Alpha-Gal Syndrome: Molecular Characterization of Amblyomma americanum α-D-galactosidase in α-gal Metabolism and Onset of Red Meat Allergy
Date of Award
Honors College Thesis
Shahid Karim, Ph.D.
Tick-borne red meat allergy is an IgE-mediated delayed hypersensitivity reaction, increasingly widespread in tick endemic areas in the United States of America, and worldwide. Bites from the lone-star tick (Amblyomma americanum) are believed to be involved as the source of the sensitization of humans to the oligosaccharide galactose-⍺-1,3-galactose (α-gal), which is found in most mammal-derived food products, including gelatin, broths, and red meat. The purpose of this study is to functionally characterize the lone-star tick α-D-galactosidase (AGS) enzyme and assess its role in α-gal metabolism. This enzyme cleaves terminal α-galactose moieties from glycoproteins and glycolipids. Hence, I hypothesized that AGS is involved in the carbohydrate homeostasis in the tick vector of Alpha-Gal Syndrome. A reverse genetic approach was utilized to characterize the functional role of α-D-galactosidase in carbohydrate metabolism, and to discover its link to red meat allergy. My results from AGS gene silencing revealed a significant increase in tick weight, supporting a critical functional role in energy utilization. The silencing of AGS induced the decreased expression of downstream genes in the tick galactose metabolism pathway. Western blotting and N-glycan analysis revealed that AGS-silenced ticks ultimately expressed less ⍺-gal epitopes due to the reduction of available UDP-galactose. Western blotting and basophil-activation experiments revealed that AGS plays a role in the tick a-gal expression and host response to tick saliva. Additional immunological assays need to be conducted to further elucidate the role of α-D-galactosidase in tick-host interactions and the possible involvement in the emergent Red Meat Allergy.
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Mohamed, Ahmed A., "Alpha-Gal Syndrome: Molecular Characterization of Amblyomma americanum α-D-galactosidase in α-gal Metabolism and Onset of Red Meat Allergy" (2020). Honors Theses. 725.