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Porcine circoviruses (PCVs) belong to the genus Circovirus, family Circoviridae, and are the smallest non-enveloped, single stranded, negative sense, circular DNA viruses that replicate autonomously in mammalian cells. Two types of PCV have been characterised, PCV1 and PCV2 and these two viruses show 83% sequence identity at open reading frame (ORF) 1 and 67% identity at ORF2. PCV1 is a non-pathogenic virus of pigs. In contrast, PCV2 has emerged as a major pathogen of swine around the world. The discovery of PCV1 and how the subsequent studies on this virus eventually led to the recognition and characterisation of PCV2, and the disease scenarios associated with PCV2, serve as a model of how multidisciplinary collaboration among field veterinarians, diagnosticians and researchers can lead to the rapid characterisation and control of a globally important emerging disease.

Porcine circoviruses (PCV) are present worldwide, infecting domestic pigs and wild boars alike. Studies under laboratory conditions indicated that PCV can be taken up by mice and the virus can replicate in these animals. The possible role of rodents in maintaining and transmitting PCV2 infection in the field has not been investigated yet. The present study reports the detection of PCV2, the pathogenic form of the virus, in mice and rats. A number of rodents, such as mice, rats and voles, were collected at PCV2-infected farms and also outside pig herds and tested for the presence of the virus by polymerase chain reaction (PCR). The results indicated that PCV2 can be present both in mice and rats (65.0% and 23.8% positivity, respectively) on the infected premises, but those rodents that were collected outside pig farms remained negative for PCV2.

In the present study whole genome of six Brazilian isolates of PCV2 were sequenced, analyzed and compared with 35 other sequences (24 from other countries and 17 from Brazil). The phylogenetic analysis showed that mostly Brazilian variants of PCV2 were grouped as PCV2-1. Two isolates among the six analyzed here could not be grouped with any other PCV2-2 analyzed in this study. One of these isolates was from an aborted fetus with myocarditis and the other from a PMWS affected pig. The results pointed here showed that both groups of PCV2 are present in Brazilian pig population without any clear geographical correlation.

When porcine circovirus type 1 (PCV1) was isolated more than 40 years ago as a non-pathogenic contaminant of a porcine kidney cell line, enthusiasm and curiosity kept within reasonable limits. Virologists became more interested, when a second variant was isolated and termed PCV2, because PCV2 is linked to postweaning multisystemic wasting disease (PMWS), a new emerging multifactorial disease in swine. Both PCV1 and PCV2 are small and rather simply organized and express only few proteins. Therefore, it was expected that the factor(s) triggering PMWS should be easily identified, but more than one decade of PCV research has not yet singled out a molecule inducing the disease onset. Unravelling the molecular features of PCV and the channels through which the virus interacts with its host are key to manage, prevent and treat PMWS and other PCV-associated diseases. Since we have learned many aspects of the molecular biology of PCV in the last years, it is time for a résumé!

Porcine circoviruses (PCVs) type 1 (PCV1) and type 2 (PCV2) show high levels of nucleotide similarity, but PCV1 is considered non-pathogenic and PCV2 has been associated with several disease outcomes in pigs, mainly postweaning multisystemic wasting syndrome (PMWS). After exploring different topologies of the origin of PCVs, it was concluded that PCV1 and PCV2 seem to have a common origin. On the other hand, PCV2 could be divided into two groups (1 and 2) and eight clusters (1A to 1C and 2A to 2E), but none of those was apparently associated with disease status or geographic area. When phylogenetic trees constructed with the whole PCV2 genome, the cap or the rep genes were compared, some incongruence was identified. The possible existence of recombination was evaluated and cluster 1B was found to have a possible recombinant origin. Selective pressure was detected in all parts of the PCV2 genome, especially in the rep gene. Finally, the cap gene was the more suitable phylogenetic and epidemiological marker for PCV2, despite the fact that the virus can undergo recombination mainly within the first part of the rep region.

