Dendritic cells (DCs) bridge innate sensing and adaptive immunity. Their functional heterogeneity derives from fundamental differences among DC subsets in ontogeny, tissue distribution, receptor repertoires, and antigen-processing pathways, establishing a specialized “division of labor” in antigen presentation, encompassing classical major histocompatibility complex (MHC) II-restricted presentation of exogenous antigens, MHC I-restricted presentation of endogenous antigens, and differences in the efficiency and preference of antigen cross-presentation. These subset-intrinsic features enable DCs to selectively instruct naïve T cells toward cytotoxic immunity, helper lineage differentiation, or immune tolerance. Recent advances reveal previously unappreciated dimensions of DC specialization. Type 1 conventional dendritic cells (cDC1s) not only excel in cross-presentation but also shape tumor immunogenicity through CLEC9A (also known as DNGR-1)-mediated recognition of F-actin-associated neoantigens, driving immune editing. Type 2 conventional dendritic cells (cDC2s) orchestrate lymph node dynamics-recruiting innate effectors to form transient “immune firewalls” and subsequently restoring tissue architecture for efficient T cell priming. In this review, we delineate how subsets-specific differences dictate specialized functions and shape immune outcomes. This review discusses DC subset biology from the perspective of veterinary vaccine research, with attention to both conserved mechanisms and species differences. We also summarize how DC-targeted delivery may be considered in veterinary precision vaccinology. Insights from large-animal models offer unique opportunities to validate next-generation vaccines against major animal diseases while informing human vaccine design through bidirectional cross-species translation.
Nipah virus (NiV) infection is a highly fatal zoonotic disease and remains a major public health concern in Bangladesh. This narrative review comprehensively examines the epidemiology, outbreak pattern, transmission dynamics, clinical manifestations, ecological drivers, public health interventions, surveillance systems, therapeutic progress, and vaccine development related to NiV infection in Bangladesh. The review was conducted through a comprehensive analysis of published literature and relevant reports from 2001 to February 2026, retrieved from PubMed, Scopus, and Google Scholar. During this period, Bangladesh reported 348 confirmed NiV cases across 35 districts, with 250 deaths and an overall case fatality rate of 71.84%. Outbreaks were concentrated mainly in the central and northwestern regions, commonly referred to as the “Nipah belt.” The principal route of transmission was consumption of raw date palm sap contaminated by greater Indian fruit bat (Pteropus medius), while person-to-person transmission through close contact with infected individuals also played an important role. Clinical features were dominated by fever, unconsciousness, respiratory distress, headache, vomiting, and other neurological symptoms. Seasonal outbreaks were strongly associated with winter sap collection, bat feeding behavior, environmental conditions, and cultural practices. Although bamboo skirts, awareness campaigns, boiling of sap, and hospital-based surveillance have contributed to prevention efforts, sustained community adoption remains limited. Bangladesh still lacks approved vaccines, specific antiviral therapy, rapid point-of-care diagnostics, and advanced biosafety infrastructure. Expanding surveillance, improving early diagnosis, implementing ecological interventions, and advancing vaccine and therapeutic research are essential to reduce future spillover and human-to-human transmission.
Getah virus (GETV), a mosquito-borne zoonotic pathogen, is a member of the genus Alphavirus within the family Togaviridae. Recent outbreaks of GETV infection in multiple regions of China have led to increased incidences of sow miscarriage and high mortality in suckling piglets, exhibiting enhanced virulence and rapid transmission that posing a substantial threat to the livestock industry and public health. Since its initial isolation in Malaysia in 1955, GETV has long been considered a pathogen of low pathogenicity. However, recent outbreaks attributed to virulence-enhanced genotype III (GIII) variant strains have been reported across numerous pig farms in China, with the mode of transmission shifting from regional and sporadic to a localized epidemic pattern. In parallel, the host range of GETV is expanding beyond traditional domestic animals such as horses, pigs and cattle, to include wildlife species like blue foxes, bears, among others. Additionally, GETV antibodies have been detected in the blood of febrile patients. In light of ongoing global warming, the threat posed by GETV infections has been significantly underestimated. Herein, this review systematically examines the genomic architecture, origins, epidemiological features, recent prevalence patterns, and evolutionary dynamics of GETV, with the objective of informing future strategies for its prevention and control.
