Search Results (460)

Porcine reproductive and respiratory syndrome virus (PRRSV)-positive pigs can be exposed to high concentration of gases, such as ammonia and hydrogen sulfide when manure and urine stored in the pits beneath them is agitated and pumped. Such acute exposure can lead to adverse health effects such as respiratory system irritation. This study aimed to explore whether PRRS-positive growing pigs experience changes in viremia detection after manure pit agitation and pumping has been performed. To address this objective, two PRRS-positive growing pig farms were conveniently selected and visited twice during the week before and after manure agitation and pumping. Blood samples were collected to assess detection of viremia, using reverse transcription-polymerase chain reaction (RT-PCR). A logistic regression model was used to evaluate serum detection of PRRSV before and after the manure management event, accounting for pig age. Although PRRSV was detected in the serum of some pigs, under the conditions of the study, there were no statistically significant changes that would indicate that viremia detections change after the pigs had been exposed to barn manure pit agitation and pumping. 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

The development of novel antiviral nanomaterials is an important approach for addressing emerging viral threats. In this study, glycyrrhizic acid-modified gold nanoparticles (GA-Au NPs) were successfully synthesized and characterized, and their inhibitory effects against porcine reproductive and respiratory syndrome virus (PRRSV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pseudovirus were systematically evaluated. At non-cytotoxic concentrations, GA-Au NPs showed inhibitory activity against PRRSV in vitro. Stage-specific assays suggested that intracellular replication-related events were prominently affected, with additional inhibitory effects observed during adsorption, invasion, and release, whereas no direct virucidal activity was detected under the tested conditions. Furthermore, GA-Au NPs dose-dependently reduced SARS-CoV-2 pseudovirus infection-associated reporter signals in HEK-293T-ACE2 cells, supporting inhibitory activity in an additional viral model. In conclusion, GA-Au NPs represent a biocompatible antiviral nanomaterial with multi-stage inhibitory activity against PRRSV and inhibitory effects in a SARS-CoV-2 pseudovirus model, supporting their further evaluation as antiviral nanomaterials in enveloped virus-related models. Full article

Porcine reproductive and respiratory syndrome virus genotype 1 (PRRSV-1), particularly the BJEU06-1-like subgroup, has shown increasing detection in China; however, the biological characteristics of newly emerging strains in southwestern regions remain insufficiently defined. Therefore, this study aimed to isolate and characterize a PRRSV-1 strain circulating in Southwestern China and to compare its biological properties and pathogenicity with those of a representative NADC30-like PRRSV-2 strain. In this study, a PRRSV-1 field strain (CDAC-SC2025) was isolated from a lung sample collected in Sichuan Province and characterized by immunofluorescence, full-genome sequencing, and maximum-likelihood phylogenetic analysis. Recombination was assessed using RDP4 and SimPlot (Baltimore, MD, USA). Pathogenicity was evaluated in newborn piglets following intranasal challenge, with monitoring of clinical signs, viremia, viral shedding, tissue viral loads, and histopathology. CDAC-SC2025 clustered within the BJEU06-1-like subgroup and showed the closest relationship to HENZMD-10 without detectable recombination. A three-amino-acid deletion (373–375 aa) was identified in nsp2. In vivo, CDAC-SC2025 induced fever, respiratory signs, growth retardation, and mortality, but the onset of death was delayed and lesion severity was lower than those caused by the NADC30-like strain DJY. Both strains exhibited predominant viral loads in the lung and tonsils, although quantitative differences were observed across tissues. Histopathology revealed moderate lesions in CDAC-SC2025-infected piglets compared with more severe multisystemic damage caused by DJY. These findings provide updated data on the biological properties of BJEU06-1-like PRRSV-1 circulating in southwestern China. Full article

Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) poses a serious threat to the swine industry in China. As a major pig-producing province, Shandong requires continuous epidemiological monitoring of PRRSV. To elucidate the molecular epidemiology of the virus, 1621 clinical samples were collected from suspected cases across different regions of Shandong Province between 2023 and 2025, primarily from Tai’an, Linyi, Jining, and Liaocheng. RT-qPCR detection showed that the positive rate for PRRSV-2 was 20.05% (325/1621). Genetic analysis based on ORF5 and NSP2 genes indicated that Sublineage L1C (NADC30-like) was the dominant strain for 38.38% of ORF5 gene and 72.73% of NSP2 sequencing results. This was followed by Sublineage L8E and L1A and L5A strains. Key virulence-related mutations were identified at residues R13 and R151 in the GP5 protein, which are associated with enhanced pathogenicity. Additionally, variations in neutralizing epitope and the number of N-glycosylation sites (ranging from 2 to 5 per strain) suggested potential immune evasion. Notably, 26.79% (15/56) of sequenced samples showed discordant ORF5 and NSP2 genotyping results, indicating widespread recombination among PRRSV strains in Shandong Province. These finding demonstrated that the genetic diversity, high recombination frequency, and key amino acid variations in circulating PRRSV strains collectively undermine vaccine effectiveness. This study highlights the need to optimize vaccination strategies, enhance biosecurity measures, and implement effective disease control and elimination programs to reduce the impact of PRRSV in Shandong Province. Full article

PRRSV-2 represents a major threat to the swine industry. Canada is one of the world’s leading pork producers and a major trading partner of live pigs with the United States, yet PRRSV-2 evolutionary dynamics in these two countries are often studied independently, partly due to limited publicly available sequence data from Canada. We analyzed more than 3000 PRRSV-2 ORF5 sequences collected between 2000 and 2024 from five Canadian provinces. Thirteen previously described sub-lineages were detected in Canada, while approximately one-third of the sequences could not be assigned to any known sub-lineage. Phylogenetic analyses incorporating global reference sequences revealed that most unclassified sequences clustered into four distinct monophyletic clades, exhibiting genetic distances greater than 9.5% from recognized sub-lineages. We propose two new sub-lineages, 1K and 1L, corresponding to clades that were prevalent and persistent over time, whereas the remaining two clades were rare and last detected in 2021. We reconstructed cross-border transmission histories and found that sub-lineages 1C, 1H, 1I, 1K, and 1L originated in Canada, whereas 1A, 1B, 1E, and 1F originated in the United States. Transmission patterns varied across sub-lineages, ranging from unidirectional to bidirectional movement. Our findings refine PRRSV-2 classification and provide insights to inform targeted surveillance, particularly at national borders. Full article

Porcine reproductive and respiratory syndrome (PRRS) remains one of the most economically devastating diseases in global swine production. The causative agent, PRRS virus (PRRSV), comprises two genetically distinct species—PRRSV-1 and PRRSV-2—that differ substantially in antigenic composition and immune recognition. Despite widespread use of modified live vaccines (MLVs), protection against heterologous and cross-species strains remains inconsistent and difficult to predict. This review synthesizes current knowledge of homologous, heterologous, and cross-species protection, with emphasis on humoral and cellular immune responses and the viral determinants that constrain breadth of immunity. Neutralizing antibodies can confer near-sterilizing homologous protection under controlled conditions; however, their delayed induction and narrow specificity limit efficacy against heterologous strains. T-cell-mediated responses are generally broader but remain highly strain- and context-dependent. Structural features of PRRSV envelope glycoproteins, including glycan shielding and immunodominant decoy epitopes, further restrict antibody-mediated cross-protection while providing targets for rational vaccine design. We also examine potential drawbacks of preexisting immunity, including antigenic mismatch and non-neutralizing antibody-dominated responses that may contribute to suboptimal outcomes following heterologous exposure. Collectively, these findings highlight the multifactorial nature of PRRSV protection and the need for next-generation vaccines capable of inducing broader and more durable immunity. Full article

Porcine reproductive and respiratory virus (PRRSV) has a significant clinical and economic impact on pig farming. The purpose of this study was to assess the global seroprevalence of PRRSV in pigs and wild boars using a systematic review and meta-analysis approach. Following the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines, a systematic review and meta-analysis on global serological data of PRRSV in pigs and wild boars was conducted. Studies published between 1993 and 2025 were searched in three electronic databases, including PubMed, Web of Science, and Scopus. A total of 86 publications, belonging to 41 countries and including 690,771 animals, were deemed eligible. Following the identification and removal of outlier studies, the pooled serological prevalence was 14% (95% CI: 9–19%), and a high between-study heterogeneity was detected (I² = 99.9%, p < 0.000001). Subgroup analyses showed statistically significant differences according to continents, with the highest prevalence found in Asia (P: 29%, 95% CI: 16–43%), and species, with a higher prevalence in domestic pigs (P: 26%, 95% CI: 18–35%) than in wild boars (P: 2%, 95% CI: 1–3%). Overall, the information hereby presented provides an overview of the global PRRSV situation and identifies key factors associated with increased prevalence, primarily related to animal density. These insights could inform future surveillance strategies and help target interventions to mitigate the disease burden and safeguard swine health. Full article

