Search Results (222)

Porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae (Mhp) are major contributors to the porcine respiratory disease complex. Although PCV2-Mhp bivalent inactivated vaccines are useful for simultaneous disease control, their immunogenicity may be improved by adjuvant optimization. This study evaluated a composite adjuvant consisting of porcine interleukin-2 (IL-2), IL-4, IL-6 and MnJ(beta), a colloidal manganese adjuvant, in an initial murine immunogenicity model. Thirty female Kunming mice were assigned to three groups (n = 10/group): bivalent antigen plus IL-2/IL-4/IL-6/MnJ(beta), bivalent antigen plus MnJ(beta), or phosphate-buffered saline. Body weight, complete blood count, peripheral blood T- and B-cell subsets, PCV2-specific IgG and Mhp-specific indirect hemagglutination titers were monitored after primary and booster immunization. The composite formulation did not suppress body-weight gain or induce sustained abnormalities in erythrocyte- or platelet-related indices. WBC, neutrophil, lymphocyte and monocyte counts were elevated in group A at days 7 and 28 post-primary immunization, indicating transient immune activation. Day-56 flow cytometry indicated increased CD19+IgM-IgD- B-cell and effector/memory T-cell-associated responses. PCV2-specific IgG increased from day 14 onward. At day 56, the OD450 value in group A reached 1.532 ± 0.006, compared with 1.095 ± 0.004 in group C1 and 0.102 ± 0.002 in group C2, corresponding to approximately 1.40-fold and 15.09-fold higher levels than the MnJ(beta)-adjuvanted and PBS control groups, respectively. Mhp-specific IHA titers were also maintained at high levels after booster immunization; at day 56, group A showed a log2 endpoint titer of 13.00 ± 0.00, corresponding to a GMT of 1:8192, whereas group C1 showed a log2 endpoint titer of 12.00 ± 0.00, corresponding to a GMT of 1:4096, and group C2 remained negative. These results indicate that the IL-2/IL-4/IL-6/MnJ(beta) composite adjuvant demonstrates potential for improving antibody and peripheral lymphocyte responses to PCV2-Mhp bivalent antigen, but protective efficacy must be confirmed in target-species challenge studies. Full article

Although commercial vaccines against porcine circovirus type 2 (PCV2) have been widely implemented globally, PCV2 remains endemic in swine populations, accompanied by ongoing genotype replacement. Meanwhile, the emergence of novel porcine circoviruses (PCVs), including PCV3 and PCV4, has further complicated the prevention and control of porcine circovirus-associated diseases (PCVAD). This study systematically characterized the epidemiological patterns and genetic diversity of PCVs circulating in Eastern China. A total of 739 clinical samples collected between 2010 and 2016 were screened for PCV2. Additionally, 653 samples obtained during 2023–2024 were analyzed using a triplex real-time quantitative PCR (qPCR) assay for the simultaneous detection of PCV2, PCV3, and PCV4. Full-genome amplification and sequencing were subsequently performed on all PCR-positive samples. Epidemiological analysis revealed an overall PCV2 positivity rate of 37.62% during 2010–2016. In the 2023–2024 cohort, the positivity rates for PCV2 and PCV3 were 35.99% and 16.39%, respectively, with a co-infection rate of 10.26%. Notably, no PCV4-positive samples were detected. Phylogenetic analysis demonstrated that PCV2d is the predominant genotype in Eastern China. Furthermore, PCV2g strains were identified in clinical samples for the first time in mainland China, while PCV3b were determined to be the dominant circulating subtype of PCV3. Multiple critical amino acid substitutions were identified within the neutralizing epitopes of the PCV2 Cap protein, and a recombination event involving a PCV2d vaccine strain and a PCV2c reference strain was detected. In contrast, the PCV3 genome exhibited a high degree of genetic conservation. Collectively, these findings expand the molecular epidemiological landscape of PCVs in Eastern China and elucidate the evolutionary dynamics of circulating PCV strains, providing important insights for the development of next-generation vaccines and region-specific PCVAD control strategies. Full article