Classical swine fever virus (CSFV) remains a significant threat to swine health, necessitating alternative vaccine strategies that overcome limitations of live-attenuated vaccines. In this study, we present a comprehensive in silico framework that integrates entropy-based conservation analysis, immunoinformatics, structural modeling, and translational feasibility assessment to rationally design a multi-epitope vaccine construct (MEVC) targeting the CSFV E2 glycoprotein. A non-redundant dataset of 312 E2 sequences was analyzed using multiple Shannon entropy profiles, revealing a dominant low-entropy region (Block 9; residues 1–426) that remained stable across multiple entropy thresholds. Residue-level conservation analysis confirmed high consensus across this block, supporting its suitability for epitope mining. Cytotoxic T lymphocyte (CTL), helper T lymphocyte (HTL), and linear B-cell epitopes were predicted within Block 9 and filtered based on binding affinity, conservation, antigenicity, and safety criteria. Epitope density analysis showed significant enrichment within Block 9 relative to the remainder of the E2 protein. The finalized MEVC was structurally modeled and validated using stereochemical and energy-based metrics, and a comparative analysis with an AlphaFold model highlighted structural uncertainty inherent to synthetic multi-epitope constructs. In silico immune simulations were performed to explore qualitative immune response trends. Physicochemical profiling and codon optimization for Escherichia coli expression indicated favorable stability, solubility, and translational feasibility, supported by optimal GC content, codon adaptation index, and absence of rare codon clusters. While all findings are computational and require experimental validation, this study provides a refined, data-driven foundation to guide future experimental development of CSFV epitope-based vaccines.
Infectious laryngotracheitis virus (ILTV) causes severe respiratory disease in chickens and remains a major concern for poultry production. Although live-attenuated vaccines are widely used, residual virulence and latency raise safety concerns. The UL50 gene encodes a conserved deoxyuridine triphosphatase (dUTPase) and has been implicated in herpesvirus virulence, but its value as a vaccine attenuation target in ILTV remains uncertain. Here, we evaluated the effects of complete UL50 ORF deletion on the pathogenicity and immunogenicity of ILTV in chickens to assess its potential as a target for developing safer live-attenuated ILTV vaccines. Four-day-old chickens were inoculated via the eye-drop or intranasal route to evaluate pathogenicity and protective efficacy against challenge with the virulent SH2016 strain. The rGD2018-ΔUL50 exhibited further attenuation, inducing only minimal clinical signs and showing no detectable viral shedding or viral replication in the larynx and trachea. In contrast, the parental low-virulence GD2018 strain caused slightly more evident mild clinical signs. Despite its marked attenuation, the UL50-deleted strain conferred partial protection against challenge, whereas GD2018-inoculated chickens were fully protected. These results indicate that UL50 plays an important role in ILTV virulence, and that its complete deletion leads to over-attenuation, compromising protective efficacy. Optimization of UL50-based attenuation strategies, such as partial modification or combination with other genetic approaches, may facilitate the development of safer and effective next-generation ILTV live vaccines.
Pet vaccines are fundamental for protecting animal health and preventing zoonotic diseases, aligning with the global "One Health" initiative. In China, this sector is undergoing a significant transition. Following the successful localization of traditional vaccines, the industry is now actively advancing toward innovative genetic engineering platforms, particularly mRNA technology. This review systematically examines the current landscape by synthesizing available data, with a focus on three key aspects: market dynamics, research and development trends, and vaccine technology platforms. Our analysis indicates that the Chinese pet vaccine market, valued at over one billion RMB, is on a strong growth trajectory fueled by a large pet population and rising health awareness. Despite rapid growth, intensified competition and product homogenization present challenges to long-term sustainable development. Technologically, the sector is defined by diverse platforms: inactivated vaccines, noted for their safety; attenuated vaccines, valued for durable immunity; subunit vaccines, offering precise targeting; viral-vector vaccines; and the promising nucleic acid vaccines, which represent the cutting edge of innovation with several candidates in clinical trials. In conclusion, the future of pet vaccines in China lies in navigating beyond price competition through continuous innovation in safer, more efficient, and multivalent formulations. Addressing both the persistent technical bottlenecks for specific pathogens and the critical challenge of market education will be crucial to fully realizing the potential of domestic vaccines and contributing to national public health security.
