Search Results (31)

Background/Objectives: More than 33 billion chickens are industrially raised for meat and egg production globally and vaccinated against Marek’s disease virus (MDV). The antigenically related herpesvirus of turkey (HVT) is used as a live-attenuated vaccine, commonly provided as a recombinant vector to protect chickens against additional unrelated pathogens. Because HVT replicates in a strictly cell-associated fashion to low levels of infectious units, adherent primary chicken or duck embryo fibroblasts are infected, dislodged from the cultivation surface and distributed as cryocultures in liquid nitrogen to the site of application. Although viable cells are complex products, application of infected cells in ovo confers protection even in presence of maternal antibodies. Methods/Results: The aim of our study was to determine whether a continuous cell line in a scalable cultivation format can be used for production of HVT-based vaccines. The AGE1.CR cell line (from Muscovy duck) was found to be highly permissive in adherent cultures. Propagation in suspension, however, initially gave very low yields. The induction of cell-to-cell contacts in carrier-independent suspensions and a metabolic shock improved titers to levels suitable for vaccine production (>10⁵ infectious units/mL after infection with multiplicity of 0.001). Conclusions: Production of HVT is challenging to scale to large volumes and the reliance on embryonated eggs from biosecure facilities is complex. We demonstrate that a cell-associated HVT vector can be propagated in a carrier-independent suspension culture of AGE1.CR cells in chemically defined medium. The fed-batch production is independent of primary cells and animal-derived material and can be scaled to large volumes. Full article

Infectious bursal disease (IBD) is a viral disease that most commonly affects young chickens and destroys lymphocytes, leading to immunosuppression. The field study aimed to investigate the effect of three different vaccines administered in ovo against IBD and spray against Newcastle disease (ND) on serological response tested for IBD and ND and histopathological analysis of the bursa of Fabricius (BF) and quantitative B lymphocytes in BF in broiler chickens. The study was conducted on a farm of four hen houses with 30,000 chicks in each building. Three different vaccination programs were used in the poultry hatchery, and one hen house IV was not vaccinated. All three groups were vaccinated at 18 days and 9 h in ovo during egg transfer against IBD at a dose of 0.05 mL/embryo, group I vector vaccine (strain vHVT013-69), group II immunocomplex vaccine (strain Winterfield 2512), group III immunocomplex vaccine (strain M.B, 0.05). Then, after hatching, the chicks were vaccinated in a spray (groups I, II, and III) against NDV (strain VG/GA, 20 mL/100 birds) and infectious bronchitis (IBV) in a spray (strain H-120, serotype Mass, and strain CR88121, serotype 793B) at a dose of 20 mL/100 chicks. On days 1, 21, 31, and 41, blood was collected for serological tests to determine the antibody titer against IBD, which was performed using two tests (IDEXX and ID-Vet) and against ND. During the necropsy of birds on days 21 and 31, the bursae of Fabricius were collected from five chickens for histopathological evaluation of BF and quantitative B lymphocyte counts; a total of 40 bursae were analyzed (10 per group). The vaccination program applied significantly (p < 0.05) affected the immune response expressed as a geometric mean titer (GMT) in the serum of the examined chickens against IBDV on days 21, 31, and 41. Differences were also demonstrated in the mass and level of BF damage and the number of B lymphocytes. No significant differences were demonstrated in the GMT in the serum of the examined chickens against NDV depending on the vaccination program applied. Full article

Avian reovirus (ARV) infections significantly impact the global poultry industry, but host responses across infection models remain poorly characterized. Using specific-pathogen-free chicken embryos, this study examined tissue-specific transcriptomic changes following in ovo inoculation with two doses of ARV S1133 at embryonic day 18. Quantitative PCR confirmed dose- and time-dependent viral replication, with the liver exhibiting the highest viral load at 24 h post-inoculation (hpi), whereas the kidneys, intestines, and bursa were only positive at 48 hpi with the higher viral dose. Transcriptomic profiling revealed the intestines mounted an extensive gene expression response, implicating early immune activation. Liver samples demonstrated strong upregulation of antiviral pathways, including interferon signaling and viral replication inhibition, while kidneys and intestines were enriched for coagulation and wound healing pathways. The bursae exhibited minimal immunity-related responses, suggesting insufficient maturation. Functional analyses confirmed tissue-specific immune and metabolic adaptations to infection. These findings indicate that ARV replication efficiency and host molecular responses are dose-, tissue-, and time-dependent. Notably, intestinal responses suggest preemptive immune engagement, while hepatic antiviral mechanisms may play a critical role in restricting viral spread. This study establishes foundational knowledge of host molecular responses to ARV in late-stage embryos, with implications for in ovo vaccination and early immunity. Full article

