Porcine Circovirus Type 2 Isolates Research Articles

Phylogenetic and Structural Analysis of Porcine Circovirus Type 2 from 2016 to 2021 in Jilin Province, China.

Porcine circovirus disease (PCVD) caused by porcine circovirus type 2 (PCV2) is widely distributed in pig farms. Up until now, nine genotypes of PCV2, PCV2a to 2i, have been identified in diseased pigs worldwide. This study analyzed 302 samples collected in the Jilin Province of China from 2016 to 2021, followed by genetic analysis of the PCV2 isolates. Meanwhile, the antigen epitopes, amino acid mutations, 3D structure of the PCV2 isolates and commercially available vaccine strains were evaluated and compared. The results showed that the predominant genotypes of PCV2 were PCV2b, followed by PCV2e and PCV2d in Jilin Province during 2016-2021. Although mutations were detected in the isolates, no recombination occurred in the PCV2 isolates, indicating a stable genotype of PCV2 in Jilin Province during these years. Moreover, the B cell epitopes in the Cap and Rep proteins of eighteen PCV2 isolates and T cell epitopes in the Cap of the isolates were changed compared to three currently used vaccine strains. The mutations in the Cap and Rep proteins did not affect their spatial conformation. Therefore, bivalent or multivalent vaccines with different genotypes of PCV2 might improve the protective effect of vaccines.

Evaluation of the protective efficacy of virus-like particles based on PCV 2b and 2d subtypes against mixed challenge in mice.

Porcine circovirus type 2 (PCV2) is an economically important swine pathogen and, although small, it has the highest evolution rate among DNA viruses. Commercial PCV2 commercial vaccines are inactivated PCV2 isolates or a subunit vaccine based on the Cap protein of PCV2. Currently, PCV2 VLPs of individual subtype vaccines are available. Although the main prevalent genotype worldwide is PCV2b, the emerging subtype PCV2d subtype is also increasingly associated with PCV disease. The aim of the study was to evaluate the protective efficacy of VLP based on the PCV2b and 2d subtypes against the mixed challenge of two hypotype PCV2 in mice. Thirty-six female SPV Kunming mice were immunized twice with PCV2b and 2d VLPs, then challenged with PCV2b and PCV2d, to assess the immunogenicity and effectiveness of the VLPs. Vaccination of the mice with PCV2b and 2d VLPs elicited a robust antibody response specific for the PCV2. The virus load detected in the 2b and 2d spleen vaccine group was the lowest compared to other groups. Furthermore, there was no pathological damage in the HE stained sections of the 2b and 2d spleen vaccine, and no virus was detected in the immunohistochemical sections. Our data suggest that the mixed PCV2b and 2d VLP vaccine could protect mice from challenge with the mixed infection of PCV2b and PCV2d..

Whole-Genome Sequence of a Porcine Circovirus Type 2 Strain Detected in Assam, India.

ABSTRACTPorcine circovirus-associated disease caused by porcine circovirus type 2 (PCV2) is a vital threat to the global pig industry. In this study, we have characterized the complete genome sequence of a PCV2 isolate, namely, Assam-01, belonging to the genotype PCV2d.

Genetic diversity of Indian porcine circovirus type 2 (PCV2) isolates (2006-2018)

Porcine circovirus type 2 (PCV2) is an emerging viral infection in swine population and results in severe economic loss to piggeries worldwide. The present study was conducted to explore the genetic diversity of PCV2 circulating in swine population of India from 2006–2018. A total of 74 heart, lungs, spleen and lymph nodes collected from different regions in Uttar Pradesh, India were subjected to molecular analysis. For studying genetic diversity, the complete nucleotide and ORF2 sequences of 95 PCV2 including 43 nucleotide sequences from India were used. DNA was extracted from samples and positive samples were subjected to full genome sequencing and phylogenetic analysis was done by maximum likelihood method. Phylogenetic analysis of 40 Indian PCV2 genomes downloaded from GenBank along with three new isolates from the current study based on the complete genome and cap gene together with nucleotide sequences of PCV2 isolates from different countries results in a tree in which Indian isolates clustered in 4 different branches includes PCV2b-1C, PCV2a-2D, PCV 2b-1A/B, PCV 2d-2 recombinant group and two new cluster in which one clustered along with unclassified PCV2 viruses from Indonesia and Croatia. The comparison of ORF2 gene among Indian isolates revealed nucleotide identity ranging from 88.6% to 99.6%, indicating the genetic diversity of PCV2 strains circulating in Indian pig. The present work reports for the first time in India the PCV2-1A/B cluster of 2b genotype and all the Indian isolates available in India from 2006–2018 were used in this analysis.