Background/Objectives: Porcine circovirus type 2 (PCV2) remains a major viral agent in pig production worldwide due to its association with economically relevant diseases and productivity losses. Nine genotypes (PCV2a–PCV2i) have been reported, with successive genotype shifts characterized by the historical predominance of PCV2a, the expansion of PCV2b, and the emergence of PCV2d as the predominant genotype in several swine-producing countries. The aim of this study was to characterize the ORF2 gene of PCV2 circulating in Jalisco, Mexico, to provide updated information for regional surveillance and control strategies. Methods: Samples were collected from 80 pig farms located in four regions of Jalisco with different pig density levels and production systems. PCV2-positive samples were subjected to ORF2 amplification and sequencing. Genotype assignment, phylogenetic analysis, and in silico recombination screening using multiple detection methods were performed. All sequences were deposited in GenBank. Results: A total of 70 ORF2-PCV2 sequences were obtained and assigned to two genotypes: PCV2d (51/70, 72.9%) and PCV2a (19/70, 27.1%). The sequences were submitted to GenBank under accession numbers PV235521–PV235590. Recombination analysis identified seven recombinant sequences, and unusual ORF2 extensions were detected in some sequences, evidencing the presence of genetic variants circulating in the region. Conclusions: These findings confirm the predominance of PCV2d in Jalisco while highlighting the continued circulation of PCV2a. The coexistence of both genotypes, together with recombinant sequences and ORF2 extensions, indicates ongoing PCV2 genetic diversification in the region. Continuous molecular surveillance remains essential to monitor viral evolution, support genotype-informed control strategies, and strengthen swine health programs. Full article

Porcine circovirus type 2 (PCV2) is the primary causative agent of a spectrum of porcine circovirus-associated diseases (PCVDs) and remains a major threat to the global swine industry. In this study, ten monoclonal antibodies (mAbs) targeting the Cap protein of PCV2 were generated and characterized. One mAb, designated 4C4, which exhibited high reactivity, strong neutralizing activity, and superior blocking efficacy, was selected for horseradish peroxidase (HRP) labeling. After optimizing the reaction parameters, a blocking ELISA was developed for the detection of the anti-PCV2 antibody. Using receiver operating characteristic (ROC) curve analysis, a cutoff value of 40% was established to distinguish positive from negative serum samples. The sensitivity and specificity of this blocking ELISA method were 98.66% and 100%, respectively. No cross-reactivity was observed with serum antibodies against classical swine fever virus (CSFV), porcine epidemic diarrhea virus (PEDV), porcine deltacoronavirus (PDCoV), porcine reproductive and respiratory syndrome virus (PRRSV), or pseudorabies virus (PRV). Intra-assay and inter-assay repeatability tests yielded coefficients of variation (CVs) all below 10%, confirming the assay’s excellent reproducibility. Simultaneous testing of 312 clinical porcine serum samples using the developed bELISA and a commercial indirect ELISA kit revealed an overall coincidence rate of 99.04%. In addition, the percentage inhibition (PI) in the bELISA was strongly correlated with serum anti-PCV2 neutralizing antibody titers. In conclusion, the blocking ELISA developed herein demonstrates high sensitivity, strong specificity, and good reproducibility, serving as a potentially effective tool for the detection of the anti-PCV2 antibody and epidemiological investigation. Full article

The Getah virus (GETV) is a mosquito-borne pathogen that infects diverse hosts, including pigs, horses, and humans, which can cause swine reproductive disorders such as abortion and stillbirth, posing a potential threat to animal and public health. Therefore, there is an urgent need for efficient and accurate serological diagnostic methods for surveillance and control of GETV. However, commercial diagnostic kits for swine GETV infection remain unavailable. In this study, we developed a novel enzyme-linked immunosorbent assay (ELISA) based on a GETV-specific epitope peptide (E2EP3) for serological detection. The N-terminally biotinylated E2EP3 peptide was synthesized, and the reaction conditions were systematically optimized, resulting in a cut-off value of 0.363. The assay exhibited no cross-reactivity with Japanese encephalitis virus (JEV), porcine circovirus type 2 (PCV2), porcine circovirus type 3 (PCV3), pseudorabies virus (PRV), or classical swine fever virus (CSFV). It demonstrated good reproducibility and high sensitivity, detecting GETV-positive serum diluted up to 1:640. The overall agreement rate reached 95%, consistent with a conventional recombinant GETV E2 protein-based ELISA. Benefiting from the biotin–streptavidin system, this assay achieved strong signal amplification and low background. Moreover, the procedure is simple, cost-effective, and stable, making it suitable for GETV large-scale serological surveillance and vaccine evaluation. Full article

