Porcine Circovirus Research Articles

PCV2 AND PCV3 GENOTYPING IN WILD BOARS FROM SERBIA

Porcine circoviruses 2 and 3 (PCV2 and PCV3) are known agents of diseases in domestic pigs and wild boars. PCV2 is an economically important pathogen causing porcine circovirus-associated diseases (PCVAD), while the recently discovered PCV3 is associated with similar disorders. Wild boars can serve as a PCV reservoir for domestic pigs, which is a particular risk for pig farms with low biosecurity. Reports of these infections in Serbia are sporadic, and this study was intended as a follow-up to an earlier study. Our aim was to assess the prevalence and genetic characteristics of PCVs circulating in wild boars in a region in north-eastern Serbia with extensive hunting areas. In our study of 103 samples, 17.48% tested positive for PCV2 and 15.53% for PCV3. The low co-infection rates in 2.94% of the PCR-positive samples, suggests these viruses circulate independently. PCV2 prevalence was lower than in our previous study (40.32% out of 124 samples), but the genetic stability of circulating strains was detected with a clear genotype shift towards PCV2d-2. Moreover, this is the first report of PCV3 occurrence in wild boar in Serbia, and the detected strains were grouped into two genotypes: PCV3-1 and PCV3-3c. The PCV3-1 sequences were clustered with German strains, indicating the prevalence of this genotype in Europe. However, no further geographical correlation could be established, as the PCV3-3c representative was separated within the cluster containing Chinese and Indian strains. Furthermore, there was no correlation between PCV positivity and pathological findings in the sampled animals indicating subclinical infection.

Retrospective investigation of porcine circoviruses in cases of porcine dermatitis and nephropathy syndrome

Porcine dermatitis and nephropathy syndrome (PDNS) is a severe condition that affects mainly growing pigs and is considered to be caused by a type III hypersensitivity reaction. Although porcine circovirus 2 (PCV-2) is the antigen linked to this condition, porcine circovirus 3 (PCV-3) has also been proposed to be causally associated with PDNS. Moreover, the initial description of porcine circovirus 4 (PCV-4) also related this novel agent to this clinicopathological entity. Therefore, this retrospective study included a large number of PDNS cases (n = 102) fulfilling specific histologic criteria in search of known porcine circoviruses (PCV-1 to PCV-4) by conventional and/or quantitative PCR (qPCR). All the samples were subjected to PCV-2 immunohistochemistry (IHC) or conventional in situ hybridization (C-ISH), and RNAscope® (R-ISH) was used to study PCV-2 and PCV-3 localization in a subset of the samples. All PDNS cases were PCV-2 positive by qPCR, while 30 of them (29.4%) yielded PCV-3 qPCR positivity; PCV-2 viral loads were significantly greater than PCV-3 viral loads. All animals were negative for PCV-1 and PCV-4. By C-ISH/IHC, 63 cases (61.8%) were positive for PCV-2, with low to moderate amounts of antigen. R-ISH demonstrated higher sensitivity, as all studied cases were positive; however, neither PCV-2 nor PCV-3 were consistently found within characteristic PDNS lesions. These results indicate that all PDNS-affected pigs were infected with PCV-2, emphasizing the likelihood that this viral antigen is causally linked to this condition. In contrast, no evidence of the association of PCV-1, PCV-3 or PCV-4 with PDNS was found.

Retinol binding protein 4 restricts PCV2 replication via selective autophagy degradation of viral ORF1 protein.

Autophagy is a highly conserved degradative process that has been linked to various functions, including defending host cells against pathogens. Although the involvement of autophagy in porcine circovirus 2 (PCV2) infection has become apparent, it remains unclear whether selective autophagy plays a critical role in PCV2 restriction. Here we show that retinol-binding protein 4 (RBP4), an adipokine for retinol carrier, initiates the autophagic degradation of PCV2 ORF1 protein. PCV2 infection increases RBP4 protein levels through MAPK-eIF4E axis in living cells. Ectopic expression of RBP4 or recombinant RBP4 treatment promotes the degradation of ORF1 protein. Mechanistically, RBP4 activates TRAF6 to induce K63-linked ubiquitination of ORF1, leading to SQSTM1/p62-mediated selective autophagy for degradation. Consequently, RBP4 deficiency increases viral loads and exacerbates the pathogenicity of PCV2 in vivo. Collectively, these results identify RBP4 as a key host restriction factor of PCV2 and reveal a previously undescribed antiviral mechanism against PCV2 in infected cells.

