Search Results (203)

The seasonal patterns of viral diseases in farm animals present significant challenges to global livestock productivity, with cold stress emerging as a potential modulator of host–pathogen interactions. This review synthesizes current knowledge on the expression dynamics of heat shock protein 70 (HSP70) in farm animals under cold-stress conditions and its potential roles as (1) a viral replication facilitator and (2) an immune response regulator. This review highlights cold-induced HSP70 overexpression in essential organs, as well as its effects on significant virus life cycles, such as porcine epidemic diarrhea virus (PEDV), porcine reproductive and respiratory syndrome virus (PRRSV), and bovine viral diarrhea virus (BVDV), through processes like viral protein chaperoning, replication complex stabilization, and host defense modulation. By integrating insights from thermophysiology, virology, and immunology, we suggest that HSP70 serves as a crucial link between environmental stress and viral disease seasonality. We also discuss translational opportunities targeting HSP70 pathways to break the cycle of seasonal outbreaks, while addressing key knowledge gaps requiring further investigation. This article provides a framework for understanding climate-driven disease patterns and developing seasonally adjusted intervention strategies. Full article

Porcine rotavirus (PoRV), a primary etiological agent of viral diarrhea in piglets, frequently co-infects with other enteric pathogens, exacerbating disease severity and causing substantial economic losses. Its genetic recombination capability enables cross-species transmission potential, posing public health risks. Globally, twelve G genotypes and thirteen P genotypes have been identified, with G9, G5, G3, and G4 emerging as predominant circulating strains. The limited cross-protective immunity between genotypes compromises vaccine efficacy, necessitating genotype surveillance to guide vaccine development. While conventional molecular assays demonstrate sensitivity, they lack rapid genotyping capacity and face technical limitations. To address this, we developed a novel diagnostic platform integrating reverse transcription recombinase-aided amplification (RT-RAA) with CRISPR–Cas12a. This system employs universal primers for the simultaneous amplification of G4/G5/G9 genotypes in a single reaction, coupled with sequence-specific CRISPR recognition, achieving genotyping within 50 min at 37 °C with 10⁰ copies/μL sensitivity. Clinical validation showed a high concordance with reverse transcription quantitative polymerase chain reaction (RT-qPCR). This advancement provides an efficient tool for rapid viral genotyping, vaccine compatibility evaluation, and optimized epidemic control strategies. 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

Porcine reproductive and respiratory syndrome virus (PRRSV) is a major viral threat to swine, causing significant economic loss in the global pig farming industry. This virus includes two major genotypes, PRRSV1 and PRRSV2, both characterized by high mutation rates and genetic variability, complicating the development of a universally effective vaccine and disease control. To address this challenge, this study utilizes immunoinformatics tools to identify conserved epitopes and design a multi-epitope vaccine candidate against PRRSV based on reverse vaccinology. The complete sequences of PRRSV-encoded proteins were retrieved worldwide, and the conserved fragments were identified through the alignment of polypeptide sequences. Subsequent screening was conducted to screen epitopes for their potential to be safe and to activate B cells, HTLs (helper T cells), and CTLs (cytotoxic T cells). By conjugating the selected epitopes with distinct adjuvant proteins, three vaccine candidates were designed and termed PRRSV-vaccine (PRRSV-V-1, PRRSV-V-2, and PRRSV-V-3, respectively). Furthermore, systematic evaluations of their physicochemical properties, structural stability, binding with pattern recognition receptors, and induction of the host immune system were performed. PRRSV-V-2 had the most promising physicochemical and structural characteristics, strong binding with toll-like receptors (TLR3 and TLR8), and the most vigorous reactions to host immune responses. As the most promising candidate, the recombinant PRRSV plasmid was in silico designed for expression in Escherichia coli. Our study proposed a novel approach to PRRSV vaccine development against PRRSV, offering a promising strategy for controlling the infection across diverse PRRSV strains in swine. Despite providing significant insights into vaccine design through computational methods, the results of this study remain predictive. So, it is open for the experimental validations of the scientific community to ensure its actual immunological properties, especially the safety and efficacy. Full article

