AbstractAlthough the poultry population is an integral part of Ethiopia\'s Gross Domestic Product (GDP) due to various infectious diseases such as infectious bursal disease (IBD), the expected economic impact in the country remains limited. The status of the diseases in Ethiopia is obscured, and thus, a systematic review and meta-analysis were employed to estimate the overall pooled prevalence of IBD in Ethiopia. Meta-analysis was conducted to determine the effects of each identified risk factor, while meta-regression and sub-group analysis were employed to assess the relationship between study-level covariates and effect size. The pooled prevalence of IBD in Ethiopia was 69.4% (95%CI 30.7 -96.2), while the pooled logit prevalence was 0.94 (95% CI: 0.68 - 1.20) with significant inter-study variance (Q test = 948.28, df = 43, p < 0.001; τ2 = 0.71, I2 = 95.47%). A small study effect was detected in the regression-based Egger test (Prob > |z| < 0.0001). Significant variation was observed among different groups such as sex, age, breed, and type of farm of the chickens. The effect size for the study period from 2018 to 2021 was significantly lower by -0.204 compared to the study period from 2009 to 2015 (p < 0.0001. In conclusion, the IBD pooled prevalence estimate is high, even though the number of studies in the country is insufficient. The high prevalence of the disease requires prompt attention from all stakeholders in the sector to bring it under control through comprehensive disease prevention and control intervention strategies.

Infectious bursal disease (IBD) is a widespread problem in the poultry industry, and vaccination is the primary preventive method. However, moderately virulent vaccines may damage the bursa, necessitating the development of a safe and effective vaccine. The Newcastle disease virus (NDV) has been explored as a vector for vaccine development. In this study, reverse genetic technology was used to obtain three recombinant viruses, namely, rClone30-VP2L (P/M)-chGM-CSF (NP), rClone30-chGM-CSF (P/M)-VP2L (NP), and rClone30-VP2L-chGM-CSF (P/M). Animal experiments showed that the three biological adjuvant bivalent vaccines effectively increased anti-NDV and anti-infectious bursal disease virus (IBDV) titres, enhancing both humoral and cellular immune responses in chickens without leading to any harm. Amongst the three biological adjuvant bivalent vaccines, the rClone30-chGM-CSF (P/M)-VP2L (NP) group had higher levels of anti-NDV antibodies at 14 days after the first immunization and stimulated a greater humoral immune response in 7-10 days. While, the rClone30-VP2L (P/M)-chGM-CSF (NP) group was the most effective in producing a higher level of IBDV antibody response. In conclusion, these three vaccines can induce immune responses more rapidly and effectively, streamline production processes, be cost-effective, and provide a new avenue for the development of Newcastle disease (ND) and IBD bivalent vaccines.

Autogenous vaccines, also known as \"custom\" vaccines, have become an essential instrument in the production veterinarian\'s toolbox for the control of emerging and evolving diseases. Autogenous vaccines require a reduced burden of U.S. Department of Agriculture licensing, making them rapidly accessible. Autogenous vaccines have made significant advancements in the ability to reduce disease within the poultry industry from a combination of several different advancements in regulation requirements, rapid and accurate diagnostic assessments, and improvements in manufacturing. The use of autogenous vaccines by poultry health professionals has also increased, and these custom-made products have been instrumental in combating diseases resulting from antigenic variants such as salmonellosis, colibacillosis, infectious coryza, infectious bursal disease, inclusion body hepatitis, viral enteritis, and viral arthritis and tenosynovitis.
Estudio recapitulativo- Avance de las vacunas autógenas en la industria avícola Las vacunas autógenas, también conocidas como vacunas “personalizadas, elaboradas de acuerdo con las necesidades del cliente” (“custom”), se han convertido en un instrumento esencial en el inventario de herramientas del veterinario de producción para el control de enfermedades emergentes y en evolución. Las vacunas autógenas requieren un procedimiento reducido para obtener la licencia por parte del Departamento de Agricultura de los Estados Unidos, lo que las hace rápidamente accesibles. Las vacunas autógenas han logrado avances significativos en la capacidad de reducir enfermedades dentro de la industria avícola gracias a una combinación de varios avances diferentes en los requisitos regulatorios, evaluaciones de diagnóstico rápidas y precisas y mejoras en la fabricación. También ha aumentado el uso de vacunas autógenas por parte de los profesionales de la salud avícola, y estos productos hechos a medida han sido fundamentales para combatir enfermedades resultantes de variantes antigénicas como la salmonelosis, la colibacilosis, la coriza infecciosa, la enfermedad infecciosa de la bolsa, hepatitis con cuerpos de inclusión, la enteritis viral y la artritis y tenosinovitis virales.