Coinfection of Mycoplasma suis and porcine circovirus type 3 is linked to reproductive failure in pig farms

Coinfection of Mycoplasma suis and porcine circovirus type 3 is linked to reproductive failure in pig farms

Well-Being and Performance of Nursery Pigs Subjected to Different Commercial Vaccines Against Porcine Circovirus Type 2, Mycoplasma hyopneumoniae and Lawsonia intracellularis

Background/Objectives: Vaccination is a strategy in pig farming for the control of several pathogens, but commercial vaccines may have detrimental side effects. This study aimed to evaluate the effects of commercial vaccines on the control of porcine circovirus type 2 (PCV2), Mycoplasma hyopneumoniae (Mhp), and Lawsonia intracellularis (L. intracellularis) and their potential side effects on welfare, behavior, acute inflammation biomarkers (C-reactive protein and haptoglobin), and the performance of piglets during the nursery phase. Methods: A total of 240 piglets, both female and castrated males, with an average weight of 6.3 ± 0.9 kg were subjected to four treatments: T1-FLEXcombo® (Ingelvac®CircoFLEX and Ingelvac®MycoFLEX) + Enterisol® Ileitis; T2-FLEXCombo® + Porcilis® Ileitis; T3-Porcilis® PCV M HYO + Porcilis® Ileitis; and T4-FLEXCombo® + 0.9% saline solution. This study measured therapeutic interventions, body condition score, behavioral changes, rectal temperature, and inflammation biomarkers post-vaccination. Results: The T3 group required more therapeutic interventions and exhibited a 23.1% higher incidence of thin body condition (p < 0.05) and 10 times more animals with depressed behavior than T1 (p < 0.05). The piglets vaccinated for L. intracellularis (T2 and T3) had rectal temperatures exceeding 39.7 °C post-vaccination, significantly higher than in T1 (p < 0.05). The T1 animals showed five times more positive behavior traits 24 h after vaccination (p < 0.05). Touch response was 29% lower in the T2 and T3 groups, and the lying down behavior was higher in these groups compared to T1. Additionally, 41.7% of the T3 animals exhibited a sitting posture 48 h after vaccination. Higher serum C-reactive protein and haptoglobin levels were observed in T3 (p < 0.05) at 24 and 48 h post-vaccination. Feed intake was higher in T1 compared to T3 between 29 and 35 days of age. It is important to note that this study did not measure immune responses to the pathogens and did not include challenge tests, and therefore, it does not assess which vaccine is superior in pathogen control. Conclusions: The vaccine programs resulted in similar zootechnical performance. However, T1, T2, and T4 showed better effects on piglet welfare and behavior compared to T3.

Prevalence and genetic evolution analysis of porcine epidemic diarrhea virus and porcine circovirus type 2 in Sichuan Province, China, from 2023 to 2024.

Porcine circovirus type 2 (PCV2) and Porcine epidemic diarrhea virus (PEDV) are highly prevalent in Sichuan, significantly affecting the swine industry's development. PCV2, known for its immunosuppressive effects, can compromise pigs' immune systems, while PEDV typically causes diarrhea in piglets, leading to high mortality rates. Despite their impact, recent studies on the epidemiology and genetic diversity of PCV2 and PEDV within Sichuan Province remain limited. This study examines clinical samples from 352 diarrheal piglets across 63 pig farms in 17 regions of Sichuan Province, revealing positivity rates of 42.33% (149/352) for PCV2 and 50.28% (177/352) for PEDV, with a co-infection rate of 27.56% (97/352). Notably, the highest positivity rates were observed in Ziyang for PCV2 at 61.90% (13/21), and in Meishan for PEDV at 73.81% (31/42), both regions also reported the highest co-infection rates of 47.62%. Seasonal analysis indicated that PEDV infections peaked during winter, whereas PCV2 showed no significant seasonal trends. Phylogenetic analysis identified 14 PCV2 strains, categorizing 2 as PCV2b (14.29%), 10 as PCV2d (71.43%), and 2 as PCV2e (14.29%). Among the 16 PEDV strains, 2 were classified as G1a (12.5%) and 14 as G2a (87.5%), with PCV2d and PEDV G2a identified as the predominant strains in the region. The study also highlights a high mutation rate at the antigenic sites of both viruses, potentially affecting vaccine efficacy. These findings underscore the need for ongoing surveillance and vaccine development tailored to the prevalent strains to improve control measures within the province.

