Unvaccinated Chickens Research Articles

Comparative Nucleotide Sequence Analysis of Glycoprotein B, C, and G of Infectious Laryngotracheitis Virus Isolated in Egypt During 2016-2018

Infectious Laryngotracheitis (ILT) is an economically important disease of poultry, causing a high mortality rate and /or reduced egg production. Tracheas from sever morbid and recently died unvaccinated household chicken were subjected to PCR assay to detect the presence of the virus through amplification of the glycoprotein B gene. All tested samples gave positive ct ranging from 13.32 to 25.53. Virus isolation was performed by inoculation—the processed tracheal swaps onto the chorioallantoic membrane. Positive pock lesion has been developed within 7 days post-inoculation. The pock lesions were subjected to PCR assay for amplification of both the full-length glycoprotein B, C, and G for sequencing analysis. Positive amplicons migrating about 2600, 1250, and 890 bp were amplified corresponding to the orf of gpB, gpC and gpG genes. Sequence alignment and phylogenetic tree revealed that all sequenced isolates gave a high degree with wild type isolate of ILT and a high degree of genetic stability was clearly evident among strains isolated in different periods (2016-2018), indicating that these glycoproteins could be used as a vaccine candidate.

Differential Response of the Chicken Trachea to Chronic Infection with Virulent Mycoplasma gallisepticum Strain Ap3AS and Vaxsafe MG (Strain ts-304): a Transcriptional Profile.

Mycoplasma gallisepticum is the primary etiological agent of chronic respiratory disease in chickens. Live attenuated vaccines are most commonly used in the field to control the disease, but current vaccines have some limitations. Vaxsafe MG (strain ts-304) is a new vaccine candidate that is efficacious at a lower dose than the current commercial vaccine strain ts-11, from which it is derived. In this study, the transcriptional profiles of the trachea of unvaccinated chickens and chickens vaccinated with strain ts-304 were compared 2 weeks after challenge with M. gallisepticum strain Ap3AS during the chronic stage of infection. After challenge, genes, gene ontologies, pathways, and protein classes involved in inflammation, cytokine production and signaling, and cell proliferation were upregulated, while those involved in formation and motor movement of cilia, formation of intercellular junctional complexes, and formation of the cytoskeleton were downregulated in the unvaccinated birds compared to the vaccinated birds, reflecting immune dysregulation and the pathological changes induced in the trachea by infection with M. gallisepticum Vaccination appears to protect the structural and functional integrity of the tracheal mucosa 2 weeks after infection with M. gallisepticum.

Efficacy of Thermostable Newcastle Disease Virus Strain I-2 in Broiler Chickens Challenged with Highly Virulent Newcastle Virus.

Newcastle disease (ND) is a major threat to poultry industry production throughout developing countries. The Newcastle disease viruses (NDVs) infecting industrialized and indigenous poultry in Iran are velogenic strains and responsible for the frequent outbreaks of ND in poultry farms even in vaccinated flocks causing serious economic losses in the commercial and indigenous poultry. However, vaccination is the only way to protect against endemic ND, and the conventional vaccines are not heat stable and consequently require complex cold-chains to be transferred to users leading to not much resistance. The present study aimed to evaluate the efficacy of thermostable NDV strain I-2 in broiler chickens vaccinated via drinking water and coated on oiled wheat grain. The horizontal transmission of I-2 strain and transmission of disease from vaccinated to unvaccinated chickens were also evaluated in this study. The obtained results showed that both routes of administration, following primary and/or secondary dose, provoked the production of necessary antibody titer and adequate protective immunity in broiler chickens. Moreover, the horizontal transmission of I-2 strain from vaccinated to unvaccinated chickens housed together induced an antibody response and protected unvaccinated chickens against a local field isolate of a virulent strain of NDV (The intravenous pathogenicity index 2.46, mean death time 59 h). Nevertheless, all unvaccinated and Newcastle challenged broilers chickens against the NDV died in this study. It is noteworthy that the transmission of the virus from challenged broiler chickens was very low to induce clinical signs in susceptible chickens. The obtained results of this study revealed the efficacy of NDV strain I-2 coated on the oiled wheat and via drinking water as it protects broiler chickens from highly virulent NDV.

