There has been a dramatic increase in e88 borne Salmonella enteritidis (SE) infection in humans. From January 1985 through 1988, there were 4976 reported SE cases in 140 outbreaks in the northeastern U.S., resulting in 896 hospitalizations and 30 deaths. Sixty five (73%) of outbreaks with identified food vehicles were related to consumption of Grade A eggs or Grade A egg products. From 1985 to 1989, the proportion of outbreaks from outside of the Mid-Atlantic and New England regions increased from 5% to 43%. It is unlikely and not economically feasible to eliminate all exposure of chickens to SE. An attenuated vaccine could prevent systemic SE infection and thus block infection of eggs. We propose to develop a vaccine with altered O-polysaccharide antigen that will not elicit antibodies which will interfere with the standard pullorum-typhoid test. This change should not compromise the vaccine's ability to protect against systemic infection. The vaccine will have incorporated two or more gene deletions in pathways for growth in chickens and thus will not itself be able to infect the egg. The study will benefit from the combination of expertise from our Company and that of Drs. Briles and Benjamin of the University of Alabama, Birmingham.Applications:There is a considerable pressure from the consumer market and Federal and State regulatory agencies on egg producers to provide eggs free of the risk of SE infection. Our approach will provide a means of immunizing chickens with a vaccine which will protect eggs from infection in the event the flocks would be exposed. Any product used for this purpose should be avirulent, self-limiting and bear an altered O-antigen, such as proposed in this study, to avoid eliciting antibodies which would confuse pullorum-typhoid diagnostic and testing programs.
