Varela-Stokes Lab Research

 Basic Sciences

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 As a parasitology lab with a primary research focus in tick-borne diseases, the majority of our time and resources is directed towards the study of rickettsiae. However, we have interests and collaborative projects ongoing in other areas of tick-associated conditions, vector-borne disease and general parasitology.

Research on Tick-Borne Rickettsiae

Our long-term goal is to better understand the biology and relationships between selected spotted fever rickettsiae in their tick vectorsin order to portray more accurately the complex epidemiology of spotted fever rickettsiosis. Our model uses the Gulf Coast tick, Amblyomma maculatum, and its associate rickettsiae- the emerging zoonotic pathogen, Rickettsia parkeri, and a poorly characterized rickettsia, “Candidatus Rickettsia andeanae”. The overall objective of our current research is to evaluate the potential contribution of R. parkeri and “Ca. R. andeanae” in A. maculatum to spotted fever rickettsioses in the U.S. by understanding interactions between rickettsiae in A. maculatum during tick feeding on vertebrate hosts.Our rationale is that understanding these interactions and their contributions to the maintenance and transmission of pathogenic rickettsiae in nature will help clarify the epidemiology of spotted fever rickettsiosis in humans.

We currently benefit from NIH (R15) funding that supports most of this rickettsial research. Dr. Jung Keun (Kevin) Lee is an Anatomic Pathologist at MSU-CVM who is studying rickettsial interactions in the A. maculatum-rickettsial systemas part of his doctoral dissertation. Dr. Gail Moraru, whose previous work included experimental and field studies on R. parkeri and immature A. maculatum in cotton rat and quail hosts returned as a post-doc to contribute her expertise to this project. Ms. Amanda Benton is an undergraduate majoring in Biochemistry who has worked on this project since Fall 2013. She was joined by Ms. Haley Parker (who is majoring in Microbiology) in Fall 2014, and Mr. Jacob Hughes (who is majoring in Biological Engineering) in Summer 2015. Outside of this extramurally funded research, our rickettsial research includes ongoing surveillance of adult A. maculatum for R. parkeri and “Ca. R. andeanae”.

In August 2014, we were granted funding for a COBRE (Center ) in Pathogen-Host Interactions Pilot Project. We are hoping to continue this research over the next year, which focuses on identifying rickettsiae and tick tissues. We recently began exploring the utility of proteomics to complete our objectives. Both our Lab Manager, Mr. John Stokes, and Post-doc, Dr. Moraru, are major contributors to that research.

Other Research

In addition to studying the Gulf Coast tick a vector of rickettsiae, we are currently studying the effects of this tick on different beef cattle breeds in Mississippi. Ms. Katie Graham is working on this project for her Master’s degree. Dr. Todd Sullivan, previously a Clinical Pathology Resident here, initiated this study on the effects of Gulf Coast ticks on Bos taurus and Bos indicus breeds in Mississippi prior to leaving the program to pursue private practice. The research has been funded by a USDA CRIS grant (MAFES-USDA “Formula” Hatch Act; CRIS Program).

In addition, we have had internally funded projects investigating Borrelia spp. in a human cell line using flow cytometry and Luminex-based assays, the avian hemosporidian parasite, Leucocytozoon, in Mississippi poultry, and most recently, a growing collaborative project investigating Toxoplasma gondii in a murine model for mental illness.

Current and past rickettsial research has benefited greatly from collaborations with several colleagues, including Dr. Jerome Goddard (Mississippi State University), Dr. Uli Munderloh (University of Minnesota), Dr. Chris Paddock (CDC), and Dr. Kevin Macaluso (Louisiana State University). Our primary collaborator on the Toxoplasma studies is Dr. Jeff Eells (a neuroscientist who is leading the studies on Toxoplasma in schizophrenia; MSU-CVM); Dr. David Lindsay (Virginia-Maryland Regional College of Veterinary Medicine) has also been an immense facilitator on the parasitology side. Other colleagues who have been a part of our research include clinicians, pathologists, immunologists and epidemiologists at MSU.