A DNA Vaccine versus Attenuated Vaccine to Protect against Salmonella Infection in Chickens

The aim of this study was to vaccinate layer hen chickens against Salmonella infection. Two vaccines were assessed for efficacy and safety: a DNA vaccine containing Salmonella genomic DNA encapsulated in a liposome as a vector and a live attenuated Salmonella vaccine comprising 5 attenuated Salmonella serovars that were attenuated using indigenous plant extracts such as garlic and onion. The results showed that both vaccines had a high protection capacity, preventing Salmonella infection after challenge with a wild type of SalmonellaTyphimurium. Hyper-immune eggs inhibited the growth of Salmonella spp in vitro in immunized chickens. ELISA demonstrated the specific antibody production to LPS of S. Typhimurium. Post-mortem studies confirmed the presence of salmonellosis in the control group but not in immunized chickens with either vaccine. This study shows that Poultry salmonellosis can be prevented by the use of prophylactic DNA or live-attenuated vaccines (LAV).