Live virus inoculation (LVI) is widely used for porcine reproductive and respiratory syndrome virus (PRRSV) stabilization, yet preparation practices and pathogen composition remain poorly characterized. This study aimed to evaluate variability in LVI preparation, quantify PRRSV genomic load, and detect additional swine pathogens. A survey was conducted to document LVI preparation methods, and samples were analyzed using reverse-transcription quantitative PCR (RT-qPCR) for PRRSV quantification and next-generation sequencing for PRRSV and the metagenomic characterization of additional pathogens. Among 61 LVI samples, substantial variability was observed in preparation practices and viral composition, with 31 distinct PRRSV variants identified and seven samples containing multiple strains. PRRSV RNA concentrations ranged from 10^1.69 to 2.52 × 10⁸ copies/mL. Metagenomic analysis detected a complete or near-complete genome for PRRSV, porcine parvovirus, and porcine circovirus type 2. Genome fragments of porcine sapovirus, porcine rotavirus, porcine astrovirus, and bacterial genetic material from Salmonella spp., Pseudomonas spp., Streptococcus spp., and Escherichia coli were also detected. These findings highlight substantial heterogeneity in LVI materials and encourage the use of next-generation sequencing to verify LVI PRRSV composition and screen for co-existing pathogens, reinforcing the need for standardized preparation protocols and further investigation into optimal viral dosing for effective immunization. Full article

Porcine circovirus type 2 (PCV2) is a pathogen of major importance in swine that is characterized by ongoing genetic evolution. To provide an updated epidemiological assessment for China, our study analyzed 1051 clinical samples collected from 27 provincial-level regions between 2023 and 2024. The overall PCV2 positivity rate was 65.18%, with detection rates showing significant seasonal variation, with higher rates in spring and summer. Genotypic analysis of 379 open reading frame 2 (ORF2) sequences identified PCV2d as the dominant genotype (78.89%), and no significant geographic clustering was observed. Coinfection with porcine reproductive and respiratory syndrome virus (PRRSV) is common, yet statistical tests have revealed an epidemiologically independent relationship between the two viruses. Notably, analysis of the capsid (Cap) protein revealed that high-frequency amino acid mutations were concentrated in immunodominant loop regions. These mutations resulted in genotype-specific substitutions within key neutralizing epitopes. This study provides the latest large-scale national baseline data on PCV2 in China for 2023–2024. It systematically analyzes the epidemiological characteristics of the dominant PCV2d genotype in the post-African Swine Fever era, the patterns of antigenic epitope mutations in the Cap protein, and their potential impact on vaccine efficacy. The study fills a gap in recent national epidemiological data on PCV2 in China and provides a basis for the targeted prevention and control of PCV2 and the updating of vaccine strains. Full article

Mycoplasma hyopneumoniae (Mhyo) and porcine circovirus type 2 (PCV2) infections cause enormous economic losses in the swine production sector. Vaccination remains the most effective strategy against the complex clinical entities caused by these pathogens. While effective vaccines against PCV2 are available, immunisation against Mhyo continues to be challenging. In parallel, intradermal (ID) vaccination can optimise time and costs while providing faster and user-safe administration. This study compares the safety and efficacy of commercial porcine vaccines against Mhyo and PCV2, including intramuscular (IM) and ID ones: (1) ID recombinant Mhyo-PCV2, (2) ID recombinant PCV2 + ID inactivated Mhyo, (3) IM bivalent inactivated Mhyo and recombinant PCV2, (4) IM bivalent inactivated Mhyo and inactivated chimeric PCV1-PCV2 and (5) IM inactivated Mhyo + IM inactivated PCV2. Safety, evaluated through clinical signs, adverse effects, local reactions, and average daily weight gain, has been confirmed for all vaccines. Following challenge with both pathogens, all products reduced PCV2 viremia and faecal shedding, proving efficacy against PCV2 infection. In contrast, only the ID recombinant Mhyo-PCV2 and the IM inactivated Mhyo + IM inactivated PCV2 vaccines, significantly reduced lung lesions related to Mhyo infection, indicating a better protection compared to the other vaccines. Full article

The circulation of viruses of medical and veterinary importance is monitored to evaluate risks to both human and animal health. Among the species most commonly used in surveillance programs, the wild boar (Sus scrofa) plays a key role due to its high population density and its contacts with rural swine herds in the areas under investigation. In the present study, molecular (real-time PCR) and serological analyses were conducted on wild boar samples collected in the regions of Apulia, Basilicata, Campania, and Calabria. Specifically, molecular detection was applied to IAVs, FLVs, and Porcine PCV-2, while serological testing was used to assess exposure to IAVs, FLVs, and ADV. Serological results showed an 8.31% positivity for IAVs, whereas viral presence detected by PCR was 1.17%. No active infections were detected for WNV, with only a single seropositive sample (0.30%), while ADV showed a seroprevalence of 2.61%. PCV-2 was detected exclusively by molecular analysis in 66 out of 223 tested animals (29.6%). The overall objective of the study is to deepen the understanding of virus circulation in the wildlife of Southern Italy, using the wild boar as an additional sentinel species for epidemiological surveillance activities. The distinctive feature of the project lies in its multi-pathogen approach applied to a reference population distributed across a particularly wide geographical area, allowing for the simultaneous assessment of the circulation of different viruses over a large territory. Full article

