2007 Annual Report
1a.Objectives (from AD-416)
(1) Investigate the molecular mechanisms that coordinate virulence and antibiotic resistance in Salmonella obtained from cattle (DT104 and S. dublin) and swine (DT104 and S. choleraesuis). (2) Characterize the molecular mechanisms involved in Salmonella survival, colonization and pathogenicity in relation to various host (swine and cattle) factors such as stress, gastric pH, and protozoa. (3) Investigate the molecular basis for swine resistance to Salmonella colonization by characterizing the immunological aspects of infection.
1b.Approach (from AD-416)
(1) Use a novel reporter system and transposon mutagenesis o identifiy DT104 genes involved in rumen protozoa-mediated hypervirulence. (2) Use an in vitro conjugation system to chracterize intra-protozoal transfer of plasmids from Klebsiella (and other bacteria) to Salmonella. (3) Compare the progression of salmonellosis for defaunated and fully-faunated calves infected with DT104. (4) Functional genomic analyses will be performed on Salmonella exposed to norepinephrine, low pH, and conditions relevant to intestinal colonization. (5) Use microarrays to identify swine genes that contribute to innate resistance to Salmonella colonization.
Hypervirulence in antibiotic resistant Salmonella adapted to cattle: Some multiresistant Salmonella have been purported to be more pathogenic than antibiotic-sensitive cohorts and we recently associated this phenomenon with exposure to protozoa from the first stomach of cattle. In research performed at the National Animal Disease Center (NADC) in Ames, IA, we demonstrated this phenomenon in a Salmonella strain that is adapted to cattle, i.e. Salmonella dublin. Host-adapted strains, like S. dublin, are adept at causing disease thus a more pathogenic strain can cause significant mortality in an infected herd. The results provide the basis for ameliorating this problem by identifying an intervention point for cattle producers. Addresses NP 108 Action Plan 1.1.5 regarding Antibiotic Resistance.
5.Significant Activities that Support Special Target Populations
|Number of new CRADAs and MTAs||1|
|Number of non-peer reviewed presentations and proceedings||3|
|Number of newspaper articles and other presentations for non-science audiences||4|
Carlson, S.A., Sharma, V.K., McCuddin, Z.P., Rasmussen, M.A., Franklin, S.L. 2007. Involvement of a Salmonella genomic island 1 gene in the rumen protozoan-mediated enhancement of invasion for multiple-antibiotic-resistant Salmonella enterica Serovar Typhimurium. Infection and Immunity. 75(2):792-800.
Uthe, J.J., Bearson, S.M., Royaee, A.R., Lunney, J.K., Stabel, T.J., Zhao, S., Tuggle, C.K. 2007. Porcine differential gene expression in response to Salmonella enterica serovars Choleraesuis and Typhimurium. Molecular Immunology. 44(11):2900-2914.
Wang, Y.F., Qu, L., Uthe, J.J., Bearson, S.M., Kuhar, D.J., Lunney, J.K., Couture, O.P., Nettleton, D., Dekkers, J.C., Tuggle, C.K. 2007. Global transcriptional response of porcine mesenteric lymph nodes to Salmonella enterica serovar Typhimurium. Genomics. 90(1):72-84.
McCuddin, Z.P., Carlson, S.A., Sharma, V.K. 2007. Experimental reproduction of bovine Salmonella encephalopathy using a norepinephrine-based stress model. British Veterinary Journal. Available:http://www.sciencedirect.com