Veterinary vaccine quality assurance has traditionally relied on animal-based potency, safety, and efficacy tests, including challenge protection and in vivo titration assays. Although historically regarded as regulatory gold standards, these methods are increasingly constrained by ethical considerations, high costs, limited throughput, and prolonged timelines. In response, strong scientific and regulatory momentum now supports alternative approaches that reduce or replace animal use while maintaining confidence in vaccine performance. This review critically examines the current landscape of non-animal and reduced-animal methodologies for veterinary vaccine evaluation within the 3Rs framework (Replacement, Reduction, and Refinement). We synthesize advances across five methodological domains: molecular and genetic quantification (including qPCR, digital PCR, and DIVA strategies); cell-based and in vitro functional potency assays; immunochemical and point-of-care platforms; physicochemical and analytical characterization; and systems-level immunological and multi-omics approaches. For each category, we discuss scientific principles, analytical performance, validation requirements, and regulatory acceptance, with emphasis on alignment with WOAH and VICH guidance. Practical challenges related to assay standardization, reference materials, infrastructure, and inter-laboratory reproducibility are addressed. Species-specific case studies spanning livestock, companion animal, and poultry vaccines including foot-and-mouth disease, lumpy skin disease, rabies, and avian influenza illustrate how integrated, weight-of-evidence strategies support batch release, consistency testing, and post-licensure surveillance. Collectively, the evidence supports a paradigm shift toward data-rich, mechanism-informed quality-control frameworks that enhance efficiency, ethical compliance, and regulatory confidence in veterinary vaccine evaluation.
Interleukin-17A (IL-17A), a pro-inflammatory cytokine primarily produced by Th17 cells, has emerged as a pivotal immunological mediator in both protective and pathological processes across different animal species in addition to human beings. Over the past decade, research has expanded significantly, elucidating IL-17A's roles in host defense, immune modulation, disease progression and vaccine induced immune responses. The present review focuses on recent advances in the understanding of IL-17A within the context of veterinary medicine. IL-17A has been implicated in protection from various diseases as well as in their pathogenesis in different contexts. Different diseases like bovine mastitis, bovine tuberculosis, canine immune-mediated hemolytic anemia, avian viral infections and many others, the raised expression of IL-17A helps predict how mild or severe a case will be. Diagnostic potential has been demonstrated, particularly in cattle, where IL-17A serves as a promising biomarker for mycobacterial infections and inflammatory responses. In vaccination, recombinant and plasmid-based IL-17A delivery has enhanced immune protection against pathogens such as bovine herpesvirus and Marek's disease virus in poultry, suggesting utility as a novel adjuvant. Furthermore, studies in swine and poultry have revealed age- and tissue-specific dynamics of IL-17A during immune maturation and infection. While IL-17A contributes to immunopathology in some contexts, it also holds promise for advancing vaccine development, diagnostics, and targeted immunotherapy in veterinary practice. The shared role of IL-17A in veterinary and human health highlights the need of a One Health approach, acknowledging the interdependence of human, animal and environmental well-being. Understanding IL-17A's function across species can reveal cross-species therapeutic strategies and vaccination programs, promoting a holistic approach to manage inflammatory and infectious diseases. Further, research into IL-17A's mechanisms and its modulation could lead to more effective treatments and prevention strategies, benefiting both human and animal health. This review highlights critical discoveries, emerging tools and future directions to harness IL-17A for improving animal health, productivity and disease control strategies in both livestock and companion animals.