An updated phylogeography and population dynamics of porcine circovirus 2 genotypes: are they reaching an equilibrium?

Porcine circovirus 2 (PCV2) emerged more than three decades ago as one of the most impactful pathogens in the swine industry. Despite being a DNA virus, one of the hallmarks of PCV2 is its high evolutionary rate, which has led to the emergence of different genotypes, each exhibiting varying degrees of evolutionary success. Current knowledge suggests the occurrence of three main waves of genotype dominance, alternating over time (i.e., PCV2a, PCV2b, and PCV2d), alongside less prevalent genotypes. However, although PCV2d is currently the most common genotype nowadays, the others continue being circulating in the pig population. The present study reconsidered the epidemiological and evolutionary patterns of PCV2 genotypes using phylodynamic analyses, benefiting from an almost 10-fold increase in ORF2 sequence availability compared to previous studies. Additionally, a phylogeographic analysis was performed to investigate viral dispersal patterns and frequency, and the selective pressures acting on the capsid protein were estimated and compared among genotypes. While successive emergence of major genotypes was confirmed, this study extends previous findings by revealing subsequent prevalence fluctuations of PCV2a and PCV2b after their initial decline. This evolutionary process may represent an example of balancing selection, specifically negative frequency-dependent selection, where a genotype fitness diminishes as it becomes more common, and vice versa. Variations in genotype- or clade-specific immunity-affected by the local prevalence of viral groups-combined with the periodic introduction of strains that have independently evolved in different regions, may have led to fluctuations in the population dynamics of major genotypes over time. These fluctuations were associated with ongoing evolution and variations in the capsid amino acid profile. These findings have profound implications for future control strategies. Although PCV2d remains the most prevalent and widespread genotype, other genotypes should not be neglected. Control strategies should thus target the entire PCV2 population, with a focus on fostering broader and more cross-protective immunity.

Antiviral role of cholesterol 25-hydroxylase in inhibiting porcine circovirus 3 replication

Cholesterol 25-hydroxylase (CH25H) has significant antiviral effects through the production of 25-hydroxycholesterol (25HC). In this study, we investigated the effects of CH25H, its catalytic product 25HC, and its catalytic mutant lacking hydroxylase activity (CH25H-M) on porcine circovirus 3 (PCV3) replication. By transfecting PCV3 persistently infected PK-15 cells with the pCAGGS-CH25H-Flag plasmid, the results demonstrated that overexpression of CH25H significantly inhibited PCV3 Cap protein expression, Cap mRNA levels, and viral titers in a dose-dependent manner. Moreover, its catalytic product 25HC inhibited PCV3 replication in PK-15 cells at concentrations below 10 µM without affecting cell viability. In contrast, knockdown of endogenous CH25H using small interfering RNA (siRNA) enhanced PCV3 replication, further confirming its antiviral role. Interestingly, the CH25H-M mutant also exhibited inhibitory effects on PCV3 replication, although the inhibition was much less effective compared with CH25H. In conclusion, CH25H plays a critical role in regulating PCV3 replication, and its antiviral effect is not entirely dependent on its enzymatic activity. These findings provide new insights into both the enzymatic and non-enzymatic antiviral mechanisms of CH25H and revealed some mechanistic immune evasion for PCV3.

Effect of yeast probiotics in lactation and yeast cell wall prebiotic and Bacillus subtilis probiotic in nursery on lifetime growth performance, immune response, and carcass characteristics.