Changes on the viral capsid surface during the evolution of porcine circovirus type 2 (PCV2) from 2009 till 2018 may lead to a better receptor binding.

Porcine circovirus type 2 (PCV2) is the primary causative agent of porcine circovirus-associated diseases (PCVAD). Three major PCV2 genotypes (PCV2a, PCV2b, and PCV2d) have been identified globally. Despite their worldwide distribution, the prevalence and genetic evolution of PCV2 in Belgium has not previously been determined. In this study, 319 samples from animals suffering from diseases likely to be associated with PCV2 were collected from 2009 to 2018 and analysed by virus titration. The overall prevalence of PCV2 in PCVAD-suspected cases was 15.7 per cent (50/319). The phylogenetic analysis demonstrated that at least three genotypes (PCV2a, PCV2b, and PCV2d) circulated in Belgium from 2009 till 2018, and that PCV2 evolved from PCV2a to PCV2b and from PCV2d-1 to PCV2d-2. Sequence comparison among the forty-three PCV2 isolates showed that they had 89.7–100 per cent nucleotide-sequence and 88.5–100 per cent amino-acid-sequence identities. Three amino acid sites were under positive selection. Three-dimensional analysis of genotype-specific amino acids revealed that most of the mutations were on the outside of the cap protein with a few conserved mutations present on the inner side. Mutations toward more basic amino acids were found on the upper and tail parts of two connecting capsid proteins which form one big contact region, most probably involved in receptor binding. The lower part was relatively conserved. This polarity change together with the formation of an extruding part drive the virus to a more efficient GAG receptor binding. Taken together, these results showed a genotype shift from PCV2a to PCV2b and later on from PCV2d-1 to PCV2d-2, and a PCV2 evolution toward a better receptor binding capacity.

Inhibition of Abl or Src tyrosine kinase decreased porcine circovirus type 2 production in PK15 cells

Porcine circovirus type 2 (PCV2) causes huge economic losses in the global swine industry and has a complex and poorly understood virus-host interaction mechanism. We reported that the C-terminal of the capsid protein of all PCV2 isolates shared a strictly conserved PXXP motif that may interact with SH3 domain-containing tyrosine kinases; however, its roles in PCV2 cell entry and replication remain unknown. In this study, we determined that mRNA levels of two SH3 domain-containing tyrosine kinases family (Abl and Src) had distinct profiles (wild-type and PXXP-mutated) during PCV2 infections of PK15 cells. Therefore, we hypothesized that activities of tyrosine kinases (Abl and Fyn) in PK15 cells may be hijacked by PCV2 via its PXXP motif of the Cap, to favor virus replication. Specific inhibitors PP2 of Lck/Fyn and STI-571 of Abl family kinases decreased viral production through suppression of DNA and Cap synthesis at the replication stage. However, based on indirect immunofluorescence assay (IFA), entry of PCV2 virus-like particles (VLPs) into PK15 cells was not altered. Elucidating mechanisms of PCV2-host interactions should provide new insights for development of new compounds to prevent or reduce PCV2 infections.

Genetic variation and phylogenetic analysis of Porcine circovirus type 2 in China from 2016 to 2018.

Infection with Porcine circovirus type 2 (PCV2), the essential cause of porcine circovirus (PCV) associated diseases, is a growing problem in swine industry around the world. High nucleotide alteration leads to the constant evolution of PCV2 and outbreak of disease caused by PCV2. In this study, 48 PCV2 strains were isolated in China between 2016 and 2018 and the genetic diversity of these PCV2 isolates was determined. Results showed that these PCV2 isolates were classified into genotypes PCV2a (4 of 48), PCV2b (13 of 48) and PCV2d (31 of 48). Among them, 54.5% isolated in 2016, 65.2% isolated in 2017 and 71.4% isolated in 2018 belonged to PCV2d. It indicated that the prevalence of PCV2d genotype increased. All strains shared 93.4%-100% nucleotide sequence identity for the whole genome. Results of the analysis using RDP 4.0 molecular recombination software showed there were no recombinant events among the 48 PCV2 isolates in this study. Further analysis indicated the presence of higher amino acid residues diversity in important epitopes (43D/G, 115D/G, 134N/T, 165P/T, 169G/R/S, and 210E/G/D) in the predominant genotype PCV2d. Animal tests showed the viral titer of the PCV2d strain LN-3 in sera was higher than that of PCV2b strain HeB-1 at 14 and 21 days post-challenge, however, the differences were not statistically significant. There were also no obvious differences between PCV2d strain LN-3 and PCV2b strain HeB-1 in the amount of PCV2 antigen in lymphoid tissues. On the account of the increasing prevalence of PCV2d genotype, it is necessary to find the cause of PCV2 genotype change, to evaluate the effect of existing commercial vaccines and to develop new vaccines based on PCV2d genotype, if necessary. Keywords: epitope; PCV2d; phylogeny; Porcine circovirus type 2; recombination; genetic diversity.