The aim of the study was to evaluate the efficacy of minerals and potential multi-strain probiotic (MSP) intervention in early life of piglets on immunoglobulin A (IgA), IgG and secretory IgA (sIgA) concentrations and growth performance and mortality. A total of eight piglet litters from parity-matched sows were enrolled and allocated into one of the four interventions: normal saline (control), multimineral (MM), MSP, and MSP+MM. The MM was injected on day 0 and 7 of birth and MSP were administered once daily per os for first 7 days of life. The growth and piglet survival rates were significantly higher in the MSP group as compared to control group. The mean sIgA concentrations were significantly elevated on day 7 in control and MSP groups, and day 21 in MM+MSP group. A significant rise of mean IgA concentration was observed on days 14 and 21 in control and MSP groups and days 7, 14, and 21 in the MM+MSP group. The mean IgG concentrations were significantly increased on days 7, 14, and 21 in the control, MM, and MM+MSP groups. The comparison of the mean IgA and IgG concentrations among the groups showed a significantly higher IgA levels on days 14 and 21 in MSP and MM+MSP groups and significantly lower IgG levels on days 0, 7, and 14 in the MM, MSP, and MM+MSP groups, and day 21 in MSP and MM+MSP groups when compared with control group. The study indicated that neonatal MSP intervention improves growth and reduces the mortality of piglets until weaning through augmenting the systemic and mucosal immune parameters.
There is a dynamic accommodation between the maternal immune system and conceptus, including the thymus and lymph nodes, during early pregnancy. Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling pathway is involved in early placentation. However, it was not fully understood that early pregnancy had effects on JAK/STAT signaling pathway in the thymus and lymph nodes of ewes. In this study, thymuses and lymph nodes of ewes were collected at day 16 of the estrous cycle (N16), and at days 13, 16, and 25 of gestation (G13, G16, and G25). Expressions of mRNA and protein of JAK/STAT members, including interferon α/β receptor 1 (IFNAR1), JAK1, tyrosine kinase 2 (TYK2), STAT3, interferon regulatory factor 9 (IRF9), B-cell lymphoma-extra large (BCL-XL), BCL-2, myelocytomatosis viral oncogene homolog (c-Myc), and p21 (a protein with a molecular weight of 21 kDa), were analyzed. The results indicated that there were increases in mRNA and protein expression of p-IFNAR1, p-JAK1, TYK2, p-STAT3, IRF9, and p21 in the thymus, and p-STAT3 and BCL-XL in lymph nodes. In addition, expression levels of p-IFNAR1 and p-JAK1 in the thymus and c-Myc in lymph nodes peaked at G16, but expression levels of c-Myc, BCL-XL, BCL-2, and P21 peaked at G13 in the thymus. Furthermore, expression levels of TYK2 and p-STAT3 in the thymus and p-JAK1, TYK2, and P21 in lymph nodes were higher at G16 and G25. P21 and p-IFNAR1 peaked at G25, but IRF9 peaked at N16. BCL-2 level was greater at N16 and G25. In summary, early pregnancy modulated JAK/STAT signaling pathway in the maternal thymus and lymph nodes in a pregnancy-stage- and tissue-specific manner, which may be associated with the establishment of maternal immune tolerance during early pregnancy in ewes.
The aim of this study was to evaluate the effects of a single dose of 25-(OH)D3 vitamin injection in pregnant holstein heifers on cytokine concentrations (IL-6 and IFN-γ) in heifer colostrum and serum, colostral lactoferrin, and IgG and vitamin D concentrations in calves. The control group (n: 10) and the vitamin D group (n: 10) were composed of heifer Holstein 8 ± 2 days before calving. Blood samples were collected on day 265 ± 2 of gestation in the vitamin D and control groups, before vitamin D and physiological saline administration, and at the time of parturition. Colostrum and serum samples were analyzed for lactoferrin, IgG, IL-6, and IFN-γ by bovine-specific ELISA, solid-matter digital refractometry, and vitamin D by LC-MS/MS. The colostral IFN-γ (p < 0.015), IgG (p < 0.035), lactoferrin (p < 0.001), and Brix (p < 0.035) concentrations of the vitamin D group were significantly higher than those of the control group. Serum IL-6 (p<0.002) and IF-γ (p<0.001) concentrations were significantly lower in the group that received vitamin D at parturition compared to the control group. In contrast, serum 25-(OH)D concentrations in heifers treated with vitamin D were significantly higher than in the control group (p<0.003). The serum 25-(OH)D concentration of calves born from heifers administered vitamin D was significantly higher than the control group (p < 0.006). Serum vitamin D concentration in calving cows showed a negative correlation with IL-6 (r=-0.663, p<0.001) and IFN-γ (r=-0.687, p<0.001) levels, while it showed a positive correlation with colostrum IFN-γ (r=0.446, p<0.048), colostral lactoferrin (r=0.686, p<0.001), and calf serum vitamin D concentration (r=0.598, p<0.005). In conclusion, this study determined that administering vitamin D to holstein heifer increased colostrum cytokine concentrations and lactoferrin levels, decreased serum pro-inflammatory cytokine concentrations at parturition, and increased colostrum IgG and Brix values. Additionally, the increased serum vitamin D concentration had a positive impact on the health and well-being of the animals by suppressing inflammatory cytokines. Vitamin D supplementation in holstein heifers can increase vitamin D levels in calves and significantly improve colostrum quality and cow health.