Porcine reproductive failure (PRF) has multiple etiological origins, primarily involving the viruses PCV2, PPV1, and PRRSV. Some emerging viruses, such as PCV3, PCV4, and novel parvoviruses (nPPVs), have also been suggested as contributors. In this study, we longitudinally evaluated 40 healthy sows (20 gilts and 20 multiparous sows) over three phases: pregnancy (PP), farrowing (FP), and their litters during lactation (LP). We detected viruses through PCR and serology in mono- and coinfections. The results showed that primary viruses were present during all three phases, with PCV2 being the most frequently detected. PCV3 positivity was highest at the time of insemination, and PPV1 was found in all. Additionally, PPV1-positive fetuses and pre-suckling piglets were identified, indicating vertical transmission. PRRSV was also present in an unstable herd, with the PRRSV2 lineage A detected and evidence of vertical transmission. The majority of coinfections were either dual or triple. The most common coinfections in the PP and LP were PCV2/PPV1 and PCV2/PCV3, while in the FF, PCV2/PPV1 and PCV2/PRRSV predominated. Notably, coinfection PCV2/PPV1 impacted the replication of PCV2. In contrast, the likelihood of detecting PRRSV decreased in fetuses coinfected with PRRSV and either PCV2, PCV3, or PPV1. The detected viruses exhibited low viral loads, indicating subclinical infections. Therefore, we propose recognizing a subclinical presentation of PRF and establishing criteria to differentiate between this and symptomatic reproductive disease. Full article

Background: African swine fever (ASF) is a highly contagious acute febrile disease with a near 100% mortality rate. There are currently no safe and effective vaccines for this disease. Cellular immunity plays an important role in the process of anti-viral, activating an effective cellular immune response is a prerequisite for the effectiveness of the vaccine. Methods: To effectively activate cellular immune responses, 133 immunodominant T cell epitopes (TEPs) were identified and synthesized into ten recombinant multi-epitope proteins (MEPs). These MEPs were subsequently conjugated to porcine ferritin (pFTH1) to generate MEPs-pFTH1 nanoparticles. Animal experiments were conducted to evaluate their immunogenicity and biocompatibility. Results: Animal experiments demonstrated that both MEPs and MEPs-pFTH1 nanoparticles induced significant humoral and cellular immune responses. Compared to MEPs monomers, the MEPs-pFTH1 nanoparticles induced a 10- to 100-fold increase in IgG and IgG2a antibody titers (p < 0.05), as well as a significantly higher number of IFN-γ⁺ cells. Serum from pigs immunized with MEPs-pFTH1 nanoparticles can significantly inhibit ASFV replication. Conclusions: Our novel self-assembled porcine ferritin nanovaccine candidate can induce strong humoral and cellular immune responses in swine and mice that effectively inhibit ASFV replication. Therefore, the nanovaccine is a highly biocompatible and safe candidate vaccine for ASF that warrants further investigation, such as conducting animal challenge experiments to evaluate the effectiveness of the vaccine. Full article

Background: Porcine circovirus disease (PCVD), caused by porcine circovirus (PCV), is a significant swine disease characterized by porcine dermatitis, nephrotic syndrome, and reproductive disorders in sows. Given the overlapping clinical presentations of PCV2, PCV3, and PCV4, a rapid and accurate method for their differential detection is essential. Methods: In this study, specific primers and probes were designed based on the conserved regions of the ORF1 genes of PCV2 and PCV4, as well as the ORF2 gene of PCV3. Results: A TaqMan triple real-time PCR method was developed, demonstrating excellent specificity, sensitivity, and repeatability, with limits of detection (LODs) of 53.3 copies/µL, 12.0 copies/µL, and 13.8 copies/µL for PCV2, PCV3, and PCV4, respectively. Using this method, 500 clinical porcine tissue samples collected from 23 provinces across China between 2023 and 2024 were analyzed. The results showed detection rates of 75.20% (376/500) for PCV2, 17.60% (88/500) for PCV3, and 4.40% (22/500) for PCV4. The detection rate of triple coinfections involving PCV2, PCV3, and PCV4 was 0.80% (4/500). PCV2 consistently presented significantly higher positive detection rates across all growth stages, and its viral copy number was significantly greater than those of PCV3 and PCV4 (* p < 0.05). Forty PCV2 ORF2 genes, fourteen PCV3 ORF2 genes, and three PCV4 ORF2 genes were identified. These included four PCV2a genotypes, thirty-five PCV2d genotypes, and one PCV2e genotypes; two PCV3a genotypes and six each of PCV3b and PCV3c genotypes; and two PCV4a genotypes and one of PCV4b genotype. Conclusions: The triple qPCR method established in this study provides a rapid, specific, and accurate approach for the detection and differentiation of PCV2, PCV3, and PCV4 genotypes. Full article

