecule of porcine circovirus (PCV1-2) in a manner allowing expression of said polypeptide product, and isolating the desired polypeptide product of the expression of said chimeric nucleic acid molecule, wherein the chimeric nucleic acid molecule comprises a nucleic acid molecule encoding an infectious, nonpathogenic PCV1 which contains the ORF2 capsid gene of a pathogenic PCV2 in place of the ORF2 capsid gene of the PCV1 nucleic acid molecule.
2. The process according to claim 1 , wherein the chimeric nucleic acid molecule comprises the nucleotide sequence set forth in SEQ ID NO:2 or its complementary strand.