CFSAN Regulatory Codes: V.B1,2, X
CFSAN Program Priority Codes:
Start Date: 00    Completion Date: 00

Statement of Research Problem:
Salmonella Enteritidis (S. E.) carried by chickens and transmitted via shell eggs has become a major source of human intestinal infections. Despite the tremendous efforts made by the poultry industry, no effective measurements for elimination of S. E. colonization have been generated. Since the rate of horizontal transmission among chickens and egg-laying hens is very rapid, general hygiene measurements are not as effective as desired. The purpose of this study is to examine variables affecting the immune response of hens against S. E., especially under stress conditions. Hens with a weak immune system are likely to be more susceptible to S. E. infections. Activating the hens' immune system, such as by immunization, can prevent or eliminate the infection. This study will help us identify the factors that can up-regulate or down-regulate the immune system of hens, leading to approaches for inhibiting the colonization of the reproductive tissues by S.E. leading to a decreased incidence of contaminated shell eggs and reduction of exposure to consumers.

Statement of Project Objective(s):
The role of the hen immune system in influencing the contamination of eggs by Salmonella Enteritidis will be studied. The goal will be to discover stress factors that can weaken the immune system and increase the chances of contamination of eggs. Potential strategies to control these stresses or to enhance immune resistance will result. Using the methods that we established in the first year of this project, we will examine the immune response of hens receiving different doses of S. E. in different phases of the hens' production cycle.

Anticipated Impact on FDA Regulatory Program:

1. Will aid in program priority to foster farm eggs quality assurance programs
2. Falls within objectives of egg safety action plan

Project Priority Changes During FY2000:
The objectives of this project were included as part of a grant proposal funded by USDA. Objectives for FY2001-2003 will be aligned with those in the grant.

Collaborators: Dr. Wenxia Song UMD; Dr. Robert Heckert UMD; D. Huyn Lillihoj, ARS

1. Compare the immune response of hens that received a low dose of S. E. with those that received a high dose.
2. Compare the immune response of hens that received the bacteria early in the production cycle (chicks) with those that received bacteria at the start of the egg production cycle (18 weeks) and with those infected during production (30 weeks).

1. Methods for infection of day old chicks were established along with development of appropriate techniques to maintain infected birds in isolators.
2. Infection of chicks with SE resulted in suppression of cell mediated immune responses in one experiment.
3. Changes in splenic lymphocyte populations were seen in SE infected chicks at 4 weeks following infection.
4. Histopathology of infected chick tissues (e.g. spleen) showed the presence of large numbers of GFP-labeled bacteria, and inflammatory cell infiltrates.
5. SE-specifc IgY was detectable in eggs from immunized hens.

1. Determine the effects of immunosuppresive agents on S.e infection and egg contamination in hens.
2. Determine the effect of dietary manipulation of lipids on immune function of hens.

1. Determine the effect of vaccination with live and attenuated or killed SE on the immune system.
2. Evaluate the effect of forced molting on immune functions and SE infection.
3. Determine the effects of hormone treatment on immune functions and SE infection.