Poultry production systems are usually exposed to important infections that could be prevented by vaccination programs. Conventional methods of vaccination such as drinking water; spray, eye, or nose inoculation; and injection are usually given after hatching and have many disadvantages. Therefore, there is a great need for searching of alternative ways for vaccination process. In ovo vaccination technology is now regarded as an alternative approach to post-hatch vaccination in modern poultry operations. This technique is effective, fast, provides uniform vaccine dosing and delivery, is suitable for massive production, and reduces labor costs. Routine in ovo vaccination is applied during the late stage of embryonic development between days 17.5 and 19.25 of egg incubation. The best route of inoculation of the vaccine is in the amniotic fluid or in the embryo’s muscles, without causing any hatchability or chick quality losses. Accordingly, the inoculation site, the age of the embryos and breeders, presence of maternal antibodies, and the sanitation of equipment’s and the environment during the vaccination process affect the efficiency of the in ovo vaccination technique. In ovo vaccination technology is currently applied for vaccination against several economically important viral diseases such as Newcastle, infectious bursal disease, Marek’s disease, infectious laryngotracheitis, infectious bronchitis, avian influenza, and avian metapneumovirus. Moreover, vaccines used for prevention of mycoplasmosis and coccidiosis could be applied in ovo instead of in post-hatching application. It can be concluded that in ovo vaccination is a rapidly growing trend of vaccine technology, and it can replace post-hatching vaccination conventional methods. Full article

Effects of in ovo and dietary sources of calcidiol (25(OH)D₃), combined with Marek’s disease vaccine (MDV), on the expression of genes involved with the antioxidant activity, muscle deposition, and immunity in the pectoralis major (P. major) muscle and spleen of 40 d of age (doa) broilers were investigated. The in ovo treatments were as follows: (1) non-injected; (2) the injection of 50 μL of commercial MDV, (3) MDV + 1.2, or (4) 2.4 μg of 25(OH)D₃. All birds received either a commercial diet containing no supplemental 25(OH)D₃ (control) or the same diet supplemented with an additional 69 µg of 25(OH)D₃ per kg of feed (Hy-D diet). At 40 doa, the pectoralis major (P. major) muscle and spleen of 48 birds (six replicates per diet x in ovo treatment combination) were collected. When compared to un-supplemented commercial diet-fed birds, in birds that were fed the Hy-D diet, the expression of the TGF-β4 gene in the spleen and P. major muscle, and the GSH-P1, GSH-P7, SOD2, MyoG, MyoD1, and Pax3 genes in the P. major muscle were up-regulated, whereas the expression of the IL-1β, IL-8, and CYP24A1 genes in the spleen and P. major muscle were down-regulated. Nevertheless, birds that received any of the in ovo injection doses of 25(OH)D₃ exhibited a higher expression of the IL-10, TGF-β4, and CYP27B1 genes in the spleen and P. major muscle. Furthermore, in comparison to the MDV-injected control group, the CAT, MyoD1, and Pax3 genes in the P. major muscle were up-regulated, and the expression of the INF-γ, IL-1β and CYP24A1 genes in the spleen and the IL-8, and IL-1β genes in the P. major muscle were down-regulated. In conclusion, a significant improvement in the expression of genes responsible for enzymatic antioxidant activity, protein synthesis, and inflammatory reactions in 40-day-old broilers occurred in response to in ovo and dietary supplemental 25(OH)D₃, and supplemental 25OHD₃ provided via either route was used to enhance the expression of genes linked to vitamin D activity (CYP27B1, CYP24A1). Full article