Infectious bursal disease (IBD) is a viral disease that affects the ability of chickens to produce humoral immune responses. One way to prevent the disease is the passage of maternally derived antibodies (MDA) from dams to offsprings via the yolk. Despite sanitary measures, which include immunization with genogroup 1 (G1) vaccines, infections with IBDV genogroup 4 (G4) in young animals have been detected. The aim of this study was to determine whether a local IBDV isolate belonging to G4 could evade the immunity generated by MDAs. Twelve-day-old animals positive for MDA, were inoculated with G1 or G4 isolates or phosphate buffered saline (PBS) as a control. After 1 wk, the animals were sacrificed and the following parameters were evaluated: bursa-body (BB) ratio, viral load, and histologic damage in the bursa of Fabricius. Results showed that G4-infected animals had significant differences in the BB ratio compared to the PBS group. In addition, viral load was significantly higher in the G4 group than in the G1 group. Histologic damage in the bursa of Fabricius was detected only in G4-infected MDA chickens. Our results suggest that infection with G4 local isolate can circumvent the immunity generated by MDA and, furthermore, that G4 isolate does not differ in its pathogenicity from G1 isolate, which underlines the need to include variant strains in vaccine formulations to reduce potential losses caused by these viruses.

Newcastle disease (ND) and infectious bursal disease (IBD) are two viral infectious diseases that are extremely damaging to the poultry industry and are widespread throughout the world. It is necessary to develop a safe and effective vaccine against IBD and ND because vaccination is an effective preventive measure. It has been discovered that recombinant proteins expressed by an expression system in which a fragment of mammalian Immunoglobulin G (IgG) Fragment crystallizable (Fc) is linked to a segment of a gene have antibody-like properties that increase the exogenous protein\'s serum half-life. Heavy chain constant region 3 and heavy chain constant region 4 (CH3-CH4) of Avian Immunoglobulin Y (IgY) is structurally very similar to mammalian Ig G Fc. In this study, a bivalent vaccine rClone30-VP2L-CH3-CH4-GMCSF was developed by using NDV rClone30-chGM-CSF vector to produce VP2L-CH3-CH4 fusion protein. The vaccine has been given to 14-day-old specific pathogen free (SPF) free chickens to test whether it has the potential to prevent IBD and ND. Anti-IBDV and anti-NDV antibody levels in serum were evaluated using ELISA and HI, respectively, and the contents of CD4+ T, CD8+ T, and B cells in leukocytes were determined via flow cytometry. The contents and mRNA transcription levels of four inflammatory factors, IL-1β, IL-4, IFN-γ and chGM-CSF, were detected by ELISA and real-time PCR respectively. The results showed that after vaccination with the rClone30-VP2L-CH3-CH4-GMCSF vaccine, the levels of anti NDV and anti IBDV antibodies in chickens were significantly higher than those of the rClone30 vaccine and commercial vaccines. Meanwhile, the contents and transcription levels of inflammatory factors in chickens inoculated with rClone30-VP2L-CH3-CH4-GMCSF were significantly increased, and the proliferation response of B cells, CD4+ and CD8+ T cells was also stronger. However, the rClone30-VP2L-CH3-CH4-GMCSF vaccine had no significant advantage over the rClone30-VP2L-GMCSF vaccine in any of the above-mentioned features. In summary, rClone30-VP2L-CH3-CH4-GMCSF can stimulate the body to produce a stronger immune response, showing its potential to be considered as vaccine against IBD and ND, but the addition of CH3-CH4 did not improve the vaccine\'s immune effect as expected. The research lays the foundation for developing vaccines for other infectious viral diseases and avoids a unrealistic vaccine optimization method.

Newcastle disease (ND) and infectious bursal disease (IBD) pose significant threats to the chicken industry, causing substantial economic losses. Currently, immunization through vaccination is the most effective strategy to prevent ND and IBD but currently used traditional vaccines, including inactivated or attenuated vaccines, face challenges in achieving a balance between immunogenicity and safety. To develop a green and efficient novel vaccine for ND and IBD, we developed a bivalent chimeric virus-like particle vaccine (ND-IBD cVLPs) displaying the ND virus (NDV) HN protein and the IBD virus (IBDV) VP2 protein based on the ND VLPs carrier platform and insect baculovirus expression system. This study aimed to evaluate the immunogenicity and protective efficacy of ND-IBD cVLPs in specific pathogen-free chickens. Chickens were immunized with 50 µg of purified ND-IBD cVLPs at 7 days old, boosted at 21 days old, and challenged at 42 days old. The results demonstrated that ND-IBD cVLPs stimulated highly effective hemagglutination inhibition antibody levels against NDV HN protein and enzyme-linked immunosorbent assay antibody levels against the IBDV VP2 protein. Furthermore, ND-IBD cVLPs provided complete protection against virulent NDV and IBDV challenges and mitigated pathological damage to the lung caused by NDV infection and the bursa of Fabricius caused by IBDV infection. These findings suggest that ND-IBD cVLPs hold promise as a safe and efficient novel vaccine candidate for the effective prevention of ND and IBD, extending the development of a foreign protein delivery platform of ND VLPs.

