Published January, 2014

Rafaela De Negri

From: Brazil

Degrees: Doctor in Veterinary Medicine from Universidade Federal de Uberlandia, Uberlandia, Minas Gerais, Brazil.

Veterinary anatomic pathology residency at University of Kentucky Veterinary Diagnostic Laboratory, Lexington, Ky.

Masters in Veterinary Science at University of Kentucky, Gluck Equine Research Center, Lexington.

Rafaela De Negri said that when the opportunity arose to come to Kentucky, she couldn’t resist. The remarkable equine caseload at UK’s Veterinary Diagnostic Laboratory gave her the opportunity to study a collection of equine diseases she wouldn’t be able to see anywhere else in the world.

“During my pathology residency, I became more engaged in veterinary  sciences, and my interest in infectious diseases grew stronger,” she said. “This led me to pursue a master’s degree with Dr. John Timoney, a renowned scientist and professor in equine infectious diseases at the Gluck Center. “

Streptococcus infections are important to the global horse industry because they can cause large outbreaks and severe disease in horse populations. There are two key pathogenic bacterial species of Streptococcus in horses: Streptococcus equi and Streptococcus zooepidemicus. 

De Negri has investigated differences in equine serum antibody responses to these two bacterial infections. Streptococcus equi, the causative agent of strangles, is highly contagious, and horses can be carriers and shed the bacteria, although they themselves might show no outward clinical signs. The other bacterium, Streptococcus zooepidemicus, causes lower respiratory and reproductive tract infections that can lead to sporadic abortions in pregnant mares.

“I investigated and compared the antibody response of horses infected with S. zooepidemicus in their respiratory and reproductive tracts and investigated the antibody responses of donkeys and horses with S. zooepidemicus bronchopneumonia,” she said.

S. equi is a clonal descendent of an ancestral strain of S. zooepidemicus. Although they share more than 98% DNA and express many similar proteins and virulence factors, they display different pathogenic properties. Of note is infection by one organism does not cross-protect the horse against the other, De Negri said.

According to De Negri, very little is known about how these two pathogens can be so similar and yet have different host interaction and cause distinctly different infections. Therefore, her research aims to gain a better understanding of the pathogenic differences of the two organisms. This information can be used for the development of improved vaccines and diagnostic tools.

De Negri recently graduated and is currently looking for a position that taps into her interest in and knowledge of molecular mechanisms of pathogenesis and immunology of infectious disease, vaccine development,

and diagnostics.

Shaila Sigsgaard is an editorial assistant for the Bluegrass Equine Digest