Immunogenicity and Efficacy of Live Infectious Bronchitis 793/B.08IR Vaccine in SPF Chickens

Infectious bronchitis virus (IBV) has a variety of serotypes with relatively limited cross-protection leading the disease to be a major problem in the poultry industry. The IBV 793/B strain has identified to circulate in Iran; therefore, the development of a specific vaccine to protect against the virulent virus has received attention. In this regard, the live IB 793/B vaccine (793/B.08IR) was developed in the Razi Vaccine and Serum Research Institute. In this study, the immunogenicity of 793/B.08IR vaccine via different routes of vaccination and efficacy of the vaccine were determined in specific-pathogen-free (SPF) chickens. Three treatment groups of 10 SPF chickens received the vaccine via eye drops, spray, and drinking water. The sera were collected from the chicks at 3 and 6 weeks after the vaccination, and IBV specific antibody was measured using enzyme-linked immunosorbent assay (ELISA) and serum neutralization (SN) test. To evaluate 793/B.08IR vaccine efficacy, 10 SPF chickens were vaccinated using eye drops. Moreover, 10 unvaccinated chickens were separately retained as negative controls. The birds were challenged with the virulent virus 3 weeks following the vaccination. Five days after the challenge, the tracheal swab was taken for virus reisolation. In the immunogenicity test, the ELISA titers of three vaccinated groups were significantly higher than the background values obtained in the control group (p<0.0001). The mean value of ELISA titer in the spray vaccinated group was higher than the spray and drinking water vaccinated groups 3 weeks following the vaccination; however, the difference was not statistically significant. No differences were observed in antibody titers among the three vaccinated groups 6 weeks after the vaccination. The results of the SN test confirmed the data obtained from the ELISA. The results of antibody titer and its increasing trend in chickens showed that 793/B.08IR vaccine induce proper immunity against the virus. In the efficacy test, IBV was isolated from 90% of the unvaccinated controls and 10% of vaccinated groups. The results of the recovery of the virus after the challenge showed that 793/B.08IR vaccine can provide a significantly improved protection against the pathogen in SPF vaccinated chickens.

Pullets had higher bursal and thymic weight indices and more antibody response to La Sota vaccination than broiler chickens (Gallus gallus domesticus).

This study investigated the immune responses to La Sota vaccination, used in protection of chickens against Newcastle disease, in light weight type breeds of chickens (pullets) and heavy weight type breeds of chickens (broilers) used in commercial poultry production. Seven‐week‐old 50 White Marshall broilers (Br) and 50 Isa Brown pullets (Pu) were randomly divided into four groups: vaccinated broilers chickens; (VBr), unvaccinated broiler chickens (UBr), and vaccinated pullet chickens (VPu) and unvaccinated pullet chickens (UPu). Chickens in groups VBr and VPu were vaccinated with La Sota vaccine, whereas groups UBr and UPu were not vaccinated. On day 0 post vaccination (PV), six chickens from group Br and Pu, and on day 4 PV, three chickens from each four groups were sacrificed and the bursa weight index (BWI), thymus weight index (TWI) and the splenic weight index (SWI) were obtained. The chickens were observed for clinical signs and lesions. Serum samples were collected from the chickens in all the groups on days 0, 7, 14, 21, 28 PV and assayed for haemagglutination inhibition (HI) antibodies. The BWI, TWI and SWI were 0.37 ± 0.05, 0.35 ± 0.17, 0.65 ± 0.26 for pullets and 0.11 ± 0.04, 0.13 ± 0.02, 0.36 ± 0.17 for broilers on day 0 PV. On day 4 PV there was no significant difference (p < .05) between the indices of the vaccinated and unvaccinated chickens. The geometrical mean antibody titres (GMT) of the pullets were 2 to 3 times higher than those of the broilers on days 7 to 28 PV. Vaccination did not produce clinical signs or lesions. The above observations show that naturally pullets produce higher antibodies than broilers because of their higher BWI.

Molecular characterization of the meq gene of Marek's disease viruses detected in unvaccinated backyard chickens reveals the circulation of low- and high-virulence strains

