Search Results (69)

Porcine circovirus type 2 (PCV2) is a globally prevalent swine pathogen that induces immunosuppression, predisposing pigs to subclinical infections. In intensive farming systems, PCV2 persistently impairs growth performance and vaccine efficacy, leading to substantial economic losses in the swine industry. Emerging evidence suggests that certain viruses exploit Suppressor of Cytokine Signaling 3 (SOCS3), a key immune checkpoint protein, to subvert host innate immunity by suppressing cytokine signaling. While SOCS3 has been implicated in various viral infections, its regulatory role in PCV2 replication remains undefined. This study aims to elucidate the mechanisms underlying the interplay between SOCS3 and PCV2 during viral pathogenesis. Porcine SOCS3 was amplified using RT-PCR and stably overexpressed in PK-15 cells through lentiviral delivery. Bioinformatics analysis facilitated the design of three siRNA candidates targeting SOCS3. We systematically investigated the effects of SOCS3 overexpression and knockdown on PCV2 replication kinetics and host antiviral responses by quantifying the viral DNA load and the mRNA levels of cytokines. PCV2 infection upregulated SOCS3 expression at both transcriptional and translational levels in PK-15 cells. Functional studies revealed that SOCS3 overexpression markedly enhanced viral replication, whereas its knockdown suppressed viral proliferation. Intriguingly, SOCS3-mediated immune modulation exhibited a divergent regulation of antiviral cytokines: PCV2-infected SOCS3-overexpressing cells showed elevated IFN-β but suppressed TNF-α expressions, whereas SOCS3 silencing conversely downregulated IFN-β while amplifying TNF-α responses. This study unveils a dual role of SOCS3 during subclinical porcine circovirus type 2 (PCV2) infection: it functions as a host-derived pro-viral factor that facilitates viral replication while simultaneously reshaping the cytokine milieu to suppress overt inflammatory responses. These findings provide novel insights into the mechanisms underlying PCV2 immune evasion and persistence and establish a theoretical framework for the development of host-targeted control strategies. Although our results identify SOCS3 as a key host determinant of PCV2 persistence, the precise molecular pathways involved require rigorous experimental validation. Full article

Porcine circovirus type 3 (PCV3) has been detected in wild boars across many countries in Europe, Asia, and South America. However, data regarding the presence of porcine circoviruses in wild boars and ticks remain limited. In this study, we investigated the presence and genetic characteristics of PCV3 in wild boars and parasitizing ticks in Jiangsu, China. Samples, including whole blood, serum, tissues, feces, and oral fluids from wild boars, as well as ticks collected from 47 wild boars, were obtained between March 2021 and November 2022. PCR results indicated that 34.0% (16/47) of wild boars tested positive for PCV3, while ELISA detected 41.9% (18/43) seropositivity. RT-qPCR results showed that 7.2% (6/83) were positive for PCV3 in 83 analyzed tick samples, with all positive samples identified as Amblyomma testudinarium. The PCV3 genome obtained from wild boars was classified as PCV3a and was closely related to the strain identified in domestic pigs in Nanjing, Jiangsu Province. Collectively, these findings confirm the presence of PCV3 in wild boars in Jiangsu and suggest a possible link of PCV3 infection among domestic pigs, wild boars, and ticks, providing new insights into the transmission risk of PCV3 at wildlife–livestock–human interfaces and highlighting the genetic homology between strains from wild and domestic pigs. Full article

Background/Objectives: This study describes multiple trials demonstrating the safety and efficacy of a tri-valent vaccine against diseases caused by Porcine Circovirus Types 2a and 2d (PCV2a, PCV2d), Mycoplasma hyopneumoniae, and Lawsonia intracellularis. Methods: For each of the PCV2a and PCV2d onset of immunity (OOIs) and duration of immunity (DOI) studies, 25 pigs were vaccinated with a tri-valent vaccine and 25 with placebo. After dual challenge with PCV2a and porcine reproductive and respiratory virus (PRRSV) (OOI) or single challenge with PCV2d (OOI and DOI), respectively, viremia and lymphoid depletion data were collected. For each of the M. hyopneumoniae OOI and DOI studies, 35 to 70 pigs were vaccinated with the tri-valent vaccine and 35 to 70 with placebo. After M. hyopneumoniae challenge, the lungs were scored for disease. For the L. intracellularis OOI study, 40 to 50 pigs were vaccinated with the tri-valent and 40 to 50 with placebo. After L. intracellularis challenge, the intestines were scored for disease. All pigs were vaccinated at approximately 3 weeks of age, and all placebo vaccines were product matched. Results: Vaccinating pigs with a tri-valent vaccine reduced viremia and lymphoid depletion due to PCV2a and PCV2d, reduced lung lesions due to M. hyopneumoniae and reduced ileum and colonization scores due to L. intracellularis. Conclusions: The trials reported here demonstrated the safety and efficacy of the first ready-to-use PCV2, M. hyopneumoniae, and L. intracellularis vaccine for pigs. Full article