Infectious bursal disease (IBD) is an avian viral disease caused in chickens by infectious bursal disease virus (IBDV). IBDV strains (Avibirnavirus genus, Birnaviridae family) exhibit different pathotypes, for which no molecular marker is available yet. The different pathotypes, ranging from sub-clinical to inducing immunosuppression and high mortality, are currently determined through a 10-day-long animal experiment designed to compare mortality and clinical score of the uncharacterized strain with references strains. Limits of this protocol lie within standardization and the extensive use of animal experimentation. The aim of this study was to establish a predictive model of viral pathotype based on a minimum number of early parameters measured during infection, allowing faster pathotyping of IBDV strains with improved ethics. We thus measured, at 2 and 4 days post-infection (dpi), the blood concentrations of various immune and coagulation related cells, the uricemia and the infectious viral load in the bursa of Fabricius of chicken infected under standardized conditions with a panel of viruses encompassing the different pathotypes of IBDV. Machine learning algorithms allowed establishing a predictive model of the pathotype based on early changes of the blood cell formula, whose accuracy reached 84.1%. Its accuracy to predict the attenuated and strictly immunosuppressive pathotypes was above 90%. The key parameters for this model were the blood concentrations of B cells, T cells, monocytes, granulocytes, thrombocytes and erythrocytes of infected chickens at 4 dpi. This predictive model could be a second option to traditional IBDV pathotyping that is faster, and more ethical.

UNASSIGNED: Infectious bursal disease (IBD) is an infectious immunosuppressive disease that affects young chickens. Instead of strict biosecurity practices, vaccination is used to control IBD. However, the disease has not been effectively managed. Variations in the observed clinical symptoms lead to confounding diagnoses. The study aimed to obtain pathological lesion data from chickens suspected of IBD virus (IBDV) infection by gross pathology, confirm IBDV infection through molecular diagnostics, and genotype the VP1 gene fragments of circulating IBDV in the field.
UNASSIGNED: The bursa of Fabricius, thymus, spleen, proventricular-ventricular junction, thigh muscles, and kidneys samples were collected from chickens suspected of IBDV infection from four commercial broiler farms in Central Java and The Yogyakarta Special Region Province between 2021 and 2022. The collected samples were examined histopathologically. Infectious bursal disease virus RNA was extracted from the bursa of Fabricius and VP1 gene was identified by reverse-transcriptase polimerase chain reaction (RT-PCR). The RT-PCR positive sample were sequenced and analyzed in Mega X for homology search and phylogenetic tree analysis.
UNASSIGNED: Macroscopic pathological lesions in the bursa of Fabricius were demonstrated by enlarged edema and thickened plica, presence of gelatinous exudate, hemorrhage, atrophy, and caseous exudate in the lumen. Moreover, the thymus had atrophy and small gray foci were observed in the spleen. Petechiae or hemorrhage was detected on the thigh muscle, and the kidney was dull and pale. Hemorrhage in the proventricular-ventricular junction was distinct. The histopathological examination of the bursa of Fabricius showed follicular vacuolization, edema, heterophilic infiltration, follicular atrophy, congestion, and hemorrhage. The thymus and spleen showed the presence of multifocal necrosis. Hemorrhage was observed in thigh muscle and mucosal part of proventricular-ventricular junction. Vacuolization was seen in renal tubules (nephrosis). Reverse transcriptase-PCR of 26 bursa of Fabricius samples from chickens suspected of IBDV infection showed four negative and 22 positive samples. Phylogenetic analysis of the VP1 gene fragment has indicated very virulent IBD (vvIBD) and belonged to B2 genotype.
UNASSIGNED: Infectious bursal diseases virus infection in broiler chicken generated macroscopic and microscopic primary lesions in the bursa of Fabricius and thigh muscle. Other organs such as the spleen, thymus, proventricular-ventricular junction, and kidney, were also involved. Molecular analysis of the VP1 gene confirmed the causative agent and grouped the virus into vvIBD and B2 genotype. All samples were collected from vaccinated birds therefore, the efficacy of available vaccine is required for urgent evaluation. Since most studies only focused on VP1, further exploration on VP2 gene is suggested notably for new-generation vaccines. Monitoring clinical signs\' transformation over time could assist field diagnostics.