Marek's disease (MD) is an important lymphoproliferative disease of chickens, caused by Gallid alphaherpesvirus 2 (GaHV-2). Outbreaks are commonly reported in commercial flocks, but also in backyard chickens. Whereas the molecular characteristics of GaHV-2 strains from the commercial poultry sector have been reported, no recent data are available for the rural sector. To fill this gap, 19 GaHV-2 strains detected in 19 Italian backyard chicken flocks during suspected MD outbreaks were molecularly characterized through an analysis of the meq gene, the major GaHV-2 oncogene. The number of four consecutive prolines (PPPP) within the proline-rich repeats of the Meq transactivation domain, the proline content, and the presence of amino acid (aa) substitutions were determined. Phylogenetic analysis was performed using the Maximum Likelihood method. Sequence analysis revealed a heterogeneous population of GaHV-2 strains circulating in Italian backyard flocks. Seven strains, detected from birds affected by classical MD, showed a unique meq isoform of 418 aa with a very high number of PPPP motifs. Molecular and clinical features are suggestive of a low oncogenic potential of these strains. The remaining 12 strains, detected from flocks experiencing acute MD, transient paralysis, or sudden death, had shorter Meq protein isoforms (298 or 339 aa) with a lower number of PPPP motifs and point mutations interrupting PPPP. These features allow us to assert the high virulence of these strains. These findings reveal the circulation of low- and high-virulence GaHV-2 strains in the Italian rural sector.

Molecular characterisation of infectious bursal disease virus in Namibia, 2017.

Between July and September 2017, samples collected from six unvaccinated chickens in Namibia were shown to be positive for infectious bursal disease virus (IBDV) by RT-PCR. Partial sequence and phylogenetic analysis of the VP1 and VP2 genes from six viruses revealed that they all belong to the very virulent pathotype (Genogroup 3) and are genetically very similar to IBDVs identified in neighbouring Zambia. This is the first molecular characterisation of IBDV in Namibia and has implications on the control and management of the disease in the country.

Molecular detection of integrated reticuloendothelial virus genes in fowlpox virus field isolates and live vaccines of poultry

Two field isolates (FWPV-W1 and FWPV-W2) obtained from unvaccinated backyard poultry chickens and four commercial live vaccines (FWPV-G, FWPV-V, FWPV-B and FWPV-H) of fowlpox virus origin were isolated on chorio-allantoic membrane (CAM) of embryonated chicken eggs. The CAM tissues infected with FWPV-W1, FWPVW2, FWPV-G, FWPV-V, FWPV-B and FWPV-H individually were subjected to DNA isolation. The isolated DNA was tested for the presence of P4b gene by PCR to confirm FWPV. Then, each of the field isolates and commercial vaccines were screened for presence of reticuloendothelial virus envelope (REV-env) gene and long terminal repeat (LTR) region by PCR. FWPV-W1 isolate was positive for REV-env gene (807 bp) and REV-LTR region (370 bp), which confirmed presence of near full-length REV integration in its genome. Whereas, FWPV-W2 isolate was positive for LTR region and negative for REV-env gene. This suggested that full-length REV is not present in all FWPV field isolates. All the four commercial live vaccines, were negative for REV-env gene. This showed that full-length REV is absent in these commercial vaccines, ensuring safety of the usage of these vaccines in India. However, the commercial vaccines were positive for REV-LTR region, which does not affect the vaccine safety.

Infections and pathology of free-roaming backyard chickens on St. Kitts, West Indies.

Free-roaming chickens on Caribbean islands are important sentinels for local avian diseases and those introduced by birds migrating through the Americas. We studied 81 apparently healthy unvaccinated free-roaming chickens from 9 parishes on St. Kitts, an eastern Caribbean island. Using commercial ELISAs, no chickens had antibodies against avian influenza virus, West Nile virus, or Salmonella Enteritidis, although seropositivity was high to infectious bursal disease virus (86%), infectious bronchitis virus (84%), Mycoplasma (37%), and avian avulavirus 1 (Newcastle disease virus, 31%). Examination of small and large intestinal contents revealed cestodes in 79% and nematodes in 75% of the chickens. Although ectoparasites and endoparasites were common (74% and 79%, respectively), only a few chickens had lesions at postmortem examination, mainly intestinal serosal nodules (12%) and feather loss (6%). Histologic examination of 18 organs from each bird revealed lesions in high percentages of organs, mainly the liver (86%), lung (75%), spleen (60%), small intestine (56%), skin (42%), and kidney (40%). Lesions included degenerative, reactive, inflammatory, and neoplastic, and were not correlated with the serologic status of the chickens except in one case of infectious bursal disease. Microscopically, Paratanaisia bragai was seen in the kidneys of 3 chickens and intestinal coccidiasis in 1 chicken. Pulmonary silicate aggregates were common, were present in intestinal serosal nodules, and were suggestive of environmental exposure.

