Veterinary microbiology最新文献

Canine distemper virus (CDV) and canine parvovirus (CPV) are highly contagious and often fatal pathogens in dogs. Current live-attenuated vaccines, while effective, carry the risk of virulence reversion. This study aimed to develop a safer, replication-defective bivalent vaccine using an adenovirus vector to simultaneously protect against both CDV and CPV. The recombinant vaccine, designated Ad5-(VP2 +H), was engineered to coexpress the CDV hemagglutinin (H) protein (CDV-H) and the CPV Viral Protein 2 (CPV-VP2). Its immunogenicity and protective efficacy were evaluated in mouse and canine models. The results demonstrated that Ad5-(VP2 +H) elicited a potent and durable antigen-specific immune response. Furthermore, compared with a commercially available live attenuated vaccine, the Ad5-(VP2 +H) candidate exhibited a superior safety profile. In conclusion, the adenovirus-vectored Ad5-(VP2 +H) vaccine is a promising and safer alternative for the simultaneous prevention of CDV and CPV in dogs. This approach addresses the key limitation of traditional live-attenuated vaccines by eliminating the risk of virulence reversion while providing effective immunity.

Microparticles (MPs) serve as critical mediators of intercellular communication by shuttling bioactive molecules, holding significant potential for clinical diagnostics and next-generation vaccine development. Brucella, an intracellular pathogen responsible for severe zoonosis, evades host immunity through persistent infection; however, the role of Brucella-induced MPs in modulating adaptive immunity remains poorly defined. In this study, we demonstrate that the infection of RAW264.7 macrophages with the attenuated Brucella melitensis strain M5 triggers robust MP release. These MPs enhance host defense by promoting bacterial clearance and restricting intracellular survival. In murine models, MPs elicit potent Th1-polarized immunity, characterized by elevated IgG2a titers and increased IFN-γ production. Mechanistically, MPs derived from M5-infected macrophages activate the nuclear factor-κB (NF-κB) pathway in bone marrow-derived dendritic cells (BMDCs), augmenting the secretion of IL-12 and TNF-α. Critically, MPs prime cytotoxic T lymphocytes (CTLs) through both direct and indirect pathways, resulting in the specific lysis of Brucella-infected targets. Collectively, Brucella-induced MPs function as integrated immunogenic units that bridge innate recognition with adaptive effector responses, unveiling a novel host-pathogen interaction axis and advancing MPs-based strategies against brucellosis.

Raccoon dog parvovirus (RDPV) is a primary causative agent of infectious enteritis in raccoon dogs. Recently, RDPV has remained prevalent in both fur-bearing and wild animal populations, exhibiting increasing pathogenicity. However, the mechanisms by which RDPV evades host innate immunity remain poorly understood. In this study, we demonstrate that RDPV infection significantly inhibits 2'3'-cGAMP-induced transcription of IFN-β and interferon-stimulated genes (ISGs) in MDCK cells. Over expression of the NS1 protein in HEK293T cells further revealed that NS1 antagonizes the cGAS-STING pathway, suppressing IFN-β and interferon-stimulated response element (ISRE) reporter activities while downregulating mRNA levels of IFN-β, ISG15, and MX1. Mechanistically, Co-immunoprecipitation (Co-IP) and confocal microscopy analyses confirmed an interaction between NS1 and IRF3, which resulted in the downregulation of IRF3 at both the mRNA and protein levels. Notably, NS1 did not affect TBK1-mediated phosphorylation of IRF3 but significantly impaired its nuclear translocation. Furthermore, NS1 was found to recruit the autophagy receptors NBR1, OPTN, and p62 to facilitate the autophagic degradation of IRF3, thereby blocking type I interferon (IFN-I) signaling. In conclusion, this study elucidates a mechanism by which RDPV NS1 inhibits the host IFN-I response via the autophagic degradation of IRF3, providing new insights into viral immune evasion and highlighting the NS1-IRF3 axis as a potential target for future antiviral strategy development against RDPV infection.

Pseudorabies virus (PRV) is an important swine pathogen causing severe economic losses worldwide. Nasal mucosa serves as the initial entry site for PRV, highlighting the importance of nasal mucosal immunity in limiting infection. Here, we investigated the immune responses and protection against PRV for the intranasal vaccination of glycoprotein B (gB) subunit vaccine adjuvanted with poly(I:C). In piglets, immunohistochemistry showed rapid uptake of the gB by the nasal mucosa within 2 h, supporting subsequent immune activation. Upon challenge with the PRV variant ZJ01, intranasal gB vaccination provided complete clinical protection with the absence of clinical signs, substantially reduced virus load in tissues and viral shedding, and no pathological lesions. Relative to intramuscular gB or the live attenuated Bartha-K61 vaccination, intranasal gB vaccination elicited stronger mucosal antibody responses and greater infiltration of CD3⁺ T cells, CD19⁺ B cells, and IgA-secreting cells in the nasal cavity. Notably, intranasal immunization followed by challenge promoted the formation of tertiary lymphoid structure (TLS) in the turbinate, providing a local niche for adaptive immune responses. Consistent with histological observation, transcriptomic profiling of nasal mucosa revealed activation of the IL-17 and TNF signaling pathways, which are implicated in the formation and maintenance of TLS. These findings demonstrate that intranasal gB vaccination might represent a promising mucosal vaccination strategy for controlling PRV infection in swine.

