Background: Porcine circovirus type 2 (PCV2) is the primary causative agent of the emerging swine disease known as postweaning multisystemic wasting syndrome (PMWS). Nowadays, polymerase chain reaction (PCR) is still the most widespread technique in pathogen detection. Loop-mediated isothermal amplification (LAMP), a novel nucleic acid amplification method developed in 2000, will possibly replace PCR in the field of detection. To establish a LAMP method for rapid detection of PCV2, two pairs of primers were designed specially from the open reading frame 2 (ORF2) sequences of PCV2. A LAMP method for rapid detection of PCV2 was established. To compare with PCR, sensitivity and specificity of LAMP were evaluated using the optimized reaction system. The LAMP products could be determined by agarose gel electrophoresis or adding SYBR Green I dye. Results: The amplification of LAMP could be obtained at 63°C for 60 min. The detection limit was nearly 1 copy of DNA plasmid, more sensitive than PCR. There was no cross-reaction with porcine circovirus type 1 (PCV1), porcine pseudorabies virus (PRV) and porcine parvovirus (PPV) under the same conditions. Conclusions: LAMP is an useful rapid detection method with high sensitivity and specificity for PCV2.

The Aeromonas salmonicida is responsible for causing furunculosis in various fish species. Furunculosis is a ubiquitous disease that affects the aquaculture industry and causes the mass mortality of turbot. Vibrio vulnificus is a pathogen that causes skin ulcers and hemorrhagic septicemia in fish, resulting in significant mortality in aquaculture. In this study, we have established a bivalent inactivated vaccine against A. salmonicida and V. vulnificus with Montanide™ ISA 763 AVG as an adjuvant. This bivalent inactivated vaccine was used to immunize turbot by intraperitoneal injection, and the relevant immune indexes were detected. The results demonstrate that the bivalent inactivated vaccine exhibited a relative percent survival (RPS) of 77% following A. salmonicida and V. vulnificus intraperitoneal challenge. The vaccinated group exhibited higher levels of acid phosphatase activity and lysozyme activity compared to the control group. ELISA results showed a significant increase in serum antibody levels in immunized turbot, which was positively correlated with immunity. In the kidney tissue, related immune genes (TLR5, CD4, MHCI and MHCII) were up-regulated significantly, showing that the vaccine can induce cellular and humoral immune responses in turbot. In conclusion, the bivalent inactivated vaccine against A. salmonicida and V. vulnificus was immunogenic, efficiently preventing turbot from infection, which has the potential to be applied in aquaculture.

Picornaviruses pose a significant threat to both human and animal health, causing many diseases in humans and swine. Porcine sapelovirus (PSV) is a globally reported enteric picornavirus commonly associated with subclinical or mild enteric infections in swine populations. Critically, unlike other neurotropic picornaviruses such as Enterovirus A71, no PSV strain has been reported to breach the blood–brain barrier (BBB). Since 2023, outbreaks of diarrhea with concurrent neurological signs like ataxia and lameness have been observed in weaned piglets across China, in particular, on a farm in Zhejiang province in 2025 with 100% morbidity and 20% mortality among the cases. Routine diagnostics ruled out common swine pathogens, but qPCR was positive for PSV. We successfully isolated three PSV strains (ZJ, FJ, SD) from affected piglets. Genetic analysis revealed that the PSV-ZJ is a novel recombinant between strains YC2011/2012 (China, 2011) and XTND/2019 (Vietnam, 2018). Pathogenicity assessment confirmed that the recombinant PSV-ZJ is highly pathogenic, causing severe diarrhea, growth retardation, and significant viral shedding via the respiratory and digestive tracts. qPCR and histopathology confirmed viral presence in intestinal and brain tissues, indicating that PSV-ZJ can cross the blood–brain barrier. This study presents the first quantitative viral load and histopathological data for a highly pathogenic recombinant PSV strain in China and emphasizes the critical role of recombination in driving viral virulence evolution, necessitating enhanced surveillance and the development of targeted preventive strategies.