The distribution and genetic diversity of economically significant pathogens, including porcine reproductive and respiratory syndrome virus (PRRSV), porcine circovirus type 2 (PCV2), porcine circovirus type 3 (PCV3), and porcine parvovirus 1 (PPV1), across extensive Russian territory within wild boars that serve as reservoirs remain poorly characterized. This study aimed to conduct a molecular epidemiological survey of these viruses in wild boar populations. The samples of 476 wild boars, collected across Russia between 2021 and 2025, were tested by PCR for the detection of viral genomes. While PRRSV was not detected, we found high detection rates for PCV2 (34.9%), PCV3 (35.5%), and PPV1 (25.4%). For PCV2, the co-circulation of two genotypes, PCV2b (5/53) and PCV2d (48/53), was observed. All 29 PCV3 sequences belonged to the PCV3a genotype. For PPV1, the presence of the PPV1a, PPV1b, and PPV1d genotype, as well as unclassified isolates, was shown. Co-infection of different viruses was detected: PCV2/PCV3 (16.0%), PCV2/PPV1 (6.9%), PCV2/PCV3/PPV1 (6.9%), and PCV3/PPV1 (4.4%). This is the first comprehensive study that demonstrates the wide dissemination and genetic diversity of PCV2, PCV3, and PPV1 within the wild boar population in Russia and highlights their role as a potential reservoir in viral evolution and spread. Full article

Porcine circovirus (PCV) is a major viral pathogen associated with multiple systemic diseases in pigs, inflicting significant economic losses to the global swine industry. To investigate the epidemiology and genetic evolution of porcine circovirus in Liaoning Province, China, PCV was detected by qPCR in 1224 clinical samples. Subsequent genetic evolution analysis of the Cap gene was conducted, and an indirect ELISA and monoclonal antibody were established. The results demonstrated PCV2 and PCV3 positivity rates of 14.13% and 21.90%, respectively, with a coinfection rate of 4.08%. All six sequences were identified as belonging to the PCV3b subtype. A representative PCV3 strain was expressed in a prokaryotic expression system and used to immunize 6-week-old female BALB/c mice, resulting in serum antibody titers reaching 1:512,000. The positive hybridoma cell line 3E6 was selected and identified as expressing IgM heavy chains and κ light chains. The prepared monoclonal antibody 3E6 exhibited specific reactivity with the Cap protein. Collectively, this study elucidates the recent epidemiological status and evolutionary characteristics of PCV in pig populations in Liaoning Province, thereby providing an important theoretical basis and reference data for disease prevention, control, diagnosis, and vaccine development. Full article

Porcine circovirus 2 (PCV2) is a DNA virus that is classified in the genus Circovirus of the Circoviridae family, which is a causative agent of Porcine Circovirus-Associated disease (PCVAD). PCVAD continues to cause substantial losses in global pig farming, with PCV2d being the prevalent genotype worldwide, including in Vietnam. In this study, we focused on generating a recombinant PCV2d Cap protein fused to the GCN4pII motif (Cap2d-pII) in a plant-based system and evaluating its immunogenicity. The Cap2d-pII gene was cloned into a plant expression vector and introduced into Agrobacterium tumefaciens for transient expression in Nicotiana benthamiana leaves. Western blot analysis confirmed the high accumulation of the Cap2d-pII protein, which was purified by Immobilized affinity chromatography and used for immunizing mice. ELISA and immunoperoxidase monolayer assay results demonstrated that immunization with the recombinant protein elicited robust humoral and cellular immune responses. At 56 days after immunization, mice vaccinated with the Cap2d-pII protein generated PCV2d-specific IgG titers and IFN-γ responses that were consistent with those in mice receiving the commercial inactivated vaccine. These observations confirm that the plant-expressed Cap2d-pII antigen effectively activates both antibody- and T cell-mediated immune pathways. Collectively, this study identifies the Cap2d-pII protein as a promising plant-derived vaccine candidate for the development of effective and affordable PCV2d subunit vaccines. Full article