Porcine epidemic diarrhea virus (PEDV) is a highly pathogenic virus that causes severe diarrhea and dehydration in piglets, leading to substantial economic losses in swine-producing regions worldwide. In-depth investigation of the interactions between host factors and viral proteins is crucial for the development of PEDV therapeutics or vaccines. This study primarily explores the impact of Zinc finger protein 16 (ZNF16) on PEDV replication. We find that ZNF16 inhibits PEDV proliferation by targeting and degrading the PEDV S1 protein via the autophagy-lysosome pathway. Mechanistically, ZNF16 recruits the E3 ubiquitin ligase STUB1 to facilitate S1 ubiquitination, which is subsequently recognized by the cargo receptor Tollip for translocation to autolysosomes, ultimately leading to viral S1 degradation and inhibition of PEDV replication. Collectively, this work elucidates a novel ZNF16-mediated antiviral mechanism in which the ZNF16-STUB1-Tollip-autolysosome axis promotes viral protein degradation to inhibit PEDV proliferation.

Escherichia (E.) coli inhabits the pig's microbiota, and some strains can cause a range of diseases when carrying specific virulence factors. Although molecular diagnostics are used to detect these virulence factors, the strength of their detection with clinical disease remains incompletely quantified under field conditions. This systematic review and meta-analysis aimed to estimate the prevalence ratio (PR) of E. coli virulence factor detection in isolates from clinically affected (i.e., enteric disease characterized by diarrhea) versus non-affected pigs. The search was conducted in February 2025 using PubMed and CAB Abstracts to identify articles reporting PCR-based detection of E. coli virulence factors in isolates from pigs with and without clinical signs (i.e., diarrhea). Meta-analyses of each virulence factor detected in two or more studies were conducted using a random-effect model. From 2575 records initially identified, 31 studies met the inclusion criteria, spanning data from 22 countries, with studies from 1998 to 2024. Eighteen virulence factors were analyzed by age category, of which seven were detected more frequently in clinically affected pigs. The F18 (PR = 2.24, 95 % CI = 1.13-4.46), STb (PR = 1.53, 95 % CI = 1.11-2.11), Stx1 (PR = 1.72, 95 % CI = 1.26-2.35), and Stx2 (PR = 1.76, 95 % CI = 1.16-2.67) had a higher frequency of detection in clinically affected pigs over all age categories. When investigating only suckling piglets, F4 (PR = 5.29, 95 % CI = 1.84-15.19), F18 (PR = 2.44, 95 % CI = 1.3-4.6), AIDA (PR = 5.32, 95 % CI = 1.45-19.51), EAST1 (PR = 1.53, 95 % CI = 1.03-2.28), STb (PR = 2.04, 95 % CI = 1.26-3.32) were detected more frequently in clinically affected piglets. The Stx2 was also more frequently detected in clinically affected pigs in the nursery phase (PR = 2.90, 95 % CI = 1.30-6.48). High heterogeneity was present in most analyses, highlighting variability in detection patterns across studies. Several traditionally tested virulence factors, such as F5, F6, and Stx2e, did not show differences between clinically affected and non-affected pigs. These findings support the role of molecular diagnostics in the characterization of pathogenic E. coli and underscore the importance of interpreting virulence factors results in conjunction with clinical signs for a more accurate diagnostic.

Rotavirus C (RVC) is an enteric pathogen frequently found in pig holdings. It is known to cause mild to severe gastrointestinal symptoms especially in suckling and weaned piglets. As most of RVC strains cannot be propagated in cell culture, serological surveys and the development of autologous vaccines are hampered. In order to gain better insight into their diversity, genetic studies are therefore particularly useful for identifying RVC genotypes. In this study, the distribution of circulating RVC genotypes (G-types and P-types) was analysed in six countries in Central Europe. Our investigations revealed the occurrence of ten different G-types, 16 different P-types and 24 different G-P-combinations. The largest number of different genotypes was found in the regions with the highest pig densities. Overall, two clearly dominant genotypes both in the comparison of countries and federal states were identified: G6 and P21. Genotype P21 has so far only been detected in Europe. Focusing on coinfections, this study revealed the lowest coinfection rates within the most frequently detected two genotypes (G6 and P21). Overall, the study provides a unique dataset that raises further questions regarding the underlying reasons for the distribution of specific RVC strains and the notably low coinfection rates observed within certain genotypes.