This study developed a genetically attenuated Salmonella enteritidis (S. enteritidis) strain, designated as SD01ΔMg (deficient in asd, crp, rfaL, rffG, and rfbB), to enhance vaccine safety while maintaining immunogenicity. The virulence of the mutant strain was evaluated by determining the median lethal dose (LD50). The deletions significantly diminished the virulence, as evidenced by a higher LD50 in chicks, reduced proliferation in HeLa and RAW264.7 cells (p < 0.01), and reduced colonization in chick organs, with no detectable bacteria by day 11 post-inoculation. The strain also exhibited nutritional dependency, with an inability to survive without DAP nutrients. Immunologically, SD01ΔMg induced robust humoral (IgG), mucosal (IgA), and cellular (IL-6, IL-10, IFN-γ, TNF-α) immune responses post-vaccination comparable to wild-type and commercial vaccine strains. The animal infection test showed that gene deletion could lead to a significant decrease in the virulence of S. enteritidis in chicks, with an approximately 10 times higher LD50 for chicks, and it demonstrated significantly lower colonization in chick tissues and organs. A toxicity protection experiment on one-day-old chicks demonstrated 80 % protection against high-dose wild Salmonella infection and organ damage mitigation. The findings confirm that targeted gene deletions effectively attenuate virulence without compromising immunogenicity. Collectively, our results underscore the strong potential of the SD01ΔMg strain for further development into a safe and efficacious live attenuated vaccine against S. Enteritidis infection.
Lumpy skin disease virus (LSDV) is an emerging transboundary pathogen associated with lumpy skin disease (LSD). Recent outbreaks of LSDV have now been reported from previously unaffected regions, including the Indian subcontinent. Rapid transmission with high morbidity and mortality, enormously impacts the bovine species, resulting in devastating economic consequences on the livestock sector. Therefore, it necessitates expedited, appropriate attention to LSDV prophylaxis and control. Various LSDV suboptimal vaccines are prevailing that range in effectiveness, efficacy, safety, and side effects. Therefore, by utilizing the immunoinformatics approach mainly, a multi-epitope vaccine candidate was designed. To achieve this, conserved regions of three key LSDV proteins GPCR, P32, and RPO30 were first identified from complete Indian LSDV genomes. From these conserved segments, epitope mapping was performed, resulting in the selection of 16 high-affinity cytotoxic T lymphocyte (CTL) epitopes, 14 helper T lymphocyte (HTL) epitopes with interferon-inducing potential, and 7 linear B-cell epitopes. Furthermore, each of these epitopes was rigorously evaluated and confirmed to be antigenic, non-allergenic, and non-toxic. Collectively, the selected epitopes demonstrated broad predicted coverage across bovine leukocyte antigen (BoLA) alleles, thereby ensuring the potential for a wide-ranging immune response. To improve stability, folding, and immunogenicity, these epitopes were combined into a 590-amino-acid construct with the addition of the β-defensin-3 adjuvant and appropriate linkers. Moreover, the resultant construct's stability, solubility, and robust antigenic potential were validated by physicochemical profiling, confirming its suitability as a promising vaccine candidate. Lastly, molecular docking and simulation analyses demonstrated strong binding to bovine TLR4, confirming the construct’s structural stability and compactness. Codon optimization and in silico cloning into the pET28a(+) vector indicated feasibility for high-yield expression and efficient purification in Escherichia coli. These findings present the first conserved-region-based LSDV MEV construct tailored for Indian and regional viral strains. This design offers broad immune coverage, favourable biophysical properties, and strong receptor engagement, indicating its potential as an effective vaccine candidate. Future in vitro and in vivo validation will be critical to confirm immunogenicity, safety, and protective efficacy, with potential translational application for large-scale livestock immunization programs across LSDV-endemic regions.
