Submitted to: Archives of Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/5/2011
Publication Date: 7/22/2011
Citation: Cheung, A.K., Long, J.X., Huang, L., Yuan, S.S. 2011. The RNA profile of porcine parvovirus 4, a boca-like virus, is unique among the parvoviruses. Archives of Virology. 56(11):2071-2078. Interpretive Summary: Porcine circovirus type 2 (PCV2) is an important viral pathogen of swine and it is the main culprit of several swine health problems collectively known as PCV-associated diseases (PCVAD). PCV2-afflicted animals when co-infected with other pathogens usually exhibit a more severe form of the disease. Previously, we identified a novel porcine parvovirus, designated PPV4, among the sick animals of the 2005 USA PCVAD outbreak. Our analysis revealed that PPV4 belongs to the Bocavirus genus of the Parvovirinae subfamily and exhibits several distinct characteristics. Since then, PPV4 have been detected among the diseased swine in China. At present, the biology and pathogenic nature of PPV4 are unknown. In this work, we examined the transcriptional profile of PPV4. The information obtained advances our understanding the molecular biology of PPV4 and aids the research of scientists in industry, universities and government agencies.
Technical Abstract: Phylogenetically, porcine parvovirus 4 (PPV4) is most related to bovine parvovirus 2 that has two open reading frames (ORFs), but its genome organization resembles that of members of the Bocavirus genus that has three ORFs. Although PPV4 transcribes its genome from a single promoter and the transcripts are generated via alternate splicing coupled with alternate polyadenylation, a strategy similar to that of the Bocaviruses, several differences were observed. Whereas the 2.5-2.6 kilobase (kb) RNAs for the Bocaviruses are assigned to encode the capsid proteins, the major PPV4 2.6 kb RNA (RNA-4) is a transitory RNA of non-linear electrophoretic mobility since it hybridized with multiple probes derived from different parts of the 5.9 kb viral genome. ORF1of PPV4 codes for four different NS proteins (or replicases), while ORF1 of the Bocaviruses codes for 1-3 NS proteins. Whereas the ORF2-encoded capsid proteins (VP1 and VP2) of Bocavirus are cleavage products of the same polypeptide encoded by a single RNA, VP1 and VP2 of PPV4 are two individual polypeptides each encoded by a separate RNA. Furthermore, the phospholipase-2 amino acid motif present in the VP1 protein of the Bocavirus is not observed in the capsid proteins of PPV4. While ORF3 of PPV4, potentially, encodes two NP proteins, ORF3 of the Bocaviruses codes for only one NP polypeptide. Taken together, PPV4 is unique among the Parvovirinae subfamily of viruses.