The interest for in ovo feeding has grown in the last decades mainly concerning probiotics, live microorganisms that can actively interact with the embryo. The aim of this study was to evaluate the effects of a multi-strain probiotic diluted in Marek’s disease vaccine (MDV) on zootechnical performances, intestinal morphology and Eimeria spp. infection. One hundred and twenty eggs of Ross 308 broiler chickens were incubated until 18 d, when 105 fertilised and vital eggs were randomly allocated into three groups. A control group (C) was inoculated with MDV; two treated groups (P1 and P2) were inoculated with MDV and different concentrations of probiotics: 1 × 10⁵ CFU/100 μL in P1 and 1 × 10⁶ CFU/100 μL in P2. After hatching, chickens were separated into three replicates (10/replicate). Zootechnical parameters were determined. At the end of the cycle (35 d), chickens were slaughtered, and the intestine was collected for morphological analysis from nine chickens per group (three/replicate). Eimeria spp. oocyst shedding was determined weekly, and parasitic lesions were analysed on the histological sample. In ovo treatment with probiotic did not influence hatching rate but significantly improved body weight and positively influenced intestinal morphometric data compared to C. Oocyst shedding in faeces resulted in an increase in C, with significant differences at sampling performed at 14, 21 and 28 d of age. These results suggest that the tested probiotic compound is safe for in ovo supplementation and effectively improves zootechnical performances and coccidian resistance. Full article

This study was undertaken to evaluate and compare the efficacy of different multi-antigen vaccines, including heat-inactivated, whole lysate, and subunit (outer membrane proteins [OMPs]) C. jejuni vaccines along with the immunostimulant CpG ODN in controlling Campylobacter colonization in chickens. In the first trial, 125 μg of C. jejuni OMPs and 50 μg of CpG ODN were administered individually or in combination, either in ovo to chick embryos or subcutaneously (SC) to one-day-old chicks. In the second trial, different concentrations of C. jejuni antigens (heat-killed, whole lysate, and OMPs) were administered SC to one-day-old chicks. The results of the first trial revealed that SC immunization with the combination of CpG ODN and C. jejuni OMPs elevated interferon (IFN)-γ, interleukin (IL)-1β, and IL-13 gene expression in the spleen, significantly increased serum IgM and IgY antibody levels, and reduced cecal C. jejuni counts by approximately 1.2 log₁₀. In contrast, in ovo immunization did not elicit immune responses or confer protection against Campylobacter. The results of the second trial showed that SC immunization with C. jejuni whole lysate or 200 μg OMPs reduced C. jejuni counts by approximately 1.4 and 1.1 log₁₀, respectively. In conclusion, C. jejuni lysate and OMPs are promising vaccine antigens for reducing Campylobacter colonization in chickens. Full article

The effects of the Marek’s disease vaccine (MDV) on the live performance, breast meat yield, and incidence of woody breast myopathy (WBM) of Ross 708 broilers were investigated when administered alone or in conjunction with in ovo and dietary supplemental 25-hydroxycholecalciferol (25OHD₃). At 18 d of incubation (doi), four in ovo injection treatments were randomly assigned to live embryonated Ross 708 broiler hatching eggs: (1) non-injected; (2) commercial MDV alone; or MDV containing either (3) 1.2 or (4) 2.4 μg of 25OHD₃. An Inovoject multi-egg injector was used to inject a 50 μL solution volume into each egg. The birds were provided a commercial diet that contained 250 IU of cholecalciferol/kg of feed (control) or a commercial diet that was supplemented with an additional 2760 IU of 25OHD₃/kg of feed (HyD-diet). In the growout period, 14 male broilers were placed in each of 48 floor pens resulting 6 replicated pens per in ovo x dietary treatment combination. Live performance variable were measured at each dietary phases from 0 to 14, 15 to 28, and 29 to 40 d of age (doa). At 14 and 40 doa, pectoralis major (P. major) and pectoralis minor (P. minor) muscles were determined for one bird within each of the six replicate pens. At 41 doa, WBM incidence was determined. No significant main or interaction effects occurred for WBM among the dietary or in ovo injection treatments. However, in response to in ovo 25OHD₃ supplementation, BW and BWG in the 29 to 40 doa period and BWG and FCR in the 0 to 40 doa period improved. In addition, at 40 and 41 doa, breast meat yield increased in response to in ovo and dietary 25OHD₃ supplementation. Future research is needed to determine the possible reasons that may have been involved in the aforementioned improvements. Full article