The absence of extraneous viruses is a requirement in the quality control of vaccines for veterinary use in the European Pharmacopoeia. A polymerase chain reaction (PCR) assay for the detection of porcine circovirus type 1 (PCV1) and type 2 (PCV2) was evaluated in 18 commercial porcine vaccines. Since vaccine components may contain PCR enhancers or inhibitors, 13 of the studied vaccines (used as diluents) were subsequently spiked with different dilutions of PCV2 and tested by PCR. Although PCV2 DNA was not detected in any of the vaccines tested, PCV1 was detected in 2/18 vaccines (11%). Eleven out of 13 PCV2 spiked vaccines showed a positive PCR result. The lack of amplification observed in two spiked vaccines suggested that use of the PCR assay to detect PCV2 could depend on vaccine composition. The results of this exploratory study have demonstrated that PCR is a rapid and fairly sensitive method for the detection of porcine circoviruses as extraneous agents in vaccine products and can be used in the quality control of pig vaccines. The study has also indicated the need for optimising the sensitivity of PCR methods for PCV genome detection in vaccine products.

Potential risk factors for clinical signs of post-weaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS) in pigs in the Netherlands were investigated in a matched case-control study using a questionnaire (personal interview). Eighty-two pig farmers were questioned about management, hygiene, husbandry systems, disease history, and preventive health care. In this study, 30 pig herds with (cases) and 30 pig herds without (controls) characteristic clinical signs of PMWS were compared. For PDNS, 11 pig herds with (cases) and 11 pig herds without (controls) characteristic clinical signs of PDNS were compared. Univariate analysis (P

Post–Weaning Multisystemic Wasting Syndrome (PMWS) can result in mortality levels of up to 80% in weaned piglets, and Porcine Circovirus type 2 (PCV2) has been identified as one of the primary causative agents. Neutraceutical products, based on plant and herbal extracts and containing high levels of natural antioxidants may be beneficial in reducing stress on the piglets’ immune system by elevating blood antioxidant levels, and assisting with the piglets defence against PMWS. The aim of this experiment was to assess the effect of supplementation with neutraceutical products on the growth performance and antioxidant activity in liver and plasma of piglets. It was undertaken on a farm positive for PCV2, but where pigs were not showing clinical signs of PMWS. Groups of newly weaned pigs were offered one of three diets ad libitum for a period of 26 days, standard creep and starter/link control rations, or one of two experimental rations (including Neutraceutical–mix, N, or Lycopene, L), chosen for their potential to boost antioxidant activity. Growth performance and feed intake were monitored, and samples of blood and liver collected at slaughter (54 days of age) and analysed for antioxidant activity. Although L pigs ate significantly less feed during the creep period (P

The use of porcine tissues is being developed as a means to alleviate the shortage of allogeneic tissues and organs available for transplantation. To reduce the possibility of a microorganism of pigs being inadvertently transferred to the recipient of the xenograft, recommendations have been published on the microbiological specifications for organ source pigs. The porcine circoviruses (PCV1 and PCV2) and porcine lymphotropic herpesviruses (PLHV1 and PLHV2) are two infectious agents of pigs which are considered to be of significance for the microbiological safety of xenotransplantation. To ensure the exclusion of these microorganisms from animals destined for use under clinical conditions, reliable breeding methodologies are required. We investigated the efficiency of established derivation procedures for the removal of PCV and PLHV. In comparison with conventionally reared pigs, caesarian and barrier derived animals showed a markedly reduced prevalence of PCVs and PLHVs. Our results indicate that the derivation of animals free of both of these microorganisms is achievable and will enhance the microbiological safety of xenotransplantation.

Porcine circoviruses (PCVs) belong to the genus Circovirus and the family Circoviridae, and they are the smallest known viruses that replicate autonomously in mammalian cells. They are nonenveloped, and they have characteristic single-stranded, negative-sense, circular DNA. Two types of divergent PCVs are recognized: PCV1 and PCV2. About 20 years ago, PCV2 began to emerge as a major pathogen of swine around the world, leading to burgeoning knowledge about the virus and porcine circovirus–associated diseases. However, much of the history of its discovery, including the controversy related to its importance, is not recorded. This review examines current issues related to the biology of PCV2 in the context of the original studies related to determining its causal association with disease and to the evolving understanding of the complex pathogenesis of PCV2 infections.