Isolation and identification of biological characteristics of porcine circovirus type 2 (PCV2) from pigs in southern Vietnam

This study aimed to isolate and examine the biological characteristics of PCV2 field strains circulating in Vietnam for further study in producing vaccine against PMWS (postweaning multisystemic wasting syndrome). Eighteen PCV2 strains were successfully isolated and belonged to genotype PCV2b (9 strains), PCV2d (6 strains) and recombinant (3 strains). The viral titers of PCV2 isolates at the third passages in PK15A cells were in the range from 1.67 to 5,50 log10TCID50/mL. Three PCV2 field strains with stable viral titers (≥ 5,0 log10TCID50/mL) through passages, which belonged to different genotypes, were selected as master seed for studying of PCV2 vaccines

Evaluation of the Efficacy and Cross-Protective Immunity of Live-Attenuated Chimeric PCV1-2b Vaccine Against PCV2b and PCV2d Subtype Challenge in Pigs.

Porcine circovirus type 2 (PCV2) commercial vaccines are either inactivated PCV2 isolates or subunit vaccine based on the Cap protein of PCV2. Currently, no live-attenuated vaccines are yet available. Although the predominant circulating subtype worldwide is PCV2b, the emerging PCV2d subtype is also increasingly associated with PCV disease. In this study, piglets were inoculated with a live-attenuated chimeric PCV1-2b vaccine before challenged with PCV2b and PCV2d isolates. Thirty-two piglets were randomly divided into seven groups: negative (sham-vaccinated, sham-challenged), VAC+PCV2b (PCV1-2b vaccinated, PCV2b-challenged), VAC+PCV2d (PCV1-2b vaccinated, PCV2d-challenged), CHAL+PCV2b (sham-vaccinated, PCV2b-challenged), CHAL+PCV2d (sham-vaccinated, PCV2d-challenged), CV+PCV2b (commercial-vaccinated, PCV2b-challenged), and CV+PCV2d (commercial-vaccinated, PCV2d-challenged). The results showed that vaccinated challenged groups demonstrated high levels of anti-PCV2 antibody and reduced PCV2b and PCV2d loads both in serum and nasal swabs compared with the challenge-only groups. PCV2 DNA was detected in the superficial inguinal lymph nodes of only one pig in each of the VAC+PCV2b and VAC+PCV2d groups (group mean values, 101.81 and 101.77 genomic copies/g, respectively), which was significantly lower than those in CHAL+PCV2b and CHAL+PCV2d animals (group mean values, 1011.65 and 1010.60 genomic copies/g, respectively; P < 0.01). In addition, PCV2 DNA in each of the VAC+PCV2b and VAC+PCV2d groups was significantly lower than those in CV+PCV2b and CV+PCV2d animals (group mean values, 108.47 and 108.34 genomic copies/g, respectively; P < 0.01), indicating that the live-attenuated PCV1-2b vaccine was more effective than commercial vaccine. The live-attenuated PCV1-2b vaccine was effective in reducing PCV2b/PCV2d viremia, shedding, and tissue viral loads in vaccinated challenged pigs compared with challenge-only piglets, indicating that the PCV1-2b prototype vaccine is a good candidate for a live-attenuated vaccine against both PCV2b and PCV2d subtypes. And we first revealed that the live-attenuated PCV1-2b vaccine could protect piglets from challenge with either PCV2b or PCV2d equivalently.