Twenty-eight mixed-parity sows (Line 241; DNA) and their offspring were used to evaluate live yeast supplementation during lactation with or without a pre/probiotic combination during the nursery period on lactation performance, lifetime growth performance, and immune response. On day 110 of gestation, sows were allotted to a lactation diet with or without a live yeast probiotic (0.10% Actisaf Sc 47 HR+; Phileo by Lesaffre, Milwaukee, WI). At weaning, their offspring (350 pigs; initially 6.1 ± 0.02kg) were randomly assigned in a 2 × 2 factorial with main effects of sow treatment and nursery treatment consisting of a control diet or a diet with a yeast cell wall prebiotic and Bacillus subtilis probiotic (0.10% YB; Phileo by Lesaffre, Milwaukee, WI) fed for 42 d followed by common diets fed until marketing. Two nursery pens were combined into 1 finishing pen, such that there were 5 and 10 pigs per pen with 17 or 18 and 8 or 9 replications per treatment during the nursery and finishing periods, respectively. There were no significant effects of yeast supplementation on lactation performance (P ≥ 0.079). There was a sow × nursery diet interaction (P = 0.024) on nursery ADG. Pigs from yeast-fed sows had increased ADG when fed control nursery diets compared to pigs from control sows fed the control nursery diet with pigs fed pre/probiotic nursery diets intermediate, regardless of sow diet. Pigs from yeast-fed sows tended (P = 0.067) to have greater final body weight (BW) (day 165). A subset of pigs was sampled throughout their lifetime to determine serum porcine circovirus type 2 (PCV2) and Mycoplasma hyopneumoniae antibody sample-to-positive (S/P) ratios and percentage inhibition of Lawsonia intracellularis. There was a tendency for a PCV2 S/P ratio sow diet × day interaction (P = 0.097) where progeny from yeast-fed sows had higher PCV2 S/P ratios at 101 d of age compared to control sow progeny (P = 0.046). There was a PCV2 S/P ratio nursery diet × day interaction (P = 0.036) where pigs fed a pre/probiotic combination had reduced S/P ratios at 66, 78, and 162 d of age (P ≤ 0.022); however, at 22 d of age pigs fed a pre/probiotic combination tended to have an increased S/P ratio (P = 0.051). In conclusion, the effects of combining a yeast probiotic in lactation diets and a pre/probiotic in nursery diets were not additive. However, feeding a live yeast probiotic during lactation resulted in tendencies (P ≤ 0.10) for increased progeny final BW and hot carcass weight.

Molecular Positivity of Porcine Circovirus Type 2 Associated with Production Practices on Farms in Jalisco, Mexico

The modernization of pig production has led to increasingly larger populations of pigs. This dynamic allows for accelerated production and ensures a steady pork supply but also facilitates the spread of infections. PCV2 is a ubiquitous virus and can cause PCV2-associated diseases, depending on production practices. This study aimed to evaluate the conditions of pig production in the state of Jalisco, Mexico, and correlate them with PCV2. A total of 4207 serum samples from 80 farms were analyzed. Epidemiological data were collected and used to investigate factors associated with PCV2 detection. A relative frequency of approximately 30% was detected, primarily in grower pigs maintained on multisite farms. Several production practices, particularly biosecurity measures, were associated with PCV2 on the analyzed farms.

Detection of viral agents associated with Porcine Respiratory Disease Complex (PRDC) in pigs in North Kerala

In pigs, stress factors such as pathogenic infections, environmental conditions, and various managemental practices can lead to a disease condition known as Porcine respiratory disease complex (PRDC). The main viral agents associated with this condition are Porcine circovirus 2 (PCV2), Porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), porcine respiratory coronavirus (PRCV), and pseudorabies virus. A study was undertaken to assess whether PCV2 and PRRSV, alone or in combination, are present in cases of respiratory ailments of pigs in North Kerala. The presence of PCV2 was detected by polymerase chain reaction (PCR) targeting the open reading frame 2 (ORF2) of the virus and PRRSV was detected by reverse transcriptase PCR (RT-PCR) targeting ORF6. A total of 54 tissue and lung samples were collected and screened for the presence of PCV2 and PRRSV. Of the samples tested, PCV2 could be detected in 22 (40.74 %) and PRRSV could be detected in 13 (24.07 %) samples. Two tissue samples showed mixed infections with PCV2 and PRRSV. The result shows that viral agents associated with PRDC are prevalent in pigs in North Kerala and that coinfections are also present. Keywords: Porcine respiratory disease complex, Porcine circovirus 2, Porcine reproductive and respiratory syndrome virus, polymerase chain reaction