Literatuurstudie naar de verspreiding van de 'wegkwijnziekte', nadat deze voor het eerst eind 1995 in Frankrijk werd waargenomen. Per Europees land wordt de huidige PMWS-situatie aangegeven

Porcine circovirus type 2 (PCV2) belongs to the genus Circovirus of the Circoviridae family and has been associated with a disease named postweaning multisystemic wasting syndrome (PMWS). In Portugal the disease caused severe problems mainly between 1995 and 2003, but is nowadays less evident probably as the result of vaccination programmes initiated in 2007. This study reports the molecular analysis of 22 PCV2 strains obtained from domestic pigs originated from different regions of Portugal. One hundred and seventy-seven samples from PCV2 suspected cases received between 2003 and 2010 were analysed, 79 (44.6%) of which tested PCV2 PCR-positive. The entire genomes of 22 viruses were amplified and sequenced. Two major groups were observed, according to the genome length and in single nucleotide polymorphisms. The nucleotide similarity found among the PCV2 strains ranged between 94% and 99%. The Bayesian inference of phylogeny based on the genome of the strains studied revealed the existence of two distinct genetic groups consistent with the nucleotide sequence observations. The majority of the strains branched in genotype PCV2b, while six strains with a common geographical origin obtained between 2007 and 2009, were included in genotype PCV2a. The analysis performed with cap and rep genes confirmed that cap is a reliable alternative to full-length genome based phylogenetic studies of PCV2.

Probe size and fixation time for detecting Porcine circovirus–2 (PCV–2) by in situ hybridization in formalin-fixed, paraffin-embedded lymph nodes from experimentally infected pigs were optimized. In situ hybridization using a 169–base pair (bp) probe detected significantly fewer PCV–2–positive cells than when using 8 other larger probes ( P < 0.05). The difference in hybridization intensity between smaller probes (169 and 225 bp) and larger probes (416, 473, 571, 631, 693, and 753 bp) was statistically significant ( P < 0.05). The PCV–2–positive cells were consistently detected in lymph nodes fixed up to 3 days; thereafter, the number of positive cells declined. The PCV–2–positive cells were detected in lymph nodes fixed for up to 730 days. The difference in hybridization intensity between samples fixed for a short term (1 or 3 days) and a longer term (4–730 days) was statistically significant ( P < 0.05). The data demonstrates that the optimal probe size and fixation time for detecting PCV–2 in formalin-fixed, paraffin-embedded lymph nodes is 473 bp and 1–3 days, respectively.

Between February 20 and October 31, 2003, 2034 sows were inseminated with semen collected from 13 Hungarian Landrace boars. Altogether 16,013 piglets were born: 13,801 (86·2 per cent) alive, 796 (4·97 per cent) stillborn and 156 (0·97 per cent) mummified. A total of 1260 (7·87 per cent) of the pigs developed signs of postweaning multisystemic wasting syndrome (PMWS). In the groups of sows inseminated with semen from each of the 13 boars, the percentages of farrowings producing piglets with signs of PMWS, stillborn piglets or mummified piglets were very high (59·4 per cent, 57·6 per cent and 13·8 per cent, respectively). There were significant differences between the proportions of piglets with signs of PMWS, stillborn piglets and mummified piglets sired by the different boars: 3·06 to 15·6 per cent, 1·76 to 8·52 per cent and 0 to 3.22 per cent, respectively.

The comparison of nucleotide and deduced amino acid sequence was conducted with 9 porcine circovirus type 2 (PCV2) strains isolated from PCV2-infected pigs with postweaning multisystemic wasting syndrome (PMWS) and 50 tissue samples obtained from PCV2-infected 50 pigs with PMWS during 2005-2007. At amino acid positions 88-89 of the ORF2 gene, 50 Korean PCV2 had amino acids PR/L consistent with group 1 PCV2, whereas 9 Korean PCV2 contained amino acids KI, characteristic of group 2 PCV2. Phylogenetically, 47, 3, 2 and 7 Korean PCV2 belonged to subgroups 1A/B (79.7%), 1C (5.1%), 2D (3.4%) and 2E (11.9%), respectively. Although the predominant Korean PCV2 was subgroup 1A/B, subgroups 1C and 2E were still circulating and subgroup 2D PCV2 were found to be newly emerged in Korea.

