Phylogenetic analysis of porcine circovirus type 2 (PCV2) pre- and post-epizootic postweaning multisystemic wasting syndrome (PMWS)

Abstract

The porcine circovirus type 2 (PCV2) genome encodes three major open reading frames (ORFs) encoding the replicase proteins (ORF1), the viral capsid protein (ORF2), and a protein with suggested apoptotic activity (ORF3). Previous phylogenetic analyses of complete genome sequences of PCV2 from GenBank have demonstrated 95-100% intra-group nucleotide sequence identity. However, although these isolates were readily grouped into clusters and clades, there was no correlation between the occurrence of specific PCV2 genotypes and the geographic origin or health status of the pig. In the present study, a unique dataset from a field study spanning the years pre and post the recognition of postweaning multisystemic wasting syndrome (PMWS) in Sweden was utilized. Using this dataset it was possible to discriminate three Swedish genogroups (SG1-3) of PCV2, of which SG1 was recovered from a pig on a healthy farm ten years before the first diagnosis of PMWS in Sweden. The SG1 PCV2/ORF2 gene sequence has been demonstrated to exhibit a high genetic stability over time and has subsequently only been demonstrated in samples from pigs on nondiseased farms. In contrast, SG2 was almost exclusively found on farms that had only recently broken down with PMWS whereas the SG3 genogroup predominated in pigs from PMWS-affected farms. These results further support the results obtained from earlier in vitro and in vivo experimental models and suggest the association of specific PCV2 genogroups with diseased and nondiseased pigs in the field.

Genotypic Change and Phylogenetic Analysis of Porcine Circovirus Type 2 in Taiwanese Pig Herds

“…The PCV2c genotype has only been found in Denmark to date [31]. In recent years, several reports have suggested that PCV2b is the predominant genotype in many countries worldwide, including Brazil [8,11], Canada [14,15], China [17,21,38], Cuba [29], Denmark [12], Germany [30], Japan [32], Korea [1,2,19,20], Slovakia [37], Spain [10], Sweden [33], Switzerland [39], Thailand [18] and the U.S.A. [6,23]. PCV2b might be more pathogenic than PCV2a [16,32].…”

Regulator of G protein signalling 16 is a target for a porcine circovirus type 2 protein

“…The interaction between poRGS16 and ORF3 varied for ORF3 proteins from the three different genogroups of PCV2 (Segalés et al, 2008;Timmusk et al, 2008) and was barely detectable for either the corresponding region of ORF3 from PCV1 (315 bp) or the full-length PCV1 ORF3 (612 bp). Interestingly, PCV1 is regarded as non-pathogenic, whereas several studies suggest that genogroups of PCV2 can differ in their contribution to the development of PMWS (Carman et al, 2008; Gagnon et al, 2007;Timmusk et al, 2008).…”

“…Interestingly, PCV1 is regarded as non-pathogenic, whereas several studies suggest that genogroups of PCV2 can differ in their contribution to the development of PMWS (Carman et al, 2008;Gagnon et al, 2007;Timmusk et al, 2008). It was recently shown that mutations within the genome of PCV2 were silent in the ORF coding for the replicase but induced amino acid substitutions in the ORF3 in the opposite transcription orientation (Timmusk et al, 2008). Thus, PCV2 could theoretically retain the unmodified Rep and Rep9 proteins despite alterations in the ORF3 protein.…”

“…Accordingly, six variable positions in the ORF3 region have been identified by Timmusk et al (2008), comparing PCV2 from different Swedish genogroups corresponding to PCV2a and PCV2b in Segalés classification (Segalés et al, 2008). To examine the possibility that ORF3 from different genogroups of PCV2 possess variable binding properties to RGS16, GST pull-down assays were performed using GST-ORF3 from PCV2a (SG1: EU386606), PCV2-St (SG2: AF055392) and PCV2b (SG3: EU408780).…”

“…A survey of the RGS16 genomic location in cow, dog, mouse and human sequences revealed that this gene is systematically encoded in the neighbourhood of RNaseL, an important element of the IFN-induced 29,59-oligoadenylate synthetase pathway. Thus, the viral infections that activate production of type I IFNs might thereby also indirectly activate transcription of a region of the genome harbouring RGS16.The interaction between poRGS16 and ORF3 varied for ORF3 proteins from the three different genogroups of PCV2 (Segalés et al, 2008;Timmusk et al, 2008) and was barely detectable for either the corresponding region of ORF3 from PCV1 (315 bp) or the full-length PCV1 ORF3 (612 bp). Interestingly, PCV1 is regarded as non-pathogenic, whereas several studies suggest that genogroups of PCV2 can differ in their contribution to the development of PMWS (Carman et al, 2008; Gagnon et al, 2007;Timmusk et al, 2008).…”