Infectious Agents Associated with Abortion Outbreaks in Italian Pig Farms from 2011 to 2021

The present study retrospectively analyzed the infectious agents associated with 829 abortion outbreaks occurring from 2011 to 2021 in northern Italy. Foetuses were subjected to necropsies, and organ samples were analyzed by direct PCR to screen for six swine pathogens. In 42.0% of the examined outbreaks, at least one infectious agent was found. Porcine reproductive and respiratory syndrome virus (PRRSV) (24.9%) and porcine circovirus-2 (PCV2) (11.5%) were the most frequently detected among the known abortion-inducing pathogens. Chlamydia spp. (5.6%), porcine parvovirus (PPV) (4.0%), and Leptospira spp. (2.6%) were less common. Although its role in swine reproductive disorders is still unclear, PCV3 was detected in 19.6% of the cases. Coinfections were detected in 25.0% of positive outbreaks, and the most frequent coinfection was represented by PRRSV and PCV2 (32.2%), followed by PRRSV and PCV3 (23%). PCV2 prevalence showed a slight but consistent reduction during the study period, while PCV3 increased in frequency. Our data suggest an overall reduction in abortion outbreaks during the study period. PRRSV was confirmed as the main abortion agent detected in the examined area, while PCV2 prevalence showed a decline. Conversely, PCV3 detection has been increasing, supporting its potential role as an abortion agent. Our results highlight the importance of implementing a consistent and standardized sampling procedure, as well as a thorough diagnostic protocol, to reduce the incidence of inconclusive diagnoses.

Synthesis and characterization of molecularly imprinted polymer nanoparticles against porcine circovirus type 2 viral-like particles.

PCV2 is a significant epidemic agricultural pathogen that causes a variety of swine diseases. PCV2 infections have significant economic impact on the swine industry, making effective strategies for rapid detection of PCV2 in pigs essential. Herein, we report on the synthesis of the so-called nano-MIPs which can be utilized for molecular recognition of PCV2. The morphology and structure of nano-MIPs were characterized using scanning electron microscopy (SEM). Nano-MIPs are spherical with sizes around 120-150nm. Binding experiments demonstrate that the fluorescence intensity of PCV2 samples decreases proportionally to increasing the concentration of nano-MIPs due to quenching, while non-imprinted polymer nanoparticles (nano-NIPs) do not affect the signal. The Stern-Volmer constant of nano-MIPs binding to PCV2 was 1.3 × 10-3mL/µg, whereas nano-NIPs led to 7 × 10-5mL/µg, i.e., 1.8 orders of magnitude lower. The detection limit for binding MIP particles to PCV2 by fluorescence measurements is 47µg/mL. This affinity test allows for designing both direct and competitive quartz crystal microbalance (QCM) assays for PCV2 leading to QCM measurements. The QCM results show nano-MIPs binding to PCV2 immobilized on the sensor surface with appreciable reproducibility. QCM sensor characteristics reveal signal saturation above around 200µg/mL at a response of - 354Hz and an LOD of approximately 35µg/mL. Nano-MIPs also show selectivity factors of 2-5 for CSFV and PRRSV probably because the three viruses have similar diameters around 50nm.

Modular Nano-Antigen Display Platform for Pigs Induces Potent Immune Responses.

Multivalent presentation of antigens using nanoparticles (NPs) as a platform is an effective strategy to enhance the immunogenicity of subunit vaccines and thus induce a high level of organismal immune response. Our previous results showed that pre-existing porcine circovirus type 2 (PCV2) antibodies could increase the antibody levels of nanoparticle vaccines carried in PCV2 VLPs. Here, we have established a generalized nanoantigen display platform, Cap-Cat virus-like particles (VLPs). By combining PCV2 VLPs with the modular linker element SpyTag003/SpyCatcher003 system, four porcine-derived viral protective antigens with different sizes and multimeric structures: the PRRSV B-cell epitope, the PEDV COE monomer, the CSFV E2 dimer, and the SIV HA trimer were efficiently demonstrated to elicit a strong immune response in mice. Crucially, the modification of antigens by the Cap-Cat VLPs platform enhanced the Th2 response and improved the Th1 response. The use of the platform demonstrates that HA antigen protects against lethal attacks by influenza viruses and reduces viral load in the lungs. We have demonstrated that the Cap-Cat VLPs platform demonstrates that antigens enhance the immune response by improving the processes of DC uptake, transport, lymph node (LN) localization, and immune cell activation. This "plug-and-display" assembly strategy facilitates the use of the Cap-Cat VLPs nanoantigen display platform for more applications and thus facilitates the development of more efficient, general-purpose porcine subunit vaccines.

