Immunological basis of differences in disease resistance in the chicken

Genetic resistance to diseases is a multigenic trait governed mainly by the immune system and its interactions with many physiologic and environmental factors. In the adaptive immunity, T cell and B cell responses, the specific recognition of antigens and interactions between antigen presenting cells, T cells and B cells are crucial. It occurs through a network of mediator proteins such as the molecules of the major histocompatibility complex (MHC), T cell receptors, immunoglobulins and secreted proteins such as the cytokines and antibodies. The diversity of these proteins that mainly is due to an intrinsic polymorphism of the genes causes phenotypic variation in disease resistance. The well-known linkage of MHC polymorphism and Marek's disease resistance difference represents a classic model revealing immunological factors in resistance differences and diversity of mediator molecules. The molecular bases in any resistance variation to infectious pathogens are vaguely understood. This paper presents a review of the major immune mediators involved in resistance and susceptibility to infectious diseases and their functional mechanisms in the chicken. The genetic interaction of disease resistance with production traits and the environment is mentioned

Systems for eliminating pathogens from exhaust air of animal houses

Recent outbreaks of highly infectious viral diseases like swine fever and avian influenza in The Netherlands have shown that despite extensive bio-security measures aiming at minimizing physical contacts between farms, disease spread could not be halted. Dust in exhaust air from swine and chicken houses may provide a favorable environment in which these viruses and other pathogenic microorganisms can survive and be transported over long distances to other farms. In a field study and in an experimental pilot-scale system, the effects of air scrubbers (bio-scrubber and acid scrubber) were tested. The field test showed higher bacterial counts in the outlet air than in the inlet air of the bio-scrubber (increase from 6.1 x 104 to 24.4 x 104 cfu/m3). An acid scrubber with sulfuric acid reduced bacteria emissions from 27 x 104 to 8.4 x 104 cfu/m3. In the pilot-scale cleaning system, different disinfectants were tested, including hydrogen peroxide, ozone, and peracetic acid. Peracetic acid gave by far the best results. It reduced bacteria and virus emissions to below detectable levels and reduced ammonia emissions by 96%. We conclude that an acid scrubber with sulfuric acid is very useful to reduce ammonia and dust emissions to the atmosphere; however, it cannot prevent the emission of pathogens. Peracetic acid reduces all these emissions, but is too costly to be used continuously. Therefore, an interesting option to prevent disease spread is to replace or supplement sulfuric acid in existing scrubbers with peracetic acid in times of high risk of disease outbreak

Acute phase proteins: a review of their function, behaviour and measurement in chickens

This review brings together and consolidates the large amount of research on acute phase proteins (APPs) that has been undertaken in chickens. Acute phase proteins are secreted from the liver as a result of inflammation or infection that can be measured in plasma. They have been well-characterised in other farm animal species and have been measured in a wide variety of poultry research areas. The acceleration in chicken APP research is in response to increased interest in ways the immune responses of the chicken can be measured and compared during infection or environmental or nutritional changes. All APPs that have been identified and characterised in chickens are described in the following review and their responses during infection discussed. The APPs are tabulated with basal values and classification to provide a comparative and useful reference. The ways APPs can be measured in chickens and the assays available are also described. This review will detail the functions of the positive APPs in chickens and their behaviour during an APR

J-virus remt de groei van vleeskuikens : eerste uitkomsten van het aviaire-leukoseproject

De J-variant van het aviaire-leukosevirus zorgt voor problemen, maar onderzoek is gaande om oplossingen te vinde

Het laatste nieuws over ALV : aviaire-leukoseproject bijna afgerond

Verslag van de uitkomsten van laboratoriumonderzoek en dierexperimente