Search Results (184)

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

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

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

Wild boars are recognized reservoirs of numerous viral pathogens, posing a significant risk to domestic pig populations, particularly in areas with poor biosecurity. This study assessed the prevalence and co-infection patterns of porcine circovirus type 2 (PCV2), porcine parvovirus (PPV), porcine cytomegalovirus (PCMV), African swine fever virus (ASFV), classical swine fever virus (CSFV), and pseudorabies virus (PRV) in wild boars from western Serbia and the Republic of Srpska (Bosnia and Herzegovina). Sixty-six spleen samples from legally hunted wild boars were analyzed by qPCR. All animals were negative for ASFV, CSFV, and PRV. The cumulative prevalence of infection with at least one of the other three viruses was 86.4% (95% CI: 76.2–92.8%). PCMV was detected in 74.2% of samples, PCV2 in 50%, and PPV in 28.8%. Co-infections were common: 42.4% of animals were positive for two viruses, and 12.1% for all three. A statistically significant association was observed between triple co-infection and sex, with higher rates in males. Subadult wild boars showed the highest PCV2 + PCMV co-infection rate (p = 0.0547). These findings highlight the need to expand molecular surveillance, particularly for PCMV, in both wild and domestic pigs, especially in regions reliant on low-biosecurity backyard farming. Full article

Porcine circoviruses are significant pathogens that affect swine populations worldwide, with implications for animal health and productivity. While PCV2 is well-documented, particularly due to widespread vaccination programs, PCV3 is less understood, and its epidemiological impact is still under investigation. This study screened for PCV2 and PCV3 in pigs and wild boars across Portugal to assess their prevalence. Also, nucleotide sequence determination was performed to evaluate the genetic diversity of these viruses. Stool samples from 160 pigs belonging to different groups (quarantine, nursery, fattening and adult pigs), as well as organ samples from 120 hunted wild boars, were analyzed. Samples were collected from twelve of the eighteen mainland Portuguese districts with positive cases being detected in nine of them. Pigs had a lower prevalence of PCV2 (1.9%) than PCV3 (11.2%), but the opposite was true in wild boars (76.7% for PCV2 and 55.0% for PCV3). The lower PCV2 prevalence in pigs can be attributed to the PCV2 vaccination program implemented. Additionally, these viruses were significantly more prevalent in wild boars (90.8% were infected with at least one of the viruses) than in domestic pigs (only 12.5%). This significant difference highlights the impact of the controlled environment in pig farms on disease prevention in contrast to the higher exposure risks faced by wild boars in their natural habitat. Compared to a previous study from 2023, we observed a slight decrease in the percentage of positive cases for both PCV2 and PCV3. Phylogenetic analysis of sequences obtained by Sanger sequencing allowed us to conclude that the samples from domestic pigs belong to the PCV2a and PCV3c clades, in contrast to the PCV2-positive cases detected in domestic pigs in 2023 that were classified in the PCV2d genotype. Conversely, samples from wild boars belong to the PCV2d and PCV3a clades. These results reveal genotype differences between wild and domestic pigs and shifts from 2023 to 2024. Our findings provide some information about the circulation of these viruses and emphasize the importance of vaccination and continued monitoring for a deeper understanding of their epidemiology to mitigate potential risks to swine health and production. Full article

Background/Objectives: Porcine Circovirus Type 2 (PCV2) impairs pigs’ immune systems and increases susceptibility to co-infections, including Classical Swine Fever (CSF), a highly contagious disease listed by the World Organisation for Animal Health (WOAH) as notifiable. Therefore, swine operations in CSF-endemic regions are encouraged to immunize piglets with both PCV2 and CSFV vaccinations. Currently, there is no commercially available bivalent vaccine for PCV2/CSFV. Methods: In this study, a total of twenty 4-week-old SPF pigs were administered our formulated PCV2/CSFV bivalent subunit vaccine, containing soluble CSFV-E2 (50 µg) and PCV2-ORF2 (100 µg) antigens with a porcine-specific CpG adjuvant. After 4 weeks of vaccination, all pigs were evaluated for efficacy against PCV2 and CSFV. Results: Pigs were only immunized once and showed significantly increased neutralizing or ELISA antibody titers against both viruses four weeks post-vaccination. After viral challenges, vaccinated pigs displayed no clinical signs or lesions and had markedly reduced CSFV and PCV2 viral loads in the serum and tissues compared to controls. Conclusions: These results demonstrate that a single dose of the PCV2/CSFV bivalent subunit vaccine is safe and effective in young pigs, induces strong antibody responses, and suppresses viral replication, making it a promising tool for swine disease control and cost-effective vaccination strategies. Full article

