Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 1, 2004
Publication Date: September 5, 2004
Citation: Babu, U., Dalloul, R.A., Okamura, M., Lillehoj, H.S., Xie, H., Raybourne, R.B., Gaines, D., Heckert, R.A. 2004. Salmonella enteritidis clearance and immune responses in chickens following salmonella vaccination and challenge. Veterinary Immunology and Immunopathology 101:251-257.
Interpretive Summary: Salmonellosis is a major cause of human food poisoning associated with Salmonella enteritidis. In this paper, scientists at the US Food and Drug Administration in collaboration with scientists at the University of Maryland and ARS discovered that live Salmonella vaccine (LV) stimulates immune system of poultry to kill Salmonella. Chickens which were vaccinated against salmonellosis using live vaccine and killed Salmonella vaccines showed enhanced clearance of on S. enteritidis (SE) and demonstrated increased cell-mediated immune response to Salmonella. Understanding immune mechanism which enhances host resistance against salmonellosis will facilitate the development of novel control strategy against salmonellosis. These finding will help poultry industry to devise more efficient vaccine strategy against salmonellosis.
Our previous work showed that the Cell-mediated immunity (CMI) was enhanced by live Salmonella vaccine (LV). The objective of this study was to evaluate the impact of live and killed Salmonella vaccines on Salmonella enteritidis (SE) clearance and to determine if the clearance was mediated by cell-mediated and/or humoral immunity. Chickens were first immunized at 2 weeks of age followed by a booster dose at 4 weeks, challenged with live SE 2 weeks later (six weeks old) and tested for CMI, antibody response and SE clearance one week post SE-challenge (seven weeks old). Spleen cell proliferation induced by SE-flagella and Concanavalin A (Con A) were significantly higher and SE shedding was significantly lower in the LV group. The splenic CD3 population was significantly lower and B cells were higher in the control group compared to all the SE-challenged groups (with and without vaccination). Serum antibody to SE flagella and envelope were significantly higher in the KV group compared to all the other groups. These results suggest that LV protects against SE infection, probably by enhancing the CMI.