Novel duck reovirus (NDRV) is a major pathogen that causes immunosuppression and secondary infections in ducklings, resulting in elevated mortality and severe economic losses to the global duck industry. However, there is currently no licensed vaccine available in China for the effective prevention and control of NDRV infections. To effectively control NDRV outbreaks, we developed a live-attenuated vaccine candidate against NDRV by serially passaging the NDRV E232 strain in specific-pathogen-free (SPF) chicken embryos and DF-1 cells. The resulting E232-P100 strain replicated efficiently in DF-1 cells, with viral titers reaching up to 10^7.0 TCID₅₀/0.2 mL. No clinical symptoms or pathological lesions were observed in two-day-old Cherry Valley ducklings inoculated with E232-P100, and no virulence reversion was observed after five rounds of in vivo back-passage in ducklings. The minimum protective dose of the attenuated E232-P100 strain was 10^3.0 TCID₅₀/0.2 mL. Evaluation of the onset of immune protection showed that complete protection was achieved by 5 days post-vaccination. Comparative genomic analysis revealed 18 amino acid substitutions between E232-P100 and the parental E232 strain, including three within the σC protein that are potentially associated with attenuation. Collectively, the E232-P100 strain represents a safe, stable, and highly protective live attenuated vaccine candidate for the prevention of NDRV infection, providing a promising foundation for the development of effective prevention strategies against NDRV epidemics in waterfowl populations.

Leptospirosis is a zoonotic disease caused by spirochetes of the genus Leptospira. Equine genital leptospirosis (EGL) has been described as a chronic and silent syndrome, presenting reproductive alterations such as abortion, stillbirth, placentitis, embryonic loss, repeat breeding syndrome, and subfertility. This study aimed to investigate the genital Leptospira infection in naturally infected mares with poor reproductive performance, as well as to genetically characterize the agents. A total of 41 mares with a history of poor reproductive performance were selected. Sera were collected for serology by Microscopic Agglutination Test (MAT), while urine, uterine mucus, and uterine fragment samples were collected for a lipL32-PCR screening. Samples positive at lipL32-PCR were submitted to secY gene sequencing. Considering MAT, 17/41 mares were seroreactive (41.5 %). The most frequent serogroup was Australis, detected in 13 animals (76.5 % of the reactive). Out of the 41 mares, 25 (61.0 %) were positive in lipL32-PCR and, of these, 21 (84.0 %) showed positive in at least one genital sample. Regarding secY nested-PCR, only six samples, all from the uterine fragment, were amplified, and all were characterized as Leptospira interrogans with ≥ 99 % of similarity with isolates of serovar Bratislava, from the Australis serogroup. Our results confirmed the diagnosis of EGL and highlighted the high detection rate of Leptospira DNA in genital samples of mares with poor reproductive performance.

Vaccination is a critical strategy for controlling H9N2 avian influenza, a subtype with significant implications for poultry health and public safety. Current vaccines hinder serological differentiation between naturally infected and vaccinated animals, complicating disease surveillance and eradication efforts. Here, we developed a novel H9-subtype differentiating-infected-from-vaccinated-animals (DIVA) vaccine using reverse genetics. The recombinant virus, Re-H9-DIVA-J2, was engineered by replacing the neuraminidase (NA) gene of a clinically isolated H9 strain (A/chicken/Guangdong/J2/2016) with the NA ectodomain from a B/Yamagata-lineage influenza virus (B/Massachusetts/2/2012), while retaining six internal genes from the H1N1 PR8 strain. The chimeric virus exhibited low pathogenicity in chicken embryos, high growth titers (HA≥8 log₂), and stable genetic inheritance of the B-type NA marker over 10 passages. Three batches of inactivated vaccines were tested in specific-pathogen-free (SPF) chickens, demonstrating robust immunogenicity with hemagglutination inhibition (HI) antibody titers peaking at 10 log₂ by 21 days post-vaccination. Challenge experiments confirmed full clinical protection and reduced viral shedding (above 90 % protection). Critically, sera from Re-H9-DIVA-J2-vaccinated chickens showed no cross-reactivity with A-type N2 protein in immunofluorescence (IFA) and ELISA assays, distinguishing them from sera of wild-type-infected or conventional H9N2-vaccinated animals. This study presents a safe, immunogenic H9 marker vaccine compatible with DIVA diagnostics, offering a promising tool for H9N2 control and eradication.