Phylogenetic analysis of two goat-origin PCV2 isolates in China

Complete genome characterization of non-porcine origin Porcine circovirus type 2 (PCV2) was first described in 2014 in China. In the present study, we first identified PCV2 nucleotides in goat samples and the prevalence of PCV2 in goat was 6.15%. However, only two new strains, Goat2014-4 and Goat2014-5, could be completely sequenced. The genome of the strain Goat2014-4, which collected from the goat infected with PPRV, contains 1766 nt; strain Goat2014-5, which originated from a healthy goat, is comprised of 1767 nt. The results showed that they shared the highest nucleotide identity with BDH and the lowest similarity with DK1980PMWSfree strain and they belonged only to genotype PCV2d. Meanwhile, they shared higher homology with porcine-origin PCV2 strains than others. Moreover, a detailed analysis of the capsid amino acid sequences revealed that there were distinct differences for goat2014-4 (708 bp) and goat2014-5 (705 bp); strain Goat2014-4 showed an elongation of two amino acids, and strains Goat2014-5 showed an elongation of one amino acid compared with other reference strains. This is the first report of the genetic analysis of goat-origin PCV2 isolates. It also provides an additional supported evidence for cross-species transmission of PCV2.

Genetic and immunogenicity analysis of porcine circovirus type 2 strains isolated in central China.

Porcine circovirus type 2 (PCV2) is an economically important pathogen in domestic pigs and wild boars all around the world. To understand the molecular epidemiology of PCV2 strains circulating in central China and to provide a potential vaccine candidate strain, we analyzed the genetic variations of 46 PCV2 isolates circulating from 2009 to 2016 in Henan Province (24 detected in the field from 2009-2013 and 22 from 2013-2016) and evaluated the efficacy of an isolate as a vaccine candidate strain in a mouse model. We found that PCV2b was the predominant genotype and PCV2b-1C was the main subtype. The PCV2 isolate DF-1, which had a virus titer of 106.5 TCID50/mL and a stable genome, was selected and used to immunize Kunming mice. Enzyme-linked immunosorbent assay (ELISA), immunoperoxidase monolayer assay (IPMA), and virus neutralization test (VNT) results indicated that the DF-1 vaccine candidate strain could elicit a level of specific antibodies and neutralizing antibodies similar to those induced by a commercial vaccine. Polymerase chain reaction (PCR) detection of virus in vaccinated mice after challenge revealed that DF-1 vaccination was effective in clearing the virus in different tissues. Hence, the PCV2 isolate DF-1, a circulating subtype of PCV2b-1C, might be used as a potential vaccine candidate strain.

Structure analysis of capsid protein of Porcine circovirus type 2 from pigs with systemic disease.

Economic losses with high mortality rate associated with Porcine circovirus type 2 (PCV2) is reported worldwide. PCV2 commercial vaccine was introduced in 2006 in U.S. and in 2008 in Brazil. Although PCV2 vaccines have been widely used, cases of PCV2 systemic disease have been reported in the last years. Eleven nursery or fattening pigs suffering from PCV2 systemic disease were selected from eight PCV2-vaccinated farms with historical records of PCV2 systemic disease in Southern Brazil. PCV2 genomes were amplified and sequenced from lymph node samples of selected pigs. The comparison among the ORF2 amino acid sequences of PCV2 isolates revealed three amino acid substitutions in the positions F57I, N178S and A190T, respectively. Using molecular modeling, a structural model for the capsid protein of PCV2 was built. Afterwards, the mutated residues positions were identified in the model. The structural analysis of the mutated residues showed that the external residue 190 is close to an important predicted region for antibodies recognition. Therefore, changes in the viral protein conformation might lead to an inefficient antibody binding and this could be a relevant mechanism underlying the recent vaccine failures observed in swine farms in Brazil.

Genotypic diversity of porcine circovirus type 2 (PCV2) and genotype shift to PCV2d in Korean pig population

Porcine circovirus type 2 (PCV2) is a causative agent of PCV2-associated disease (PCVAD), which leads to enormous economic losses in the swine industry worldwide. A high nucleotide substitution rate allows for the continuous evolution of PCV2 and the emergence of novel PCV2 strains. However, the distribution of emerging PCV2 genotypes and the co-existence of multiple genotypes in Korea have not been elucidated. The objective of this study was to determine the genetic diversity of PCV2 in Korean pig herds between 2009 and 2016. The overall prevalence of PCV2, from various samples originating from commercial pigs, was 53.8% (325/604). Two cases of a genotype shift to PCV2d at the farm level showed that the genotype shift started before 2012. In addition, genotype-specific PCR, on pen-based oral fluid samples for nationwide PCV2 surveillance in 2016, indicated that the infection pattern of PCV2 genotypes at the farm level was as follows; none (6/69), PCV2a (6/69), PCV2b (2/69), PCV2d (33/69), PCV2a/b (2/69), PCV2a/d (4/69), PCV2b/d (11/69), and PCV2a/b/d (2/69), respectively. This suggests that the genotype shift to PCV2d occurred on a nationwide scale and that the co-existence of different genotypes is common in Korean pig herds. In addition, seven sites on the capsid protein of Korean PCV2 were identified as being under positive selection pressure, all of which are related to the epitope region and neutralization activity. These data provide evidence of increased genetic diversity and shifts among Korean PCV2 isolates.

