Search Results (9)

Background/Objectives: Porcine circovirus type 2 (PCV2) infection causes porcine circovirus disease (PCVD), a global immunosuppressive disease in pigs. Its clinical manifestations include post-weaning multisystemic wasting syndrome (PMWS) and porcine dermatitis and nephropathy syndrome (PDNS), which cause significant economic losses to the swine industry. The Cap protein, which is the major protective antigen of PCV2, can self-assemble to form virus-like particles (VLPs) in the insect baculovirus expression system. Few studies have compared the expression of Cap proteins in different baculovirus expression systems. Methods: In this study, we compared two commonly commercialized baculovirus construction systems with the Cap protein expression in various insect cells. Results: The results demonstrate that the flashBAC system expressed the Cap protein at higher levels than the Bac-to-Bac system. Notably, when expressing four copies of the Cap protein, the flashBAC system achieved the highest protein yield in High Five cells, where it reached 432 μg/mL at 5 days post-infection (dpi) with 27 °C cultivation. Animal experiments confirmed that the purified Cap protein effectively induced specific antibody production in mice and swine. Conclusions: This study provides critical data for optimizing the production of the PCV2 Cap protein, which is of great significance for reducing the production cost of PCV2 vaccines and improving the industrial production efficiency. Full article

Pigs are affected by a variety of pathogenic agents that need to be identified correctly and diagnosed even when co-infections may complicate the application of specific and targeted assays. Next-generation sequencing can provide new perspective to monitor viruses infecting or co-infecting diseased pigs. In this study, we tested, for the first time for diagnostic purposes in a livestock species, a new method based on whole-genome sequencing of all the DNAs extracted from the blood of nine pigs sampled from a farm where there was a suspected outbreak of Post-weaning Multisystemic Wasting Syndrome. We then used unmapped reads on the porcine reference genome to mine for viral sequences using a specifically designed bioinformatic pipeline. Within this fraction of reads, viral sequences ranged from 0.002% to 4.4% of the total unmapped reads and were derived from twelve different viruses known to infect pigs, where three were herpesviruses, eight were parvoviruses, and one was a circovirus. All pig sequencing datasets were positive for one or more viruses, with various potential viral loads. Suid betaherpesvirus 2, also known as Porcine cytomegalovirus (PCMV), was the most frequently identified virus as five out of the nine pig sequencing datasets contained viral sequences from this virus. The results may suggest a heterogeneous viral profile of the diseased pigs that may be derived from potential secondary infections or co-infections. This pilot application demonstrated that a whole-genome sequencing approach can complement other routine diagnostic assays in veterinary virology. Other studies and improvements are needed to validate the results and apply this approach in routine monitoring applications. Full article

Viruses in the Circoviridae family can infect mammals and birds. Porcine circovirus type 2 (PCV2) significantly affects the livestock industry by causing porcine circovirus-associated diseases, such as postweaning multisystem wasting syndrome, respiratory disease complex, and dermatitis nephropathy syndrome. Additionally, beak and feather disease virus in parrots, canine circovirus in dogs, and columbid circovirus (pigeon circovirus) in racing pigeons induce immunosuppression, followed by secondary infections in these hosts. Although the PCV2 capsid protein has been demonstrated to inhibit type I interferon (IFN) signaling, the molecular mechanisms of Circoviridae-induced immunosuppression are largely unknown. In this study, we examined whether these functions are conserved across Circoviridae capsid proteins. Our results illustrated that although the nuclear localization of capsid proteins is conserved, their effects on IFN-β signaling vary by species, revealing the diverse roles of Circoviridae capsid proteins in modulating immune responses. Full article

Both porcine circovirus (PCV) and porcine parvovirus (PPV) cause various diseases and bring huge economic losses to the global swine industry. PCV2 is associated with several diseases and syndromes, including postweaning multisystemic wasting syndrome (PMWS), porcine dermatitis and nephropathy syndrome (PDNS) and porcine respiratory disease complex (PRDC). The classical PPV is one of the most common causes of reproductive failure in pigs. In this study, tissue samples (tonsil, lung, mesenteric lymph node, hilar lymph node and superficial inguinal lymph node) were collected from pigs with suspected PCV2-associated disease (PCVAD), and viral DNA was extracted. The coinfection of PCV2 and PPV1–5 was detected using the polymerase chain reaction (PCR) method. Phylogenetic analysis based on capsid genes of PCV2, PPV2, PPV3 and PPV5 was conducted. The prevalence rates of PCV2, PPV1, PPV2, PPV3, PPV4 and PPV5 were 51.2%, 15.9%, 36.6%, 19.5%, 14.6% and 10.9% on the individual pig level, respectively. The coinfection rates of PCV2 with PPV1, PPV2, PPV3, PPV4 and PPV5 were 8.5%, 25.6%, 17.1%, 13.4% and 3.7%, respectively. The prevalence of PPV2, PPV3 and PPV4 in PCV2-positive pigs was significantly higher than those in PCV2-negative pigs. Phylogenetic analyses were performed using the neighbor-joining (NJ) method with 1000 bootstraps. The results indicated the existence of PCV2d and two major clusters of PPV2, PPV3 and PPV5 in the Guangxi Autonomous Region. PCV2d was the dominant strain, and the novel PPVs were circulating in domestic pigs in the Guangxi Autonomous Region. The results of this study underline the importance of active surveillance of PCV2d and PPVs from the swine population in this area. Full article

