Search Results (97)

Infectious bursal disease virus (IBDV) is a pathogen that causes Gumboro disease in young chickens. Vaccine strains and field IBDV genotypes are disseminated in chickens from commercial poultry farms worldwide. This study aimed to detect the field IBDV genotypic diversity in poultry farms in Latin America, mainly in Brazil. Bursal samples from 69 broiler flocks in eleven Latin American countries were obtained between 2015 and 2025. All 69 samples tested were positive for IBDV; the VP2 (segment A) and VP1 (segment B) genes were sequenced. Phylogenetic and amino acid substitution analyses were performed with large genetic datasets, including previously identified IBDV genotypes worldwide. The results revealed four A (A1, A2, A3, and A4) and three B (B1, B2, and the candidate B6) genogroups in Latin America. Furthermore, genotypes A1B1 (1.4%), A2B1 (59.4%), A3B2 (20.3%), A3B6 (2.9%), and A4B1 (15.9%) were identified. A2B1 could be subdivided into A2aB1a (24.4%), A2bB1a (29.3%), A2dB1b (19.5%), and A2eB1a (26.8%). In Brazil, the field genotypes A3B2, A4B1, and A3B6 were demonstrated. These findings highlight an important IBDV genotypic diversity in Latin American countries and reinforce the need for continuous molecular surveillance to support control and vaccination programs. Full article

Animal infectious diseases impose severe economic burdens on livestock industries, threaten wildlife populations, and compromise food security. Although vaccination remains the cornerstone of disease prevention, conventional vaccine platforms are often constrained by safety, efficacy, or manufacturing scalability. This narrative review provides a comprehensive analysis of the state of the art in herpesvirus-vectored vaccines for veterinary applications, focusing on five well-characterized alphaherpesviruses: Bovine herpesvirus type 1 (BoHV-1), Pseudorabies virus (PRV), Marek’s disease virus (MDV), Equine herpesvirus type 1 (EHV-1), and Duck enteritis virus (DEV). The intrinsic characteristics of herpesviruses, including large, stable genomes; the capacity for foreign gene insertion; broad host tropism; and the ability to elicit robust humoral and cellular immunity, are examined, and their performance is compared with that of traditional vaccine platforms. Key advances in vectored vaccine development are highlighted, from proof-of-concept studies to the creation of advanced multivalent constructs. These approaches demonstrate protective efficacy against a range of significant animal pathogens, including foot-and-mouth disease virus, porcine reproductive and respiratory syndrome virus, avian influenza virus, infectious bursal disease virus, and West Nile virus. The literature was identified through systematic searches of PubMed, Google Scholar, and Web of Science (1990–2026), followed by title/abstract screening and reference chaining. Future directions in vector engineering, mucosal delivery, and synthetic biology approaches are considered. Herpesvirus-vectored vaccines represent a versatile platform for enhancing animal health, supporting sustainable agriculture, and mitigating zoonotic risks. Full article

The genetic and antigenic diversity of H5Nx HPAI Gs/GD lineage continues to be a great challenge facing conventional inactivated vaccines. To overcome this challenge, a recombinant herpes virus of turkey (rHVT) vaccine expressing the viral protein 2 (VP2) of infectious bursal disease (IBD) and H5, rHVT+IBD+H5, was developed using computationally optimized broadly reactive antigen (COBRA) technology. In the current study, the protective efficacy of a commercially available vector trivalent vaccine rHVT+IBD+H5 using COBRA technology was assessed. A total of 120 commercial broilers were divided equally into six groups (G1B–G6B). The chickens in G1B–G3B were challenged with the most recent circulating HPAI-H5N1 clade 2.3.4.4.b Egyptian isolate (GenBank accession No. OQ933425) at 28 days old (DO), while the chickens in G4B and G5B were kept as vaccinated (as G1B and G2B, respectively) and non-challenged, and G6B was the non-vaccinated non-challenged group. In G1B, the chickens were vaccinated with Vaxxitek^® rHVT+IBD+H5 at 1 DO and boostered with a commercially available subunit Baculovirus bivalent inactivated H5+ND (Volvac^® B.E.S.T AI+ND) at 10 DO and had a 100% survival rate. The standalone vaccinated chicken G2B, using rHVT+IBD+H5 at 1 DO, had a highly significant survival rate (90%) vs. 0% (100% mortality) in the non-vaccinated challenged control, G3B. All the vaccinated groups had higher seroconversion at 45 DO especially using H5-coated antigen plates for the enzyme-linked immunosorbent assay (ELISA) test. The viral shedding titers and time were evaluated using a quantitative real-time polymerase chain reaction (RT-qPCR) in the collected oropharyngeal and cloacal swabs at 3, 5, 7, and 10 days post-challenge (DPC). In conclusion, vaccination with rHVT+IBD+H5 either as a standalone or when boostered with subunit Baculovirus bivalent inactivated ND+H5 resulted in 90 and 100% protection, respectively, without significant difference in the quantity and duration of viral shedding between both groups against HPAI-H5N1 clade 2.3.4.4.b experimental challenge in broilers. Full article