With the rapidly increasing demand for poultry products and the current challenges facing the poultry industry, the application of biotechnology to enhance poultry production has gained growing significance. Biotechnology encompasses all forms of technology that can be harnessed to improve poultry health and production efficiency. Notably, biotechnology-based approaches have fueled rapid advances in biological research, including (a) genetic manipulation in poultry breeding to improve the growth and egg production traits and disease resistance, (b) rapid identification of infectious agents using DNA-based approaches, (c) inclusion of natural and synthetic feed additives to poultry diets to enhance their nutritional value and maximize feed utilization by birds, and (d) production of biological products such as vaccines and various types of immunostimulants to increase the defensive activity of the immune system against pathogenic infection. Indeed, managing both existing and newly emerging infectious diseases presents a challenge for poultry production. However, recent strides in vaccine technology are demonstrating significant promise for disease prevention and control. This review focuses on the evolving applications of biotechnology aimed at enhancing vaccine immunogenicity, efficacy, stability, and delivery. Full article

Poultry farming is one of the pillar industries of global animal husbandry. In order to guarantee production, poultry are frequently vaccinated from the moment they are hatched. Even so, the initial immunity of chicks is still very poor as they are in the “window period” of immune protection. In ovo vaccination pushes the initial immunization time forward to the incubation period, thereby providing earlier immune protection for chicks. In ovo vaccination is currently a research hotspot of poultry disease prevention and control, which is in line with the intensification of poultry production. However, the vaccines currently available for in ovo vaccination are limited and cannot meet the needs of industrial development, so how to efficiently activate the adaptive immune response of chicken embryos becomes the key to restrict product development and technological progress of in ovo vaccination. Its breakthrough, to a large extent, depends on systematic illustration of the mechanism underlying the adaptive immune response post immunization. Clarification of this issue will provide us with theoretical support and potential solutions for the development of novel vaccines for in ovo vaccination, the augmentation of efficacy of current vaccines and the optimization of immune programs. Full article

Yolkin is a polypeptide complex isolated from hen egg yolk that exhibits immunomodulating properties. The aim of the present study was to determine whether in-ovo-delivered yolkin affects leukocyte populations and cytokine levels in broiler chickens. The experiment was carried out on eggs from Ross 308 broiler breeder birds. Yolkin was administered in ovo on the 18th day of incubation, once, at the following three doses: 1, 10, or 100 µg/egg. The immunological parameters were assessed in 1-, 7-, 14-, 21-, 28-, 35-, and 42-day-old birds kept under farming conditions and routinely vaccinated. The leukocyte populations were determined in the thymus, spleen, and blood. The cytokine (IL-1β, IL-2, IL-6, and IL-10) levels were determined in the plasma of the broiler chickens. Each experimental group included eight birds. The most pronounced effect of yolkin was an increase in the population of T cells, both CD4⁺ and CD8⁺, mainly in the blood. This effect on the lymphocyte subsets may be valuable regarding chicken immune responses, mainly against T-dependent antigens, during infection or after vaccination. Full article

Infectious laryngotracheitis (ILT) is an economically important disease in chickens. We previously showed that an in ovo adjuvantation of recombinant herpesvirus of the turkey-Laryngotracheitis (rHVT-LT) vaccine with CpG-oligonucleotides (ODN) can boost vaccine-induced responses in one-day-old broiler chickens. Here, we evaluated the protective efficacy of in ovo administered rHVT-LT + CpG-ODN vaccination against a wild-type ILT virus (ILTV) challenge at 28 days of age and assessed splenic immune gene expression as well as cellular responses. A chicken-embryo-origin (CEO)-ILT vaccine administered in water at 14 days of age was also used as a comparative control for the protection assessment. The results showed that the rHVT-LT + CpG-ODN or the CEO vaccinations provided significant protection against the ILTV challenge and that the level of protection induced by both the vaccines was statistically similar. The protected birds had a significantly upregulated expression of interferon (IFN)γ or interleukin (IL)-12 cytokine genes. Furthermore, the chickens vaccinated with the rHVT-LT + CpG-ODN or CEO vaccine had a significantly higher frequency of γδ T cells and activated CD4+ or CD8+ T cells, compared to the unvaccinated-ILTV challenge control. Collectively, our findings suggest that CpG-ODN can be used as an effective adjuvant for rHVT-LT in ovo vaccination to induce protective immunity against ILT in broiler chickens. Full article