Klebsiella species belong to a group of well-studied human pathogen with emerging global reports on antimicrobial resistance and hyper-virulent clones. Its occurrence has been reported with high abundance in diverse niches (environmental nexus) including poultry farm and may constitute a reservoir of genetic elements and strains transmission. Its hyper-virulent character has aroused public health concern which necessitates study. The study investigates isolation and molecular characterization of antibiotic resistance determinants amongst klebsiella sp recovered from poultry farm and their potential eco-health implications. Samples were collected from poultry farms including Ugbor (poultry A), Sapele road nexus (poultry B), Ekenwan region (poultry C) and Evboriaria region (poultry D) between August and October 2020. Recovered isolates were analysed using standard microbiological, veterinary antibiotic susceptibility testing (CLSI-VAST) standard guideline and molecular biology techniques. Observed results showed that the mean total heterotrophic bacterial counts for feeds ranged from 18.0 × 105 ± 3.04 (poultry C) to 28.2 × 105 ± 1.55 cfu/g (poultry B) while Shigella-Salmonella counts ranged from 2.32 × 103 ± 0.84 (Poultry C) to 8.30 × 103 ± 1.27 cfu/g (poultry A). The mean total heterotrophic bacterial counts for water-samples ranged from 0.85 × 105 ± 0.49 (poultry A) to 1.85 × 105 ± 0.35 cfu/ml (poultry B). The mean total heterotrophic counts for poultry dung ranged from 11.9 × 105 ± 2.96 (poultry C) to 36.4 ± 4.17 cfu/g (poultry B). Following the AST screening, it was revealed that all isolates recovered were resistant to Ceftazidime, Cefixime and Cefuroxime with an apparent resistance to Gentamicin, Augumentin, Ciprofloxacin and Ofloxacin and 100 % susceptible to Nitrofurantoin. The 16S rRNA sequencing analysis showed 100 % similarity of two strains as Klebsiella quasipneumoniae implicating the poultry farm as potential dissemination hub for such hyper-virulent and multiple-antibiotic-resistant (MAR) phenotype and genotype in the environment which may serve as cross-contamination subjects of MAR strains during processing and distribution of products.
Lawsonia intracellularis is the cause of proliferative enteropathy (PE), which is highly prevalent in swine, causing substantial economic losses to the sector. The available PE vaccines have protection-related limitations. Therefore, the objective of the present study was to evaluate the ability of L. intracellularis recombinant protein, fused with tetanus toxin T helper (TT-Th) carrier molecule, to stimulate a specific immune response in a mouse experimental model. rLiTT expression was performed in Escherichia coli BL21 Star™ (DE3) cells, evaluated by SDS-PAGE, and confirmed by Western blot using a monoclonal anti-His antibody, showing a band of 18 kDa size, also the rLiTT was recognized by sera from naturally infected pigs, vaccinated pigs, and rLiTT vaccinated mice, showing its antigenicity. Specific antibodies (IgG, IgM, and IgA) against rLiTT were detected after the prime vaccine dose in mice immunized with rLiTT adsorbed on aluminum hydroxide (rLiTT/AH). The upregulation of NFkB, IL4, IL12, and IFN-y cytokine genes was evaluated in vaccinated mice splenocytes and peritoneal macrophages to assess the cell response. Thus, the experimental vaccine shows promising results to be tested in pigs.
Dendritic cells (DCs) are professional antigen-presenting cells (APCs) that play a pivotal role in bridging innate and adaptive immunity, making them a central focus in vaccine development. As a C-type lectin receptor expressed on cDC1 and cDC2 subsets, CD205 facilitates receptor-mediated endocytosis, enabling antigen presentation through both MHC class I and class II pathways, which are critical for activating cytotoxic and helper T cells. In this study, we introduced a CD205-targeted bispecific nanobody (BiNb-CD205/FMDV) as a novel platform for enhancing antigen delivery and immune activation of foot-and-mouth disease virus (FMDV) in pigs. In vitro experiments demonstrated that BiNb-CD205/FMDV could bind efficiently to porcine bone marrow-derived dendritic cells (BMDCs) and show a strong colocalization with acidic organelles such as lysosome, indicating significantly enhancing antigen uptake and effective processing. In vivo immunization results revealed Nb4-Nb205 was effective at enhancing LPB-specific antibody titers, inducing enhanced CD4+ and CD8+ T cell responses. Elevated cytokine levels, including IFN-γ and IL-4 further supported robust immune activation, indicating a balanced Th1/Th2 response. Our results provide preliminary evidence for the feasibility of CD205-targeted bispecific nanobody platforms in enhancing antigen presentation and immune responses. This highlights the potential to expand targeted delivery to the field of animal epidemic diseases and provides a reference for the general application of nanotechnology in viral diseases.