Foot-and-mouth disease (FMD) continues to impose significant constraints on livestock health and productivity in Egypt due to the persistent circulation, evolution, and transboundary introduction of antigenically diverse foot-and-mouth disease virus (FMDV) serotypes and lineages. Since the 1950s, Egypt has experienced recurrent incursions of serotypes O, A, and SAT2, accompanied by progressive antigenic shifts, including the emergence of O/EA-3, A/Africa G-IV, and SAT2 Lib-12. Recent developments have further reshaped the national epidemiological landscape. In 2022, the detection of FMDV-A-Egy-AHRI-RL385-Ven-2022, phylogenetically linked to the EURO-SA lineage, provided the first evidence of intercontinental viral introduction into Egypt. This was followed in 2025 by the first confirmed incursion of serotype SAT1 (topotype I), previously absent from Egypt and its vaccine formulations. The introduction of SAT1 into a fully naïve livestock population triggered rapid viral spread and revealed a critical immunological gap associated with longstanding trivalent vaccination strategies. Vaccine-matching analyses conducted at the Central Laboratory for Evaluation of Veterinary Biologics revealed that ongoing antigenic drift, particularly within serotypes A and SAT2, had diminished the protective capacity of traditional vaccines. In response, vaccine formulations were updated to incorporate A EURO-SA, A Africa G-IV, and SAT2 Lib-12, and a monovalent SAT1 vaccine was developed for emergency deployment. This review integrates historical, molecular, antigenic, and epidemiological evidence to assess recent FMDV evolution in Egypt and its implications for vaccination policy. The findings highlight the urgent need for adaptive FMD control strategies that combine continuous genomic surveillance, systematic vaccine matching, and dynamic antigen updating to protect Egypt's livestock sector against an increasingly complex and evolving viral threat.
Seasonal heat stress pre- and postnatally is associated with altered health and growth in dairy calves. This study investigated the potential associations between birth season and the inflammatory response and oxidative stress status in Holstein calves during the first 90 days of life. Calves born in summer (n = 20) and winter (n = 21) were monitored longitudinally. Blood samples were collected from the calves immediately after birth (before colostrum intake; hour 0), at 12 and 24 h, and subsequently on days 4, 6, 8, 15, 21, 30, 60, and 90. Total protein (TP), Brix percentage, inflammatory parameters (IL-17A, IL-10, IL-6, IL-1β, TNF-α, IFN-γ, haptoglobin, LPS), and oxidative stress markers (NO, PON1, TAS, TOS, OSI) were measured in serum samples. Data was evaluated using Linear Mixed Models. TNF-α, NO, and OSI levels were significantly higher in the summer group, while haptoglobin, IL-6, IL-10, IL-17A, and IFN-γ levels were higher in the winter group. PON1 levels increased after day 15 in both groups but remained lower in the summer group, potentially reflecting a depletion of antioxidant capacity. LPS and IFN-γ levels showed a decreasing trend from day 30, and IL-1β and IL-10 levels from day 60 until day 90. Serum TP and Brix values were higher in the winter group. In conclusion, the elevated acute-phase and cytokine responses coupled with more severe clinical findings in winter calves reflect a dysregulated inflammatory process due to higher infection pressures in winter conditions. The gradual decline in LPS and inflammatory mediators over time may associated with the maturation of the intestinal epithelial barrier and the achievement of immune homeostasis.