Infectious bursal disease virus (IBDV) is an immunosuppressive pathogen posing a major threat to poultry health worldwide. Its marked phenotypic variability is driven by the rapid evolution of its double-stranded RNA genome, primarily achieved through mutation and reassortment. Although extensive evidence has been generated on molecular determinants of antigenicity and pathogenicity, interpretation is often hindered by heterogeneity and lack of systematicity. This scoping review synthesizes over 35 years of research on amino acid positions influencing IBDV phenotype. A total of 62 studies reporting 107 functionally relevant sites were identified and critically appraised based on evidence type, methodological approach, and ability to infer causality. The results confirmed the central role of VP2, particularly its hypervariable region, while also highlighting the increasingly recognized contribution of other viral proteins. Despite good agreement, comparability across studies was limited by substantial heterogeneity in experimental design and the frequent focus on partial genomic regions. Notably, some molecular markers were context-dependent or inconsistently associated with phenotypic outcomes, underscoring the need for proper interpretation of molecular determinants and for more standardized and comprehensive approaches, including full-genome analyses and reverse genetics. Overall, these findings provide a valuable framework for enhancing molecular diagnostics and supporting the rational design of next-generation vaccines. Full article

The infectious bursal disease virus (IBDV) can cause severe immunosuppression and high mortality in chickens, posing a significant threat to the poultry farming industry. Pyroptosis mediated by gasdermin E (GSDME) may be closely related to the tissue damage caused by IBDV. In this study, 3-week-old specific-pathogen-free (SPF) White Leghorns chickens were inoculated intranasally with 1000 copies/200 μL of very virulent IBDV (vvIBDV) Gx strain, and we analyzed GSDME expression in chicken tissues and the cleavage site of GSDME by Caspase-3. Tissue distribution results showed that GSDME and IL-1β transcription in the bursa of Fabricius and kidneys were significantly upregulated by more than five-fold (p < 0.01) following vvIBDV infection, indicating a close association with vvIBDV-induced tissue lesions. Further studies demonstrated that Caspase-3 could cleave GSDME at conserved sites (D270), releasing the active N-terminal fragment (GSDME-N) to induce pyroptosis. Furthermore, although IBDV proteins cannot directly cleave GSDME, the viral protein VP3 enhances Caspase-3-mediated GSDME cleavage, thereby triggering pyroptosis. The above results reveal the role of GSDME-dependent pyroptosis in the pathogenesis of IBDV and provide new ideas for the prevention and control strategies against IBDV. Full article

Infectious pancreatic necrosis virus (IPNV), a member of the family Birnaviridae, is a major pathogen of farmed salmonids and an important model in fish virology. Despite its small genome, which encodes only five viral proteins, IPNV exhibits complex molecular processes that govern genome expression, replication, and particle assembly. Comprehensive descriptions of the molecular biology and replication cycle of IPNV were largely established in reviews published in the mid-1990s, whereas more recent reviews have primarily focused on virulence determinants, epidemiology, or host–virus interactions. This review provides an updated synthesis of available experimental knowledge on the molecular biology of IPNV by integrating classical and recent studies addressing virion architecture, genome organization, and the functions of viral proteins. Particular attention is given to the molecular events involved in the viral replication cycle, including virus entry, genome transcription, translation and replication in the cytoplasm, polyprotein processing by the viral protease, and the coordination between genome replication and virion assembly. When appropriate, experimental observations from the related Avibirnavirus infectious bursal disease virus are considered to provide additional context for molecular mechanisms conserved within the family Birnaviridae. Together, these studies outline the current understanding of the molecular processes governing IPNV replication and morphogenesis. Full article