Porcine circoviruses (PCVs), encompassing porcine circovirus type 1 (PCV1), porcine circovirus type 2 (PCV2), porcine circovirus type 3 (PCV3), and porcine circovirus type 4 (PCV4), have been documented in China and represent a significant threat to the swine industry. Nevertheless, there is a paucity of data regarding the infection characteristics of PCVs across different age groups within intensive pig farming operations. In this investigation, a systematic cross-sectional methodology was employed to collect 415 testicular processing fluid samples and 1583 serum samples from 30 breeding farms and 27 fattening farms in China. All samples underwent analysis using real-time quantitative polymerase chain reaction (qPCR). Among the testicular fluid samples from suckling pigs, the detection rates for PCV1, PCV2, PCV3, and PCV4 were 56.9%, 31.1%, 75.4%, and 2.2%, respectively. The lowest mean cycle threshold (Ct) values for PCV1 and PCV3 were observed in testicular fluid as opposed to serum samples. At the individual level, the detection rate of PCV1 was significantly higher in fattening pigs (28.7%) and sows (28.7%) compared to nursery pigs (8.5%). The detection rate of PCV2 was highest in fattening pigs (43.1%) and lowest in sows (19.2%). The infection profile of PCV3 contrasted markedly with that of PCV2, exhibiting the lowest prevalence in fattening pigs (8.1%) and the highest in sows (46.1%). PCV4 was infrequently detected across all age groups, with prevalence rates ranging from 0% to 1.7%. Furthermore, the incidence of mixed infections involving the four PCV types was observed to be 12.7% in nursery pigs, 16.8% in fattening pigs, and 22.4% in sows. Notably, no strong correlation was identified between any two co-detected PCV types across all pig age categories. The findings of this study contribute valuable insights into the infection dynamics of PCVs across different pig age groups. Additionally, this research offers critical reference information for devising strategies to prevent PCV infections in intensive pig farming operations in China. Full article

Background/Objectives: Porcine circovirus type 2 (PCV2) has a major impact on swine productivity. Vaccines are used to aid in control and mitigate production losses. We investigated the protection provided by an intradermal PCV2 vaccine against a field strain in Taiwan. Methods: We conducted a safety and efficacy study. In the safety study, four Specific Pathogen Free (SPF) piglets were enrolled in the study. One was selected as the control and left unvaccinated, one was selected to be intradermally vaccinated with five times the standard dose (1 mL, Porcilis^® PCV ID), and the other two were vaccinated with two times the standard dose (0.4 mL, Porcilis^® PCV ID). All animals were observed for 3 weeks for adverse events post-vaccination. In the efficacy study, twelve SPF pigs negative for the PCV2 antibody were randomly divided into two groups. The first group of six pigs was vaccinated (Porcilis PCV ID, 0.2 mL) intradermally at 3 weeks of age. The second group of six pigs was sham vaccinated with 0.2 mL of normal saline. At 7 weeks of age, all pigs were challenged with the PCV2 strain CYC08 (1 × 10⁵ TCID₅₀/mL) by nasal and intramuscular injection. Clinical monitoring of body temperature and mortality was conducted daily. At 11 weeks of age, all animals were sacrificed for histopathological analysis. Results: No adverse events were reported in the safety study. In the efficacy study, the vaccinated animals had statistically improved results in the following areas post-challenge: body temperature rise, viremia, virus shedding, mortality, tissue histopathological and microscopic scores. Conclusions: The study results support that a one-dose PCV2 vaccine administered intradermally with a needle-free injector is safe and provides protection when challenged with a field PCV2 strain. Full article