Subclinical bacteriuria (SBU) is defined as the presence of significant bacteriuria in dogs, in the absence of clinical signs attributable to lower urinary tract infection (UTI). The local immunological factors potentially associated with the asymptomatic phenotype displayed in dogs with SBU, have not been explored. This study aimed to investigate the local immune response in dogs with SBU through cytokine and myeloperoxidase (MPO) expression in urine. Furthermore, we aimed to investigate the discriminatory potential of urinary interleukin 6 (uIL-6), uIL-8, uIL-10 and uMPO between dogs with SBU and UTIs (cystitis and pyelonephritis). ILs and MPO were analyzed with canine and human commercially available sandwich enzyme-linked immunosorbent assays (ELISA), respectively. In total 54 dogs were included in the study counting 14, 15, seven and 18 SBU, cystitis, pyelonephritis and non-bacteriuric control dogs, respectively. The study found higher uIL-8 levels in dogs with bacteriuria and levels increasing with disease severity. UIL-8 levels also differed between dogs with SBU and pyelonephritis, although overlapping values hindered reliable classification of individual dogs as having either SBU or UTI. UMPO concentrations increased with disease severity and differed between dogs with pyelonephritis and SBU without overlapping values. Notably, no differences in uMPO were detected between non-bacteriuric control dogs and dogs with SBU indicating a reduced neutrophil activity in dogs with SBU compared to dogs with UTI. These results suggest a discriminatory potential of MPO in canine SBU and UTIs, making it an interesting candidate for further investigation. UIL-6 and uIL-10 were undetectable in most urine samples.
Managing subclinical ketosis (SCK), which Indian mithun (Bos frontalis) cows experience at least once within four weeks postpartum, requires understanding the interaction of immuno-inflammatory mediators and hyperketonemia. This study aimed to explore the interplay of SCK with the major immunoglobulins (IgG, IgA), acute-phase proteins (haptoglobin, Hpt; serum amyloid A, SAA), and immune-antioxidant enzymes (lactoperoxidase, LPO; lysozyme, LZM; superoxide dismutase, SOD) in postparturient mithun cows. Thirty SCK mithun cows were selected based on blood BHBA (≥1.10 mmol/l) from two semi-intensive mithun farms. Serum concentrations of IgG, IgA, Hpt, SAA, LPO, LZM and SOD were measured at 1, 2 and 4 weeks postpartum by enzyme-linked immunosorbent assay. SCK group had significantly lower IgA values in the first week postpartum and higher IgG values in the second and fourth week. Higher concentrations (P < 0.05) of Hpt, SAA, SOD, and LZM were seen in SCK mithuns during the first week postpartum compared to healthy controls. No significant differences were observed in postpartal LPO. Hpt and SAA concentrations showed a significant positive correlation with BHBA (R=0.39, P < 0.001 and R=0.27, P < 0.001, respectively) and NEFA (R=0.17, P < 0.01 and R=0.13, P < 0.001, respectively). Serum IgA and SCK biomarkers (BHBA, NEFA) had negative relationships (R=0.44, P < 0.001 and R=0.41, P < 0.05, respectively). These findings illustrate that immunologic dysregulation, inflammation and oxidative stress mediate less severe ketosis (SCK) in the early postpartum mithun cows. Conclusively, this justifies the need of developing strategies to control postpartum hyperketonemia in mithun cows. Future studies on the viability of using antiinflammatory and antioxidant therapy to prevent SCK from worsening to clinical ketosis are warranted.
