Newcastle disease vaccination of broilers

摘要

Newcastle disease (ND) is predominantly a respiratory disease affecting chickens of all ages. The virus initially targets and damages the respiratory tract. Systemic protection by antibodies alone will not prevent damage to the respiratory tract. To prevent local tissue damage, a strong local immune response is vital for complete protection of the respiratory tract against a ND infection. ND virus strains can have different preferences for target organs (tropism). There are ND virus strains with a high tropism towards the respiratory tract (respiratory strains) and other ND virus strains with a high tropism towards the enteric tract (enteric strains). ND strains with a high respiratory tropism (La Sota type, Clone 30, Hitchner BI) are the first choice for ND vaccines to induce good local immunity in the respiratory tract, forming a strong first line of defence against ND infection. On the contrary the enteric ND strains bypass the respiratory tract and replicate primarily in the enteric tract, inducing a local reaction there.