Complete Genome Characteristics of Porcine circovirus Type 2 (PCV2) Isolates from Papuan Pigs, Indonesia

Porcine circovirus type 2 (PCV2) has been recognised as an important pathogen in the pig industry world-wide. The virus was recently identified in Papuan pigs, yet information about the characteristics of Papuan PCV2 isolates is limited. The aim of the present study was to characterise the complete genome of Papuan PCV2 isolates. Viral DNA was isolated from 13 blood samples of village pigs from the Jayawijaya region. Four of the PCR positive samples were selected for full genome sequencing. Neighbour Joining phylogeny with P-distance model showed that the four Papuan PCV2 isolates belong to genotype PCV2-IM3. Sequence identity analysis of the Papuan PCV2 genomes further showed 99.5% to 99.6% similarity with a Chinese PCV2-IM3 reference strain. The current study revealed that genotyping based on the ORF2 sequence resulted in a substantially different characterisation of PCV2 genotypes compared to classification based on the complete genome sequences. Furthermore, the study showed that the topology of the PCV2 phylogeny based on the ORF2 sequence was different from the topology based on capsid proteins. Genotyping using the complete genome, ORF2 region or capsid protein sequences resulted in substantial variance in the classification of the PCV2 isolates. The clinical consequence of these different genotyping methods needs further study.

Prevalence and genetic variation of porcine circovirus type 2 in Hebei, China from 2004 to 2014

Porcine circovirus type 2 (PCV2), the primary causative agent of porcine circovirus-associated disease (PCVAD), causes severe economic losses to the pig industry in China since 2002. To investigate the molecular epidemic characteristics and genetic evolution of PCV2, 12 PCV2 isolates obtained from different pig farms with various clinical symptoms of PCVAD in Hebei, China from 2004 to 2014 were sequenced and analyzed. The phylogenetic analysis showed that the 12 isolates were divided into two distinct genotypes, PCV2b (7/12) and PCV2d (5/12), based on the sequences of either viral complete genome or open reading frame 2 (ORF2). Of the 7 PCV2b strains, 5 were isolated from 2004 to 2008 while all PCV2d were isolated from 2009 to 2014. This exhibited that PCV2b isolates were the most common before 2009 and then PCV2d isolates became predominant and widely distributed in pig farms. Sequence comparisons among total isolates indicated that the nucleotide identity ranged from 95.5% to 100% for complete genome and 93.1%–100% for ORF2. Compared with seven PCV2b isolates, there were thirteen amino-acid substitutions in the ORF2 region and one additional amino-acid K at this region terminal for five PCV2d isolates. The results suggest that a higher genetic variation and a distinct genotype shift occurred among the PCV2 isolates collected from 2004 to 2014 in Hebei.

In silico analyses of antigenicity and surface structure variation of an emerging porcine circovirus genotype 2b mutant, prevalent in southern China from 2013 to 2015.

Porcine circovirus type 2 (PCV2) is the pivotal pathogen causing porcine circovirus-associated diseases. In this study, 62 PCV2 isolates were identified from seven farms in southern China from 2013 to 2015 and phylogenetic trees were reconstructed based on whole-genome sequences or the cap gene. In this investigation, PCV2b was the main genotype in circulation throughout these farms. Furthermore, an emerging mutant (PCV2b-1C), isolated from PCV2-vaccinated farms, was the predominant strain prevalent on these farms. In addition, we isolated a new cluster that may represent evolution of the virus through recombination of PCV2b-1A/1B and PCV2b-1C. Finally, we discuss evidence that antigenicity and surface structure variation of the capsid resulted from mutation of the C-terminal loop (Loop CT) of the PCV2b-1C Cap in silico.