A novel double antibody sandwich quantitative ELISA for detecting porcine epidemic diarrhea virus infection.

Porcine epidemic diarrhea (PED), a contagious intestinal disease caused by the porcine epidemic diarrhea virus (PEDV), has caused significant economic losses to the global pig farming industry due to its rapid course and spread and its high mortality among piglets. In this study, we prepared rabbit polyclonal antibody and monoclonal antibody 6C12 against the PEDV nucleocapsid (N) protein using the conserved and antigenic PEDV N protein as an immunogen. A double-antibody sandwich quantitative enzyme-linked immunosorbent assay (DAS-qELISA) was established to detect PEDV using rabbit polyclonal antibodies as capture antibodies and horseradish peroxidase (HRP)-labeled 6C12 as the detection antibody. Using DAS-qELISA, recombinant PEDV N protein, and virus titer detection limits were approximately 0.05 ng/mL and 103.02 50% tissue culture infective dose per mL (TCID50/mL), respectively. There was no cross-reactivity with porcine reproductive and respiratory syndrome virus (PRRSV), porcine rotavirus (PoRV), porcine pseudorabies virus (PRV), porcine deltacoronavirus (PDCoV), or porcine circovirus (PCV). The reproducibility of DAS-qELISA was verified, and the coefficient of variation (CV) for intra- and inter-batch replicates was less than 10%, indicating good reproducibility. When testing anal swab samples from PEDV-infected piglets using DAS-qELISA, the coincidence rate was 92.55% with a kappa value of 0.85 when using reverse transcription-polymerase chain reaction (RT-PCR) and 94.29% with a kappa value of 0.88 when using PEDV antigen detection test strips, demonstrating the reliability of the method. These findings provide fundamental material support for both fundamental and practical studies on PEDV and offer a crucial diagnostic tool for clinical applications. KEY POINTS: • A new anti-PEDV N protein monoclonal antibody strain was prepared • Establishment of a more sensitive double antibody sandwich quantitative ELISA • DAS-qELISA was found to be useful for controlling the PEDV spread.

Frequency and Genetic Analysis of Porcine Circovirus Type 2, Which Circulated between 2014 and 2021 in Jiangsu, China

Porcine circovirus-associated diseases, caused by porcine circovirus type 2 (PCV2), are widespread and result in significant economic losses to the global swine industry. PCV2 can currently be divided into nine genotypes (PCV2a to PCV2i), with the currently dominant one being the PCV2d genotype. In this study, 2675 samples from 804 pig farms in 13 cities in Jiangsu Province, China, were collected between 2014 and 2021 and subjected to polymerase chain reaction analysis to investigate the frequency and genetic diversity of PCV2. The results showed that 41.42% (1108/2675) of samples tested positive for PCV2. The researchers further analyzed the genetic characteristics of 251 PCV2 strains and found that they belonged to the following four genotypes: PCV2a, PCV2b, PCV2d, and PCV2i. The dominant genotype was PCV2d, with a frequency of 49.80% (125/251). The detection rate of PCV2b was significantly higher than those of PCV2a and PCV2i, at 35.46% (89/251), 7.57% (19/251), and 7.17% (18/251), respectively. The percentage of different genotypes of PCV2 varied irregularly over time. We have further revealed the fingerprint of PCV2i genomic nucleotides for the first time. In conclusion, this study illustrates the high frequency and evolutionary features of PCV2 in Jiangsu Province over the past few years.