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

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

Porcine cytomegalovirus/porcine roseolovirus (PCMV/PRV), a porcine herpesvirus, has been shown to significantly reduce the survival time of porcine xenotransplants in non-human primates. The virus was detected in all the examined organs of baboons transplanted with PCMV/PRV-positive organs and it was also transmitted to the first human recipient of a pig heart, contributing to the patient’s death. PCMV/PRV induces consumptive coagulopathy and thrombocytopenia in xenotransplant recipients. Initial studies in baboons revealed that the virus triggered increased release of tumor necrosis factor α (TNFα) and interleukin 6 (IL-6), along with elevated levels of tissue plasminogen activator (tPA) and plasminogen activator inhibitor 1 (PAI-1) complexes. Since there is no evidence that PCMV/PRV infects primate cells, including human cells, the virus appears to directly interact with immune and endothelial cells, disrupting cytokine signaling and coagulation pathways. The highest viral load was detected in the explanted pig heart, suggesting active replication at this site. Additionally, cells expressing PCMV/PRV proteins were identified in all the examined baboon organs, where pig cells were also found. Since PCMV/PRV affects only xenotransplant recipients and not healthy humans, this condition should be classified as a xenozoonosis. Interestingly, antibodies against human herpesvirus 6 (HHV-6) cross-react with PCMV/PRV and may contribute to protection against infection in humans. Further research is needed to uncover the molecular mechanisms underlying this xenozoonotic disease. Full article

Porcine reproductive and respiratory syndrome (PRRS) is one of the most serious diseases threatening the swine industry worldwide. However, no satisfactory control strategy has existed until now. In this study, the effectiveness of tylvalosin against PRRSV and the underlying mechanism was investigated. The results showed that in porcine alveolar macrophages (PAMs), tylvalosin can inhibit the replication of the NADC30-like and NADC34-like strains in a dose-dependent manner. It is worth noting that pre-incubation with tylvalosin had no significant inhibitory effect on the NADC30-like strain but did inhibit the NADC34-like strain. Co-incubation of both viruses and tylvalosin or post-incubation with tylvalosin after viral infection inhibited PRRSV. We further analyzed the effect of tylvalosin on different stages of PRRSV replication and found that the stages in the PRRSV life cycle could be blocked by tylvalosin. Tylvalosin has an antiviral effect on all four stages of the NADC34-like strain’s infectious cycle but has no effect against the adsorption phase of the NADC30-like strain. These results demonstrated that tylvalosin suppressed PRRSV infection in PAMs and inhibited PRRSV infection at multiple steps of the viral life cycle. This study will contribute to the clinical prevention and control of PRRS and provide a basis for further exploration of the anti-PRRSV effects of tylvalosin. Full article

Porcine epidemic diarrhea virus (PEDV) causes a highly contagious intestinal disease with severe economic impacts on the global swine industry. The non-structural protein 13 (nsp13), a viral helicase, is essential for viral replication, making it a promising target for antiviral drug development. In this study, through virtual screening and molecular dynamics simulations, Vancomycin, a small-molecule drug also clinically used as an antibacterial agent, was identified to exhibit a stable binding affinity for PEDV nsp13. The NTPase and ATP-dependent RNA helicase activities of PEDV nsp13 were confirmed in vitro, and the optimal biochemical reaction conditions for its dsRNA unwinding activity were established. Further experiments demonstrated that Vancomycin effectively inhibited the dual enzymatic activities of PEDV nsp13 and reduced PEDV infections in vitro. This research highlights Vancomycin as a novel inhibitor of PEDV nsp13, providing valuable mechanistic insights and serving as a model for antiviral drug discovery. While this study suggests its potential for repurposing as a therapeutic agent against PEDV, further investigations are required to evaluate its feasibility in vivo, particularly in terms of safety, efficacy, and practical applicability. Full article