Transmissible viral proventriculitis (TVP) is an emerging disease in chickens, linked to chicken proventricular necrosis virus (CPNV), a recently identified birnavirus. Here, we provide the first molecular confirmation of TVP in Bangladesh from a coloured meat-type parent stock (PS) flock, while documenting a contemporaneous white layer flock with consistent clinical signs and characteristic gross lesions. Affected birds exhibited growth retardation, diarrhoea, and increased mortality, alongside hallmark gross changes in proventricular enlargement and wall thickening. From the meat-type PS, proventricular samples were collected for histopathology and molecular diagnostics. Histological analysis revealed severe glandular epithelial damage, necrosis, mononuclear infiltration, epithelial hyperplasia, and metaplasia. Using RT-PCR on nucleic acid extracted from FTA card samples, CPNV was detected. In addition, infectious bronchitis virus (IBV), infectious bursal disease virus (IBDV), and avian reovirus (ARV) nucleic acids were also identified. The amplified CPNV VP1 fragment was sequenced, and phylogenetic analysis placed the Bangladeshi strain within clades of previously reported CPNV isolates. This study represents the first molecularly confirmed report of CPNV associated with TVP in Bangladesh, highlighting the need for active surveillance in commercial and breeder poultry flocks to understand the virus’s epidemiology and support the development of control strategies. Full article

Quebrachitol, an optically active cyclitol derived from plants, has recently gained attention as a potential natural product with therapeutic properties, though its antimicrobial effects remain unclear. This systematic review aims to determine, appraise, and consolidate evidence of the antimicrobial potential of quebrachitol. PRISMA-guided searches of PubMed, Scopus, and Google Scholar (2000–2024) identified English-language experimental in vitro, in vivo, and in ovo studies. Data on antimicrobial activity, dosage or treatment duration, and mechanisms were extracted, with study quality assessed using QUIN and SYRCLE tools. Of 866 studies screened, 11 met inclusion criteria: seven in vitro, one in vivo, one in ovo, and two combining both approaches. Quebrachitol demonstrated inhibitory effects against Salmonella sp., Candida albicans, infectious bursal disease virus (Avibirnavirus gumboroense), Newcastle disease virus, Plasmodium sp., and notably, biofilm formation by Staphylococcus epidermidis and methicillin-resistant Staphylococcus aureus (MRSA). Overall, quebrachitol exhibits promising antimicrobial potential, but rigorous in vivo studies are required to confirm its efficacy and safety in addressing antimicrobial resistance. Full article

Infectious bursal disease virus (IBDV) and avian reovirus (ARV) are major immunosuppressive pathogens controlled through the widespread use of live attenuated vaccines. Concerns persist regarding potential immune interference when these vaccines are co-administered, though comprehensive in vivo data are lacking. Here, we reported the immunogenicity and protective efficacy of a live IBDV vaccine (W2512G-61) and a live ARV vaccine (ZJS) administered simultaneously or sequentially at 3-, 5-, and 7-day intervals in specific-pathogen-free (SPF) chickens. The IBDV live vaccine elicits strong, interval-independent humoral immunity and conferred 100% protection, demonstrating no compromise from ARV co-administration. Conversely, ARV-specific immunity was severely impaired by close temporal vaccination. ARV protection rates fell from 86.7% (ARV-only) to 46.7% with simultaneous administration and from 93.3% to 66.7% with a 3-day interval. Extending the interval to five or seven days eliminated this interference, restoring ARV antibody titers and protection to levels equivalent to ARV-only control vaccinated groups. This study provides the first definitive evidence of asymmetric immune interference between live IBDV and ARV vaccines. The results establish a minimum safe interval of five days to prevent interference and ensure robust ARV vaccine efficacy. These findings offer critical, evidence-based guidance for optimizing vaccination schedules to improve disease control in commercial poultry production. Full article

