Picture of Raul Almeida 


Dr. Raúl A. Almeida Research Associate Professor, Director Tennessee Quality

Milk Laboratory  



2506 River Drive
352 Brehm Animal Science Building
Knoxville, Tennessee 37996
Phone: (865) 974-0991
Fax: (865) 974-7297
email: ralmeida@utk.edu




MVD (DVM), Universidad del Litoral, Argentina, Veterinary Medicine, 1977 

MSc, Iowa State University, Veterinary Microbiology, 1989 

Ph.D., Iowa State University, Veterinary Microbiology, 1991

Appointment:  100% Research


Professional Interest: Bacterial pathogenesis, host cell-pathogen interaction, bovine mastitis, control mechanism


To establish infection, pathogens should overcome host defenses and at the same time exploit the presence of host factors to gain access and persist in the host. To succeed in this this process, bacterial pathogens undergo a series of adaption processes which include the expression of virulence factors that enable the establishment and their persistence in the host.  

For several bovine mastitis pathogens, microbial virulence strategies are based on the attachment and internalization into host cells. Such a strategy allows bacterial pathogens to reach an intracellular environment where most of the host mechanisms are not effective.  To achieve that, bacterial mastitis pathogens express factors that specifically bind to host factors (milk proteins, extracellular matrix proteins) present in milk that are taken and or produced by bovine mammary cells. Such a pathogenic mechanism allows a close contact between host cells and the invading bacterial pathogen that ends in the entry and persistence on the pathogen in the mammary gland. 

Still, the struggle of the invading pathogens for surviving doesn’t ends there. Research conducted in our laboratory showed that to enter into host target cells, mastitis bacterial pathogens direct their own uptake and entry into the cytoplasm of the host cell engulfed into endocytic vesicles. In many occasions these vesicles are linked to bactericidal mechanisms, as for example the fusion with the lysosome. Still, some mastitis pathogen strains through the biding of host protein present in milk, exploit intracellular trafficking pathways not linked with host cell’s microbicide mechanisms. Such a survival strategy permits the reaching a microenvironment totally frees of host defense mechanisms and where long lasting persistence is possible.  

My research interest have been focused on the identification of virulence factors of bovine mastitis pathogens used to adhere to, internalize and persist into mammary epithelial cells. The aim of my research is to better understand the pathogenesis of bovine mastitis pathogens, as well as the identification of temporally expressed bacterial factors during the early interaction with host cells, with the ultimate goal to use these bacterial factors to elaborate efficient vaccines to controls this extremely economically important  disease of dairy cows. 


Selected Publications 

  • Almeida, R. A., O. Kerro Dego, S. I. Headrick, M. J. Lewis, B. E. Gillespie, and S. P. Oliver.  2015.  Role of SUAM in the Pathogenesis of Streptococcus uberis mastitis.  Veterinary Microbiology, 2015, 179:332-5.

  • Almeida, R. A., O. Kerro Dego, M. E. Prado, S. I. Headrick, M. J. Lewis, L. J. Siebert, G. M. Pighetti, and S. P. Oliver.  2015.  Protective effect of anti-SUAM antibodies on Streptococcus uberis mastitis.  Journal of Veterinary Research, 46:133.

  • Almeida, R. A., O. Kerro Dego, S. I. Headrick, M. J. Lewis, and S. P. Oliver.  2015.  Role of Streptococcus uberis adhesion molecule in the pathogenesis of Streptococcus uberis mastitis.  Veterinary Microbiology, volume 179, Page 332 – 335.

  • Yuan, Y., O. Kerro Dego, X. Chen, E. Abadin, S. Chan, S. Kovacevic, R. A. Almeida, and S. P. Oliver.  2014.  Conservation of Streptococcus uberis Adhesion Molecule Gene in Streptococcus uberis Strains from Geographically Diverse Areas.  Journal of Dairy Science, 97: 7668-7673.

  • Gillespie, B. E., M. J. Lewis, S. Boonyayatra, L. Maxwell, A. M. Saxton, S. P. Oliver, and R. A. Almeida.  2012.  Evaluation of bulk tank milk microbiological quality of nine dairy farms in Tennessee.  Journal of Dairy Science, 95:4275-9.

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