LSU School of Veterinary Medicine professor receives research grant renewal for $1.6 million

Funding supports research of spotted fever components transmitted by ticks

BATON ROUGE, LA—Kevin Macaluso, PhD, Mary Louise Martin Professor in the Department of Pathobiological Sciences, recently renewed his research funding for his work investigating rickettsial pathogens, such as Rickettsia rickettsi, which is the causative agent of Rocky Mountain spotted fever, one of the most severe tick-borne diseases in the United States. The co-investigator on the grant renewal is Juan Martinez, PhD, LSU SVM Associate Professor. This $1,665,000 grant renewal period is 2015-2020.

The award supports costs associated with the research, along with three PhD students and two research associates. The original grant for this work produced 15 papers and one book chapter, and three students received their doctoral degrees.

The title for this project is “Molecular basis for spotted fever group Rickettsia vector competence in ticks,” and the objective is to define the role of tick and rickettsial molecules during the tick infection and transmission events.

“Our long-term goal is to define the molecular processes that are central to rickettsial transmission by ticks,” said Dr. Macaluso. “The bacterial-derived elements required for infection have been described using various in vitro models. Our research indicates that the rickettsial infection of ticks resembles similar paths described for the infection of vertebrate hosts, more commonly known as animals with a backbone, such as dogs and cats, as well as humans. Ultimately understanding the transmission biology will lead to novel points of intervention for tick-borne rickettsial diseases.”

Because the role of rickettsial proteins in tick infection is currently unknown, Dr. Macaluso and his team of researchers hypothesize that there will be a distinct profile associated with the infection. They believe that a central molecule, known as Relish, is responsible for the balance between successful rickettsial colonization and clearance from the arthropod host.

More Information about Rickettsia rickettsi

The natural history and ecology of spotted fever group (SFG) Rickettsia species and the epidemiology of each disease caused by these pathogens are linked inextricably with the distribution, biting preferences, and behaviors of the corresponding ixodid tick vectors. Rocky Mountain spotted fever (RMSF) caused by Rickettsia rickettsii, is the prototypical TBRD and is the most severe of all tick-borne rickettsioses.

Initially described during the late 19th century by investigators in the western United States, RMSF is now recognized throughout many other countries of North, Central, and South America, including Canada, Mexico, Panama, Costa Rica, Columbia, Brazil, and Argentina. Within one week following the bite of an infected tick, patients experience an abrupt onset of high fever that is often accompanied by headache, nausea, vomiting, anorexia, and generalized myalgia. A rash begins on the second to fourth day of fever, first appearing as small (1-5 mm), pink, blanching macules, typically on the wrists, ankles, and forearms, which then evolve to maculopapules. Severe manifestations include pulmonary edema and hemorrhage, cerebral edema, myocarditis, renal failure, disseminated intravascular coagulopathy, and gangrene.

Despite the current availability of effective treatment (i.e., tetracyclines) and advances in medical care, an estimated 2-6% of U.S. patients die from RMSF.

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