Tokarz, Rafal

Rafal Tokarz, PhD
Associate Research Scientist
Center for Infection and Immunity
Mailman School of Public Health, Columbia University
New York, NY

Novel Approaches to Serologic Diagnosis of TBD

Dr. Tokarz’s research focuses on microbial discovery and the epidemiology of human infectious diseases. His primary interests center on investigating respiratory and tick-borne pathogens and understanding their roles in human disease.

Dr. Tokarz’s work in the field of tick-borne disease has been driven by two main hypotheses: 1) co-infections in human-biting ticks are common and can result in human poly-microbial infections; and 2) viral infections represent a proportion of undiagnosed tick-transmitted diseases. He designed and implemented one of the first multiplex PCR assays that targeted tick-borne agents and was one of the first scientists to document high rates of pathogen co-infections in ticks within New York State. His recent work has focused on exploring the diversity of the tick virome. He performed the first investigation of the virome of the three main human-biting ticks in New York State and thus far has discovered over 20 novel tick-associated viruses. He is now examining the potential for transmissibility and pathogenesis of these viruses.

In an effort to understand the etiology of respiratory diseases, Dr. Tokarz has participated in pathogen surveillance studies on specimens originating from Asia, Africa, Europe, South and North America. As part of this work, he used cutting edge molecular platforms to identify and characterize novel viral agents. Dr. Tokarz identified and characterized the first defined cluster of one such virus, enterovirus D68, an emerging agent implicated in a severe outbreak of pediatric respiratory disease in the US in 2014. He performed the first comprehensive phylogenetic characterization of this virus, identified the three main clades circulating worldwide and developed a classification system now employed by investigators in this field. In his current work, Dr. Tokarz is examining the pathogenesis of this virus and how its genetic variation influences the severity of disease.

Conference Lecture Summary

Tick-borne diseases are the most common vector-borne diseases in the United States, with serology being the primary method of diagnosis. We developed the first multiplex, array-based assay for serodiagnosis of tick-borne diseases called the TBD-Serochip. The TBD-Serochip was designed to discriminate antibody responses to 8 major tick-borne pathogens present in the United States, including Anaplasma phagocytophilum, Babesia microti, Borrelia burgdorferi, Borrelia miyamotoi, Ehrlichia chaffeensis, Rickettsia rickettsii, Heartland virus and Powassan virus. Each assay contains approximately 170,000 12-mer linear peptides that tile along the protein sequence of the major antigens from each agent with 11 amino acid overlap. This permits accurate identification of a wide range of specific immunodominant IgG and IgM epitopes that can then be used to enhance diagnostic accuracy and integrate differential diagnosis into a single assay. To test the performance of the TBD-Serochip, we examined sera from patients with confirmed Lyme disease, babesiosis, anaplasmosis, and Powassan virus disease. We identified a wide range of specific discriminatory epitopes that facilitated accurate diagnosis of each disease. We also identified previously undiagnosed infections. Our results indicate that the TBD-Serochip is a promising tool for a differential diagnosis not available with currently employed serologic assays for TBDs.