Vaccines are an important tool to help control and eradicate human and animal diseases worldwide. Given the complexity and unpredictability of immune responses in certain situations, the World Small Animal Veterinary Association (WSAVA) published guidelines to improve immunization of small animals. Therefore, this review aims to discuss these guidelines, which guide the three-yearly revaccination in small animals, as opposed to the annual booster, use of monovalent vaccines, and replacement of revaccination with serological tests, when possible, in addition to suggesting changes to the vaccination schedule for puppies. By reviewing articles and publications on small animal vaccination, the rationale for the guidelines was discussed. Considering the social and economic divergences between developed countries, where the guidelines are currently applied, and emerging and underdeveloped countries, the difficulties of the guidelines’ implementation in Brazil were assessed. The guidelines have current foundations, and vaccinating with multipurpose vaccines more frequently may increase the chances of adverse reactions in small animals. However, the country still presents difficulties in implementing the guidelines in their entirety, in addition to the challenges involving abandoned animals, the unavailability of monovalent vaccines and serological tests accessible to the poorest population limits the adherence of guardians and professionals to the WSAVA guidelines.
Currently, the spread of H9N2 avian influenza virus (AIV) and avian infectious bronchitis virus (IBV) is one of the major predicaments facing the poultry industry. Virus-like particles (VLPs)-based vaccine, as one of the most promising alternative to traditional vaccines, provides new perspectives for the prevention of poultry diseases. Here, we generated a chimeric VLPs (VLPs) vaccine against both AIV and IBV by using baculovirus/insect cell expression system, and evaluated its efficacy in chickens. The VLPs is composed of three proteins: HA, M1, and rS. The HA and M1 proteins were derived from the H9N2 AIV A/chicken/Anhui/LH99/2017 (AH/99, H9N2), while rS was composed of the S1 subunit of the QX-type IBV CK/CH/JS/CZ211063 (CZ211063, GI-19) protein and the transmembrane domain (TM) and cytoplasmic tail domain (CTD) of the H9N2 AIV HA protein. Subcutaneous immunization with the VLPs vaccine induced a robust humoral immune responses, providing complete protection against H9N2 AIV in chickens. Furthermore, challenge experiments with QX-type IBV indicated that VLPs vaccine immunization significantly inhibited viral replication in the trachea, lung, and kidney, and suppressed viral shedding in the throat and cloaca. Additionally, histopathological analysis revealed that the VLPs vaccine effectively mitigated QX-type IBV-induced tissue damages in the respiratory and renal systems. Collectively, these results suggest that the VLPs vaccine developed in this study is a promising vaccine candidate for the avian influenza and infectious bronchitis control, and highlight the potential of VLP-based vaccines as a viable alternative to traditional egg-dependent vaccines in the prevention of poultry diseases.
Bovine respiratory syncytial virus, bovine parainfluenza type 3 virus, and bovine corona virus cause respiratory disease in calves during the first weeks of life and protection should be achieved as young as possible to cover the period with the highest risk. Maternal antibodies present in the colostrum that calves receive immediately after birth may result in positive serum antibody titers against these viruses which may interfere with vaccination. However, in this investigation we show that two new intranasal vaccines containing these three, live viral attenuated viruses can provide protection in calves with or without maternally derived antibody titers at a very young age.
Rabies, caused by the neurotropic rabies virus, remains a significant public health concern worldwide. It remains a deadly zoonotic disease with a near 100% fatality rate once clinical symptoms manifest, causing about 59,000 deaths annually, of which 59.6% occur in Asia and 36.4% in Africa. Dog-mediated rabies accounts for over 99% of human cases. This review provides a comprehensive overview of rabies, covering its epidemiology, pathogenesis, Etiology, and developments in rabies vaccines. Once the virus enters the body through the bite of an infected animal it travels via peripheral nerves to the central nervous system, leading to fatal encephalitis if left untreated. Vaccination of domestic animals plays a pivotal role in preventing transmission to humans. Post-exposure prophylaxis (PEP) remains the cornerstone of rabies prevention in individuals exposed to potentially infected animals, comprising rabies vaccine and Rabies immunoglobulin administration. Advances in molecular virology have shed light on the pathogenesis of rabies, revealing the intricate interactions between the virus and the host immune system. Despite decades of research, treatment options for established rabies infection remain limited, emphasizing the importance of preventive measures. Experimental therapies, including monoclonal antibodies and novel antiviral agents, promise to improve outcomes in rabies patients. Regardless of the established efficacy of rabies vaccines, challenges remain in ensuring widespread accessibility and coverage, particularly in resource-limited regions. Strategies to enhance pre-exposure prophylaxis with affordable vaccine delivery are essential for achieving global rabies control and elimination goals, underscoring the need for sustained surveillance, vaccination, and public awareness efforts. Continued research into the virology and immunology of rabies is essential for the development of novel interventions to combat this deadly disease.