Haemagglutination inhibition antibody responses of pullet and broiler chickens (&lt;i&gt;Gallus gallus domesticus&lt;/i&gt;) to Newcastle disease virus LaSota vaccination

Newcastle disease outbreaks still occur sporadically in commercial vaccinated flocks and remains a constant threat to poultry producers despite advances in vaccination against the disease. Another aspect that can be a complementary control strategies or that is well recognized but is often neglected is the differences in immune response due to genetic or breed/type variation. This study investigated the immune responses to LaSota vaccination in light weight type or breeds of chickens (pullets) and heavy weight type or breeds of chickens (broilers) used in commercial poultry production. Fifty seven-week-old White Marshall broilers (Br) and 50 Isa Brown pullets (Pu) of the same age were randomly divided into 4 groups viz: vaccinated broilers chickens (VaBr), unvaccinated broiler chickens (UBr), vaccinated pullet chickens (VaPu) and unvaccinated pullet chickens (UPu). Chickens in groups VaBr and VaPu were vaccinated with LaSota vaccine while groups UBr and UPu were not vaccinated. The chickens were observed for clinical signs and lesions. Serum samples were collected from the chickens in all the groups on days 0, 7, 14, 21, 28 post vaccination (PV), and assayed for haemagglutination inhibition (HI) antibodies. The geometrical mean antibody titres (GMT) of the pullets were 2 to 3 times higher than those of the broilers on days 7 to 28 PV. Vaccination produced neither clinical signs nor lesions. The above observations show that naturally pullets produce higher antibodies than broilers, and suggest breed-based variation on immune responses to Newcastle disease vaccination. The knowledge from the present study may lead to genetic approach to vaccine development and development of more effective vaccination strategies to be used in commercial poultry production. Keywords: Broilers, Haemagglutination inhibition antibody, LaSota vaccination, Pullets

Comparison of the Transcriptomes and Proteomes of Serum Exosomes from Marek's Disease Virus-Vaccinated and Protected and Lymphoma-Bearing Chickens.

Marek’s disease virus (MDV) is the causative agent of Marek’s disease (MD), a complex pathology of chickens characterized by paralysis, immunosuppression, and T-cell lymphomagenesis. MD is controlled in poultry production via vaccines administered in ovo or at hatch, and these confer protection against lymphoma formation, but not superinfection by MDV field strains. Despite vaccine-induced humoral and cell-mediated immune responses, mechanisms eliciting systemic protection remain unclear. Here we report the contents of serum exosomes to assess their possible roles as indicators of systemic immunity, and alternatively, tumor formation. We examined the RNA and protein content of serum exosomes from CVI988 (Rispens)-vaccinated and protected chickens (VEX), and unvaccinated tumor-bearing chickens (TEX), via deep-sequencing and mass spectrometry, respectively. Bioinformatic analyses of microRNAs (miRNAs) and predicted miRNA targets indicated a greater abundance of tumor suppressor miRNAs in VEX compared to TEX. Conversely, oncomiRs originating from cellular (miRs 106a-363) and MDV miRNA clusters were more abundant in TEX compared to VEX. Most notably, mRNAs mapping to the entire MDV genome were identified in VEX, while mRNAs mapping to the repeats flanking the unique long (IRL/TRL) were identified in TEX. These data suggest that long-term systemic vaccine-induced immune responses may be mediated at the level of VEX which transfer viral mRNAs to antigen presenting cells systemically. Proteomic analyses of these exosomes suggested potential biomarkers for VEX and TEX. These data provide important putative insight into MDV-mediated immune suppression and vaccine responses, as well as potential serum biomarkers for MD protection and susceptibility.

Serologic Status of Newcastle Disease in Native Chickens by Hemagglutination Inhibition Test

Newcastle disease (NCD) is a poultry disease caused by avian Paramyxovirus type 1, characterized by gastrointestinal, respiratory and neurological symptoms. The study established the prevalence of NCD in native chickens and evaluated the protection levels of vaccinated chickens. Blood serum samples were subjected to hemagglutination inhibition test. A total of 75 blood samples were collected from five sites in Davao City: 60 samples from four unvaccinated native chicken farms, and 15 from a vaccinated broiler farm. Results showed seven (7) unvaccinated native chickens with positive titer levels ranging from 2 to 32, of which two(2) were considered significant, indicating protection even without an elicited immune response. This cannot be simply attributed to environmental factors considering uniform exposure of other individuals to similar conditions but exhibited no positive titers. The significant titer count of vaccinated samples ranging from 16 to 128 is attributed to their vaccination history. Differences in titer levels despite similar vaccine administration indicate a disparity in levels of protection due to different individual antibody immune responses, and efficacy of vaccines. Analysis by Chi-square goodness of fit test showed no difference in the titer levels of native chickens, which was expected as they did not have previous exposure to NCD and most had no titers.

