Live Salmonella vaccines

Live vaccines contain wild Salmonella strains that have been modified to be less virulent. This involves removal of virulence factors or rendering the strain incapable of survival or multiplication. The SG 9R strain is a natural occurring non-virulent strain.

Vaccination with live vaccines induces immunity against Salmonella by simulating a natural infection

Advantage:

Live vaccines are effective at two levels:

1. Non-specific immunity
The presence of the vaccine strain in the intestinal tract prevents colonization by other Salmonella strains. This is independent of serotype and serogroup.

2. Specific immunity
Immunity is developed that is specific to the serogroup to which the vaccine strain belongs