The immunosuppressive nature of porcine reproductive and respiratory syndrome virus (PRRSV) remains the central obstacle to its effective control. Conventional microRNA (miRNA)-based antiviral approaches are limited by their modest potency and the high risk of viral escape. Here, we rationally designed an engineered miRNA carrying a 5′-triphosphate (5′-PPP) terminus that integrates RIG-I-driven innate immune activation and sequence-specific gene silencing within a single molecule. In vitro-transcribed 5′-PPP miRNAs are efficiently recognized by the pattern-recognition receptor RIG-I, triggering a robust type I interferon response that counteracts PRRSV-induced immunosuppression. In MARC-145 cells, one such construct, 5′-PPP BZL-sRNA-20, potently inhibited PRRSV replication through the synergistic action of immune activation and gene silencing. However, in porcine alveolar macrophages (PAMs)—the natural host cells for PRRSV—the antiviral effect depended primarily on 5′-PPP-induced interferon responses, with the targeting sequence providing limited or context-dependent benefits. Dual-luciferase assays confirmed that the gene-silencing activity depends on 5′-PPP modification, which enhances the stability of BZL-sRNA-20. This bifunctional strategy establishes an “immune activation plus targeting” paradigm by simultaneously acting as a RIG-I ligand that triggers broad antiviral responses and specifically cleaves viral RNA via direct base-pairing to conserved regions of the PRRSV genome. These findings reveal the potential of engineered 5′-PPP miRNAs as immunomodulatory antiviral agents, while highlighting that the contribution of RNAi targeting varies depending on the cellular context. Full article

This study aimed to evaluate effect of Gordonia alkanivorans on phagocytic activity of porcine alveolar macrophages (PAMs) and immune function in piglets. Quantitative PCR and fluorescence tracing were used to measure phagocytic efficiency of G. alkanivorans-intervened PAMs against PRRSV and E. coli. Sixty-four 45-day-old cross-bred piglets with equal sex were randomly divided into four groups (n = 16/group). Growth performance, immune function, and intestinal flora were analyzed. G. alkanivorans extract exhibited half cytotoxic concentration of 36.43 mg/mL, half effective concentration of 0.1009 mg/mL, and half inhibitory concentration of 0.0043 mg/mL in PAMs, significantly increasing their phagocytic efficiency by 98.5% against PRRSV and 2.31- to 13.46-fold against E. coli. Dietary supplementation with G. alkanivorans elevated antibody-positive rates against classical swine fever virus (47.92%) and pseudorabies virus (14.58%), modified serum cytokine: Interleukin (IL)-1β, IL-2, Tumor Necrosis Factor -α, Interferon (IFN)-α, IFN-γ, IL-4, and IL-10 (−144.51% to +191.72%). It increased intestinal operational taxonomic units by 152%, the Shannon index by 14.62%, and the Chao index by 11.37%, while reducing the Firmicutes/Bacteroidetes ratio by 713.90%. In conclusion, G. alkanivorans enhances immunity and antiviral activity in piglets by gut and immune regulation. Full article

