The continuously evolving PRRSV has been plaguing pig farms worldwide for over 30 years, with conventional vaccines suffering from insufficient protection and biosecurity risks. To address these challenges, we identified 10 PRRSV-specific CTL epitopes through enzyme-linked immunospot assay (ELISPOT) and constructed a multi-epitope peptide (PTE) by linking them in tandem. This PTE was then fused with a modified porcine Fc molecule to create the recombinant protein pFc-PTE. Our findings indicate that pFc-PTE effectively stimulates PRRSV-infected specific splenic lymphocytes to secrete high levels of interferon-gamma (IFN-γ) and is predicted to be non-toxic and non-allergenic. Compared to PTE alone, pFc-PTE not only induced a comparable cellular immune response in mice but also extended the duration of the immune response to at least 10 weeks post-immunization. Additionally, pFc-PTE predominantly induced a Th1 immune response, suggesting its potential advantage in enhancing cellular immunity. Consequently, pFc-PTE holds promise as a novel, safe, and potent candidate vaccine for PRRSV and may also provide new perspectives for vaccine design against other viral diseases.

Duck enteritis virus (DEV), the pathogen of duck viral enteritis, belongs to the α-herpesvirus subfamily. Like other herpesviruses, it has a large genome with multiple non-coding and non-essential regions for viral replication. It is suitable as a live virus vector for inserting and expressing antigenic genes from other pathogens to develop multivalent vaccines. With the advancement of molecular biology research and experimental technology, genetic modification of the DEV genome has matured, leading to the successful construction of recombinant DEV live vector vaccines. These vaccines have demonstrated the ability to resist DEV and other pathogens, showing potential as recombinant viral vaccine vectors and playing a crucial role in the development of new avian vaccines. This article provides an overview of the progress of research on recombinant vaccines using DEV as the vector. It includes the biological characteristics of DEV and its advantages and limitations as a vaccine vector, methods for constructing recombinant DEV, the technical platform for efficiently building recombinant DEV, factors affecting the immune protection efficacy of recombinant DEV, and the application of recombinant DEV in vaccine development. Aiming to provide a reference for the development of duck enteritis virus vector-based vaccines.

Porcine reproductive and respiratory syndrome virus (PRRSV) causes reproductive disorders in sows and severe pneumonia in piglets, alongside immunosuppressive effects on the host. It poses a significant global threat to the swine industry, with no effective control measures currently available due to its complex pathogenesis and high variability. Conventional inactivated and attenuated vaccines provide inadequate protection and carry biosafety risks. In this study, we designed a universal multi-epitope peptide vaccine against PRRSV using bioinformatics and immunoinformatics approaches to address these limitations. By selecting sequences from seven representative PRRSV strains, we predicted highly conserved and immunogenic T cell (Th and CTL) epitopes across all encoded proteins. These were rationally concatenated with reported B cell neutralizing epitopes into a multi-epitope vaccine construct. We performed comprehensive assessments of the construct’s physicochemical and biochemical properties, along with predictions and refinements of its secondary and tertiary structures. Molecular docking simulations with TLR2 and TLR4 revealed strong potential binding interactions. Immune simulations indicated that the multi-epitope vaccine could induce robust humoral and cellular immune responses. This study provides a scientific foundation for the development of safe and effective PRRSV subunit vaccines and offers new perspectives for designing vaccines against other viral diseases.

Porcine epidemic diarrhea virus (PEDV) is a highly contagious coronavirus that infect pigs’ intestinal epithelial cells, causing high morbidity and mortality. Due to the rapid mutation of PEDV, vaccine efficacy is uncertain, prompting exploration of alternative treatments. Nanobodies, also known as variable heavy chain domains of heavy chain-only antibodies (VHHs), offer significant potential in biomedical applications due to their small size and high specificity. In this study, yeast two-hybrid technology was employed to screen for eight specific VHH sequences targeting the PEDV S protein from a synthetically constructed nanobody yeast library. The VHH genes were then cloned into expression plasmids for recombinant protein production, and the resulting VHHs (termed PEDV S-VHHs) were purified. Indirect immunofluorescence assay (IFA) and Western blotting analysis confirmed that these VHHs specifically bind to both PEDV and its S protein. Neutralization assays demonstrated that seven PEDV S-VHHs exhibited potent neutralizing activity against PEDV. Additionally, a combination of these seven antibodies showed enhanced antiviral effects. Preliminary predictions were also made regarding the binding sites between these VHHs and PEDV. The PEDV S-VHHs described in this study hold potential as candidates for the prevention and treatment of PEDV infection.

Duck circovirus type 1 (DuCV-1) threatens the duck industry globally, with no approved vaccines available. This study aimed to establish a prokaryotic expression system for DuCV-1 virus-like particle (VLP) and clarify the role of the putative nuclear localization signal (NLS) in capsid (Cap) protein function and assembly. Codon-optimized full-length Cap and putative NLS-deleted dCap (residues 1-36) were expressed in Escherichia coli. Deletion of the putative NLS reduced Cap expression by 50%, solubility from 88% to 32.6%, and completely abolished VLP assembly. Full-length Cap self-assembled into 13-17 nm icosahedral VLP, structurally consistent with native virions. Homology modeling revealed the Cap monomer adopts a conserved jelly-roll fold, with the putative NLS mediating critical inter-subunit interactions at the 2-fold axis of the icosahedral capsid. Collectively, the putative NLS is an essential multifunctional motif for Cap protein folding, solubility, and VLP assembly, providing a theoretical and experimental basis for DuCV VLP-based vaccine development.

Pseudorabies virus (PRV) is a highly contagious pathogen in swine that can cross species barriers and infect other mammals, including humans. Given the potential for interspecies transmission and its threat to public health, understanding the molecular biology of PRV strains is essential for developing effective control measures and preparing for future pandemics. In this study, a novel PRV strain, PRV-HL-2021, was isolated from an outbreak in Heilongjiang Province, China. The viral genome was used to establish a reverse genetics system based on a fosmid library of the PRV-HL-2021 genome. This system facilitated the creation of recombinant PRV, including one expressing EGFP and another with deletions in the US9, gI, and gE genes. PRV-HL-2021 was found to be highly lethal to mice in vivo. The recombinant PRV strains, such as rPRV-US9-EGFP and rPRV-delgI/gE/US9, exhibited growth characteristics similar to the parental PRV-HL-2021 strain. The isolation and characterization of PRV-HL-2021 contribute to a better understanding of the genetic diversity of PRV strains. The developed reverse genetics system provides valuable tools for investigating viral functions, creating genetically modified PRV strains, and advancing the development of safer vaccines. These findings will enhance strategies for controlling PRV outbreaks and mitigating its impact on both animal and public health.