Background/Objective: Infectious bursal disease (IBD) is an acute and highly contagious immunosuppressive disease in chickens caused by infectious bursal disease virus (IBDV). In recent years, a novel variant IBDV (nVarIBDV) has emerged and spread widely, inducing severe immunosuppression and posing a substantial threat to the poultry industry. More importantly, owing to antigenic variations, nVarIBDV can escape the immune protection of the existing vaccines. Therefore, it is imperative to develop a new vaccine that is antigenically matched to nVarIBDV. Methods: The major protective antigen gene VP2 of the representative nVarIBDV strain SHG19 was inserted into the eukaryotic expression plasmid pCAGGS to construct the recombinant plasmid pCASHGVP2. Subsequently, pCASHGVP2 was encapsulated in lipid nanoparticles (LNPs) to form pCASHGVP2-LNP nanoparticles. Finally, using the SPF chicken model, the immune efficacy of pCASHGVP2-LNP was preliminarily assessed by administering two vaccine doses (10 and 20 μg) and two immunization regimens (single or double immunization). Results: Efficient VP2 protein expression from pCASHGVP2 was confirmed by in vitro transfection experiments. The prepared pCASHGVP2-LNP nanoparticles exhibited an optimal particle size distribution and acceptable polydispersity index, indicating a homogeneous formulation. Furthermore, animal experiments showed that the candidate DNA vaccine elicited specific neutralizing antibodies after double immunization and protected immunized chickens from disease induced by nVarIBDV challenge. Conclusions: This study reports the first development of an LNP-encapsulated VP2 DNA vaccine (pCASHGVP2-LNP) against nVarIBDV, highlighting its potential application for the prevention of nVarIBDV. Full article

Background: Large-scale production of poultry viral vaccines increasingly requires robust suspension cell platforms. However, most avian cell lines, including DF-1, are strictly anchorage-dependent, limiting scalability. Aquaporin-1 (AQP1) regulates cell–cell adhesion and membrane dynamics, making it a potential target for engineering suspension growth. This study aimed to generate a stable DF-1 suspension cell line via AQP1 disruption and evaluate its potential for enhanced infectious bursal disease virus (IBDV) production. Methodology: DF-1 cells were engineered using a CRISPR/Cas9 ribonucleoprotein system to create a truncated AQP1 gene. DF-1/AQP1⁻ cells were assessed for morphology, tumorigenicity in nude mice, and genetic stability across 20 passages. Suspension growth, cell density, and viability were measured. Cells were infected with IBDV strain BJQ902, and viral titers were compared with wild-type DF-1 and monolayer DF-1/AQP1⁻ cells. Results: DF-1/AQP1⁻ cells maintained normal morphology, were non-tumorigenic, and retained stable AQP1 mutations. They grew as true suspension cultures without adaptation, reaching 4.0 × 10⁶ cells/mL with >95% viability. Suspension DF-1/AQP1⁻ cells cells produced significantly higher viral titers (9.0 log TCID₅₀/mL; 8.63 log EID₅₀/mL) than both monolayer DF-1/AQP1⁻ and wild-type DF-1 cells. Virus production time was shortened in suspension cultures. Conclusions: Targeted AQP1 disruption converts DF-1 cells into a stable, non-tumorigenic suspension cell line with markedly enhanced IBDV production, providing a scalable platform for next-generation avian vaccine manufacturing. Full article

The present study was carried out to analyze the complete genome sequences of infectious bursal disease virus (IBDV) isolates obtained from field outbreaks in the southern regions of India. Bursal tissue samples were collected and screened by RT-PCR, targeting the VP2 gene. Positive samples were subjected to serological identification via AGID. Following this, eight samples (BGE14, BGE15, MDI14, THI14, EDE14, RPM14, VCN14, and NKL14) were subjected to virus isolation in 9 to 11-day-old embryonated chicken eggs, and their complete genomes were sequenced. Analysis of the VP2 hypervariable region (HVR) revealed that all eight isolates had five unique and highly conserved amino acids (A222, I242, Q249, I256, and S299). However, all the isolates reveal a substitution of Isoleucine by Valine at residue 294 (I294V). Furthermore, analysis of segment B from all Indian IBDV sequences revealed that the triplet amino acid pattern was NEG (residues 145–147) and the amino acid at position 242 was consistently D across all isolates. These findings suggest that segment B of the isolates in this study resembled that of vaccine strains and non-vvIBDV strains. Additionally, the presence of the signature D242 in all Indian isolates, characteristic of non-vvIBDV strains, implies a potential attenuation. Moreover, in the phylogenetic analysis of VP2-HVR, all isolates clustered with very virulent reference strains, while segment B clustered with classical attenuated strains. Notably, the phylogenetic analysis of VP2-HVR and VP1 of these viruses demonstrated genetic variances, suggesting evolutionary changes in segment B across all eight Indian isolates, likely indicative of natural genome reassortment resulting in these specific outbreaks in the flocks. Full article