Porcine reproductive and respiratory syndrome (PRRS), which is caused by the porcine reproductive and respiratory syndrome virus (PRRSV), results in substantial economic losses for the global pig farming industry. A critical step in the infection process is the binding of PRRSV to the CD163 receptor on the surface of porcine alveolar macrophages. This study successfully generated CD163−/− Landrace pigs using CRISPR/Cas9 gene editing technology. Following an experimental challenge with two distinct Type II PRRSV strains, the edited pigs exhibited complete resistance to infection. Virological and pathological examinations confirmed the absence of viral replication and the presence of characteristic pulmonary lesions and other organ damage in CD163−/− pigs. In contrast, wild-type control pigs exhibited high viral loads and severe pulmonary lesions, as well as damage to other organs. Our findings provide direct evidence that CD163 is an essential receptor for PRRSV infection in vivo. The CD163−/− pig model offers an effective genetic strategy for breeding pigs with an inherent resistance to PRRSV. 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 reproductive and respiratory syndrome virus (PRRSV) infection relies on glycolytic reprogramming to support replication, but the mechanisms driving this metabolic shift remain poorly understood. The stimulator of interferon genes (STING), an innate immune adaptor, recently emerged as a metabolic regulator by directly binding and inhibiting hexokinase-2 (HK₂), a key rate-limiting enzyme in glycolysis. Whether PRRSV exploits the STING-HK₂ axis to unleash glycolysis for its own replication is unknown. Here we demonstrate that PRRSV infection induced STING degradation and promoted HK₂ suppression, activating glycolysis for viral replication. In PRRSV-infected Marc-145 cells, lactate production (a glycolysis marker) and HK₂ expression increased time-dependently, peaking at 48 h post-infection (hpi). Conversely, STING protein levels decreased significantly at 36 hpi and further at 48 hpi, suggesting a correlation between STING downregulation and glycolytic activation. The HK₂ inhibitor 2-deoxy-D-glucose reduced lactate production and viral load, while the glycolysis activator PS48 enhanced both. STING knockdown via siRNA increased HK₂ expression, lactate secretion, and PRRSV nucleocapsid protein levels, whereas STING overexpression suppressed these phenotypes. Co-immunoprecipitation and confocal microscopy demonstrated direct STING-HK₂ interaction and cytoplasmic co-localization, maintained during PRRSV infection. HK₂ overexpression promoted viral replication without altering STING levels, confirming HK₂ as a downstream effector. In conclusion, PRRSV-triggered degradation of STING enhances HK₂ expression, promoting lactate accumulation and accelerating viral replication. These findings suggest that the STING-HK₂ axis can act as a critical viral metabolic checkpoint and highlight targeting metabolic–immune crosstalk as a potential anti-viral strategy. Full article

The detection rate of Porcine Reproductive and Respiratory Syndrome Virus type 1 (PRRSV-1) in China has been increasing, with its growing genetic diversity and evolving pathogenicity posing significant challenges to disease control. In this study, a novel PRRSV-1 strain, designated GD18-2, was identified from a pig farm in Guangdong Province that experienced an outbreak despite vaccination with a PRRSV-2 vaccine. Whole-genome sequencing indicated that the GD18-2 strain possesses a genome length of 14,932 bp and exhibits 81.4% to 83.9% nucleotide identity with classical PRRSV-1 strains. Phylogenetic analyses based on both the complete genome and the ORF5 gene indicated that GD18-2 belongs to a distinct, new lineage. A unique amino acid deletion (positions 306–357) was identified in the non-structural protein Nsp2, along with specific mutations within the hypervariable regions of the structural proteins GP3 and GP4. Pathogenicity assessment demonstrated that GD18-2 induced fever, respiratory symptoms, and mortality in piglets. In pregnant sows, it caused reproductive failure (abortion, stillbirth, weak piglets) and was capable of vertical transmission via the placenta. This study highlights the emergence of a PRRSV-1 strain with a unique genetic background and high pathogenicity in southern China, underscoring the necessity for enhanced molecular epidemiological surveillance and updated control strategies. Recombination analysis using RDP4 revealed no significant recombination events in GD18-2. Full article

Porcine epidemic diarrhea virus (PEDV) is a major pathogen responsible for severe diarrhea, dehydration, and high mortality in neonatal piglets, continually threatening global swine production. Rapid differentiation of its major genotypes (classical G1, variant G2, and recombinant S-INDEL) is vital for molecular epidemiology and effective disease control, yet existing approaches rely mainly on time-consuming sequencing and phylogenetic analysis of the S gene. To overcome this limitation, we developed a novel triplex TaqMan-based real-time PCR assay for rapid detection and differentiation of the three PEDV genotypes. The assay demonstrated high sensitivity, with the lowest detection limit of 10² copies/μL, and strong specificity, showing no cross-reactivity with six other common swine pathogens (TGEV, PDCoV, PoRV, PRRSV, CSFV, and PRV). It also exhibited excellent reproducibility, with both intra- and inter-assay coefficients of variation maintained below 1.5%. In clinical validation, the assay showed 100% concordance with results obtained from S gene sequencing and phylogenetic analysis. Furthermore, testing of 160 clinical samples revealed cases of co-infection involving G2 and S-INDEL strains. In conclusion, this rapid, specific, and reproducible assay provides a reliable tool for routine molecular diagnosis, facilitating large-scale epidemiological surveillance and enabling genotype-informed control strategies against PEDV. Full article