Natural outbreak of Marek's disease in indigenous chicken and Japanese quail (Coturnix coturnix japonica) in Jos, Plateau State, Nigeria.

Carcasses of an indigenous adult chicken and Japanese quail from different flocks were presented to a veterinary clinic for postmortem (PM) examination in 2014 in Jos, Plateau State, Nigeria. PM observations revealed cutaneous, hepatic, and splenic tumors in the Indigenous chicken. The quail carcass was emaciated with hepatic tumors. Histopathology revealed severe focally extensive non-encapsulated circumscribed large nodules with pleomorphic population of cells mainly composed of lymphoplasmacytic and mixed neutrophilic polymorphonuclear cells in the chicken. The pleomorphic infiltration of lymphohistioplasmacytic cells mixed with neutrophilic polymorphonuclear cells in the quail was consistent with Marek’s disease virus (MDV) infection. Polymerase chain reaction (PCR) was carried out, and the Meq oncogene of the MDV was amplified in the samples collected from the chicken and quail to confirm the presence of the virulent MDV. The samples were also subjected to PCR for detection of MDV Rispens CVI988 vaccine strain which was detected in both chicken and quail samples. The findings in this study represent the first report of confirmatory diagnosis of MD using histopathology in an indigenous chicken and Japanese quail in Nigeria. It is also the first report of the detection of MDV Rispens CVI988 vaccine strain in unvaccinated chicken and quail in Nigeria.

Production of probiotic-fortified composite poultry feed from food and agricultural waste material.

Objective:The objective of the study was to ascertain the feasibility of fortifying composite poultry feed from food and agricultural waste material with the probiotic organism Lactobacillus fermentum and determine the efficiency of formulated probiotic-fortified feed via animal feeding tests.Materials and Methods:Probiotic-fortified feed (G3) was formulated using proximate analysis values of waste materials. Alternative diets were G1—Feed Mill of Nigeria starter mash and G2—Ground corn. For growth comparison test, 30 1-day-old Agricol broiler chicks were randomized into three groups of 10 chicks each with each group being placed on a separate diet (G1, G2, and G3). Probiotics antimicrobial efficacy feeding assay consisted of the treatment diets T1—Feed Mill of Nigeria starter mash and T2—probiotic-fortified feed. Twenty 1-day-old unvaccinated chicks were placed into two groups of 10 chicks each and fed 0.5 ml of 9.0 × 108 CFU/ml Escherichia coli 0157:H7 on day 1 after which they were placed on treatment diets. Data collected were analyzed and interpreted using the SPSS Statistical tool version 25.Results:Chicks fed G1 and G3 diets performed similarly (p < 0.05) in terms of measured parameters (weight, height, and wingspan) and had better performance compared to chicks on G2. In the E. coli treatment group, chicks placed on treatment diets T1 and T2 showed similar levels of E. coli cell reduction every week. Performance based on measured parameters was also similar (p < 0.05).Conclusion:Feasibility of fortifying composite animal feed with the probiotic organism L. fermentum was ascertained and the efficiency of the feed via animal feeding tests was proven.

Single Nucleotide Polymorphism Genotyping Analysis Shows That Vaccination Can Limit the Number and Diversity of Recombinant Progeny of Infectious Laryngotracheitis Viruses from the United States.