As an important virulent infectious disease of waterfowl, duck plague (DP) is distributed worldwide. Owing to the lack of specific drugs, people are reliant on the development of vaccines to control this disease. To date, many studies have reported that different vaccine development technologies have been used to develop DP vaccines. In this paper, the development and research status of different DP vaccines are reviewed and analyzed, and the development prospects of DP vaccines are also discussed.
A canine population's immune resistance to canine distemper virus (CDV), canine parvovirus (CPV), and infectious hepatitis virus (CAV-1) was evaluated. In this study, a total of 112 sera were analyzed. Animals were considered as vaccinated if, in the last two years, they had received at least one dose of a vaccine that provides joint protection against CDV, CPV, and CAV-1. Animals that had never received any dose of these vaccines were designated as non-vaccinated. CDV, CPV, and CAV-1 antibodies were detected via a modified solid-phase enzyme-linked immunosorbent assay (ELISA), which detects IgG antibody levels in sera and provides semi-quantitative results in <30 min. In total, 41.1 % of the dogs had been vaccinated, and 58.9 % of dogs were designated as non-vaccinated. Overall, 90.2 %, 92.0 %, and 78.6 % of the tested dogs had positive results for the presence of IgG antibodies against CPV, CDV, and CAV-1, respectively. CPV antibodies were present in 87.9 % (58/66) of the vaccinated and 93.5 % (43/46) of the non-vaccinated dogs, while CDV antibodies were present in 95.5 % (63/66) of the vaccinated and 87.0 % (40/46) of the non-vaccinated dogs. Finally, CAV-1 antibodies were present in 84.8 % (56/66) of the vaccinated and of 69.6 % (32/46) the non-vaccinated dogs.
Members of the family Poxviridae cause diseases such as smallpox and monkeypox, which are pathogenic to humans and negatively affect animal husbandry and development. The deadly smallpox virus was eradicated by large-scale intensive vaccination with live Vaccinia virus (VACV). However, in recent years, other VACVs have emerged as threats to human and animal health in developing countries. Vaccination is the most effective and widely used means of prevention and control of viral diseases. Different types of vaccines have been used to control poxvirus infection, including traditional attenuated, nucleic acids, recombinant subunits, virus vectors, polypeptides, gene deletions, and inactived vaccines. This review summarizes recent advances in the field of poxvirus vaccine research. It also discusses existing gaps and forecasts potential directions for future research.
The hypodermic syringe and needle are the leading technology in vaccine administration as they provide immediate and direct dosing at a low cost. This is convenient for administration of initial and booster doses for humans, however, for livestock and wildlife, multiple doses can be problematic due to accessibility and housing issues. Devices for delayed/multi-dose delivery of vaccines are becoming increasingly popular as they have the potential to stimulate full immunity from a single injection and can be altered depending on the pathogen and target species. The current challenge with delayed/multi-dose delivery devices is that they are not progressing to commercial development for numerous reasons. This review aims to investigate currently research devices and examine how these devices can be implemented in livestock and wildlife populations.
Saccharomyces boulardii has emerged as a promising probiotic agent in bolstering the immune system. In vaccinology, its application can be explored to optimize vaccine efficacy by augmenting host immune response and consequently enhancing the immunogenicity of antigenic formulations. However, it is imperative to conduct further research to comprehend the effectiveness of this probiotic in novel vaccines targeting significant pathogens affecting animal health. Hence, this study investigated the effects of a short (3 - 5 days) or continuously (56 days) S. boulardii supplementation (3 × 108 CFU/ml) on the adaptive immunity of sheep immunized with a recombinant antigen against Paeniclostridium sordellii (rAPS). Four immunized groups (G1-G4) were evaluated, varying the regimen of S. boulardii supplementation. Elevated levels of anti-rAPS IgG immunoglobulins were detected in all vaccinated animals. Daily supplementation with S. boulardii (G1) resulted in higher IgG levels, reaching antibody titers of up to 25600, which were 16 times higher than those observed in not supplemented group (G4) and 4 times higher than in the group supplemented for 3 days (G3) or 5 days (G2) before each immunization. These findings demonstrate that S. boulardii can enhance vaccine-induced immune responses against P. sordellii, particularly IgG-mediated immune responses in sheep. The possibility of a short supplementation for 5-3 days is a very important finding for animal husbandry, considering the supplementation and supply management cost.
