RESUMO
The antigenic characterization of IBDV, a virus that causes an immunosuppressive disease in young chickens, has been historically addressed using cross virus neutralization (VN) assay and antigen-capture enzyme-linked immunosorbent (AC-ELISA). However, VN assay has been usually carried out either in specific antibody negative embryonated eggs, for non-cell culture adapted strains, which is tedious, or on chicken embryo fibroblasts (CEF), which requires virus adaptation to cell culture. AC-ELISA has provided crucial information about IBDV antigenicity, but this information is limited to the epitopes included in the tested panel with a lack of information of overall antigenic view. The present work aimed at overcoming those technical limitations and providing an extensive antigenic landscape based on original cross VN assays employing primary chicken B cells, where no previous IBDV adaptation is required. Sixteen serotype 1 IBDV viruses, comprising both reference strains and documented antigenic variants were tested against eleven chicken post-infectious sera. The VN data were analysed by antigenic cartography, a method which enables reliable high-resolution quantitative and visual interpretation of large binding assay datasets. The resulting antigenic cartography revealed i) the existence of several antigenic clusters of IBDV, ii) high antigenic relatedness between some genetically unrelated viruses, iii) a highly variable contribution to global antigenicity of previously identified individual epitopes and iv) broad reactivity of chicken sera raised against antigenic variants. This study provides an overall view of IBDV antigenic diversity. Implementing this approach will be instrumental to follow the evolution of IBDV antigenicity and control the disease.
RESUMO
Day-old chick quality is an essential element for the overall profitability of the broiler productive cycle and has been associated with the growth performance and feed conversion rate. An effect on the development of the immune system was also reported, which could likely account for reduced susceptibility to infectious diseases and improved animal welfare parameters. Besides direct cost reduction, lower antimicrobial use and improved animal welfare are crucial in the directive of European Union legislation and are at the forefront of customer choices. Several factors contribute to determining the chick quality. Breeder flocks genetics, health, and management affect the egg features, quality, and bacterial load. However, hatchery practices play a pivotal role, since adequate hygiene and handling are fundamental in reducing egg contamination and cross-contamination. The presence of rotten eggs is often regarded as a major risk, since the internal bacterial load can contaminate the needle used for in-ovo vaccination, the nearby eggs, and the whole incubator/hatching room when broken. In the present multicentric study, representative of 40 hatcheries located in 11 European countries, a remarkable impact of the rotten egg percentage on the hatchery productive parameters, representative of the hatchability, embryo mortality, and level of contamination, was demonstrated. Efficient rotten egg removal and the application of appropriate detection and removal tools should thus provide remarkable benefits for hatchery performance and indirectly for downstream poultry production.