Infectious laryngotracheitis (ILTV; Gallid alphaherpesvirus 1) causes mild to severe respiratory disease in poultry worldwide. Recombination in this virus under natural (field) conditions was first described in 2012 and more recently has been studied under laboratory conditions. Previous studies have revealed that natural recombination is widespread in ILTV and have also demonstrated that recombination between two attenuated ILTV vaccine strains generated highly virulent viruses that produced widespread disease within poultry flocks in Australia. In the United States, natural ILTV recombination has also been detected, but not as frequently as in Australia. To better understand recombination in ILTV strains originating from the United States, we developed a TaqMan single nucleotide polymorphism (SNP) genotyping assay to detect recombination between two virulent U.S. field strains of ILTV (63140 and 1874c5) under experimental in vivo conditions. We also tested the capacity of the Innovax-ILT vaccine (a recombinant vaccine using herpesvirus of turkeys as a vector) and the Trachivax vaccine (a conventionally attenuated chicken embryo origin vaccine) to reduce recombination. The Trachivax vaccine prevented ILTV replication, and therefore recombination, in the trachea after challenge. The Innovax-ILT vaccine allowed the challenge viruses to replicate and to recombine, but at a significantly lower rate than in an unvaccinated group of birds. Our results demonstrate that the TaqMan SNP genotyping assay is a useful tool to study recombination between these ILTV strains and also show that vaccination can limit the number and diversity of recombinant progeny viruses.IMPORTANCE Recombination allows alphaherpesviruses to evolve over time and become more virulent. Historically, characterization of viral vaccines in poultry have mainly focused on limiting clinical disease, rather than limiting virus replication, but such approaches can allow field viruses to persist and evolve in vaccinated populations. In this study, we vaccinated chickens with Gallid alphaherpesvirus 1 vaccines that are commercially available in the United States and then performed coinoculations with two field strains of virus to measure the ability of the vaccines to prevent field strains from replicating and recombining. We found that vaccination reduced viral replication, recombination, and diversity compared to those in unvaccinated chickens, although the extent to which this occurred differed between vaccines. We suggest that characterization of vaccines could include studies to examine the ability of vaccines to reduce viral recombination in order to limit the rise of new virulent field strains due to recombination, especially for those vaccines that are known not to prevent viral replication following challenge.

Potential and safety tests of egg drop syndrome candidate vaccine from Medan isolate, Indonesia

Aim:The study was aimed to prepare and examine the potential and safety concerns of egg drop syndrome (EDS) vaccine candidate seed. The potential and safety trials of EDS Medan isolate vaccine need to be done before commercial scale of EDS vaccines are made.Materials and Methods:The safety test of EDS candidate vaccine was tested on 4-week-old specified pathogen-free chickens in an experimentally isolated enclosure.Results:The result of the safety test obtained 27.3 hemagglutination inhibition (HI) unit of geometric mean titer antibody post-vaccination. However, the potency test of the EDS candidate vaccine was conducted on 17-week-old laying hens. Test results of the EDS potency vaccine in layer obtained antibody titer increased in every week of blood taking with average titer of antibody: Before vaccinated was 22.9 HI unit, 1 week after vaccination was 23.7 HI unit, 2 weeks post-vaccination was 25 HI unit, and 3 weeks after vaccination was 27.3 HI units. In contrast, decreasing trend was observed in control group (unvaccinated chicken).Conclusion:Serologically, the seed vaccine of EDS virus isolates from Medan was able to produce protective antibody titers starting in the 2nd and 3rd weeks post-vaccination.

Pathogenicity of Avipoxviruses in Chickens Isolated from Field Outbreaks Reported in Chhattisgarh

Virulence of field isolates of Avipoxviruses was assayed by pathogenicity test performed in 5 weeks old unvaccinated chickens. Viruses as dry scab were collected from naturally pox infected chickens, turkeys and pigeon and propagated in CAM of embryonated chickens upto various passages. In two separate trials 1 and 2, the chickens were infected with 5th and 20th passage CAM suspension, respectively by feather follicle method. All chicken groups in both trials (except control group) developed primary lesions as ‘take’ reaction from 48 to 72 hr PI and there after further progressive development of primary lesion did not differ among field isolates. In trial 1, secondary stage began with recovery from primary lesions at feather follicle, spread of infection to comb and wattles with development of secondary pox lesions and finally recovery from disease was observed after 15 days in FPV and TPV infected chickens, but not in PPV infected chickens. In trial 2, secondary pox lesions were not observed in any of the chickens, indicating that 20 passage virus induced ‘take’ at site without further spread of infection. All the recovered birds and controlled birds were challenged with the virulent FPV. The result has indicated 100% survival of birds except in control birds. Precipitating antibodies was confirmed in all birds group except control group using AGID and CIE test.