Since its emergence in China in 2018, African swine fever virus (ASFV) has posed a severe threat to the pig farming industry due to its high transmissibility and mortality rate. The clinical signs of ASFV infection often overlap with those caused by other swine viruses such as classical swine fever virus (CSFV), porcine reproductive and respiratory syndrome virus (PRRSV), pseudorabies virus (PRV), and porcine circovirus type 2 (PCV2), making timely and precise diagnosis a considerable challenge. To address this, we established a TaqMan-based multiplex real-time quantitative PCR (qPCR) assay capable of simultaneously detecting ASFV, CSFV, PRRSV, PRV, and PCV2. Specific primer-probe sets were developed targeting conserved genomic regions: the ASFV P72 gene, CSFV 5’UTR region, PRRSV ORF6, PCV2 cap gene, and PRV gB gene. After thorough optimization, the assay demonstrated robust analytical performance, exhibiting strong target specificity with no cross-detection of non-target pathogens. The detection threshold was determined to be 10 copies/μL per virus, indicating high assay sensitivity. Repeatability analysis revealed low variability, with intra- and inter-assay coefficient of variation values remaining below 2.3%. When applied to 95 clinical samples, the multiplex assay yielded results that were fully consistent with those obtained using commercially available singleplex qPCR kits. In conclusion, the multiplex TaqMan qPCR method developed in this study is characterized by high specificity, sensitivity, and reproducibility. It provides a reliable and efficient diagnostic tool for the simultaneous detection and differential diagnosis of ASFV and other clinically similar viral infections in swine, thereby offering robust technical support for swine disease surveillance and control. 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

Background/Objectives: Porcine circovirus type 2d (PCV2d) is the predominant genotype associated with porcine circovirus-associated disease (PCVAD), leading to significant economic losses. In South Korea, current vaccine lot-release testing relies on a T/C-ratio-based guinea pig assay, which lacks scientific justification and methodological robustness. This study aimed to develop and validate a statistically defined in-house ELISA using rabbit-derived polyclonal antibodies against PCV2d for the standardized evaluation of immunogenicity. Methods: Polyclonal IgG was generated by immunizing a rabbit with inactivated PCV2d, and it was purified through Protein A chromatography. Guinea pigs (n = 18) were immunized with IMMUNIS^® DMVac, an inactivated PCV2d vaccine candidate developed by WOOGENE B&G, at different doses. In-house ELISA parameters were optimized (antigen coating, blocking agent, and substrate incubation), and analytical performance was evaluated by ROC, linearity, reproducibility, and specificity. Sera from guinea pigs and pigs were analyzed under validated conditions. Results: The optimal performance was achieved using 10⁵ genomic copies/mL of the antigen coating and a 5% BSA blocking agent. The assay showed strong diagnostic accuracy (AUC = 0.97), reproducibility (CVs < 5%), and linearity (R² = 0.9890). Specificity tests with PCV2a, PCV2b, and PRRSV showed minimal cross-reactivity (<7%). The cross-species comparison revealed a positive correlation (R² = 0.1815) and acceptable agreement (bias = −0.21) between guinea pig and porcine sera. The validated cut-off (S/P = 0.4) enabled accurate classification across both species and aligned well with commercial kits. Conclusions: The in-house ELISA offers a robust, reproducible, and scientifically validated platform for immunogenicity verification, supporting its application in Korea’s national lot-release system. Homologous competition assays with PCV2d are planned to further confirm antigen specificity. Full article

Porcine circovirus type 2 (PCV2) is the main cause of porcine circovirus-associated disease (PCVAD). Despite the widespread use of anti-PCV2 vaccines, their efficacy varies, influenced by co-infection and evaluation methods. This study assessed the efficacy of Ingelvac CircoFLEX^® PCV2 vaccine under natural conditions. One hundred serum samples were collected from vaccinated and non-vaccinated piglets aged 21 to 173 days. PCR and antibody positivity rates did not show significant differences between the two groups, but PCV2 gene load at 91 days was significantly lower (p = 0.0095) in the vaccinated group. Anti-PCV2 antibody titers were also significantly lower in the vaccinated group at 91, 145, and 173 days (p < 0.0001). PCV2 was isolated from 50% of piglets in the non-vaccinated group (50%), compared with none (0%) in the vaccinated group, suggesting that PCV2 gene load in the non-vaccinated group did not correlate with viremia. Both groups were positive for antibodies to porcine reproductive and respiratory syndrome virus (PRRSV) at 63 days, prior to the surge in PCV2 gene load, suggesting PRRSV may enhance PCV2 replication. These findings highlight that while the vaccine reduced PCVAD damage, evaluation should incorporate methods such as virus isolation instead of relying solely on PCR. Full article

