Submitted to: Veterinary Immunology and Immunopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 8, 2005
Publication Date: June 20, 2005
Citation: Babu, U., Dalloul, R.A., Okamura, M., Lillehoj, H.S., Xie, H., Raybourne, R.B., Gaines, D., Heckert, R.A. 2005. Salmonella enteritidis clearance and immune responses in chickens following salmonella vaccination and challenge.Veterinary Immunology and Immunopathology. 101:251-257.
Interpretive Summary: Although Salmonella-associated food poisoning can result in significant financial burden on the health care system, limited information exists on the host immune response to this pathogen. In this study, scientists at US Food and Drug Administration and at ARS collaborated on a CSREES National Research Initiative grant funded study to evaluate host immune response of chickens. The results showed that oral vaccination with live attenuated Salmonella vaccine enhanced cell-mediated immunity with increased bacteria clearance. This finding suggests that Salmonella vaccination using live attenuated bacteria could be an effective method for salmonellosis control and offers useful information for managing Salmonella infection in chickens as well as shell egg contamination.
Cell-mediated and humoral immunity as well as Salmonella enteritidis (SE) clearance were assessed upon administration of live and killed Salmonella vaccines to young chickens. Two mainobjectives of our studies wereto evaluate the impact of vaccines on the immune response of young chickens, to determine the efficacy of vaccines on SE clearance and the role of cell-mediated and humoral immune response in SE infection. For the vaccine study, 2 week-old white Leghorn chickens were either orally gavaged with a live vaccine (LV) strain of Salmonella typhimurium or given a commercial killed SE vaccine (KV) by intramuscular injection. Indices of CMI included splenic lymphocyte proliferation and flow-cytometric analysis of cell subpopulations. ConA-induced proliferation was significantly higher in chickens treated with the LV compared to control or KV birds at 7, 11 and 14 DPI. ConA-induced spleen cell proliferation in the KV group was significantly lower than that in the control group at 7, 11 and 14 DPI. Transient changes in splenic lymphocyte populations were observed in KV and LV groups. SE-specific serum Ab titer was significantly higher in the KV group than in the control or the LV group. For the challenge study, chickens were first immunized at 2 weeks of age followed by a booster dose at 4 weeks, challenged with live SE 2 weeks later and tested for CMI, antibody response and SE clearance one week post SE-challenge.