1a.Objectives (from AD-416):
1) Establish the duration of infection of Salmonella within the peripheral lymph nodes of cattle as influenced by serotype;. 2)Develop an understanding of cellular tropism across various serotypes with and without interventions; and. 3)Conduct rapid and well-controlled evaluation of candidate interventions designed to reduce the duration of infection within lymph nodes of cattle.
1b.Approach (from AD-416):
Studies will be conducted on dairy calves, utilizing a parent project-developed transdermal model for peripheral lymph node uptake of Salmonella. The first study will examine the duration of infection of Salmonella in several peripheral lymph nodes. Using the transdermal model, different Salmonella serotypes will be administered to individual animals to determine if duration of infection is influenced by serotype. Utilizing information regarding the molecular characterization of Salmonella sub-populations that invade lymph nodes, a second study will compare the response of Salmonella following intradermal administration of vaccine interventions. Finally, results from the first two sets of experiments will be utilized to design and test interventions for their ability to prevent and eliminate lymph node colonization by Salmonella following intradermal administration.
This is a new project with the goal of increasing our understanding of Salmonella uptake and elimination from the peripheral lymph nodes of cattle. The work will focus on evaluating interventions such as vaccines; cattle were purchased in FY 2013 for the first vaccine study, which will begin in early FY 2014, followed by a second study in mid FY 2014. Cannulation of the peripheral lymph nodes in living animals will be done to increase understanding of how Salmonella reaches these lymph nodes and how long it persists. As project work progresses, important new procedures and protocols will be developed. These new approaches will prevent lymph nodes in slaughter cattle from being a point source of Salmonella contamination of ground beef products reaching the consumer.