Background: Porcine circovirus type 2 (PCV2) remains one of the most important pathogens that infects swine, causing considerable economic losses worldwide. PCV2 vaccines are commercially available, and the development of experimental vaccines that could confer better protection against emerging genotypes is underway. The expression of virus-like particles (VLPs) carrying different PCV2 capsid (Cap) peptides in E. coli was recently reported. These chimeric particles were adjuvated with an oil-in-water emulsion with polymer and induced different titers of serum IgG in BALB/c mice after a single subcutaneous injection. The aim of this study was to assess the immune response and protective efficacy elicited by VLPs carrying the PCV2b Cap carboxy-terminal peptide in the target species. Methods: Domestic pigs (Sus scrofa domesticus) were immunized intramuscularly with 25 μg of adjuvated chimeric VLPs on days 0 and 14 and challenged on day 28 with a PCV2b Mexican isolate. PCV2 peptide-specific IgG seroconversion, serum cytokines, viral load in nasal swabs and organs, and histopathological score were determined. Results: IgG levels peaked 28 days post-immunization. Interleukin-12 and -18 and interferon-gamma increased 21 days after immunization. In addition, genomic material of PCV2 was detected in nasal swabs from one specimen on day 7, two specimens on day 14, and two specimens on day 21 following viral challenge. Finally, histological lesions were not less severe in immunized specimens compared to non-vaccinated/challenged specimens. Conclusions: These results suggest that immunization with chimeric VLPs could contribute to controlling viral shedding in pig herds where a PCV2b genotype is most prevalent. Full article

Porcine circovirus type 2 (PCV2), a widely distributed immunosuppressive virus, causes substantial economic losses in the global swine industry. C1QTNF6 has emerged as a novel immunoregulatory factor attracting increasing research interest due to its dual roles in both pro-inflammatory and antiviral immune responses. However, the role of C1QTNF6 in regulating PCV2 replication remains poorly characterized. Here, we analyzed C1QTNF6 expression patterns and identified its highly specific expression in placental tissues in both humans and pigs. We then overexpressed C1QTNF6 and conducted RNA sequencing analysis. Remarkably, 68 upregulated genes were identified, and most of them were interferon-stimulated genes (ISGs), including MX2 and ISG15. Functional enrichment analysis revealed that these genes were primarily associated with defense response to viruses and antiviral innate immune response. Subsequently, experimental data show that PCV2 infection significantly suppressed inflammatory responses and markedly downregulated the expression of C1qtnf6, MX2, and IFIT2. Moreover, experimental data indicated that C1QTNF6 inhibits PCV2 replication by targeting ISGs, while restoring MX2 expression. To verify whether C1QTNF6-MX2 antiviral axis mediates this antiviral effect, we constructed an MX2 overexpression plasmid and demonstrated that MX2 overexpression indeed significantly suppressed PCV2 replication. Together, these results provide important insights into PCV2-host interactions and the development of novel antiviral strategies. Full article

Porcine circovirus types 2 (PCV2) and 3 (PCV3) are major pathogens affecting swine health and productivity, yet important gaps remain in understanding their evolution and circulation in Europe, particularly within wild boar populations that may serve as reservoirs. This study examined the genetic diversity and evolutionary dynamics of PCV2 and PCV3 in Portugal, drawing on viral genomes obtained from domestic pigs and wild boars to explore transmission patterns, spillover events and the contribution of recombination to viral emergence. We identified two PCV2 genotypes (PCV2a and PCV2d) and two PCV3 genotypes (PCV3-2a and PCV3-3g) circulating in Portuguese swine. Phylogeographic reconstruction revealed multiple introductions of both PCV2 and PCV3 from China into Europe, followed by regional diversification and subsequent spread within European wild boar populations. Evidence of bidirectional viral exchange between domestic pigs and wild boars was also observed. Recombination played a notable role in PCV2 evolution, with consistent signals detected among PCV2a sequences and indications that the PCV2h genotype likely originated from a recombinant event involving a Portuguese PCV2a strain and a Chinese PCV2d strain. By contrast, no recombination was detected in PCV3, suggesting that its evolution is primarily mutation-driven. Overall, these findings highlight the complex evolutionary history of swine circoviruses in Europe and underscore the importance of continuous genomic surveillance in both domestic and wild hosts. The study reinforces the value of a One Health approach for monitoring and controlling emerging circoviruses with implications for animal health and livestock production. Full article