Monitoring of Respiratory Disease Patterns in a Multimicrobially Infected Pig Population Using Artificial Intelligence and Aggregate Samples

A 24/7 AI sound-based coughing monitoring system was applied in combination with oral fluids (OFs) and bioaerosol (AS)-based screening for respiratory pathogens in a conventional pig nursery. The objective was to assess the additional value of the AI to identify disease patterns in association with molecular diagnostics to gain information on the etiology of respiratory distress in a multimicrobially infected pig population. Respiratory distress was measured 24/7 by the AI and compared to human observations. Screening for swine influenza A virus (swIAV), porcine reproductive and respiratory disease virus (PRRSV), Mycoplasma (M.) hyopneumoniae, Actinobacillus (A.) pleuropneumoniae, and porcine circovirus 2 (PCV2) was conducted using qPCR. Except for M. hyopneumoniae, all of the investigated pathogens were detected within the study period. High swIAV-RNA loads in OFs and AS were significantly associated with a decrease in respiratory health, expressed by a respiratory health score calculated by the AI The odds of detecting PRRSV or A. pleuropneumoniae were significantly higher for OFs compared to AS. qPCR examinations of OFs revealed significantly lower Ct-values for swIAV and A. pleuropneumoniae compared to AS. In addition to acting as an early warning system, AI gained respiratory health data combined with laboratory diagnostics, can indicate the etiology of respiratory distress.

Detection of Porcine Circovirus (PCV) Using CRISPR-Cas12a/13a Coupled with Isothermal Amplification.

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.

Detection of PCV2d in Vaccinated Pigs in Colombia and Prediction of Vaccine T Cell Epitope Coverage against Circulating Strains Using EpiCC Analysis.

Porcine circovirus type 2 (PCV2) is strongly linked to a group of syndromes referred to as porcine-circovirus-associated diseases (PCVADs), which are controlled through vaccination; however, this does not induce sterilizing immunity but is instead involved in the evolution of the virus and is considered a factor in vaccine failure. This study sampled 84 herds (167 pigs) vaccinated against PCV2 and with clinical signs of PCVADs in five provinces across Colombia. PCV2 was identified and further characterized at the molecular level via genotyping and phylogenetic reconstructions. In addition, PCV2-associated lesions were examined via histopathology. Furthermore, the PCV2-Cap sequences retrieved were compared with three vaccines via the EpiCC tool and T cell epitope coverage. The prevalence of PCV2 was 82% in pigs and 92.9% in herds. The highest viral loads were identified in lymphoid tissue, and PCV2d emerged as the most predominant in pigs and herds (93.4% and 92.3%). Sequences for PCV2-ORF2 (n = 57; 55 PCV2d and 2 PCV2a) were determined, and PCV2d sequences were highly similar. The most common pneumonia pattern was suppurative bronchopneumonia, while the most common lung lesion was exudation in the airways; in lymphoid tissue, there was lymphoid depletion. The bivalent vaccine (PCV2a and PCVb) exhibited a higher EpiCC score (8.36) and T cell epitope coverage (80.6%) than monovalent PCV2a vaccines. In conclusion, PCV2d currently circulates widely in Colombia. Despite vaccination, there are clinical cases of PCV2, and immunoinformatic analyses demonstrate that bivalent vaccines improved the average coverage.

Epidemiological investigation and analysis of the infection of porcine circovirus in Xinjiang

Porcine circoviruses, particularly porcine circovirus type 2 (PCV2) and porcine circovirus type 3 (PCV3), significantly impact the global pig industry due to their high prevalence and pathogenicity. Conversely, porcine circovirus type 1 (PCV1) and porcine circovirus type 4 (PCV4) currently have low positivity rates. This study aimed to characterize the distribution and epidemiology of porcine circoviruses in Xinjiang, while also analyzing the genetic diversity and evolution of PCV2 and PCV3, which pose the greatest threats to the industry. In this study, we collected blood and tissue samples from 453 deceased pigs across eight regions in Xinjiang Province from 2022 to 2024. We utilized real-time PCR to detect the presence of PCV1, PCV2, PCV3, and PCV4. The positive rates were 15%, 71%, 25%, and 17%, respectively. Genetic analysis showed 9 PCV2 sequences and 12 PCV3 sequences. The capsid protein of PCV2 showed significant variability. In contrast, the amino acid sequences of capsid in PCV3 were relatively stable. Moreover, we predicted antigenic epitopes for PCV3 capsid using IEDB and ElliPro. The findings from this study provide valuable epidemiological data on PCV coinfection in the Xinjiang region and enhance the understanding of virus diversity nationwide. This research may serve as an important reference for the development of strategies to prevent and control porcine circovirus infections.