Toxoplasma gondii (T. gondii) is an obligate intracellular parasite that manipulates host cell apoptosis and inflammation to support its survival and replication. Our previous work demonstrated that T. gondii activates the Hippo signaling pathway through phosphorylation of mammalian STE20-like protein kinase 2 (MST2), thereby promoting host cell apoptosis. However, the impact of Hippo pathway inhibition on apoptosis, inflammation, and host protection during infection remains unclear. Here, we demonstrate that T. gondii infection induces apoptosis in RAW264.7 macrophages and causes acute liver injury in mice, accompanied by increased levels of inflammatory cytokines. These changes were associated with decreased total protein levels of MST2, large tumor suppressor homolog 1 (LATS1), and Yes-associated protein (YAP), but increased phosphorylation of these Hippo components. Treatment with XMU-MP-1, a selective MST1/2 inhibitor, alleviated apoptosis, dampened macrophage-mediated excessive inflammation, reduced liver damage and parasite burden, and prolonged survival in acutely infected mice. These findings provide the first direct evidence that pharmacological inhibition of the Hippo signaling pathway mitigates T. gondii-induced apoptosis and immunopathology. Our results highlight the potential of XMU-MP-1 as a host-directed therapeutic strategy. Its efficacy against T. gondii in combination with antiparasitic agents may have remarkable clinical application value.
This randomized controlled clinical trial aimed to evaluate whether the adjunctive administration of Saccharomyces boulardii (S. boulardii) to standard treatment could accelerate clinical recovery and improve hematological indicators of systemic inflammation in dogs with naturally occurring canine parvovirus (CPV) enteritis. Additionally, the study assessed the levels of nuclear factor-κB (NF-κB) and interleukin 8 (IL-8) associated with inflammatory pathways. This study consisted of three groups, each with 10 dogs aged 3-5 months. The control group comprised apparently healthy dogs. Group 1 received standard treatment, and Group 2 received S. boulardii plus standard treatment. Clinical scores were recorded on Days 0 and 5 in the study and control groups, and blood samples were collected on Days 0 and 5 in the study and control groups. Complete blood count, serum biochemical analyses, and serum NF-κB and serum IL-8 values were investigated. Compared to standard treatment alone, S. boulardii administration in addition to standard treatment rapidly improved clinical scores in dogs with CPV, significantly increased white blood cell count, neutrophil, and lymphocyte counts, decreased IL-8 and NF-κB concentrations, increased albumin concentrations, and decreased alanine aminotransferase activities. In conclusion, it was determined that S. boulardii administration, in addition to standard treatment, in parvovirus-infected dogs could be beneficial for rapidly improving clinical scores and reducing inflammation.
Porcine epidemic diarrhea virus (PEDV)-induced piglet diarrhea remains one of the most threatening infectious diseases in the swine industry across many countries. Although commercial vaccines are available, their efficacy in preventing the incidence and prevalence of porcine epidemic diarrhea (PED) remains unsatisfactory. Here we developed three subunit vaccine candidates based on four antigenic domains of the PEDV spike (S) protein expressed in E. coli: core neutralizing epitope (COE), S1 subunit domain A (S1A), and more conservative antigenic epitopes heptad repeat 1 (HR1) and heptad repeat (HR2) in S2 protein. Vaccination of the three vaccine candidates (COE, COE-S1A, and COE-HR1-HR2) induced substantial humoral and cellular expression, as evidenced by increase in specific antibody production and mRNA expression of both Th1 and Th2 cytokines. Among them, the COE-HR1-HR2 construct demonstrated a superior outcome. Furthermore, comparative screening of immune adjuvants was conducted to optimize vaccine efficacy. CpG ODN, in combination with the COE-HR1-HR2 fusion protein, induced enhanced humoral and cellular immune responses compared with Freund's adjuvant and GEL 02, and was comparable to ISA660VG. Taken together, in view of the incomplete protection provided by current vaccines against PEDV, there is an urgent need for next-generation formulations that can effectively reduce disease burden and promote robust herd immunity. Our preliminary findings indicate that the COE-HR1-HR2 candidate, by integrating the core S1 and conserved S2 antigenic epitopes, offers the potential for developing novel multi-epitope vaccine against PEDV that could induce protective immunity thereby reducing disease development.
