Research My research interest is in the area of anaerobic bacteriology of the gastrointestinal tract of animals, particularly the rumen of cattle. The investigations have focused on the role of microbes in rumen function and dysfunction, particularly in animals fed high-grain diets. My research is a blend of basic and applied studies and involves collaborative interaction with molecular biologists, pathologists, and food microbiologists. Major investigations involve the understanding of the pathogenic mechanism of F. necrophorum in liver abscesses in cattle, the involvement of Clostridium perfringens and Sarcina sp., in abomasal bloat in calves and understanding the role of ciliated protozoa in starch and lactic acid fermentation in the rumen. The applied aspect is concerned with the evaluation of antimicrobial or nonantimicrobial compounds as potential feed additives, development of a vaccine for the prevention of liver abscesses and foot rot in cattle and development of methods to control frothy bloat in feedlot cattle, and develop experimental model to study acidosis and laminitis in dairy cows. Additionally, I am part of the team to study the ecology of E. coli 0157:H7 in cattle, and I am particularly interested in understanding the factors influencing the persistence of E. coli 0157:H7 in the gut and subsequent shedding in the feces. Currently, my research has focused
on the following specific projects: 1. Role of leukotoxin as a virulence
factor in the pathogenesis of Fusobacterial infections, and development
of recombinant Fusobacterium
necrophorum leukotoxin vaccine for the control
of liver abscesses and foot rot in cattle. 2. Development of an
experimental model to study subacute ruminal acidosis and laminitis in
dairy cows. 3. Role of Sarcina
ventriculi in abomasal bloat in neonatal
calves. 4. Role of ruminal ciliated protozoa in starch and lactic acid
fermentations in grain-fed cattle. I teach both professional courses in the DVM curriculum: Bacteriology and Mycology (5 credits) course for sophomore DVM students (joint teaching). Rumen Physiology and Microbiology (3 credits) for freshman DVM students (joint teaching) as well as graduate courses: Rumen Metabolism (3 credits) and Rumen Microbiology (3 credits) for graduate students in Animal Sciences, Microbiology, Veterinary Medicine, and Agronomy. Selected Publications Nagaraja, T. G. 1995. Ionophores and Antibiotics in Ruminants. p 173-204. In: Biotechnology in Animal Feeds and Animal Feeding. Wallace, R. J. and A. Chesson (eds.), VCH Publ., NY. Nagaraja, T. G., C. J. Newbold, C. J. Van Nevel and D. I. Meyer. 1997. Manipulation of ruminal fermentation. P. 523-632. In: The Rumen Microbial Ecosystem. Hobson. P. N. and C. S. Stewart (eds), Blackie Academic, NY. Nagaraja, T. G. 2000. Gastrointestinal Microbiology. P 485-498. In: Encyclopedia of Microbiology, vol. 2, Academic Press, NY. Publications Nagaraja, T. G., S. I. Godfrey, S. W. Winslow, J. B. Rowe, and K. E. Kemp. 1995. Effect of virginiamycin on ruminal fermentation in faunated or ciliate-free sheep overfed with barley grain. Small Rumen. Res. 17:1-8. Nagaraja, T. G., S. I. Godfrey, S. W. Winslow, and J. B. Rowe. 1995. Responses in ciliated protozoa and rumen fermentation in sheep supplemented with barley plus virginiamycin. Aust. J. Agric. Res. 46:1137-1147. Godfrey, S. I., T. G. Nagaraja, S. W. Winslow, and J. B. Rowe. 1995. Rumen microbial adaptation to long term feeding of virginiamycin in sheep fed barley and virginiamycin as a supplement. Aust. J. Agric. Res. 46:1149-1158. Tan, Z. L., T. G. Nagaraja, and M. M. Chengappa. 1995. Fusobacterium necrophorum: Virulence factors, pathogenic mechanism and control measures. Vet. Res. Commun.20:113-140 Okwumabua, O., Z. L. Tan., J. Staats, R. D. Oberst, M. M. Chengappa, and T. G. Nagaraja. 1996. Ribotyping to differentiate Fusobacterium necrophorum subsp. necrophorum and subsp. funduliforme from bovine ruminal contents and liver abscesses. Appl. Environ. Microbiol. 62:469-472. Saginala, S., T. G. Nagaraja, Z. L. Tan, K. F. Lechtenberg, M. M. Chengappa, K. E. Kemp, and P. M. Hine. 1996. Serum neutralizing antibody response and protection against experimentally induced liver abscesses in steers vaccinated with Fusobacterium necrophorum. Amer. J. Vet. Res. 57:483-488. Nagaraja, T. G., S. B. Laudert and J. C. Parrott. 1996. Liver abscesses in feedlot cattle. Part 1.Causes, pathogenesis, pathology and diagnosis. Comp. Cont. Edu. Pract. Vet. 18 (9) :S230-S256. Nagaraja, T. G., S. B. Laudert and J. C. Parrott. 