Characterization of Spleen Transcriptome and Immunity Against Avian Colibacillosis After Immunization With Recombinant Attenuated Salmonella Vaccine Strains

Avian pathogenic Escherichia coli (APEC) causes extraintestinal infections in poultry. Vaccines targeting APEC in chickens have been partially successful, but many lack heterologous protection. Recombinant attenuated Salmonella vaccine (RASV) strains can induce broad immunity against Salmonella and be modified to deliver E. coli antigens. Along with vaccine characteristics, understanding the host response is crucial for developing improved vaccines. The objectives of this study were to evaluate host responses to vaccination with an RASV producing E. coli common pilus (ECP) and assess protection against APEC infection in chickens. Four-day-old White Leghorn chickens were unvaccinated or orally vaccinated and boosted 2 weeks later with RASV χ8025(pYA3337), RASV χ8025(pYA4428) carrying ecp operon genes, or a combination of χ8025(pYA3337) and χ8025(pYA4428) (Combo). To assess host responses, serum IgY and intestinal IgA antibody titers were measured, and spleen samples (n = 4/group) were collected from unvaccinated and Combo vaccinated 4-week-old chickens for RNA-seq. Vaccine protection potential against Salmonella and APEC was evaluated in vitro using bacterial inhibition assays. Five-week-old chickens were challenged via air sac with either an APEC O2 or O78 strain. E. coli was enumerated from internal organs, and gross colibacillosis lesions were scored at necropsy. RASV immunized chickens elicited anti-E. coli antibodies. The spleen transcriptome revealed that 93% (89/96) of differentially expressed genes (DEG) were more highly expressed in Combo vaccinated compared to unvaccinated chickens, with signal as the most significantly impacted category. RNA-seq analysis also revealed altered cellular and metabolic processes, response to stimulus after vaccination, and immune system processes. Six DEG including genes linked to transcription regulation, actin cytoskeleton, and signaling were highly positively correlated with antibody levels. Samples from RASV immunized chickens showed protection potential against Salmonella strains using in vitro assays, but a variable response was found for APEC strains. After APEC challenges, significant differences were not detected for bacterial loads or gross lesions scores, but χ8025(pYA3337) immunized and χ8025(pYA4428) immunized chickens had significantly fewer number of APEC-O2-positive samples than unvaccinated chickens. This study shows that RASVs can prime the immune system for APEC infection, and is a first step toward developing improved therapeutics for APEC infections in chickens.

Saponin-adjuvanted vaccine protects chickens against velogenic Newcastle disease virus.

Despite extensive vaccination campaigns, Newcastle disease virus (NDV) remains endemic in many countries worldwide, and factors that contribute to this failure include mismatched vaccines, partial immunization, and poor husbandry practices. In order to overcome the problem of genetic divergence between circulating field strains and vaccine strains, we saponin-adjuvanted an Egyptian field strain and assessed its safety and immunogenicity in chickens. Immunization of chickens with the vaccine followed by challenge with a velogenic reference strain revealed the potential of the saponin-adjuvanted vaccine to induce a strong immune response that resulted in complete protection of chickens. Importantly, in vaccinated chickens, virus shedding was abolished, providing an added advantage over the currently available commercial live-attenuated and inactivated vaccines, which are unable to prevent shedding. A histopathological investigation demonstrated that the vaccinated chickens had less-severe lesions than challenged unvaccinated and mock-vaccinated chickens. We propose using this formulation as an alternative and improved NDV vaccine platform that can be exploited to control disease not only in Egypt but also in other disease-endemic countries.

Evaluation of unintended 1/96 infectious bronchitis vaccine transmission in broilers after direct contact with vaccinated ones

Infectious bronchitis virus is characterised by an extreme degree of variability which deeply affects the first-choice control strategies against the disease. Each country tends to adopt its own protocols and even vaccine producers themselves can also adopt different strategies in attempts to confront local epidemiological concerns. In the present study, we tested the potential environmental persistence, transmission ability and replication capability of a non-directly administrated vaccine strain at a hatchery and during transportation. To this purpose, we examined a single hatchery, where combined vaccination (Mass-like plus 793B-like strains) is commonly administered following the protectotype concept, whereas a single broiler flock receives only the Mass priming. Two groups of solely Mass-primed chicks were kept in contact with chicks vaccinated with both strains, during hatchery procedures and transportation, respectively. A regularly vaccinated control group was selected and all three were monitored by swab sampling until 11 days of age. Vaccine titres were quantified using vaccine-specific real-time RT-PCRs to check the kinetics of both strains. Mass titres were consistent among the groups, while the absence of the 1/96 vaccine strain in unvaccinated chicks confirmed the low risk of unintended vaccine transmission, which could complicate the diagnostic process and the epidemiological scenario.