Research related to the investigation of the activation and regulation of the immune system of domestic buffaloes is still very limited. The main factor linked to this limitation is the scanty availability of commercial monoclonal antibodies (mAb) against buffalo immune markers that allow the use of multiparametric techniques, such as flow cytometry, to study the modulation of the immune system of these animals. The evaluation of the cross-reactivity of commercially available mAbs against other species for cytokines and components of the immune system of buffaloes, is the fastest and least expensive way to expand the tools to assess immune response in those animals. Therefore, sixteen commercial mAbs anti-cell markers (CD4, CD8, CD14, CD21, CD25, CD28, CD45RB, CD45RO, WC1, and CD80) and anti-cytokines or other effector molecules of the immune system (TNF-α, IFN-γ, IL-4, IL-17A, granzyme B and perforin) that recognize molecules from bovine and human species were evaluated in whole blood samples from buffaloes and cattle. Two experiments were performed: Experiment 1, with six buffaloes, evaluated the specificity of mAb binding, and experiment 2, with twelve buffaloes and twelve cattle, evaluated the cross-reactivity of the mAbs. Samples were processed and analyzed by flow cytometry. Of the mAbs analyzed 15 clones were validated for flow cytometry of buffalo cells; only the CD4 clone did not show cross-reactivity to buffaloes amplifying the spectrum analyses of immune response in this animal species. This validated panel enables standardized flow cytometric immunophenotyping in buffaloes for research on vaccination, infectious disease, and immune regulation.
Waste milk (WM) is unsuitable for human consumption due to the presence of drug residues, particularly antimicrobials and anti-inflammatory agent, as well as its high microbial load and somatic cell counts (SCC). Consequently, WM is commonly used to feed dairy calves. This study aimed to evaluate the effects of WM on humoral and cellular immunity in Holstein calves. Calves were assigned to three groups: saleable milk (SM, n = 10), pasteurized waste milk (PWM, n = 10), and raw WM (n = 10). Animals were monitored daily using standardized health scoring systems, and clinical samples were collected on days 7, 21, 35, 49, and 63 of life. Peripheral blood mononuclear cells (PBMC) were isolated, cultured, and stimulated with concanavalin A (ConA), Escherichia coli, Lactobacillus johnsonii, L. reuteri, and Bifidobacterium longum to assess proliferation (BrdU incorporation) and cytokine production (ELISA). Humoral responses were evaluated by serum total protein (STP), Brix refractometry, and IgG concentration. Generalized linear models revealed significant group differences. Clinical profiles were similar among groups. PWM and WM calves exhibited higher monocyte, lymphocyte, and total PBMC counts. Proliferation was greater in SM and PWM calves in response to ConA, E. coli, and L. johnsonii. SM and PWM calves showed higher IL-4 production, whereas WM calves had increased IL-17. IL-10 production was highest in SM. IgG concentrations increased across all groups; however, WM calves exhibited earlier and higher levels, while SM calves maintained the lowest. STP and Brix (%) trends paralleled IgG results. In conclusion, WM elicited an earlier and more intense pro-inflammatory immune response, PWM showed intermediate effects, and SM promoted greater IL-10 production, potentially modulating inflammation in calves.