Porcine circovirus type 3 (PCV3) is an emerging pathogen that causes porcine dermatitis, nephropathy syndrome-like symptoms, multisystemic inflammation, and reproductive failure. The PCV3 capsid (Cap) protein interacts with DDX21, which functions mainly through controlling interferon (IFN)-β levels. However, how the interaction between DDX21 and PCV3 Cap regulates viral replication remains unknown. In the present study, upon shRNA-mediated DDX21 depletion in PK-15 cells, we observed impaired PCV3 proliferation via a lentivirus-delivered system, as indicated by reduced replicase (Rep) protein levels and viral titers. Furthermore, DDX21 negatively regulated IFN-β and interferon-stimulated gene (ISG) levels, promoting PCV3 replication. Mechanistically, PCV3 Cap co-localized and interacted with DDX21, and the nuclear localization signal (NLS) of PCV3 Cap and ⁷⁶³GSRSNRFQNK⁷⁷² at the C-terminal domain (CTD) of DDX21 were indispensable to the interaction. Moreover, PCV3 infection prevented the repression of DDX21 to facilitate its pro-viral activity. Taken together, these results show that DDX21 promotes PCV3 replication by binding to the PCV3 Cap protein and prohibiting IFN-β response, which provides important insight on the prevention and control of PCV3 infection. Full article

Coinfections with porcine circovirus types 2, 3, and 4 (PCV2, PCV3, and PCV4) are increasingly being detected in the swine industry. However, there is no commercially available vaccine which prevents coinfection with PCV2, PCV3, and PCV4. The development of a vaccine expressing capsid (Cap) fusion proteins of multiple PCVs represents a promising approach for broadly preventing infection with PCVs. In this study, we developed a PCV subunit vaccine candidate (Cap 2-3-4) by predicting, screening, and fusing antigenic epitopes of Cap proteins of PCV2, PCV3, and PCV4. Immunoprotection assays showed that the prokaryotic expression of Cap 2-3-4 could effectively induce high levels of PCV2, PCV3, and PCV4 Cap-specific antibodies and successfully neutralize both PCV2 and PCV3. Furthermore, Cap 2-3-4 demonstrated a potent ability to activate cellular immunity and thus prevent lung damage in mice. This study provides a new option for the development of broad vaccines against PCVs. Full article

Porcine circovirus 3 (PCV3) is a small non-enveloped circovirus associated with porcine dermatitis and nephropathy syndrome (PDNS). It has occurred worldwide and poses a serious threat to the pig industry. However, there is no commercially available vaccine. PCV3 capsid protein (Cap) is an ideal antigen candidate for serodiagnosis. Here, a novel fully automated chemiluminescence enzyme immunoassay (CLEIA) was developed to detect antibodies (Abs) to Cap in porcine serum. Recombinant PCV3 Cap, self-assembled into virus-like particles (VLPs), was produced using baculovirus and coupled to magnetic particles (Cap-MPs) as carriers. Combined with an alkaline phosphatase (AP)–adamantane (AMPPD) system, Cap-Abs can be rapidly measured on a fully automated chemiluminescence analyzer. Under optimal conditions, a cut-off value of 31,508 was determined, with a diagnostic sensitivity of 96.8% and specificity of 97.3%. No cross-reactivity was observed with PCV1 and PCV2 and other common porcine pathogens, and both intra-assay and inter-assay coefficients were less than 5% and 10%, respectively. Prepared Cap-MPs can be stored at 4 °C for more than 6 months. Importantly, this CLEIA had a good agreement of 95.19% with the commercially available kit, demonstrating excellent analytical sensitivity and significantly reduced operating time and labor. A serological survey was then conducted, and showed that PCV3 continues to spread widely in South China. In conclusion, our CLEIA provides time and labor-saving, and a reliable tool for PCV3 epidemiological surveillance. Full article

Objectives: This study investigated the dynamics of porcine circovirus type 2 (PCV2) and PCV3 on a commercial farm following PCV2 vaccination. Methods: Serum samples from 35 pigs, starting at 3 weeks of age, were collected weekly until 21 weeks of age. Oral fluids from six pens of pigs of the same age were also analyzed. Viral DNA was assessed in pooled sera and individual oral fluid samples, while antibodies (IgG and IgA) were measured in the serum and oral fluids. Productive parameters, including weekly mortality and cumulative mortality, were evaluated. Results: The results revealed that PCV2 and PCV3 co-infection was detected in pigs at 8 weeks of age, with PCV3 being detected in oral fluids two weeks earlier. PCV3 DNA was detected in oral fluids at 4 weeks of age. PCV2 IgG antibodies in the serum increased gradually after vaccination, peaking at 7 weeks of age, then declined and stabilized until 21 weeks of age. PCV3 IgG antibodies fluctuated early but were uniformly positive after 13 weeks of age. In oral fluids, PCV2 IgG and IgA antibodies showed a strong response only at 3 and 23 weeks of age. In contrast, a strong and consistent IgG response was observed in oral fluids in the absence of PCV2 and PCV3 co-infection of pigs at 3 to 11 weeks of age. The farm’s productive parameters remained stable throughout the study. Conclusions: These findings suggest that PCV2 and PCV3 co-infection, along with high PCV3 detection levels in serum and oral fluids, may have an impact on the efficacy of PCV2 vaccination. Full article

