Evaluation of young chickens challenged with aerosolized Salmonella Pullorum

Salmonella entericaserovar Pullorum (S. Pullorum) is an important pathogen specific to avian species, which poses a serious threat to the poultry industry. The transmission ofS. Pullorum occurs both horizontally and vertically but the airborne transmission ofS. Pullorum has been neglected historically. In this study, the effects of aerosolizedS. Pullorum on young chickens were investigated. The results showed that the colonization and morbidity induced by bioaerosol infection are dose dependent. The bacteria colonized in chicken lung for more than 14 days following the exposure to >= 1.25 x 10(6) CFU/m(3)of aerosolizedS. Pullorum. Tachypnoea and depression were present in all the chickens between 5 and 7 days after infection, and some died, following the exposure to >= 1.25 x 10(8) CFU/m(3)of aerosolizedS. Pullorum. RT-PCR results showed that significant expressions of inflammatory cytokines, including tumour necrosis factor alpha, interleukin 1 beta (IL-1 beta), IL-6, and IL-8 were noted in the lung and spleen. Histopathological examination showed lung swelling, with obvious lesions, including inflammatory cell infiltration, tissue injury, and acute haemorrhage. These results suggest that uncontrolled and detrimental inflammation is caused by a high dose of aerosolizedS. Pullorum. These results further extend our understanding of the pathogenicity of air-transmittedS. Pullorum on chickens.