Several causes may induce change and atrophy in the bursa of Fabricius (BF). Databases on BF standards are available from published studies, however,

To gather recent data regarding the infectious bronchitis (IB) and infectious bursal disease (IBD) situation in Europe, a large-scale field epidemiological survey using diagnostic samples has been implemented in 2013 for about six months in several European countries: France, Germany, Greece, Italy, the Netherlands, Poland, Portugal, the Republic of Ireland, Spain and the UK. In 234 flocks that were sampled, strains from 10 different IBV genotypes were detected: the 793B genotype was detected most frequently, followed by QX, Massachusetts (Mass) and the Xindadi-like strains. Strains belonging to the Q1, Ark, D274, D1466, Italy-02 and B1648 genotypes were detected as well, although less frequently. The separate sampling of tracheas and kidneys for IBV detection using reverse transcriptase PCR was very useful, as different genotypes or significant differences in sequences of the same genotype were detected between both organs. The data of this survey also provided valuable information about the replication of IBD vaccines and subsequent infectious bursal disease virus (IBDV) antibody responses under field conditions. The detection of five non-vvIBDV field strains of two different genotypes shows the presence of non-vvIBDV non-vaccine strains, which can easily be undetected in Europe due to the focus on sampling of clinically ill birds. Detection of vaccine virus in the bursa and antibody response to the IBD vaccination in flocks that had been vaccinated by the drinking water with a live attenuated vaccine compared to a vaccination in the hatchery using an immune-complex vaccine showed a delayed replication of the vaccines that had been applied by the drinking water, indicating mistakes in the timing and/or application of the vaccines.

Newcastle Disease is one of the most important infectious poultry diseases worldwide and is associated with high morbidity, mortality, and economic loss. In several countries, vaccination is applied to prevent and control outbreaks; however, information on the ability of vaccines to reduce transmission of ND virus (NDV) is sparse. Here we quantified the transmission of velogenic NDV among 42-day-old broilers. Chickens were either vaccinated with a single dose of a vector vaccine expressing the F protein (rHVT-ND) at day-old in the presence of maternally derived antibodies or kept unvaccinated. Seeders were challenged 8 h before the co-mingling with the corresponding contacts from the same group. Infection was monitored by daily testing of cloacal and oro-nasal swabs with reverse transcription-real-time PCR and by serology. Vaccinated birds were completely protected against clinical disease and virus excretion was significantly reduced compared to the unvaccinated controls that all died during the experiment. The reproduction ratio, which is the average number of secondary infections caused by an infectious bird, was significantly lower in the vaccinated group (0.82 (95% CI 0.38–1.75)) than in the unvaccinated group (3.2 (95% CI 2.06–4.96)). Results of this study demonstrate the potential of rHVT-ND vaccine in prevention and control of ND outbreaks.

Background/Objectives: The risk of the introduction of highly pathogenic avian influenza virus (HPAIV) in geese breeding and fattening flocks is heightened due to the necessity of free-range access to grazing grounds. This study aimed to evaluate the safety, immunogenicity, and protective efficacy of five commercial vaccines against HPAIV subtype H5N1 (clade 2.3.4.4b) in subadult fattening geese. Methods: A prime-boost vaccination trial was conducted using five commercial vaccines, including H5 expressing vaccines of novel technology (subunit, vector, RNA) and whole inactivated virus (WIV) vaccines. Based on serological results, one RNA and one WIV vaccine were selected for a homologous challenge experiment. Results: Two vaccines of novel technology (vector, RNA) required a booster dose to raise specific antibodies titers above a threshold of four log₂ using a hemagglutination inhibition (HI) assay, whereas a subunit vaccine and two WIV vaccines induced seroconversion after primary vaccination. In the challenge experiment, all unvaccinated control geese succumbed to infection by day four. In contrast, all vaccinated geese that had seroconverted exhibited full clinical protection. Although sterile immunity was not achieved, viral excretion was significantly reduced in the vaccinated groups compared to controls. Conclusions: Vaccination substantially mitigated the impact of HPAIV H5N1, clade 2.3.4.4b infection in geese, greatly improving animal welfare by preventing severe disease. Additionally, there was a significant reduction in viral burden. Further studies are necessary to verify the potential of these vaccines to reduce susceptibility to infection and virus excretion in order to achieve suppression of the between-flock reproduction number to < 1 in geese flocks at high risk of infection.

Effective control of infectious bronchitis is a challenge in commercial poultry operations due to the high transmissibility of the virus. Although multiple IBV lineages are circulating in the United States, the DMV1639-type IBV strain (GI-17) is currently the major circulating variant, creating production losses in the poultry industry. This study aimed to test whether the combination of a GA08 (GI-27) and a Mass-type (GI-1) IB vaccines could significantly reduce the transmission of a DMV1639-type (GI-17) field IBV strain in 4-week-old commercial broilers. Half of the birds were directly challenged, whereas the other half of the groupmates were put in contact 24 hours later. Two replicates of the same study setup, including 10 directly challenged and 10 contact birds per group, were run. Transmission of the challenge virus was significantly reduced in vaccinates (R = 0.0), whereas all unvaccinated birds became infected (R = 9.6). Reduced transmission of the DMV1639 IB challenge virus by the combined vaccination programme in broiler chickens was also accompanied by clinical protection. These data are important because prevention of IBV transmission by vaccination will result in overall reduced viral replication and consequently in reduced likelihood of genetic changes that can lead to new variants. This is the first published evidence of the successful transmission control of a DMV1639 IBV strain in chickens.

Background/Objectives: The risk of introduction of highly pathogenic avian influenza virus (HPAIV) in geese breeding and fattening flocks is heightened due to the necessity of free-range access to grazing grounds. This study aimed to evaluate the safety, immunogenicity, and protective efficacy of five commercial vaccines against HPAIV subtype H5N1 (clade 2.3.4.4b) in subadult fattening geese. Methods: A prime-boost vaccination trial was conducted using five commercial vaccines, including H5 expressing vaccines of novel technology (subunit, vector, RNA) and whole inactivated virus (WIV) vaccines. Based on serological results, one RNA and one WIV vaccine were selected for a homologous challenge experiment. Results: Two vaccines of novel technology (vector, RNA) required a booster dose to raise specific antibodies titers above a threshold of 4 log2 by hemagglutination inhibition (HI) assay, whereas a subunit vaccine and two WIV vaccines induced seroconversion after primary vaccination. In the challenge experiment, all non-vaccinated control geese succumbed to infection by day 4. In contrast, all vaccinated geese that had seroconverted exhibited full clinical protection. Although sterile immunity was not achieved, viral excretion was significantly reduced in the vaccinated groups compared to controls. Conclusions: Vaccination substantially mitigated the impact of HPAIV H5N1, clade 2.3.4.4b infection in geese, greatly improving animal welfare by preventing severe disease. Additionally, there was a significant reduction in viral burden. Further studies are necessary to verify the potential of these vaccines to reduce susceptibility to infection and virus excretion in order to achieve suppression of the between-flock reproduction number to below 1 in geese flocks at high risk of infection.