In ovo injection of the Marek’s disease (MD) vaccine (MDV) has been widely practiced in commercial US hatcheries. However, the MDV is very sensitive and may not be compatible with some nutrients when administered together by in ovo injection. When individually administered by in ovo injection, L-Ascorbic acid (L-AA) and 25-hydroxyvitamin D₃ (25OHD₃) have previously exhibited very promising results on the post-hatch physiological and immunological characteristics of broilers subjected to stressful commercial conditions. However, the compatibility of the MDV with these vitamins has not been previously explored. Their compatibility must first be established before their combined administration by in ovo injection can be considered. Therefore, the objective in this study was to determine the compatibility of the MDV with various levels of 25OHD₃ or L-AA. The treatments employed were MDV-alone, MDV in combination with 0.6 (low) or 2.4 (high) μg doses of 25OHD₃, or MDV in combination with 1.2 (low) or 12 (high) mg doses of L-AA. The live and dead ratio of primary chick embryo fibroblast cells infected by the MD virus (CEF-MDV) in each treatment was determined every 30 min for 2 h. The L-AA at both the low and high doses resulted in a 70% death of CEF-MDV within 1 h, but either dose of the 25OHD₃ exhibited only an approximate 5% lower CEF-MDV survival as compared to those in the MDV-alone treatment. Therefore, it is suggested that the two designated doses of 25OHD₃ have the potential to be effectively combined with the MDV for subsequent administration by in ovo injection. Full article

With poultry products as one of the leading reservoirs for the pathogen, in a typical year in the United States, it is estimated that over one million individuals contract non-typhoidal Salmonella infections. Foodborne outbreaks associated with Salmonella infections in poultry, thus, continue to remain a significant risk to public health. Moreover, the further emergence of antimicrobial resistance among various serovars of Salmonella is an additional public health concern. Feeding-based strategies (such as use of prebiotics, probiotics, and/or phytobiotics as well as essential oils), non-feeding-based strategies (such as use of bacteriophages, vaccinations, and in ovo strategies), omics tools and surveillance for identifying antibiotic-resistance genes, post-harvest application of antimicrobials, and biosecurity measures at poultry facilities are practical interventions that could reduce the public health burden of salmonellosis and antibiotic resistance associated with poultry products. With the escalating consumption of poultry products around the globe, the fate, prevalence, and transmission of Salmonella in agricultural settings and various poultry-processing facilities are major public health challenges demanding integrated control measures throughout the food chain. Implementation of practical preventive measures discussed in the current study could appreciably reduce the public health burden of foodborne salmonellosis associated with poultry products. Full article

In ovo administration as a possible alternative method of 6/85 MG vaccination was assessed. After 18 days of incubation (doi), the eggs were administered a particular dosage of a live attenuated 6/85 MG vaccine in either the air cell (AC) or amnion (AM). The treatments included non-injected eggs and eggs injected into the AC or AM with diluent alone as controls. Treatments also included eggs injected with diluent, which contained 1.73 × 10², or 1.73 × 10⁴ CFU of 6/85 MG. Hatchability of viable injected eggs (HI) and residual embryonic mortality were determined at 22 doi. At hatch and at three weeks posthatch, one hatched chick per treatment replicate was bled and swabbed for the detection of 6/85 MG in the choanal cleft using PCR, serum plate agglutination (SPA), and ELISA methods. The results show that AC in ovo injection of 6/85 MG had no negative impacts on HI or on the live performance of pullets, but that it failed to provide adequate protection (p ≤ 0.0001) in hatchlings or three-week-old pullets. The 1.73 × 10⁴ 6/85 MG CFU dosage injected into the AM decreased the hatchability of injected eggs containing viable embryos (HI; p = 0.009) and was associated with a significant increase in late dead mortality (p = 0.001). Hatchling and three-week-old chick mortalities (p = 0.008) were significantly greater in the 1.73 × 10⁴ CFU-AM treatment group in comparison with the other treatment groups. In addition, the 1.73 and 1.73 × 10² 6/85 MG-AM treatments had no negative effects on the hatching process or on posthatch growth, and the 1.73 × 10² 6/85 MG-AM treatment was more effective in the protection of pullets against MG (p ≤ 0.0001) as compared with the low dosage and non-injected treatment groups. Further research is needed to examine the influence of the 6/85 MG in ovo vaccine on layer immune competence. Full article