FSCC is a relatively common tumor of the skin and mucocutaneous regions in cats, yet the molecular features that accompany its varying degrees of differentiation are not fully clarified. In this study, we examined 27 FSCC cases and compared well, moderately, and poorly differentiated tumors using routine histopathology together with immunohistochemical, immunofluoresence, and RT-PCR based analyses. Differentiation grade was determined by keratin pearl formation, tumor island morphology, squamous differentiation, mitotic activity, and the extent of peritumoral inflammation. Poorly differentiated tumors showed a consistent pattern in which oxidative DNA damage (8-OHdG) was noticeably higher, while the Nrf2/HO-1 pathway was clearly suppressed and Keap1 expression increased. These changes were accompanied by stronger IL-6 and ICAM-1 staining and marked activation of inflammatory markers related to the TLR4/NF-κB/COX-2 axis. In contrast, well-differentiated tumors tended to retain higher Nrf2 and HO-1 expression with lower activation of pro-inflammatory pathways, suggesting a more balanced redox response. The inflammatory burden and mitotic activity were also most pronounced in poorly differentiated lesions. Overall, the findings indicate that deterioration of differentiation in FSCC parallels a shift toward heightened oxidative stress and amplified inflammatory signaling. The combined dysregulation of the Nrf2/HO-1/Keap1 and TLR4/NF-κB/COX-2 appears to contribute to a more aggressive tumor microenvironment, offering potential insight into the biological behavior of these lesions.
Bovine babesiosis is caused by Babesia bovis and Babesia bigemina and requires species-resolved serosurveillance to guide control programs. With this goal in mind, we developed an indirect bead-based liquid microarray (xMAP/Luminex) immunoassay using recombinant SBP4 (B. bovis) and RAP-1 (B. bigemina). Antigens immunoreactivity was confirmed by dot-blot and western blot. and antigens were covalently coupled to magnetic microspheres. Assay conditions were optimized with anti-bovine IgG-phycoerythrin detection, and diagnostic performance was assessed in 89 bovine sera previously classified by antigen-matched ELISAs; cut-offs were defined as the mean signal of negatives plus two standard deviations. The assay discriminated against species-specific antibodies and achieved sensitivity/specificity of 79.17%/94.12% for B. bovis (SBP4) and 96.92%/95.65% for B. bigemina (RAP-1). These results indicate high specificity and promising sensitivity, with inherent scalability to multiplex panels and high-throughput testing. Larger, geographically diverse validations-ideally including PCR as an independent reference-are warranted to refine cut-offs, quantify agreement, and assess intra-/inter-assay reproducibility for routine surveillance.
Bacterial infections are currently the most significant hindrance to the worldwide adoption of sustainable aquaculture, causing unprecedented economical losses and challenges to food security. Teleosts have an extremely well-developed innate and adaptive immune system, but the functional integrity of these immune systems is adversely affected under universal aquaculture-related stress factors. The current review critically and comprehensively synthesizes the two most important challenges, addressing immune resilience, which include: (1) the complex functional interactions between innate and adaptive immune mechanisms, and (2) the combined modulation of these immune mechanisms under environmental factors mentioned above. Our focus primarily centers on the role of major stressors such as temperature change, water quality measures, (physiological) chronic stressing, and microbiome diversity on innate host immunity and resistance to bacterially infected diseases. Finally, we not only conclude the current state regarding the latest research progress on the role and mechanisms utilized in the transition phase from the latent to chronic infection phase based on autophagy-related responses but also emphasize the need to adopt an integrated research area named 'Eco-Immunology' to measure and develop effective interventions against fish diseases. It is the prime requirement to improve the host's resistance to diverse farming conditions to develop sustainable and effective aquaculture. This review uniquely integrates innate-adaptive immune crosstalk with environmentally driven immune reprogramming and autophagy-mediated control of chronic bacterial infections, framing teleost antibacterial immunity within an eco-immunological perspective relevant to sustainable aquaculture.