1996. Liver abscesses in feedlot cattle. Part 2. Incidence, economic importance and prevention. Comp. Cont. Edu.Pract. Vet. 18 (10): S264-S273. Saginala, S., T. G. Nagaraja, Z. L. Tan, K. F. Lechtenberg, M. M. Chengappa, and P. M. Hine. 1996. The serum neutralizing antibody response in cattle to Fusobacterium necrophorum leukotoxoid and possible protection against experimentally induced liver abscesses. Vet. Res. Commun. 20:493-504. Saginala, S., T. G. Nagaraja, K. F. Lechtenberg, M. M. Chengappa, K. E. Kemp and P. M. Hine. 1997. Effect of Fusobacterium necrophorum leukotoxoid vaccine on susceptibility to experimentally induced liver abscesses in cattle J. Anim. Sci. 75: 1393-1399. Narayanan Sanjeevkumar, T. G. Nagaraja, O. Okwumabua, J. Staats, M. M. Chengappa, and R. D. Oberst. 1997. Ribotyping to compare Fusobacterium necrophorum isolates from bovine liver abscesses, ruminal walls, and ruminal contents. J. Anim. Sci. 63:4671-4678. Lechtenberg, K. F., T. G. Nagaraja, and M. M. Chengappa. 1998. Antimicrobial susceptibility of Fusobacterium necrophorum isolated from bovine hepatic abscesses in cattle. Amer. J. Vet. Res. 59:44-47. Nagaraja, T. G. and M. M. Chengappa. 1998. Liver abscesses in feedlot cattle: A review. J. Anim. Sci. 76:287-298. Goad, D. W., C. L. Goad, and T. G. Nagaraja. 1998. Ruminal microbial and fermentative changes associated with experimentally induced subacute acidosis in steers. J. Anim. Sci. 76:234-241. Narayanan Sanjeevkumar, T. G. Nagaraja, N. Wallace, Jacque Staats, M. M. Chengappa, and R. D. Oberst. 1998. Biochemical and ribotypic comparison of Actinomyces pyogenes and A. pyogenes isolates from liver abscesses, ruminal wall, and ruminal contents of cattle. Amer. J. Vet. Res. 59:271-276. Beharka, A. A. T. G. Nagaraja, J. L. Morrill, G. A. Kennedy, and R. D. Klemm. 1998. Effects of form of the diet on anatomical, microbial, and fermentative development of the rumen of neonatal calves. J. Dairy Sci. 81:1946-1955. Nagaraja, T. G., A. B. Beharka, M. M. Chengappa, L. H. Carroll, A. P. Raun, S. B. Laudert, and J. C. Parrott. 1999. Bacterial flora of liver abscesses in feedlot cattle fed tylosin or no tylosin. J. Anim. Sci. 77:973-978. Nagaraja, T. G., Y. D. Sun, N. Wallace, K. E. Kemp and J. C. Parrott. 1999. Effects of tylosin on concentrations of Fusobacterium necrophorum and fermentation products in the rumen of cattle fed a high-concentrate diet. Amer. J. Vet. Res. 60:1061-1066. Coe, M. L., T. G. Nagaraja, Y. D. Sun, N. Wallace, E.G. Towne, K. E. Kemp, and J. P. Hutcheson. 1999. Effect of virginiamycin on ruminal fermentation in cattle during adaptation to a high concentrate diet and during an induced acidosis. J. Anim. Sci. 77:2259-2268. Vishnubhatla, A., D. Y. C. Fung, R. D. Oberst, M. P. Hays, T. G. Nagaraja, and S. J. A. Flood. 2000, Rapid 5’ nuclease (TaqMan) assay for detection of virulent strains of Yersinia enterocolitica Appl. Environ. Microbiol., 66:4131-4135. Narayanan, S. K., T. G. Nagaraja, M. M. Chengappa, G. C. Stewart 2001. Electrophoretic mobility anomalies associated with PCR amplification of the intergenic spacer region between 16S and 23S ribosomal RNA genes of Fusobacterium necrophorum. J. Microbiol. Meth., 46:165-169. Narayanan, S. K., T. G. Nagaraja, M. M. Chengappa, G. C. Stewart 2001. Cloning, sequencing, and expression of the leukotoxin gene from Fusobacterium necrophorum. Infect. Immun., 69: 5447-5455. Vishnubhatla, A., R. D. Oberst, D. Y. C. Fung, W. Wonglumson, M. P. Hays, T. G. Nagaraja. 2001. Evaluation of a 5’ nuclease (TaqMan) assay for the detection of virulent strains of Yersinia enterocolitica in raw meat and tofu samples. J. Food Protection, 64:355-360. Narayanan, S. K., T. G. Nagaraja, M. M. Chengappa, and G. C. Stewart 2001. Leukotoxins of gram-negative bacteria. Vet. Microbiol., 2248: 1-20. Loughin, T. M., D. E. Johnson, S. E Ives, and T. G. Nagaraja. 2002. Methods for selecting crossover designs with applications to an experiment with two factors in a split plot. J. Agric. Biol. Environ. Stat., 7: 1430-156. Narayanan, S. K., G. C. Stewart, M. M. Chengappa, L. Willard, W. Shuman, M. Wilkerson, and T. G. Nagaraja. 2002. Fusobacterium necrophorum leukotoxin induces activation and apoptosis of bovine leukocytes. Infect. Immun., 70: 4609-4620. Ives, S. E., E. C. Titgemeyer, T. G. Nagaraja, A. del Barrios, D. J. Bindel, and L. C. Hollis. 2002. Effects of virginiamycin and monensin plus tylosin on ruminal protein metabolism in steers fed corn-based finishing diets with or without wet corn gluten feed. J. Anim. Sci., 80: 3005-3015.
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