The advent of turkey herpesvirus (HVT) vector vaccine technology (vHVT) has made a huge improvement in the prevention and control of several poultry diseases. The objective of this study was to compare, under experimental conditions, the protection conferred by different vaccination programs based on an HVT double-insert (infectious bursal disease {IBD] and Newcastle disease [ND]) vector vaccine (vHVT-IBD-ND) and an HVT single-insert (vHVT-ND) vector vaccine followed by a vaccination with a live ND vaccine at Day 1 only or at Days 1 and 14. Commercial broilers were vaccinated by the recombinant ND virus vaccines subcutaneously at 1 day old, in the hatchery, and challenged at 30 days of age using the Moroccan ND virus velogenic viscerotropic JEL strain. The results showed that the tested vaccine induced 95% to 100% clinical protection against mortality and clinical signs. The humoral immune response to vaccination was detected from 3 wk of age using enzyme-linked immunosorbent assay and hemagglutination inhibition tests. ND challenge virus shedding was significantly reduced in the vaccinated birds as compared to controls. Significant reduction of the cloacal shedding suggests that the vHVT-IBD-ND vaccine stimulates actively the immunity against the tested ND challenge virus. No significant differences were found between the vaccination programs based on vHVT-IBD-ND or on vHVT-ND.
Evaluación de la eficacia de las vacunas recombinantes contra el virus de la enfermedad de Newcastle (vHVT-IBD-ND de doble inserto y vHVT-ND de inserto único) seguidas de una vacunación con una vacuna viva para la enfermedad de Newcastle contra un desafío de la enfermedad de Newcastle velogénico marroquí en pollos de engorde comerciales. El advenimiento de la tecnología de vacunas recombinantes (vHVT) del virus herpes del pavo (HVT) ha provocado una mejora en la prevención y el control de varias enfermedades avícolas. El objetivo de este estudio fue comparar, en condiciones experimentales, la protección conferida por diferentes programas vacunales basados en una vacuna recombinante HVT con doble inserto (bursitis infecciosa [EII] y enfermedad de Newcastle [ND]) (vHVT-IBD-ND) y una vacuna recombinante HVT con inserto única (vHVT-ND) seguida de una vacunación con una vacuna para Newcastle viva aplicada en el día 1 o en los días 1 y 14. Pollos de engorde comerciales se vacunaron con las vacunas recombinantes del virus de la enfermedad de Newcastle por vía subcutánea al día de edad, en la incubadora y se expusieron a los 30 días de edad utilizando la cepa JEL viscerotrópica velogénica del virus de la enfermedad de Newcastle de Marruecos. Los resultados mostraron que la vacuna evaluada indujo una protección clínica del 95% al 100% contra la mortalidad y los signos clínicos. La respuesta inmune humoral a la vacunación se detectó a partir de las 3 semanas de edad mediante ensayo inmunoabsorbente ligado a enzimas y pruebas de inhibición de la hemaglutinación. La excreción del virus de Newcastle de desafío se redujo significativamente en las aves vacunadas en comparación con los controles. La reducción significativa de la eliminación cloacal sugiere que la vacuna vHVT-IBD-ND estimula activamente la inmunidad contra el virus de Newcastle de desafío analizado. No se encontraron diferencias significativas entre los programas de vacunación basados en vHVT-IBD-ND o en vHVT-ND.

The status of Infectious bursal disease (IBD) in indigenous chickens and backyard poultry in Rwanda has not been previously elucidated. This cross-sectional study was to determine the seroprevalence of infectious bursal disease in indigenous chickens and to identify the associated factors. The study was been done in three districts in the Eastern province of Rwanda where blood from 364 indigenous chickens were collected. ID Screen® IBD indirect enzyme-linked immunosorbent assay (ELISA) test was used to detect IBD antibodies in these birds. 145 questionnaires were also administered to poultry farmers to obtain information on biosecurity measures and associated factors to IBD outbreaks. The study revealed 48.4% (176/364) prevalence of the chicken with IBDV antibodies with statistical significance (P < .05) among/between location and age groups. The questionnaire revealed that there were other important associated factors which included chicken scavenging for seed as a source of food (59.3% of farmers reported), absence of routine vaccination (53.8%), live chickens are purchased from the open market with no information about IBD outbreaks and vaccination (30.0%), open disposal of dead chickens suspected of IBD (58.9%). IBD virus antibodies are present in indigenous chicken in Eastern Rwanda hence further investigation to better understand the epidemiology of IBD virus in indigenous chickens is desired and more research is needed to identify the role of indigenous chickens in the spread of IBD virus in Rwanda.