Recently, the emergence of HP-PRRSV (Highly Pathogenic porcine reproductive and respiratory syndrome virus) and the exacerbation of mixed infections of PRRSV and PCV have resulted in significant economic losses for the Chinese pig industry. This study collected a total of 226 samples suspected of infection with the aforementioned viruses from diverse pig farms in seven urban districts of central and northern Guangdong Province between 2020 and 2022. The positive rates of PRRSV, PCV2, and PCV3 in the samples were 33.2%, 37.6%, and 7.5%, respectively, and there were various mixed-infection scenarios present in the samples. This study successfully isolated multiple strains of PRRSV2 and PCV2 from their positive samples, and obtained the gene sequences of six PCV3 (ORF1 + ORF2) from samples. The associated sequences obtained were subjected to bioinformatic analysis and revealed the following:Predominantly prevalent strains of PRRSV in Guangdong Province include HP-PRRSV and NADC30-like variants, whereas PCV2 is primarily represented by the 2b and 2d subtypes. Specifically, the amino acid variation patterns exhibited by the PRRSV GP5 and NSP2 proteins of the strains sg_2108, qy_2008, and fs_2108 under environmental selective pressure are remarkably similar to the characteristics of Highly Pathogenic PRRSV; thus, it is inferred that they may possess higher virulence. The detected PCV3 strains were predominantly concentrated within the PCV3a-IM branch. All PRRSV strains involved in this study are wild-type-PRRSV (wt-PRRSV), comprising three recombinant strains and seven highly virulent strains. Among these strains, the ORF1a gene exhibited the highest variability in their genomes. Environmental selective pressure may enhance the virulence and immune evasion capabilities of PRRSV and drive mutations in the Cap proteins of PCV2 and PCV3. Conversely, PCV2 and PCV3 strains demonstrated greater stability in genetic evolution. In conclusion, this study enhances the epidemiological data regarding PRRSV, PCV2, and PCV3 in Guangdong Province, China, and is significant for the surveillance, prevention, and active control of these three diseases. Full article

The impact of porcine circovirus (PCV) on the worldwide pig industry is profound, leading to notable economic losses. Early and prompt identification of PCV is essential in managing and controlling this disease effectively. A range of detection techniques for PCV have been developed and primarily divided into two categories focusing on nucleic acid or serum antibody identification. The methodologies encompass conventional polymerase chain reaction (PCR), real-time fluorescence quantitative PCR (qPCR), fluorescence in situ hybridization (FISH), loop-mediated isothermal amplification (LAMP), immunofluorescence assay (IFA), immunohistochemistry (IHC), and enzyme-linked immunosorbent assay (ELISA). Despite their efficacy, these techniques are often impeded by the necessity for substantial investment in equipment, specialized knowledge, and intricate procedural steps, which complicate their application in real-time field detections. To surmount these challenges, a sensitive, rapid, and specific PCV detection method using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR)-Cas12a/13a coupled with isothermal amplification, such as enzymatic recombinase amplification (ERA), recombinase polymerase amplification (RPA), and loop-mediated isothermal amplification (LAMP), has been developed. This novel method has undergone meticulous optimization for detecting PCV types 2, 3, and 4, boasting a remarkable sensitivity to identify a single copy per microliter. The specificity of this technique is exemplary, with no observable interaction with other porcine viruses such as PEDV, PRRSV, PRV, and CSFV. Its reliability has been validated with clinical samples, where it produced a perfect alignment with qPCR findings, showcasing a 100% coincidence rate. The elegance of merging CRISPR-Cas technology with isothermal amplification assays lies in its on-site testing without the need for expensive tools or trained personnel, rendering it exceptionally suitable for on-site applications, especially in resource-constrained swine farming environments. This review assesses and compares the process and characteristics inherent in the utilization of ERA/LAMP/RPA-CRISPR-Cas12a/Cas13a methodologies for the detection of PCV, providing critical insights into their practicality and effectiveness. Full article