Porcine respiratory and reproductive syndrome is a viral disease that impacts the health and profitability of swine farms, largely due to significant variation in the vaccination response. The objective was to identify and validate molecular markers associated with the antibody response in gilts following vaccination against the PRRSV. The study included one hundred (n = 100) 6-month-old Yorkshire gilts that were negative for the PRRSV. Gilts were randomly assigned to one of two treatments, PRRS-vaccinated (n = 75) and control (n = 25) groups. Blood samples collected on day 21 were analyzed to evaluate the antibody response, as indicated by the sample-to-positive (S/P) ratio, to the PRRSV following vaccination. DNA was extracted and genotyped using a low-density chip containing 10,000 single nucleotide polymorphisms (SNPs). A genome-wide association study (GWAS) was conducted to identify candidate SNPs associated with the S/P ratio, which were validated in two independent gilt populations (n = 226). The SNPs rs707264998, rs708860811, and rs81358818 in the genes RNF144B, XKR9, and BMAL1, respectively, were significantly associated (p < 0.01) with the S/P ratio and demonstrated an additive effect. In conclusion, three SNPs are proposed as candidate markers for an enhanced immune response to vaccination against the PRRSV and may be beneficial in genetic selection programs. Full article

Following its initial documented emergence in Hunan’s swine facilities in 2017, GETV has inflicted considerable financial damage upon China’s pork production sector. Beyond its impact on swine, GETV also poses a potential risk to other animal species and public health, primarily due to its mosquito-borne transmission. Between September 2020 and May 2021, a GETV outbreak occurred on a commercial swine farm in Sichuan Province, where affected animals exhibited movement disorders, neurological symptoms, and mild diarrhea, with severe cases resulting in mortality. To elucidate the genetic characteristics and transmission dynamics of the virus, a comprehensive investigation of this outbreak was conducted. Clinical samples from diseased or deceased swine were collected and analyzed by PCR, confirming the presence of GETV infection. Additionally, differential diagnostic assays were performed for other common swine pathogens, including porcine reproductive and respiratory syndrome virus (PRRSV), pseudorabies virus (PRV), classical swine fever virus (CSFV), and atypical porcine pestivirus (APPV). All tests yielded negative results, confirming GETV as the sole etiological agent of the outbreak. The GETV-positive samples were inoculated into BHK-21 cells, leading to the isolation of a GETV strain (SC202009). Whole-genome sequence analysis revealed that SC202009 belongs to the GIII genotype of GETV, with a nucleotide sequence identity ranging from 95.1% to 99.8% compared to reference sequences in GenBank. This high level of sequence identity suggests that SC202009 is closely related to other circulating strains in the region, indicating potential local transmission networks and endemic viral circulation. The nucleotide sequence identity of the E2 gene ranged from 94.2% to 99.6%, while the E2 protein amino acid sequence identity ranged from 97.2% to 99.5%. Phylogenetic analysis further indicated that SC202009 is genetically distant from the original Malaysian prototype strain (MM2021) but shares high sequence identity with several strains isolated in Sichuan Province, including SC266, SC201807, and SC483. Notably, NMJA_F2_18-8L-NH-Cxp-Y-1-1 was isolated from Culex pipiens, suggesting a mosquito-borne transmission route. These findings provide novel insights into the regional dissemination patterns and genetic diversity of GETV in China. These results also highlight the importance of the continuous surveillance of viral genetic variations and the elucidation of transmission dynamics to develop effective control strategies and mitigate potential public health risks. Future studies should focus on the ecological and environmental factors influencing GETV transmission, particularly the role of mosquito vectors in cross-species viral spread, to enhance targeted prevention and control measures for this emerging arboviral threat. Full article