While Yersinia ruckeri is known for causing systemic vascular damage, its potential to invade the central nervous system remains poorly understood. This study investigated the spatiotemporal distribution, pathological progression, antimicrobial resistance (AMR), and biochemical alterations associated with Y. ruckeri across 12 commercial rainbow trout farms in Türkiye. Advanced diagnostics using MALDI-TOF MS enabled rapid and accurate identification of the pathogen. Disease prevalence peaked in farms experiencing thermal stress (18 °C) and high biomass density. Histopathological examination revealed inflammatory alterations suggestive of neural involvement, including perivascular cuffing, neuronal degeneration, and focal neuroinflammation. In addition, Y. ruckeri was isolated from brain tissue in 15 infected fish and confirmed by MALDI-TOF MS, supporting the possibility of central nervous system involvement during systemic infection. Furthermore, the observation of neuroinflammation and perivascular cuffing suggests that the pathogenesis of Y. ruckeri is not limited to systemic vascular damage but also involves the central nervous system, which may explain the distinct behavioral changes and complex clinical progression of the disease. Antimicrobial susceptibility testing showed consistent multidrug resistance to amoxicillin, gentamicin, netilmicin, erythromycin, and sulfisoxazole. Serum biochemical analysis confirmed significantly elevated ALT levels, with ROC analysis identifying ALT as an excellent early biomarker (AUC = 0.956), having an optimal cut-off value of 71.4 U/L with high sensitivity (91.8%) and specificity (92.5%). The identified ALT threshold may provide a practical biomarker for the early detection and monitoring of ERM under field conditions. Collectively, this study provides new insights into ERM pathogenesis and highlights the need for improved antimicrobial stewardship and environmental risk management in aquaculture.
Milk somatic cell count (SCC) indicates udder health and milk quality, but levels much lower than the normal range may signal mammary gland immunocompromise. This study evaluated the immunological status of the buffalo mammary gland across graded low SCC levels under non-infectious conditions (<2 ×10⁵ cells/mL). Forty-eight clinically healthy Murrah buffaloes in early lactation were categorized into four SCC groups: Group 1 (0.20-0.60 ×10⁵ cells/mL), Group 2 (0.61-0.90 ×10⁵ cells/mL), Group 3 (0.91-1.40 ×10⁵ cells/mL), and Group 4 (1.41-1.90 ×10⁵ cells/mL). Buffaloes were screened using the California mastitis test (CMT) and infrared thermography (IRT) to eliminate subclinical mastitis (SCM). Immunological assessments included milk differential leukocyte counts (DLC), phagocytic activity (PA) of neutrophils and macrophages, lymphocyte proliferation response (LPR), cytokine concentrations (IL-2, IL-6, IL-8, TNF-α, IL-10), and milk cortisol levels. Buffaloes having low SCC showed predominant lymphocytes along with significantly (p < 0.05) higher PA and T-cell proliferation, indicating strong mammary immune competence. With increasing SCC, neutrophil proportion and pro-inflammatory cytokines (IL-2 and TNF-α) increased significantly (p < 0.05). However, IL-10 and cortisol remained consistent across all groups. IRT imaging showed uniform udder temperature, indicating no inflammation. The findings show that very low SCC in buffalo milk reflects immune balance, not immunosuppression, due to effective leukocyte function and cytokine regulation.
Streptococcus suis (S. suis, SS), a significant zoonotic pathogen, causes large-scale swine epidemics and substantial economic losses. Based on capsule antigen differences, at least 29 serotypes have been identified. Given that existing commercial vaccines target only serotypes 2 or a few others, and lack immunoprotection against serotype 9, this study designed and developed a bivalent inactivated candidate vaccine to cover serotypes 2 and 9, evaluation of the protective efficacy of weaning piglets. The vaccinated piglets were in normal condition without adverse reactions and deaths, indicating that the vaccine was very safe. Experimental vaccine induced significantly higher levels of specific antibodies than the commercial vaccine. Further pathogenicity tests confirmed that the vaccine exhibited 100% immunoprotection efficacy against both Streptococcus suis serotype 2 and serotype 9 strains, and significantly reduced mortality and clinical severity of disease following infection with these two bacterial strains. According to a search of the public literature, this study provides evidence that the bivalent vaccine demonstrates no less than the efficacy of existing commercial vaccines, while exhibiting high safety and superior immunoprotection efficacy, offering a reliable technical solution for the prevention and control of co-infection with Streptococcus suis type 2 and type 9.