Infectious Bursal Disease (IBD) is an immunosuppressive viral disease caused by the Infectious Bursal Disease Virus (IBDV). It primarily affects young chickens, targeting the bursa of Fabricius, and poses significant economic threats to the poultry industry. To date, in addition to strict biosecurity measures, large-scale immunization is the optimal strategy and effective method to prevent and control IBDV infection. The emergence of new variant strains has made it more urgent to develop new vaccination strategies against IBD. Over the past few decades, many high-quality vaccines have been available on the market for the control of IBD, which can provide solid protection against the infections and diseases caused by classic IBDV to very virulent IBDV that had been continuously evolving and were endemic worldwide. However, viruses are not static. As they continue to circulate and evolve in the fields, novel antigenic variant viruses have been emerged in the last few years, and vaccines need to keep up with their pace. Collectively, this review summarizes the strategic evolution of IBDV vaccines from traditional methods to cutting-edge molecular platforms, providing promising strategies for developing the next-generation vaccines with higher safety, efficacy, and the ability to keep pace with the antigenic drift in IBDV. Full article

Over the past decade, diseases associated with fowl adenoviruses (FAdVs) have exhibited a new epidemic trend worldwide. The presence of numerous FAdVs serotypes, combined with the virus’s broad host range, positions it as a significant pathogen in the poultry industry. In the current context of intensive poultry production and global trade, co-infections involving multiple FAdVs serotypes, as well as co-infections with FAdVs alongside infectious bursal disease or infectious anemia virus, may occur within the same region or even on the same farm. The frequency of these outbreaks complicates the prevention and control of FAdVs. Therefore, the development of effective, targeted vaccines is essential for providing technical support in the management of FAdVs epidemics. Ongoing vaccine research aims to improve vaccine efficacy and address the challenges posed by emerging FAdVs outbreaks. This review focuses on vaccines developed and studied worldwide for various serotypes of FAdVs in the past decade. It encompasses inactivated vaccines, live attenuated vaccines, e.g., host-adapted attenuated vaccines and gene deletion vaccines, viral vector vaccines, and subunit vaccines (including VLP proteins and chimeric proteins). The current limitations and future development directions of FAdVs vaccine development are also proposed to provide a reference for new-generation vaccines and innovative vaccination strategies against FAdVs, as well as for the rapid development of highly effective vaccines. Full article

Infectious bursal disease virus (IBDV) is one of the most important immunosuppressive viruses in poultry, causing the global spread of infectious bursal disease (IBD). It poses a significant threat to the healthy development of the poultry industry. Vaccination is an effective approach for controlling IBDV infection. Therefore, reliable immune monitoring for IBDV is critical for maintaining poultry health. The enzyme-linked immunosorbent assay (ELISA) is a common technique used to detect specific antibodies in clinical serum testing and for the serological evaluation of IBDV vaccines. Among the currently available and under development IBDV vaccines, IBD VP2 subunit-based vaccines account for a considerable proportion. These vaccines stimulate the production of antibodies that are specific only to VP2. However, most IBDV antibody ELISA kits approved for use have applied the whole virus as the coating antigen, which does not adequately meet the diverse requirements for IBDV detection across different conditions. This study utilized a prokaryotic expression system to express the VP2 protein of the IBDV epidemic strain, assembling it into virus-like particles to be used as coating antigens. This approach enabled the establishment of an indirect ELISA method for detecting IBDV VP2 antibody (VP2-ELISA). The optimal coated antigen concentration was determined to be 2.5 μg/mL, with overnight coating at 4 °C; sealing with 5% skim milk at 37 °C for 4 h; serum dilution at 1:500 with incubation at 37 °C for 30 min; secondary antibody dilution at 1:4000 with incubation at 37 °C for 40 min; and then incubation with the substrate solution 3,3′,5,5′-tetramethylbenzidine at room temperature for 20 min. The criterion for interpreting the detection results was OD_450nm ≥ 0.111 indicates IBDV antibody positivity, while OD_450nm < 0.111 indicates negativity. The established VP2-ELISA can specifically detect IBDV-positive sera at the lowest serum dilution of 1:6400, with intra- and inter-batch coefficients of variation of <2%. This indicates that the VP2-ELISA exhibits good specificity, sensitivity, and stability. Detection experiments using 20 laboratory-immunized chicken serum samples and 273 clinical serum samples demonstrated that the results of VP2-ELISA were consistent with those of commercial ELISA kits coated with whole virus. In summary, the VP2-ELISA developed in this study offers advantages in immune response detection for IBD VP2 subunit-based vaccines and is appropriate for evaluating the efficacy of IBD vaccines and detecting clinical serum samples. Full article