Foot and mouth disease virus (FMDV) is a highly pathogenic virus that mainly infects cloven hooved animals, such as pigs. The establishment of a rapid, sensitive and accurate point-of-care detection method is critical for the timely identification and elimination of infected pigs for controlling this disease. In this study, a RT-RAA-CRISPR/Cas13a method was developed for the detection of FMDV serotype O in pigs. Six pairs of RT-RAA primers were designed based on the conserved gene sequence of FMDV serotype O, and the optimal amplification primers and reaction temperatures were screened. The CRISPR-derived RNA (crRNA) was further designed based on the optimal target band sequence and the most efficient crRNA was screened. The results revealed that FMDV-O-F4/R4 was the optimal primer set, and the optimal temperature for the RT-RAA reaction was 37 °C. Moreover, crRNA4 exhibited the strongest detection signal among the six crRNAs. The established RT-RAA-CRISPR/Cas13a method demonstrated high specificity and no cross-reactivity with other common swine pathogens such as Senecavirus A (SVA), porcine reproductive and respiratory virus (PRRSV), porcine epidemic diarrhea virus (PEDV), porcine circovirus type 2 (PCV2), classical swine fever virus (CSFV), and pseudorabies virus (PRV), additionally, it was observed to be highly sensitive, with a detection limit of 19.1 copies/µL. The repeatability of this method was also observed to be good. This method could produce stable fluorescence and exhibited good repeatability when three independent experiments yielded the same results. A validation test using three types of simulated clinical samples (including swab, tissue, and serum samples) revealed a 100% concordance rate. The detection results could be visualized via a fluorescence reader or lateral flow strips (LFSs). Thus, a highly specific and sensitive RT-RAA-CRISPR/Cas13a detection method was developed and is expected to be applied for the rapid detection of FMDV serotype O in situ. 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

Reproductive failure has significant socioeconomic impacts on smallholder pig farms. This systematic review was conducted to compile the types of reproductive failures and their underlying causes reported in smallholder pig farms from East and Southeast Asia and to identify relevant knowledge gaps. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, 26 peer-reviewed studies met the eligibility criteria and were included in our synthesis. These studies were conducted in 11 countries, with Vietnam, China, and Thailand representing the highest share (53.8%). Only six studies (23%) investigated reproductive failure as their primary objective. Stillbirth, mummification, late-term abortion, and weak-born piglets were the predominant reproductive failures reported from smallholder pig farms across the region. The most frequently cited viral pathogens associated with these failures were porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus type 2 (PCV-2). Common non-infectious risk factors included extreme climate conditions (e.g., heat stress), poor diet and housing, and suboptimal boar management. Our synthesis highlighted a dearth of research focused on reproductive failure in smallholder pig farms in the region and emphasised the need for more targeted studies to clarify the biological, environmental, and managerial risk factors contributing to reproductive failure. This will facilitate the development of targeted prevention and control measures that account for the unique farming conditions and challenges smallholder farms face in East and Southeast Asia. Full article

Mycoplasma hyopneumoniae (Mhyo) and porcine circovirus type 2 (PCV2) are critical pathogens in the swine industry, both contributing significantly to the porcine respiratory disease complex (PRDC). Given their impact, it is logical to control these pathogens simultaneously. Consequently, combined vaccinations against Mhyo and PCV2 are gaining popularity in swine health management. We present the efficacy of the first commercial combined vaccine prepared of a genotype PCV2d strain and Mhyo and tested against experimental challenge infections with target pathogens in comparative trials with other commercial products. In these studies, three-week-old piglets were vaccinated according to the manufacturers’ instructions. Five weeks later, they were challenged with two Mhyo strains over three consecutive days or with a PCV2d strain once. Positive controls included challenged pigs without prior vaccination, while non-vaccinated/non-challenged pigs served as negative controls. The key parameters measured were lung lesion scores and seroconversion for Mhyo, and viraemia, rectal shedding, lymph node and lung viral content, and seroconversion for PCV2. Findings and conclusion: The results showed no compromising effects between the vaccine components and highlighted significant differences in efficacy among the various products tested. Additionally, oral fluid sampling demonstrated a strong correlation with the viraemia and fecal shedding of PCV2, underscoring the diagnostic and animal welfare benefits of this sampling method. Full article

The widespread distribution and genetic diversity of porcine circovirus type 2 (PCV2) seriously threatens the swine industry worldwide. This study investigates the molecular epidemiology of PCV2 in Henan Province (2020–2023) through PCR screening (385 samples) and whole-genome sequencing (34 strains). The overall detection rate was 71.17% (274/385), with annual rates of 81.16% (112/138) in 2020, 72.41% (84/116) in 2021, 62.50% (55/88) in 2022, and 53.49% (23/43) in 2023, indicating a declining trend. Phylogenetic analysis revealed the dominance of the PCV2d genotype, comprising 82.4% (28/34) of sequenced strains. Evolutionary analysis identified strong negative selection pressure on ORF2, with an elevated substitution rate of 1.098 × 10⁻³ ssy. These findings provide critical insights into the predominance and adaptive evolution of PCV2d, and significantly improve our understanding of its genetic diversity and evolutionary dynamics. Full article