Literatuurstudie naar de verspreiding van de 'wegkwijnziekte', nadat deze voor het eerst eind 1995 in Frankrijk werd waargenomen. Per Europees land wordt de huidige PMWS-situatie aangegeven

Potential risk factors for clinical signs of post-weaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS) in pigs in the Netherlands were investigated in a matched case-control study using a questionnaire (personal interview). Eighty-two pig farmers were questioned about management, hygiene, husbandry systems, disease history, and preventive health care. In this study, 30 pig herds with (cases) and 30 pig herds without (controls) characteristic clinical signs of PMWS were compared. For PDNS, 11 pig herds with (cases) and 11 pig herds without (controls) characteristic clinical signs of PDNS were compared. Univariate analysis (P

INFECTION with porcine circovirus type 2 (PCV-2) in pigs has been associated with several diseases including postweaning multisystemic wasting syndrome (PMWS). Although PMWS was not clinically apparent until early 2005, it is now considered one of the most economically significant diseases of pigs

Background Straw is one of the most effective rooting materials to reduce tail biting in pigs. A so-called foraging-tower (FT) provides only small quantities of straw compatible with liquid manure systems. The focus of the present study was on the effect of providing straw by FT in order to prevent tail biting in tail docked pigs. Four consecutive batches of 160 pigs, randomly divided into a straw (SG) and a control group (CG) were followed up from weaning to slaughter. Results Tail wounds (Score ≥ 2) were detected in 104 out of 12,032 single observations (SG n = 48; CG n = 56) in 9 pens (SG n = 4/32; CG n = 5/32) mainly focused on the fattening period of batch 2 due to a failure in the ventilation system. No significant differences concerning the distribution of Score ≥ 2 in pens of the SG and CG could be identified. Bite marks (Score 1) were documented in 395 observations at animal level (SG n = 197, CG n = 198) in all batches. In the nursery period, the air velocity significantly increased the chance that at least one pig per pen and week showed a tail lesion score ≥1 (p = 0.024). In the fattening period ammonia concentration was positively associated with tail lesions (p = 0.007). The investigation of blood samples revealed infections with Mycoplasma hyopneumoniae in all batches and a circulation of Porcine Reproductive and Respiratory Syndrome Virus (NA-vaccine strain) and Porcine Circovirus Type 2 in two batches each. The average daily straw consumption was 3.5 g/pig (standard deviation (SD) = 1.1) during the rearing period and 31.9 g/pig (SD = 7.7) during the fattening period. Conclusion Due to the low prevalence of tail biting in all batches the effect of the FT tower could not be evaluated conclusively. The operation of the FT with an average daily straw consumption of 3.5 g/pig (SD = 1.1) during the rearing period and 31.9 g/pig (SD = 7.7) during the fattening period did not affect the weight gain. Exploratory behaviour seems to cause bite marks (score 1), which do not necessarily result in tail biting. The main outbreak of tail biting was probably triggered by a failure of the ventilation system, which resulted in a number of climatic and air quality changes including higher ammonia concentrations and sudden temperature changes. Electronic supplementary material The online version of this article (doi:10.1186/s40813-017-0052-7) contains supplementary material, which is available to authorized users.

Background The objective of this study was to investigate the association between average daily gain and the number of Lawsonia intracellularis bacteria in faeces of growing pigs with different levels of diarrhoea. Methods A longitudinal field study (n = 150 pigs) was performed in a Danish herd from day 29 to 47 post weaning. Every third day all pigs were weighed, subjected to a clinical examination and faecal samples were obtained. Faecal samples were subjected to dry matter determination and absolute quantification by PCR for L. intracellularis and porcine circovirus type 2 (PCV2). Association between average daily gain, faecal dry matter content, numbers of L. intracellularis bacteria and PCV2 genome copies in faeces was investigated in a multilevel mixed-effects linear model. Results Increasing numbers of L. intracellularis log10 bacteria/g faeces were significantly associated with decreasing average daily gain (P P 10 copies/g faeces was not significantly associated with average daily gain of the pigs (P > 0.5). Conclusion The results suggest a potential application of a PCR quantifying L. intracellularis in growing pigs. Faecal dry matter content must be taken into consideration in interpretation of such test results.