THE IMMUNE RESPONSE INDUCED BY E. COLI IN CHICKENS AND AVAILABLE VACCINES.

The paper aimed to present the available vaccines for E.coli in chicken and discuss the immune response induced by E.coli. It is based on statistical data provided by already published articles and data interpreted from specialised journals. Avian pathogenic E. coli (APEC) represents the most economically significant disease which has a negative impact on the industry of broilers. In many countries, a common practice during the last decades has been to administer antibiotics in order to suppress infection with APEC, but lately market pressures, by trade and statutory restraints, have limited the use of antibiotics and this has led to the development of specially designed E.coli vaccines, to stimulate an immune response against pathogenic E. coli, besides vaccination against primary respiratory and immuno-suppressive pathogens. Chickens display different mechanisms to protect against and to combat pathogenic infection. Typically APEC is inhaled or ingested, by crossing the mucosal barrier; it cannot penetrate the skin, which generally acts as a protective element. In broilers, the source of infection are, usually, the contaminated drinking water or the inhaled dust, laden with APEC. Antimicrobial drugs remain an important tool in reducing of incidence as of mortality, associated with this disease, but a vaccine-based approach for the disease control remains highly desirable, which is why the focus of this paper will be to analyze and criticize each available type of E.coli vaccine, including the advantages and disadvantages of each, in terms of preparation, efficiency, costs and other important factors. The latest developments in molecular biology have created new vaccine strains effective against APEC, like the modified gene-deleted vaccines which stimulate both, tissue (cellular) associated immunity and humoral (circulating antibody) immunity. The first commercial E. coli vaccine for chickens was licensed by the US Department of Agriculture in 2006, so this paper will also try to focus on the newest research, directed after this year. [ABSTRACT FROM AUTHOR]