Porcine circovirus 3 (PCV-3) has emerged as a significant pathogen affecting global swine populations, yet its epidemiology and clinical implications remain incompletely understood. This retrospective study aimed to investigate the prevalence and histopathological features of PCV-3 infection in pigs from Switzerland, focusing on archival cases of suckling and weaner piglets presenting with suggestive lesions. An in-house qPCR assay was developed for detecting PCV-3 in frozen and formalin-fixed paraffin-embedded tissues, enhancing the national diagnostic capabilities. Histopathological reassessment identified PCV-3 systemic disease (PCV-3-SD) compatible lesions in 19 (6%) of archival cases, with 47% testing positive by qPCR across various organs. Notably, vascular lesions predominated, particularly in mesenteric arteries, heart, and kidneys. The study confirms the presence of PCV-3 in Switzerland since at least 2020, marking the first documented cases within the Swiss swine population. Despite challenges in in situ hybridization validation due to prolonged formalin fixation, the findings indicate viral systemic dissemination. These results contribute to the understanding of PCV-3 epidemiology in Swiss pigs, emphasizing the need for continued surveillance and further research on its clinical implications and interaction with host factors. Our study underscores the utility and limitations of molecular techniques in confirming PCV-3 infections. Full article

The porcine circovirus type 3 (PCV3) infection is an emerging disease associated with clinical signs of porcine dermatitis and nephropathy syndrome (PDNS)-like clinical signs. Currently, there is a lack of effective vaccines and therapeutics against this disease. Therefore, rapid, effective, sensitive, and specific detection methods are crucial for the timely identification, prevention, and control of PCV3. In this study, we developed one- and two-pot visual detection methods for PCV3 using a clustered regularly interspaced short palindromic repeat (CRISPR)/Cas12a detection system combined with recombinase polymerase amplification (RPA). These two methods demonstrated no cross-reactivity with eight other swine viruses and exhibited minimum detection limits of five and two copies of viral DNA, respectively, revealing their high specificity and sensitivity. During a clinical sample detection within 30 min, the coincidence rates between the one- and two-pot detection methods and real-time quantitative polymerase chain reaction (qPCR) were 100%. In conclusion, both one- and two-pot RPA-CRISPR/Cas12a detection methods have significant potential for the rapid, sensitive, and specific visual detection of PCV3. Full article

Detection methods have been developed to prevent transmission of zoonotic or xenozoonotic porcine viruses after transplantation of pig organs or cells to the recipient (xenotransplantation). Eleven xenotransplantation-relevant viruses, including porcine cytomegalovirus, porcine roseolovirus (PCMV/PRV), porcine lymphotropic herpesviruses -1, -2, -3 (PLHV-1, 2, 3), porcine parvovirus (PPV), porcine circovirus 2, 3, 4 (PCV2, 3, 4), hepatitis E virus genotype 3 (HEV3), porcine endogenous retrovirus-C (PERV-C), and recombinant PERV-A/C have been selected. In the past, several pig breeds, minipigs, and genetically modified pigs generated for xenotransplantation had been analyzed using these methods. Here, spleen, liver, and blood samples from 10 German slaughterhouse pigs were screened using both PCR-based and immunological assays. Five viruses: PCMV/PRV, PLHV-1, PLHV-3, and PERV-C, were found in all animals, and PCV3 in one animal. Some animals were latently infected with PCMV/PRV, as only virus-specific antibodies were detected. Others were also PCR positive in the spleen and/or liver, indicative of an ongoing infection. These results provide important information on the viruses that infect German slaughterhouse pigs, and together with the results of previous studies, they reveal that the methods and test strategies efficiently work under field conditions. Full article

Porcine parvoviruses (PPVs) are among the most important agents of reproductive failure in swine worldwide. PPVs comprise eight genetically different species ascribed to four genera: Protoparvovirus (PPV1, PPV8), Tetraparvovirus (PPV2-3), Copiparvovirus (PPV4-6), and Chaphamaparvovirus (PPV7). In 2016, PPV7 was firstly detected in the USA and afterwards in Europe, Asia, and South America. Recently, it was also identified in Italy in pig farms with reproductive failure. This study aimed to evaluate the circulation of PPV7 in domestic and wild pigs in Sardinia, Italy. In addition, its coinfection with Porcine Circovirus 2 (PCV2) and 3 (PCV3) was analysed, and PPV7 Italian strains were molecularly characterised. PPV7 was detected in domestic pigs and, for the first time, wild pigs in Italy. The PPV7 viral genome was detected in 20.59% of domestic and wild pig samples. PPV7 detection was significantly lower in domestic pigs, with higher PCV2/PCV3 co-infection rates observed in PPV7-positive than in PPV7-negative domestic pigs. Molecular characterisation of the NS1 gene showed a very high frequency of recombination that could presumably promote virus spreading. Full article