Submitted to: European Society for Veterinary Virology
Publication Type: Proceedings
Publication Acceptance Date: June 1, 2001
Publication Date: N/A
Technical Abstract: During productive infection, viral antigens, RNAs and progeny viruses all increased in a time dependent manner. Viral antigens and cell-free progeny viruses began to appear at 18 h and 30 h p.i., respectively. Viral transcripts were detected by 18 h p.i. and the capsid protein RNA of 950 nt was the most abundant RNA species. Two other RNAs of sizes 750 and 450 nt, derived from the Rep gene region, were also detected. These two RNAs share 3' common nucleotide sequences and they are transcribed in the same orientation as the proposed unspliced Rep RNA or the recently described Rep' RNA. The 35 kD capsid protein was observed at 30 h p.i. by Western blo analysis and it appeared to be the most immunodominant protein in swine exposed to PCV2. The capsid protein of PCV1 and PCV2 each contains a nuclea localization signal sequence capable of targeting a reporter protein to the nucleoli of transfected cells when the capsid proteins were expressed as 3' fusion polypeptides. Previous reports indicated that PCV2 capsid protei localized predominantly in the nuclei of infected cell. In this work, we observed an abundant amount of PCV2 capsid proteins in the cytoplasm of man cells of the infected cultures. The presence of virus nucleic acids in cell containing cytoplasmic capsid proteins suggested that these proteins were synthesized inside the infected cells. Elucidation of the changes that affected the localization pattern of PCV2 capsid proteins, nuclear verses cytoplasmic, requires further investigation.