Evaluation of protection against experimental salmonellosis in sheep immunised with 1 or 2 doses of live aromatic‐dependent Salmonella typhimurium

Publisher Website
Google Scholar
Abstract
SUMMARY The minimum number of doses of a live aromatic dependent (aro‐) Salmonella typhimurium vaccine strain (SL1479), given by the intramuscular, oral or subcutaneous route required to protect sheep from experimentally‐induced clinical salmonellosis, was determined. A significant reduction in mortalities and diarrhoea occurred in those sheep immunised with one or 2 intramuscular doses or 2 subcutaneous doses. On the other hand, sheep immunised with one subcutaneous dose were not protected. Immunisation with one or 2 oral doses also resulted in a significant reduction in mortality, although reduction in the prevalence of severe diarrhoea was less consistent. Sheep immunised with a single intramuscular dose of aro‐S. typhimurium developed high levels of serum antibodies and significant delayed‐type cutaneous hypersensitivity response to homologous Salmonella lipopolysaccharide and flagellin, whereas those with a single oral dose did not. It was concluded that immunisation of sheep with a single oral or intramuscular dose of live aro‐S. typhimurium reduced mortalities and the prevalence of diarrhoea in sheep due to infection with virulent S. typhimurium.