COMPLETE GENOME SEQUENCE OF PORCINE CIRCOVIRUS TYPE 2 UKRAINIAN ISOLATES

Porcine circovirus type 2 (PCV2) is associated with distinct syndromes and diseases in swine, collectively known as porcine circovirus-associated diseases (PCVAD), which include postweaning multisystemic wasting syndrome (PMWS), PCV2-associated pneumonia as a part of the porcine respiratory disease complex (PRDC), PCV2-associated enteritis, PCV2-associated reproductive failure, and porcine dermatitis and nephropathy syndrome (PDNS) (1–3). PCV2-infection is widespread and essentially all pig herds are infected with PCV2. Porcine circovirus 2 (PCV2), a member of the genus Circovirus in the family Circoviridae, is a very small single-stranded negative-sense DNA virus of approximately 1.7 kb (4). The genome of PCV2 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) (5). Previous reports showed that there were five PCV2 genotypes, including PCV2a, PCV2b, PCV2c, PCV2d, and PCV2e (6– 9). Here, we report the complete genome sequence of Ukrainian PCV2 isolates from different regions of Ukraine.

Genetic and phylogenetic analysis of a new porcine circovirus type 2 (PCV2) strain in China.

Porcine circovirus type 2 (PCV2) is the etiological agent associated with several pig diseases that are collectively referred to as porcine circovirus-associated disease (PCVAD). Unfortunately, PCV2 has had a serious economic impact on the swine industry. In this study, we report the genome sequence of a novel PCV2 isolate (JS2015) identified in pigs in Jiang Su, China. The complete DNA sequence was 1766 nucleotides long with an A+T content of 52.7%. It lacked a guanine (G) at nucleotide position 1045 compared to other reference PCV2 strains with a sequence length of 1766 nucleotides. Genetic characterization and phylogenetic analysis showed that the isolate JS2015 was most closely related to members of the PCV2d (AY181946) lineage. Our data provide insight into the epidemiology of porcine circovirus and may facilitate further study of the origin and evolution of PCV2.

Genetic characterisation and phylogenetic analysis of PCV2 isolates from India: Indications for emergence of natural inter-genotypic recombinants

Porcine circovirus type 2 (PCV2), the necessary agent in pathogenesis of porcine circovirus diseases (PCVDs), has a worldwide distribution and is considered as one of the most important emerging viral pathogens of economic importance. PCV2 has been divided into four major genotypes namely PCV2a with five clusters or subtypes (2A–2E), PCV2b with three clusters (1A–1C), PCV2c and PCV2d, based on capsid (cap) gene analysis. PCV2 genome is rapidly evolving through events of recombination and mutation. Though, PCV2a was the predominant genotype initially, PCV2b shared majority of PCV2 sequences submitted to GenBank since 2003. In India, data regarding molecular characterisation of PCV2 is scant or absent. In the present study, we thoroughly analysed genetic heterogeneity of PCV2 strains circulating in Indian pig population. The results revealed that pigs in this region harboured PCV2 viruses of different genotypes including PCV2a–2D, PCV2b–1C and PCV2d. More interestingly, two isolates (PCV2Izn-89-13 and PCV2Izn-218-13) were classified as recombinant strains. Further detailed analysis suggested that these strains evolved from inter-genotypic recombination between PCV2a–2C and PCV2b–1C genotypes within cap gene. This study reports for the first time, the emergence of recombinant PCV2 strains in the Indian pig population.

Phylogenetic analysis of 32 porcine circovirus type 2 isolates from Shandong, China.

Porcine circovirus type 2 (PCV2), the essential causative agent of postweaning multisystemic wasting syndrome (PMWS), can be divided into distinct genotypes. Thirty-two PCV2 isolates obtained made from pigs in Shandong Province between 2005 and 2013. Complete genome sequences were obtained in three replicates for each virus isolate, and the sequences were submitted to the NCBI database. The ORF1-encoded amino acid sequences had 98.4%-100% identity among the 32 isolates, and there were no significant differences among the three potential glycosylation positions: aa 23-25 (NPS), aa 256-258 (NQT) and aa 286-288 (NAT). The amino acid sequences of ORF2 had 88%-100% identity among the 32 isolates and the potential glycosylation position in the cap protein, aa 143-145 (NYS), had no variation. Phylogenetic analysis revealed that the PCV2b/1C genetic lineage was prevalent in swine populations in Shandong Province. It also suggested that selection pressure has made the PCV2 isolates more genetically distant from current vaccine strains.