This study aimed to evaluate the efficacy of a new trivalent vaccine containing inactivated Porcine Circovirus 1-2a and 1-2b chimeras and a Mycoplasma hyopneumoniae bacterin administered to pigs around 3 weeks of age. This trivalent vaccine has already been proved as efficacious in a split-dose regimen but has not been tested in a single-dose scenario. For this purpose, a total of four studies including two pre-clinical and two clinical studies were performed. Globally, a significant reduction in PCV-2 viraemia and faecal excretion was detected in vaccinated pigs compared to non-vaccinated animals, as well as lower histopathological lymphoid lesion plus PCV-2 immunohistochemistry scorings, and incidence of PCV-2-subclinical infection. Moreover, in field trial B, a significant increase in body weight and in average daily weight gain were detected in vaccinated animals compared to the non-vaccinated ones. Circulation of PCV-2b in field trial A and PCV-2a plus PCV-2d in field trial B was confirmed by virus sequencing. Hence, the efficacy of this new trivalent vaccine against a natural PCV-2a, PCV-2b or PCV-2d challenge was demonstrated in terms of reduction of histopathological lymphoid lesions and PCV-2 detection in tissues, serum and faeces, as well as improvement of production parameters. Full article

Porcine circovirus type 2 (PCV-2) is associated with several syndromes affecting swine, also known as porcine-circovirus-associated diseases, of which post-weaning multi-systemic wasting syndrome stands out due to its high economic impact on swine production. Recent data suggest the increasing circulation of the PCV-2d genotype in several countries worldwide. To provide updated data on PCV-2 genotypes currently circulating in swine in Portugal, we screened wild boar stools collected from several districts across Portugal, during the 2018–2020 hunting seasons, for PCV-2 and genetically characterized detected strains. From a total of 76 stool samples of wild boar tested by PCR for the partial PCV-2 ORF2 gene, two sequences were obtained (2/76; 2.6%, 95% confidence interval: 0.032–9.18). Bidirectional sequencing showed that the sequences were 100% identical and both of the PCV-2d genotype, showing for the first time the presence of this genotype in Portugal. Monitoring wild PCV-2 reservoirs is important for both veterinary public health and economic reasons, since PCV-2 infection has a strong economic impact on the swine industry. Full article

The nucleotide oligomerization domain (NOD)-like receptor 2 (NOD2) is an intracellular pattern recognition receptor that detects components of peptidoglycans from bacterial cell walls. NOD2 regulates bowel microorganisms, provides resistance against infections such as diarrhea, and reduces the risk of inflammatory bowel diseases in humans and mice. We previously demonstrated that a specific porcine NOD2 polymorphism (NOD2-2197A > C) augments the recognition of peptidoglycan components. In this study, the relationships between porcine NOD2-2197A/C genotypes affecting molecular functions and symptoms in a porcine circovirus 2b (PCV2b)-spreading Duroc pig population were investigated. The NOD2 allele (NOD2-2197A) with reduced recognition of the peptidoglycan components augmented the mortality of pigs at the growing stage in the PCV2b-spreading population. Comparison of NOD2 allele frequencies in the piglets before and after invasion of PCV2b indicated that the ratio of NOD2-2197A decreased in the population after the PCV2b epidemic. This data indicated that functional differences caused by NOD2-2197 polymorphisms have a marked impact on pig health and livestock productivity. We suggest that NOD2-2197CC is a PCV2 disease resistant polymorphism, which is useful for selective breeding by reducing mortality and increasing productivity. Full article

Porcine circovirus type 2 (PCV2) is closely linked to postweaning multisystemic wasting syndrome (PMWS) and other PCV-associated diseases (PCVADs), which influence the global pig industry. MicroRNAs (miRNAs) are evolutionarily conserved classes of endogenous small non-coding RNA that regulate almost every cellular process. According to our previous transcription study, PCV2 infection causes up-regulation of genes related to inflammation. To reveal the function of miRNAs in PCV2 infection and PCV2-encoded miRNAs, next generation sequencing and data analysis was performed to explore miRNA expression in PCV2-infected cells and non-infected cells. Data analysis found some small RNAs matched the PCV2 genome but PCV2 does not express miRNAs in an in vitro infection (PK-15 cells). More than 297 known and 427 novel miRNAs were identified, of which 44 miRNAs were differently expressed (DE). The pathways of inflammation mediated by chemokine and cytokine signaling pathway (P00031), were more perturbed in PCV2-infected cells than in mock controls. DE miRNAs and DE mRNA interaction network clearly revealed that PCV2 regulates the cellular inflammatory response through dysregulating the cellular miRNA-mRNA network. MiRNA overexpression and down-expression results demonstrated that miRNA dysregulation could affect PCV2 infection-induced cellular inflammatory responses. Our study revealed that host miRNA can be dysregulated by PCV2 infection and play an important role in PCV2-modulated inflammation. Full article

Mycoplasma hyopneumoniae (Mhp) and porcine circovirus type 2 (PCV2) are the main pathogens for mycoplasmal pneumonia of swine (MPS) and post-weaning multisystemic wasting syndrome (PMWS), respectively. Infection by these pathogens often happens together and causes great economic losses. In this study, a kind of recombinant baculovirus that can display P97R1P46P42 chimeric protein of Mhp and the capsid (Cap) protein of PCV2 was developed, and the protein location was identified. Another recombinant baculovirus was constructed without tag proteins (EGFP, mCherry) and was used to evaluate the immune effect in experiments with BALB/c mice and domestic piglets. Antigen proteins P97R1P46P42 and Cap were expressed successfully; both were anchored on the plasma membrane of cells and the viral envelope. It should be emphasized that in piglet immunization, the recombinant baculovirus vaccine achieved similar immunological effects as the mixed commercial vaccine. Both the piglet and mouse experiments showed that the recombinant baculovirus was able to induce humoral and cellular responses effectively. The results of this study indicate that this recombinant baculovirus is a potential candidate for the further development of more effective combined genetic engineering vaccines against MPS and PMWS. This experiment also provides ideas for vaccine development for other concomitant diseases using the baculovirus expression system. Full article